WorldWideScience

Sample records for atmospheric co2 concentration

  1. Deep Sea Memory of High Atmospheric CO2 Concentration

    Science.gov (United States)

    Mathesius, Sabine; Hofmann, Matthias; Caldeira, Ken; Schellnhuber, Hans Joachim

    2015-04-01

    Carbon dioxide removal (CDR) from the atmosphere has been proposed as a powerful measure to mitigate global warming and ocean acidification. Planetary-scale interventions of that kind are often portrayed as "last-resort strategies", which need to weigh in if humankind keeps on enhancing the climate-system stock of CO2. Yet even if CDR could restore atmospheric CO2 to substantially lower concentrations, would it really qualify to undo the critical impacts of past emissions? In the study presented here, we employed an Earth System Model of Intermediate Complexity (EMIC) to investigate how CDR might erase the emissions legacy in the marine environment, focusing on pH, temperature and dissolved oxygen. Against a background of a world following the RCP8.5 emissions path ("business-as-usual") for centuries, we simulated the effects of two massive CDR interventions with CO2 extraction rates of 5 GtC yr-1 and 25 GtC yr-1, respectively, starting in 2250. We found that the 5 GtC yr-1 scheme would have only minor ameliorative influence on the oceans, even after several centuries of application. By way of contrast, the extreme 25 GtC yr-1 scheme eventually leads to tangible improvements. However, even with such an aggressive measure, past CO2 emissions leave a substantial legacy in the marine environment within the simulated period (i.e., until 2700). In summary, our study demonstrates that anthropogenic alterations of the oceans, caused by continued business-as-usual emissions, may not be reversed on a multi-centennial time scale by the most aspirational geoengineering measures. We also found that a transition from the RCP8.5 state to the state of a strong mitigation scenario (RCP2.6) is not possible, even under the assumption of extreme extraction rates (25 GtC yr-1). This is explicitly demonstrated by simulating additional scenarios, starting CDR already in 2150 and operating until the atmospheric CO2 concentration reaches 280 ppm and 180 ppm, respectively. The simulated

  2. Uncertainties of predictions of future atmosphere CO2 concentrations

    International Nuclear Information System (INIS)

    Linear carbon cycle models, tuned to reproduce the CO2 increase observed at Mauna Loa, independently of their individual assumptions, predict almost identical CO2 concentration trends for fossil energy scenarios assuming a slightly increasing production in the next few decades. The basic information for such prognoses therefore is the airborne fraction observed over the last 20 years. Uncertainties in this quantity are due to possible errors in the estimate of fossil fuel consumption and the corresponding CO2 emission, possible natural fluctuations in the baseline CO2 level, and uncertainties regarding the biospheric CO2 input and uptake as a result of deforestation and reforestation and land management. Depending on different assumptions the effective airborne fraction, defined as the ratio of CO2 increase due to fossil fuel CO2 alone to the integrated CO2 production, might be as low as 0.38 or as high as 0.72, compared to the apparent airborne fraction of 0.55. The effective airborne fraction derived from carbon cycle models, considering only the CO2 uptake by the ocean, lies in the range 0.60--0.70. A value as low as 0.40 seems therefore highly improbable. A high biospheric anthropogenic CO2 input therefore must have been accompanied by a high CO2 fertilization effect. Model considerations, however, are not in contradiction with a high biospheric input with the maximum production before 1958, which also would imply low preindustrial CO2 concentrations in the range 270--280 ppm as reported recently

  3. CO2 background concentra-tion in the atmosphere over the Chinese mainland

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Based on the long-term monitoring data on CO2 concentration, variation trend and characteristics of CO2 background concentration in the atmosphere over the Chinese mainland are analyzed. Results show that the increasing trend of CO2 background concentration in the atmosphere over the Chinese mainland has appeared during the period of 1991-2000. The average annual CO2 growth increment is 1.59 μL/L, and the average annual CO2 growth rate is 0.44%. Distinct seasonal variations of CO2 background concentration are observed, and the averaged amplitude of CO2 seasonal variations is 10.35 μL/L. Regional variation characteristics of CO2 background concentration in the atmosphere and possible impact of human activities on these variations over the Chinese mainland are discussed as well.

  4. Constraining terrestrial ecosystem CO2 fluxes by integrating models of biogeochemistry and atmospheric transport and data of surface carbon fluxes and atmospheric CO2 concentrations

    OpenAIRE

    Zhu, Q.; Zhuang, Q.; D. Henze; Bowman, K.; M. Chen; Liu, Y.; He, Y.; Matsueda, H.; Machida, T.; Sawa, Y.; W. Oechel

    2014-01-01

    Regional net carbon fluxes of terrestrial ecosystems could be estimated with either biogeochemistry models by assimilating surface carbon flux measurements or atmospheric CO2 inversions by assimilating observations of atmospheric CO2 concentrations. Here we combine the ecosystem biogeochemistry modeling and atmospheric CO2 inverse modeling to investigate the magnitude and spatial distribution of the terrestrial ecosystem CO2 sources and sinks. First, we constrain a terrestri...

  5. The optimal atmospheric CO2 concentration for the growth of winter wheat (Triticum aestivum).

    Science.gov (United States)

    Xu, Ming

    2015-07-20

    This study examined the optimal atmospheric CO2 concentration of the CO2 fertilization effect on the growth of winter wheat with growth chambers where the CO2 concentration was controlled at 400, 600, 800, 1000, and 1200 ppm respectively. I found that initial increase in atmospheric CO2 concentration dramatically enhanced winter wheat growth through the CO2 fertilization effect. However, this CO2 fertilization effect was substantially compromised with further increase in CO2 concentration, demonstrating an optimal CO2 concentration of 889.6, 909.4, and 894.2 ppm for aboveground, belowground, and total biomass, respectively, and 967.8 ppm for leaf photosynthesis. Also, high CO2 concentrations exceeding the optima not only reduced leaf stomatal density, length and conductance, but also changed the spatial distribution pattern of stomata on leaves. In addition, high CO2 concentration also decreased the maximum carboxylation rate (Vc(max)) and the maximum electron transport rate (J(max)) of leaf photosynthesis. However, the high CO2 concentration had little effect on leaf length and plant height. The optimal CO2 fertilization effect found in this study can be used as an indicator in selecting and breeding new wheat strains in adapting to future high atmospheric CO2 concentrations and climate change. PMID:26253981

  6. Algae Technology for Reduction of Atmospheric CO2 Concentrations

    International Nuclear Information System (INIS)

    After a short overview about the climate situation with regard to CO2, the physiology of photosynthesis will be explained in nonprofessional's style using algae as an example. The photosynthesis products and their conversions into valuable materials for human nutrition or into base substances for diverse industries will be described. Furthermore, I will introduce the state of the art on current scientific projects aiming to improve algae productivity and for the synthesis of therapeutically medicinal proteins. A highly productive algae facility will be introduced including its integration in an energy concept.(author)

  7. Effect of elevated atmospheric CO2 concentration on soil CO2 and N2O effluxes in a loess grassland

    Science.gov (United States)

    Cserhalmi, Dóra; Balogh, János; Papp, Marianna; Horváth, László; Pintér, Krisztina; Nagy, Zoltán

    2014-05-01

    Increasing atmospheric CO2 concentration proved to be the primary factor causing global climate change. Exposition systems to study the response to increasing CO2 levels by the terrestrial vegetation include the open top chamber (OTC) exposition system, also used in this study. Response of biomass growth and ecophysiological variables (e.g. emission of greenhouse gases (CO2, N2O) from the soil) to elevated atmospheric CO2 concentration were investigated in the OTC station, located in the Botanical Garden of the Szent István University, Gödöllő , Hungary. Loess grassland (Salvio nemorosae - Festucetum rupicolae) monoliths were studied in OTCs with target air CO2 concentration of 600 mikromol.mol-1 in 3 chambers. The chamber-effect (shade effect of the side of the chambers) was measured in 3 control chambers under present CO2 level. This management was compared to 3 free air parcels under the natural conditions. Changes of soil temperature and soil water content were recorded in each treatment, while PAR, air temperature, precipitation, wind velocity and humidity were measured by a micrometeorological station. Plant biomass was cut down to 5 cm height once a year. Leaf area index (LAI) was estimated weekly from ceptometer measurements, soil CO2 and N2O effluxes were also measured weekly during the growing period and less frequently during the rest of the year. Soil water content in the upper 30 cm of the soil was lower in the chambers by 3 % (v/v) in average than in the field plots. Soil temperature in the chambers at 3 cm depth was 1.5oC lower than in the free air parcels probably due to the shading effect of the larger biomass in the chambers. In the chambers (both the high CO2 and control ones) biomass values (536.59 ±222.43 gm-2) were higher than in the free parcels (315.67 ±73.36 gm-2). Average LAI was also higher (3.07 ± 2.78) in the chambers than in the free air treatment (2.08 ± 1.95). Soil respiration values in the high CO2 treatment was higher in

  8. NEW CONSTRAINT ON ESTIMATION OF THE ANTHROPOGENIC CO_2 BUDGET : RELATIONSHIP BETWEEN CONCENTRATION AND δ^<13>C OF ATMOSPHERIC CO_2 DETERMINED FROM ICE CORE ANALYSIS

    OpenAIRE

    カトウ, キクオ; コマキ, カオリ; Kikuo, Kato; Kaori, KOMAKI

    1997-01-01

    Studies on ice cores from Antarctica and Greenland revealed variations in the concentration and δ^C of ancient atmospheric CO_2. Since the Industrial Revolution, addition of anthropogenic CO_2 to the atmosphere has caused a significant increase in atmospheric CO_2,accompanied by a decrease in δ^C of atmospheric CO_2. The relationship between them shows that the δ^C value of CO_2 which remained in the atmosphere is significantly larger than -25‰ of that originated from coal burning and defores...

  9. Measurement of Concentration of CO2 in Atmosphere In Situ Based on TDLAS

    Science.gov (United States)

    Xin, Fengxin; Guo, Jinjia; Chen, Zhen; Liu, Zhishen

    2014-11-01

    As one of the main greenhouse gases in the atmosphere, CO2has a significant impact on global climate change and the ecological environment. Because of close relationship between human activities and the CO2 emissions, it is very meaningful of detecting atmospheric CO2accurately. Based on the technology of tunable diode laser absorption spectroscopy, the wavelength of distributed feedback laser is modulated, Fresnel lens is used as the receiving optical system, which receives the laser-beam reflected by corner reflector, and focuses the receiving laser-beam to the photoelectric detector. The second harmonic signal is received through lock-in amplifier and collected by AD data acquisition card, after that the system is built up.By choosing the infrared absorption line of CO2at 1.57μm, the system is calibrated by 100% CO2 gas cell. The atmospheric CO2 in situ is measured with long open-path way. Furthermore, the results show that CO2 concentration decreases along time in the morning of day. It is proved that TDLAS technology has many advantages, including fast response, high sensitivity and resolution. This research provides a technique for monitoring secular change of CO2 in atmosphere.

  10. The characteristics of atmospheric CO2 concentration variation of four national background stations in China

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Atmospheric carbon dioxide is an important kind of greenhouse gas which influences global temperature. Its concentration variation could indicate the distribution of human and natural activities in various regions. Through the non-dispersive infrared method, flask sampling of atmospheric CO2 concen- tration was measured weekly at four national background stations including Waliguan, Shangdianzi, Lin’an, and Longfengshan. Based on the data collected from September 2006 to August 2007, along with the Waliguan station’s experience on in situ observational data processing, the selection methods for sampling data through the atmospheric background CO2 concentration analysis were preliminarily discussed. On the basis of this result, the variation features of the four typical regions’ atmospheric background CO2 concentration was analyzed for the first time. The results show that the atmospheric CO2 concentration at Waliguan, Shangdianzi, Lin’an, and Longfengshan is 383.5, 385.9, 387.8, and 384.3 ppm, respectively. During the research period, CO2 concentration at the Waliguan station changed slightly. However, the CO2 concentration changed sharply at the Shangdianzi and the Lin’an stations due to the great influence of human activities in the Jingjinji and the Changjiang Delta economic zones, and changed regularly with seasons at Longfengshan station under dual influences of human activities and plant photosynthesis. The results from this study can lay the foundation for more profound studies on atmospheric CO2 concentration level of different areas in China, and could be used to improve the understanding of carbon source and sink distribution.

  11. An approach for verifying biogenic greenhouse gas emissions inventories with atmospheric CO2 concentration data

    International Nuclear Information System (INIS)

    Verifying national greenhouse gas (GHG) emissions inventories is a critical step to ensure that reported emissions data to the United Nations Framework Convention on Climate Change (UNFCCC) are accurate and representative of a country’s contribution to GHG concentrations in the atmosphere. Furthermore, verifying biogenic fluxes provides a check on estimated emissions associated with managing lands for carbon sequestration and other activities, which often have large uncertainties. We report here on the challenges and results associated with a case study using atmospheric measurements of CO2 concentrations and inverse modeling to verify nationally-reported biogenic CO2 emissions. The biogenic CO2 emissions inventory was compiled for the Mid-Continent region of United States based on methods and data used by the US government for reporting to the UNFCCC, along with additional sources and sinks to produce a full carbon balance. The biogenic emissions inventory produced an estimated flux of −408 ± 136 Tg CO2 for the entire study region, which was not statistically different from the biogenic flux of −478 ± 146 Tg CO2 that was estimated using the atmospheric CO2 concentration data. At sub-regional scales, the spatial density of atmospheric observations did not appear sufficient to verify emissions in general. However, a difference between the inventory and inversion results was found in one isolated area of West-central Wisconsin. This part of the region is dominated by forestlands, suggesting that further investigation may be warranted into the forest C stock or harvested wood product data from this portion of the study area. The results suggest that observations of atmospheric CO2 concentration data and inverse modeling could be used to verify biogenic emissions, and provide more confidence in biogenic GHG emissions reporting to the UNFCCC. (letter)

  12. The space and time impacts on U.S. regional atmospheric CO2 concentrations from a high resolution fossil fuel CO2 emissions inventory

    OpenAIRE

    Katherine D. Corbin; Denning, A Scott; Gurney, Kevin R

    2011-01-01

    To improve fossil fuel CO2 emissions estimates, high spatial and temporal resolution inventories are replacing coarse resolution, annual-mean estimates distributed by population density. Because altering the emissions changes a key boundary condition to inverse-estimated CO2 fluxes, it is essential to analyse the atmospheric impacts of redistributing anthropogenic emissions. Using a coupled ecosystem–atmosphere model, we compare 2004 atmospheric CO2 concentrations resulting from coarse and hi...

  13. Relationship between carbon-14 concentrations in atmospheric CO2 and environmental samples

    International Nuclear Information System (INIS)

    Concentration of organically-bound 14C in the tree-ring cellulose of a pine tree grown in Shika-machi (37.1degN, 136.5degE), Ishikawa prefecture, Japan, was measured for the ring-years from 1949 to 1999 and compared with those in several trees from East Asia region reported by other researchers. Temporal variation of organically-bound 14C concentration in the tree-ring cellulose in Shika-machi showed essentially similar variations to those of other reports. However, small difference of Δ14C values was found during the period of 1970-1981 between our data and those of other reports, in addition to the difference during the period of 1963-1967 caused by the so-called latitude dependence of the 14C variations in the northern troposhere. These results suggest that the 14C concentration in atmospheric CO2 was considerably disturbed during the period of 1970-1981, especially in 1970, 1976, and 1978-1981, in the East Asia region. This phenomenon may be interpreted by the possibility of the several times of injections of 14C originated from a series of Chinese thermonuclear bomb tests. Temporal variation of 14C concentration in atmospheric CO2 in Kanazawa city, Ishikawa prefecture, Japan (36.3degN, 136.4degE), was also measured during the period of 1991-1999. An interesting result in comparing 14C concentrations in the tree-ring cellulose with those of atmospheric CO2 is that each of 14C concentrations in a series of tree rings reflected summer means of 14C concentrations in atmospheric CO2. It suggests that the carbon necessary for synthesizing tree-ring cellulose was mainly supplied from atmospheric CO2 in summer season. It is noteworthy that surface soils collected from different sites were found to demonstrate extremely low 14C concentrations than atmospheric CO2. It may be ascribed to the slow exchange rate of carbon between soils and atmospheric CO2. (author)

  14. The effect of atmospheric CO2 concentration on carbon isotope fractionation in C3 land plants

    Science.gov (United States)

    Schubert, Brian A.; Jahren, A. Hope

    2012-11-01

    Because atmospheric carbon dioxide is the ultimate source of all land-plant carbon, workers have suggested that pCO2 level may exert control over the amount of 13C incorporated into plant tissues. However, experiments growing plants under elevated pCO2 in both chamber and field settings, as well as meta-analyses of ecological and agricultural data, have yielded a wide range of estimates for the effect of pCO2 on the net isotopic discrimination (Δδ13Cp) between plant tissue (δ13Cp) and atmospheric CO2 (δ13CCO2). Because plant stomata respond sensitively to plant water status and simultaneously alter the concentration of pCO2 inside the plant (ci) relative to outside the plant (ca), any experiment that lacks environmental control over water availability across treatments could result in additional isotopic variation sufficient to mask or cancel the direct influence of pCO2 on Δδ13Cp. We present new data from plant growth chambers featuring enhanced dynamic stabilization of moisture availability and relative humidity, in addition to providing constant light, nutrient, δ13CCO2, and pCO2 level for up to four weeks of plant growth. Within these chambers, we grew a total of 191 C3 plants (128 Raphanus sativus plants and 63 Arabidopsis thaliana) across fifteen levels of pCO2 ranging from 370 to 4200 ppm. Three types of plant tissue were harvested and analyzed for carbon isotope value: above-ground tissues, below-ground tissues, and leaf-extracted nC31-alkanes. We observed strong hyperbolic correlations (R ⩾ 0.94) between the pCO2 level and Δδ13Cp for each type of plant tissue analyzed; furthermore the linear relationships previously suggested by experiments across small (10-350 ppm) changes in pCO2 (e.g., 300-310 ppm or 350-700 ppm) closely agree with the amount of fractionation per ppm increase in pCO2 calculated from our hyperbolic relationship. In this way, our work is consistent with, and provides a unifying relationship for, previous work on carbon isotopes

  15. Response of biomass and nitrogen yield of white clover to radiation and atmospheric CO2 concentration

    International Nuclear Information System (INIS)

    The objectives of the present study were to test (i) whether the effect of season-long CO2 enrichment on plant dry matter production of white clover (Trifolium repens cv. Karina) depends on the temperature or can solely be explained by changes in radiation use efficiency, and (ii) whether the atmospheric CO2 concentration affects the relationship between tissue %N and plant biomass. Plants were grown in pots with adequate nutrient and water supply and were exposed to ambient and above ambient CO2 concentrations (approximately +80 ppm, +160 ppm, +280 ppm) in open-top chambers for two seasons. Nitrogen fertilizer was given only before the experiment started to promote N2 fixation. Plants were clipped to a height of 5 cm, when the canopy had reached a height of about 20 cm and when the CO2 effect had not been diminished due to self-shading of the leaves. Photon exposure (400–700 nm) measured above the canopy was linearly related to the above ground biomass, the leaf area index and the nitrogen yield (r2 > 0.94). The slopes of the curves depended on the CO2 concentration. Since most of the radiation (>90%) was absorbed by the foliage, the slopes were used to calculate the CO2 effect on the radiation use efficiency of biomass production, which is shown to increase curvilinearly between 380 and 660 ppm CO2 from 2.7 g MJ−1 to 3.9 g MJ−1. CO2 enrichment increased above ground biomass by increasing the leaf number, the individual leaf weight and the leaf area; specific leaf weight was not affected. The relative CO2 response varied between harvests; there was a slight but not significant positive relationship with mean daytime temperature. At the beginning of the season, plant nitrogen concentration in the above ground biomass was decreased by CO2 enrichment. However, at later growth stages, when the plants depended solely on N2 fixation, nitrogen concentration was found to be increased when the nitrogen concentration value was adjusted for the decrease due to the

  16. Concentration variations of atmospheric CO2 observed at Syowa Station, Antarctica from 1984 to 2000

    International Nuclear Information System (INIS)

    Systematic and continuous measurements of the atmospheric CO2 concentration have been carried out at Syowa Station, Antarctica since February 1984. The measurement system was renewed in 1995, but the continuity of the data from the two systems was confirmed by operating them simultaneously. The CO2 data taken for 17 years from 1984 to 2000 showed clear evidence for a seasonal cycle, a secular trend and interannual variations. The seasonal cycle was variable from year to year, with especially larger amplitudes in 1992 and 1998 and a large phase delay in 1993. A rapid increase in the CO2 concentration was observed in 1987, 1994 and 1998 in association with ENSO events. The average rate of the secular CO2 increase for the last 17 years was calculated to be 1.49 ppmv/yr. Short-term CO2 variations with amplitudes of around 1.0 ppmv were found in the austral summer season of several years after 1990, probably due to an intrusion of CO2-depleted air mass into the Antarctic region

  17. Rapid response of tree cellulose radiocarbon content to changes in atmospheric 14CO2 concentration

    International Nuclear Information System (INIS)

    A detailed radial profile for the 14C concentration in tree cellulose, covering growth rings for the years 1962-1964, was obtained for a Sitka spruce of the US Pacific Coast using accelerator mass spectrometry. The tree cellulose 14C closely follows atmospheric 14CO2 concentrations, responding to changes with a delay of not more than a few weeks. The delay in response is mostly due to the addition of between 13 and 28% of biospheric CO2 to the canopy-air CO2 used by the tree for stem cellulose. Delayed incorporation and the use of stored photosynthate of the previous fall appear less important. 63 refs., 4 figs., 3 tabs

  18. Spatial variations in atmospheric CO2 concentrations during the ARCTAS-CARB 2008 Summer Campaign

    Science.gov (United States)

    Vadrevu, K. P.; Choi, Y.; Vay, S. A.

    2009-12-01

    The Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) was a major NASA field campaign designed to understand the transport and transformation of trace gases and aerosols on transcontinental and intercontinental scales and their impact on the composition of the arctic atmosphere and climate. Preceding the summer ARCTAS deployment, measurements were conducted over the state of California in collaboration with the California Air Resources Board (CARB) utilizing the airborne chemistry payload already integrated on the NASA DC-8. In situ CO2 measurements were made using a modified infrared CO2 gas analyzer having a precision of 0.1 ppmv and accuracy of ±0.25 ppmv traceable to the WMO scale. This analysis focuses on the atmospheric CO2 variability and biospheric/atmospheric exchange over California. We used multi-satellite remote sensing datasets to relate airborne observations of CO2 to infer sources and sinks. Georeferencing the airborne CO2 transect data with the LANDSAT derived land cover datasets over California suggested significant spatial variations. The airborne CO2 concentrations were found to be 375-380ppm over the Pacific ocean, 385-391ppm in the highly vegetated agricultural areas, 400-420 in the near coastal areas and greater than 425ppmv in the urban areas. Analysis from MODIS fire products suggested significant fires in northern California. CO2 emissions exceeded 425ppmv in the fire affected regions, where mostly Douglas and White Fir conifers and mixed Chaparral vegetation was burnt. Analysis from GOES-East and GOES-West visible satellite imagery suggested significant smoke plumes moving from northern California towards Nevada and Idaho. To infer the biospheric uptake of CO2, we tested the potential correlations between airborne CO2 data and MODIS normalized difference vegetation index (NDVI) and enhanced vegetation index (EVI). Results suggested significant anti-correlations between the airborne CO2 data and

  19. A terrestrial biosphere model optimized to atmospheric CO2 concentration and above ground woody biomass

    Science.gov (United States)

    Saito, M.; Ito, A.; Maksyutov, S. S.

    2013-12-01

    This study documents an optimization of a prognostic biosphere model (VISIT; Vegetation Integrative Similator for Trace gases) to observations of atmospheric CO2 concentration and above ground woody biomass by using a Bayesian inversion method combined with an atmospheric tracer transport model (NIES-TM; National Institute for Environmental Studies / Frontier Research Center for Global Change (NIES/FRCGC) off-line global atmospheric tracer transport model). The assimilated observations include 74 station records of surface atmospheric CO2 concentration and aggregated grid data sets of above ground woody biomass (AGB) and net primary productivity (NPP) over the globe. Both the biosphere model and the atmospheric transport model are used at a horizontal resolution of 2.5 deg x 2.5 deg grid with temporal resolutions of a day and an hour, respectively. The atmospheric transport model simulates atmospheric CO2 concentration with nine vertical levels using daily net ecosystem CO2 exchange rate (NEE) from the biosphere model, oceanic CO2 flux, and fossil fuel emission inventory. The models are driven by meteorological data from JRA-25 (Japanese 25-year ReAnalysis) and JCDAS (JMA Climate Data Assimilation System). Statistically optimum physiological parameters in the biosphere model are found by iterative minimization of the corresponding Bayesian cost function. We select thirteen physiological parameter with high sensitivity to NEE, NPP, and AGB for the minimization. Given the optimized physiological parameters, the model shows error reductions in seasonal variation of the CO2 concentrations especially in the northern hemisphere due to abundant observation stations, while errors remain at a few stations that are located in coastal coastal area and stations in the southern hemisphere. The model also produces moderate estimates of the mean magnitudes and probability distributions in AGB and NPP for each biome. However, the model fails in the simulation of the terrestrial

  20. Analysis of influence of atmosphere extinction to Raman lidar monitoring CO2 concentration profile

    Institute of Scientific and Technical Information of China (English)

    Zhao Pei-Tao; Zhang Yin-Chao; Wang Lian; Zhao Yue-Feng; Su Jia; Fang Xin; Cao Kai-Fa; Xie Jun; Du Xiao-Yong

    2007-01-01

    Lidar (Light detection and ranging) system monitoring of the atmosphere is a novel and powerful technique tool. The Raman lidar is well established today as a leading research tool in the study of numerous important areas in the atmospheric sciences. In this paper, the principle of Raman lidar technique measurement CO2 concentration profile is presented and the errors caused by molecular and aerosol extinction for CO2 concentration profile measurement with Raman lidar are also presented. The standard atmosphere extinction profile and 'real-time' Hefei area extinction profile are used to conduct correction and the corresponding results are yielded. Simulation results with standard atmosphere mode correction indicate that the errors caused by molecule and aerosol extinction should be counted for the reason that they could reach about 8 ppm and 5 ppm respectively. The relative error caused by Hefei area extinction correction could reach about 6%. The errors caused by the two components extinction influence could produce significant changes for CO2 concentration profile and need to be counted in data processing which could improve the measurement accuracies.

  1. Response of thermohaline circulation to higher atmospheric CO2 concentration and absence of ice sheets

    Science.gov (United States)

    Motoi, T.; Chan, W.-L.; Yih, H.

    2003-04-01

    Response of thermohaline circulation to higher CO2 concentration in the atmosphere and absence of large ice sheets are investigated by using a coupled ocean-atmosphere model. Two runs, named C run and x4CNIS run are carried out. The C run is control run with standard atmospheric CO2 concentration of 300 ppm and Greenland and Antarctic ice sheets. The x4CNIS run has atmospheric CO2 concentration of 1200 ppm, which is 4 times that of the standard value, and no ice sheet. Both the C run and x4CNIS run are integrated for more than 10000 years until equilibrium response is completed. The intensity of thermohaline circulation in the North Atlantic Ocean in x4CNIS run decreases to 3 Sv from 17 Sv during the first two hundred years and turns to gradually increasing phase from 3 Sv to 8 Sv for about 2000 years. It then increases rapidly from 8 Sv to 30 Sv within 200 years and reaches stable level of 24 Sv, which is larger than that of 17 Sv at begining, with larger oscillations. The temperatures of surface and deep waters in the sub-antarctic region and of deep tropical water are about 6.5 deg. warmer in the x4CNIS run than in the C run.

  2. Effects of long-term elevated atmospheric CO2 concentrations on Pinus ponderosa

    International Nuclear Information System (INIS)

    This report details the results from an experiment of the effects of long-term elevated atmospheric CO2 concentrations on ponderosa pine (Pinus ponderosa Laws.) saplings and seedlings. The study began in 1983 as a pilot study designed to explore the feasibility of using open-top chambers for continuous multi-year exposures on sapling-sized trees and to examine possible CO2 responses so that future research could be adequately designed. however, following the first year of exposure, preliminary results from the study indicated that measurements of CO2 responses should be intensified. Open-top chambers proved suitable for use in multiyear exposures of mature trees. With respect to the preliminary examination of CO2 responses, many interesting observations were made. The nature of the preliminary results suggests that future long-term field CO2 exposures on perennial species may be critical to the understanding and preparation for future environments. Other research reported here attempted to adapt an existing western coniferous forest growth and succession model for use in elevated CO2 scenarios using differential species responses, and assessed the usefulness of the model in that regard. Seven papers have been processed separately for inclusion in the appropriate data bases

  3. Temporal variations of atmospheric CO2 concentration in a temperate deciduous forest in central Japan

    International Nuclear Information System (INIS)

    In order to examine the temporal variation of the atmospheric CO2 concentration in a temperate deciduous forest, and its relationship with meteorological conditions, continuous measurements of CO2 and meteorological parameters have been made since 1993 on a tower at Takayama in the central part of Japan. In addition to an average secular increase in atmospheric CO2 of 1.8 ppm/yr, diurnal variation with a maximum during the night-time to early morning and a minimum in the afternoon is observed from late spring to early fall; the diurnal cycle is not so clearly observed in the remaining seasons of the year. A concentration difference between above and below the canopy, and its diurnal variation, can also be seen clearly in summer. Daily mean concentration data show a prominent seasonal cycle. The maximum and the minimum of the seasonal cycle occur in April and from mid August to mid September, respectively. Day-to-day changes in the diurnal cycle of CO2 are highly dependent on the day-to-day variations in meteorological conditions. However, CO2 variations on longer time scales (>10 d) appear to be linearly related to changes in respiration. At Takayama, variations in the 10-d standard deviation of daily mean CO2 data and 10-d averaged respiration show distinct relationships with soil temperature during spring and fall seasons. In spring, respiration has a stronger exponential dependence on soil temperature than in fall. Interestingly, in summer when soil temperature becomes greater than about 15 deg C, biological respiration becomes more variable and independent of the soil temperature. Thus, at the Takayama site, the Q10 relationship is seasonally dependent, and does not represent well the biological respiration process when the soil temperature rises above 15 deg C

  4. 222Rn and 14CO2 concentrations in the surface layer of the atmosphere

    International Nuclear Information System (INIS)

    Long-term monitoring of the Δ14C in the atmospheric near-ground CO2 has been realized in Bratislava and Zlkovce, situated near the nuclear power plant Jaslovske Bohunice. Until 1993, the monthly mean Δ14C values showed a high variability. The annual means of Δ14C were about 30 per mille higher at Zlkovce than in highly industrialised Bratislava. An important change in the behaviour of the 14C data has occurred since 1993. The records from both stations show the similar course, mainly due to the fact that there do not occur deep winter minima in Bratislava. This behaviour corresponds to the lower values of the total fossil fuel CO2 emissions in the years after 1993 when compared to the previous years. At present, both sets of data show that the 14C concentration is about 10% above the natural level. Since 1987 also the 222 Rn concentration in the surface layer of the atmosphere has been measured in Bratislava. These measurements provided an extensive set of the 222 Rn data characteristic for the inland environment with high level of atmospheric pollution. The seasonal and daily variations of the 222 Rn concentration were observed. The investigation of the relation between the monthly mean diurnal courses of the 222 Rn concentration and the atmospheric stability proved a high correlation between them. The 222 Rn data were used to interpret the anomalous Δ14C values in the surface layer of the atmosphere. (author)

  5. Responses to iron limitation in Hordeum vulgare L. as affected by the atmospheric CO2 concentration.

    Science.gov (United States)

    Haase, S; Rothe, A; Kania, A; Wasaki, J; Römheld, V; Engels, C; Kandeler, E; Neumann, G

    2008-01-01

    Elevated atmospheric CO2 treatments stimulated biomass production in Fe-sufficient and Fe-deficient barley plants, both in hydroponics and in soil culture. Root/shoot biomass ratio was increased in severely Fe-deficient plants grown in hydroponics but not under moderate Fe limitation in soil culture. Significantly increased biomass production in high CO2 treatments, even under severe Fe deficiency in hydroponic culture, indicates an improved internal Fe utilization. Iron deficiency-induced secretion of PS in 0.5 to 2.5 cm sub-apical root zones was increased by 74% in response to elevated CO2 treatments of barley plants in hydroponics but no PS were detectable in root exudates collected from soil-grown plants. This may be attributed to suppression of PS release by internal Fe concentrations above the critical level for Fe deficiency, determined at final harvest for soil-grown barley plants, even without additional Fe supply. However, extremely low concentrations of easily plant-available Fe in the investigated soil and low Fe seed reserves suggest a contribution of PS-mediated Fe mobilization from sparingly soluble Fe sources to Fe acquisition of the soil-grown barley plants during the preceding culture period. Higher Fe contents in shoots (+52%) of plants grown in soil culture without Fe supply under elevated atmospheric CO2 concentrations may indicate an increased efficiency for Fe acquisition. No significant influence on diversity and function of rhizosphere-bacterial communities was detectable in the outer rhizosphere soil (0-3 mm distance from the root surface) by DGGE of 16S rRNA gene fragments and analysis of marker enzyme activities for C-, N-, and P-cycles. PMID:18453445

  6. Changing atmospheric CO2 concentration was the primary driver of early Cenozoic climate.

    Science.gov (United States)

    Anagnostou, Eleni; John, Eleanor H; Edgar, Kirsty M; Foster, Gavin L; Ridgwell, Andy; Inglis, Gordon N; Pancost, Richard D; Lunt, Daniel J; Pearson, Paul N

    2016-05-19

    The Early Eocene Climate Optimum (EECO, which occurred about 51 to 53 million years ago), was the warmest interval of the past 65 million years, with mean annual surface air temperature over ten degrees Celsius warmer than during the pre-industrial period. Subsequent global cooling in the middle and late Eocene epoch, especially at high latitudes, eventually led to continental ice sheet development in Antarctica in the early Oligocene epoch (about 33.6 million years ago). However, existing estimates place atmospheric carbon dioxide (CO2) levels during the Eocene at 500-3,000 parts per million, and in the absence of tighter constraints carbon-climate interactions over this interval remain uncertain. Here we use recent analytical and methodological developments to generate a new high-fidelity record of CO2 concentrations using the boron isotope (δ(11)B) composition of well preserved planktonic foraminifera from the Tanzania Drilling Project, revising previous estimates. Although species-level uncertainties make absolute values difficult to constrain, CO2 concentrations during the EECO were around 1,400 parts per million. The relative decline in CO2 concentration through the Eocene is more robustly constrained at about fifty per cent, with a further decline into the Oligocene. Provided the latitudinal dependency of sea surface temperature change for a given climate forcing in the Eocene was similar to that of the late Quaternary period, this CO2 decline was sufficient to drive the well documented high- and low-latitude cooling that occurred through the Eocene. Once the change in global temperature between the pre-industrial period and the Eocene caused by the action of all known slow feedbacks (apart from those associated with the carbon cycle) is removed, both the EECO and the late Eocene exhibit an equilibrium climate sensitivity relative to the pre-industrial period of 2.1 to 4.6 degrees Celsius per CO2 doubling (66 per cent confidence), which is similar to the

  7. Can seasonal and interannual variation in landscape CO2 fluxes be detected by atmospheric observations of CO2 concentrations made at a tall tower?

    OpenAIRE

    Smallman, Luke; Williams, Mathew; Moncrieff, John

    2014-01-01

    The coupled numerical weather model WRF-SPA (Weather Research and Forecasting model and Soil-Plant-Atmosphere model) has been used to investigate a 3 yr time series of observed atmospheric CO2 concentrations from a tall tower in Scotland, UK. Ecosystem-specific tracers of net CO2 uptake and net CO2 release were used to investigate the contributions to the tower signal of key land covers within its footprint, and how contributions varied at seasonal and interannual timescales. In addition, WRF...

  8. Can seasonal and interannual variation in landscape CO2 fluxes be detected by atmospheric observations of CO2 concentrations made at a tall tower?

    Directory of Open Access Journals (Sweden)

    T. L. Smallman

    2013-08-01

    Full Text Available The Weather Research and Forecasting (WRF meteorological model has been coupled to the Soil Plant Atmosphere (SPA terrestrial ecosystem model, hereafter known as WRF-SPA. SPA generates realistic land-atmosphere exchanges through fully coupled hydrological, carbon and energy cycles. Here we have used WRF-SPA to investigate regional scale observations of atmospheric CO2 concentrations made over a multi-annual period from a tall tower in Scotland. WRF-SPA realistically models both seasonal and daily cycles, predicting CO2 at the tall tower (R2 = 0.67, RMSE = 3.5 ppm, bias = 0.58 ppm, indicating realistic transport, and appropriate source sink distribution and magnitude of CO2 exchange. We have highlighted a consistent post harvest increase in model-observation residuals in atmospheric CO2 concentrations. This increase in model-observation residuals post harvest is likely related to a lack of an appropriate representation of uncultivated components (~ 36% of agricultural holding in Scotland of agricultural land (e.g., hedgerows and forest patches which continue to photosynthesise after the crop has been harvested. Through the use of ecosystem specific CO2 tracers we have shown that tall tower observations here do not detect a representative fraction of Scotland's ecosystem CO2 uptake. Cropland CO2 uptake is the dominant ecosystem signal detected at the tall tower, consistent with the dominance of cropland in the area surrounding the tower. However cropland is over-represented in the atmospheric CO2 concentrations simulated to be at the tall tower, relative to the simulated surface cropland CO2 uptake. Observations made at the tall tower were able to detect seasonal variation in ecosystem CO2 uptake, however a majority of variation was only detected for croplands. We have found evidence that interannual variation in weather has a greater impact than interannual variation of the simulated land surface CO2 exchange on tall tower observations for the

  9. Impacts of increased atmospheric CO2 concentration on photosynthesis and growth of micro- and macro-algae

    Institute of Scientific and Technical Information of China (English)

    WU HongYan; ZOU DingHui; GAO KunShan

    2008-01-01

    Marine photosynthesis drives the oceanic biological CO2 pump to absorb CO2 from the atmosphere, which sinks more than one third of the industry-originated CO2 into the ocean. The increasing atmospheric CO2 and subsequent rise of pCO2 in seawater, which alters the carbonate system and related chemical reactions and results in lower pH and higher HCO3- concentration, affect photosynthetic CO2 fixation processes of phytoplanktonic and macroalgal species in direct and/or indirect ways. Although many unicellular and multicellular species can operate CO2-concentrating mechanisms (CCMs) to utilize the large HCO3- pool in seawater, enriched CO2 up to several times the present atmospheric level has been shown to enhance photosynthesis and growth of both phytoplanktonic and macro-species that have less capacity of CCMs. Even for species that operate active CCMs and those whose photosynthesis is not limited by CO2 in seawater, increased CO2 levels can down-regulate their CCMs and therefore enhance their growth under light-limiting conditions (at higher CO2 levels, less light energy is required to drive CCM). Altered physiological performances under high-CO2 conditions may cause genetic alteration in view of adaptation over long time scale. Marine algae may adapt to a high CO2 oceanic environment so that the evolved communities in future are likely to be genetically different from the contemporary communities. However, most of the previous studies have been carried out under indoor conditions without considering the acidifying effects on seawater by increased CO2 and other interacting environmental factors, and little has been documented so far to explain how physiology of marine primary producers performs in a high-CO2 and low-pH ocean.

  10. Impacts of increased atmospheric CO2 concentration on photosynthesis and growth of micro-and macro-algae

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Marine photosynthesis drives the oceanic biological CO2 pump to absorb CO2 from the atmosphere, which sinks more than one third of the industry-originated CO2 into the ocean. The increasing atmos-pheric CO2 and subsequent rise of pCO2 in seawater, which alters the carbonate system and related chemical reactions and results in lower pH and higher HCO3- concentration, affect photosynthetic CO2 fixation processes of phytoplanktonic and macroalgal species in direct and/or indirect ways. Although many unicellular and multicellular species can operate CO2-concentrating mechanisms (CCMs) to util-ize the large HCO3- pool in seawater, enriched CO2 up to several times the present atmospheric level has been shown to enhance photosynthesis and growth of both phytoplanktonic and macro-species that have less capacity of CCMs. Even for species that operate active CCMs and those whose photo-synthesis is not limited by CO2 in seawater, increased CO2 levels can down-regulate their CCMs and therefore enhance their growth under light-limiting conditions (at higher CO2 levels, less light energy is required to drive CCM). Altered physiological performances under high-CO2 conditions may cause genetic alteration in view of adaptation over long time scale. Marine algae may adapt to a high CO2 oceanic environment so that the evolved communities in future are likely to be genetically different from the contemporary communities. However, most of the previous studies have been carried out under indoor conditions without considering the acidifying effects on seawater by increased CO2 and other interacting environmental factors, and little has been documented so far to explain how physi-ology of marine primary producers performs in a high-CO2 and low-pH ocean.

  11. Low Temperature Performance of Selective Catalytic Reduction of NO with NH3 under a Concentrated CO2 Atmosphere

    Directory of Open Access Journals (Sweden)

    Xiang Gou

    2015-10-01

    Full Text Available Selective catalytic reduction of NOx with NH3 (NH3-SCR has been widely investigated to reduce NOx emissions from combustion processes, which cause environmental challenges. However, most of the current work on NOx reduction has focused on using feed gas without CO2 or containing small amounts of CO2. In the future, oxy-fuel combustion will play an important role for power generation, and this process generates high concentrations of CO2 in flue gas. Therefore, studies on the SCR process under concentrated CO2 atmosphere conditions are important for future SCR deployment in oxy-fuel combustion processes. In this work, Mn- and Ce-based catalysts using activated carbon as support were used to investigate the effect of CO2 on NO conversion. A N2 atmosphere was used for comparison. Different process conditions such as temperature, SO2 concentration, H2O content in the feed gas and space velocity were studied. Under Mn-Ce/AC conditions, the results suggested that Mn metal could reduce the inhibition effect of CO2 on the NO conversion, while Ce metal increased the inhibition effect of CO2. High space velocity also resulted in a reduction of CO2 inhibition on the NO conversion, although the overall performance of SCR was greatly reduced at high space velocity. Future investigations to design novel Mn-based catalysts are suggested to enhance the SCR performance under concentrated CO2 atmosphere conditions.

  12. Measurement of Lower-Atmospheric CO2 Concentration Distribution Using a Compact 1.6 μm DIAL

    Science.gov (United States)

    Shibata, Yasukuni; Nagasawa, Chikao; Abo, Makoto

    2016-06-01

    Knowledge of present carbon sources and sinks including their spatial distribution and their variation in time is one of the essential information for predicting future CO2 atmospheric concentration levels. The differential absorption lidar (DIAL) is expected to measure atmospheric CO2 profiles in the atmospheric boundary layer and lower troposphere from a ground platform. We have succeeded to develop a compact 1.6 μm DIAL system for measuring CO2 concentration profiles in the lower atmosphere. This 1.6 μm DIAL system consists of the optical parametric generator (OPG) transmitter that excited by the LD pumped Nd:YAG laser with high repetition rate and the receiving optics that included the near-infrared photomultiplier tube operating at the analog mode and a 25 cm telescope. CO2 concentration profiles were obtained up to 2.5 km altitude.

  13. Short-term carbon cycling responses of a mature eucalypt woodland to gradual stepwise enrichment of atmospheric CO2 concentration.

    Science.gov (United States)

    Drake, John E; Macdonald, Catriona A; Tjoelker, Mark G; Crous, Kristine Y; Gimeno, Teresa E; Singh, Brajesh K; Reich, Peter B; Anderson, Ian C; Ellsworth, David S

    2016-01-01

    Projections of future climate are highly sensitive to uncertainties regarding carbon (C) uptake and storage by terrestrial ecosystems. The Eucalyptus Free-Air CO2 Enrichment (EucFACE) experiment was established to study the effects of elevated atmospheric CO2 concentrations (eCO2 ) on a native mature eucalypt woodland with low fertility soils in southeast Australia. In contrast to other FACE experiments, the concentration of CO2 at EucFACE was increased gradually in steps above ambient (+0, 30, 60, 90, 120, and 150 ppm CO2 above ambient of ~400 ppm), with each step lasting approximately 5 weeks. This provided a unique opportunity to study the short-term (weeks to months) response of C cycle flux components to eCO2 across a range of CO2 concentrations in an intact ecosystem. Soil CO2 efflux (i.e., soil respiration or Rsoil ) increased in response to initial enrichment (e.g., +30 and +60 ppm CO2 ) but did not continue to increase as the CO2 enrichment was stepped up to higher concentrations. Light-saturated photosynthesis of canopy leaves (Asat ) also showed similar stimulation by elevated CO2 at +60 ppm as at +150 ppm CO2 . The lack of significant effects of eCO2 on soil moisture, microbial biomass, or activity suggests that the increase in Rsoil likely reflected increased root and rhizosphere respiration rather than increased microbial decomposition of soil organic matter. This rapid increase in Rsoil suggests that under eCO2, additional photosynthate was produced, transported belowground, and respired. The consequences of this increased belowground activity and whether it is sustained through time in mature ecosystems under eCO2 are a priority for future research. PMID:26426394

  14. Modelling representation errors of atmospheric CO2 concentrations at a regional scale

    OpenAIRE

    Tolk, L. F.; Meesters, A. G. C. A.; Dolman, A. J.; Peters, W

    2008-01-01

    Inverse modelling of carbon sources and sinks requires an accurate quality estimate of the modelling framework to obtain a realistic estimate of the inferred fluxes and their uncertainties. So-called "representation errors" result from our inability to correctly represent point observations with simulated average values of model grid cells. They may add substantial uncertainty to the interpretation of atmospheric CO2 mixing ratio data. We simulated detailed variations in the CO2 mixing ratios...

  15. Plant Respiration and Elevated Atmospheric CO2 Concentration: Cellular Responses and Global Significance

    OpenAIRE

    GONZALEZ-MELER, MIQUEL A.; Taneva, Lina; Trueman, Rebecca J

    2004-01-01

    • Background Elevated levels of atmospheric [CO2] are likely to enhance photosynthesis and plant growth, which, in turn, should result in increased specific and whole-plant respiration rates. However, a large body of literature has shown that specific respiration rates of plant tissues are often reduced when plants are exposed to, or grown at, high [CO2] due to direct effects on enzymes and indirect effects derived from changes in the plant's chemical composition.

  16. Variations of near-surface atmospheric CO2 and H2O concentrations during summer on Muztagata

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Expeditions during the summers of 2002 and 2003 implemented continuous monitoring of near-surface (2 m height) atmospheric CO2 and H2O concentrations at the 4500 m elevation on Muztagata. The resultant data sets reveal a slight decrease of CO2 concentrations (of about 5μmol·mol-1) and changes in the diurnal variations from the end of June to the middle August. The daily maximum CO2 concentrations occur between 02:30―05:30 AM (local time) and the minimum levels occur between 12:00―15:30 PM. The atmospheric CO2 concentrations in the summer of 2002 were around 5μmol·mol-1 lower than those during the same period of 2003, whereas the diurnal amplitude was higher. In contrast, we found that the daily mean atmospheric H2O content in 2003 was much lower than that in 2002 and there exists a striking negative correlation between CO2 and H2O concentrations. We therefore suggest that the near-surface atmospheric CO2 concentration is affected not only by photosynthesis and respiration, but also by the air H2O content in the glaciated region around Muztagata.

  17. Modeling atmospheric CO2 concentration profiles and fluxes above sloping terrain at a boreal site

    Directory of Open Access Journals (Sweden)

    T. Aalto

    2006-01-01

    Full Text Available CO2 fluxes and concentrations were simulated in the planetary boundary layer above subarctic hilly terrain using a three dimensional model. The model solves the transport equations in the local scale and includes a vegetation sub-model. A WMO/GAW background concentration measurement site and an ecosystem flux measurement site are located inside the modeled region at a hilltop and above a mixed boreal forest, respectively. According to model results, the concentration measurement at the hill site was representative for continental background. However, this was not the case for the whole model domain. Concentration at few meters above active vegetation represented mainly local variation. Local variation became inseparable from the regional signal at about 60-100 m above ground. Flow over hills changed profiles of environmental variables and height of inversion layer, however CO2 profiles were more affected by upwind land use than topography. The hill site was above boundary layer during night and inside boundary layer during daytime. The CO2 input from model lateral boundaries dominated in both cases. Daily variation in the CO2 assimilation rate was clearly seen in the CO2 profiles. Concentration difference between the hill site and the forest site was about 5ppm during afternoon according to both model and measurements. The average modeled flux to the whole model region was about 40% of measured and modeled local flux at the forest site.

  18. Future atmospheric CO2 concentration and environmental consequences for the feed market: a consequential LCA

    DEFF Research Database (Denmark)

    Saxe, Henrik; Hamelin, Lorie; Hinrichsen, Torben; Wenzel, Henrik

    such altered chemical composition and crop yields would have for the production of pig feed. Results revealed, among others, that an extra European demand of pig feed under an atmospheric [CO2] of 550 μmole mole-1 would lead to ca. 6% less expansion of additional arable land worldwide, in comparison to...... feed produced under today’s conditions. However, this did not translate into lower greenhouse gas emissions, because the benefit of increased crop yield was counteracted by changes in the composition of the feed formulation. Among the important changes, feed produced under high [CO2] was shown to...... integrate 23% more soymeal and 5% less wheat than at present....

  19. Effects of elevated atmospheric CO2 concentration on leaf dark respiration of Xanthium strumarium in light and in darkness.

    Science.gov (United States)

    Wang, X; Lewis, J D; Tissue, D T; Seemann, J R; Griffin, K L

    2001-02-27

    Leaf dark respiration (R) is an important component of plant carbon balance, but the effects of rising atmospheric CO(2) on leaf R during illumination are largely unknown. We studied the effects of elevated CO(2) on leaf R in light (R(L)) and in darkness (R(D)) in Xanthium strumarium at different developmental stages. Leaf R(L) was estimated by using the Kok method, whereas leaf R(D) was measured as the rate of CO(2) efflux at zero light. Leaf R(L) and R(D) were significantly higher at elevated than at ambient CO(2) throughout the growing period. Elevated CO(2) increased the ratio of leaf R(L) to net photosynthesis at saturated light (A(max)) when plants were young and also after flowering, but the ratio of leaf R(D) to A(max) was unaffected by CO(2) levels. Leaf R(N) was significantly higher at the beginning but significantly lower at the end of the growing period in elevated CO(2)-grown plants. The ratio of leaf R(L) to R(D) was used to estimate the effect of light on leaf R during the day. We found that light inhibited leaf R at both CO(2) concentrations but to a lesser degree for elevated (17-24%) than for ambient (29-35%) CO(2)-grown plants, presumably because elevated CO(2)-grown plants had a higher demand for energy and carbon skeletons than ambient CO(2)-grown plants in light. Our results suggest that using the CO(2) efflux rate, determined by shading leaves during the day, as a measure for leaf R is likely to underestimate carbon loss from elevated CO(2)-grown plants. PMID:11226264

  20. Statistical Analysis of Long Term Trends in Atmospheric CO2 Concentration at Baseline Stations

    OpenAIRE

    Antonovsky, M.Y.; Buchstaber, V. M.; Zubenko, A.A.

    1988-01-01

    Carbon dioxide is one of several greenhouse gases that can modify the earth's heat balance by absorbing outgoing radiation from the earth's surface, thereby increasing the amount of heat retained by the atmosphere (the so-called greenhouse effect). Changes in CO2 are therefore of considerable importance. In this paper, the long-term trends are assessed at four baseline stations -- Mauna Loa (Hawaii), Barrow (Alaska), American Samoa and South Pole. The authors conclude that a parabolic model ...

  1. An inverse modeling approach for tree-ring-based climate reconstructions under changing atmospheric CO2 concentrations

    Science.gov (United States)

    Boucher, É.; Guiot, J.; Hatté, C.; Daux, V.; Danis, P.-A.; Dussouillez, P.

    2013-11-01

    Over the last decades, dendroclimatologists have relied upon linear transfer functions to reconstruct historical climate. Transfer functions need to be calibrated using recent data from periods where CO2 concentrations reached unprecedented levels (near 400 ppm). Based on these transfer functions, dendroclimatologists must then reconstruct a different past, a past where CO2 concentrations were much below 300 ppm. However, relying upon transfer functions calibrated in this way may introduce an unanticipated bias in the reconstruction of past climate, particularly if CO2 levels have had a noticeable fertilizing effect since the beginning of the industrial era. As an alternative to the transfer function approach, we run the MAIDENiso ecophysiological model in an inverse mode to link together climatic variables, atmospheric CO2 concentrations and tree growth parameters. Our approach endeavors to find the optimal combination of meteorological conditions that best simulate observed tree ring patterns. We test our approach in the Fontainebleau forest (France). By comparing two different CO2 scenarios, we present evidence that increasing CO2 concentrations have had a slight, yet significant, effect on reconstruction results. We demonstrate that higher CO2 concentrations augment the efficiency of water use by trees, therefore favoring the reconstruction of a warmer and drier climate. Under elevated CO2 concentrations, trees close their stomata and need less water to produce the same amount of wood. Inverse process-based modeling represents a powerful alternative to the transfer function technique, especially for the study of divergent tree-ring-to-climate relationships. The approach has several advantages, most notably its ability to distinguish between climatic effects and CO2 imprints on tree growth. Therefore our method produces reconstructions that are less biased by anthropogenic greenhouse gas emissions and that are based on sound ecophysiological knowledge.

  2. Ship-board report on atmospheric CO2 concentrations recorded on continuous from Mediterranean sea to Antarctica

    International Nuclear Information System (INIS)

    The paper presents the results obtained from continuous measurements performed during two cruises with hemispherical courses. In this way, it has been obtained the latitudinal trend of CO2 in continuity of space and time along two hemispheric courses in 1994-95 and 1996-97 from Europe to Antarctica. The results are compared with measurements from the National Oceanic Atmospheric Administration (NOAA) Climate Monitoring and Diagnostic Laboratory (CMDL) cooperative air sampling network. The fitting of data recorded on board with the historical data sets recorded at Palmer Station is also presented, highlighting the current annual increase in atmospheric CO2 concentrations

  3. Contribution of various carbon sources toward isoprene synthesis mediated by altered atmospheric CO2 concentrations

    Science.gov (United States)

    Trowbridge, A. M.; Asensio, D.; Eller, A. S.; Wilkinson, M. J.; Schnitzler, J.; Jackson, R. B.; Monson, R. K.

    2010-12-01

    Biogenically released isoprene is abundant in the troposphere, and has an essential function in determining atmospheric chemistry and important implications for plant metabolism. As a result, considerable effort has been made to understand the underlying mechanisms driving isoprene synthesis, particularly in the context of a rapidly changing environment. Recently, a number of studies have focused on the contribution of recently assimilated carbon as opposed to stored/alternative intracellular or extracellular carbon sources in the context of environmental stress. Results from these studies can offer clues about the importance of various carbon pools for isoprene production and elucidate the corresponding physiological changes that are responsible for these dynamic shifts in carbon allocation. We performed a 13CO2-labeling study using proton-transfer-reaction mass spectrometry (PTR-MS) to examine the kinetics of the incorporation of recently assimilated photosynthate into isoprene emitted from poplar (Poplar x canescens) under sub-ambient, ambient, and elevated CO2 growth conditions. We also monitored the importance of pyruvate-derived carbon for isoprene biosynthesis and obtained a detailed account of where individual carbons are derived from by analyzing the ratio of the 3C subunit of isoprene (M41+) (a fragment which contains two carbons from pyruvate) to the ratio of the parent isoprene molecule (M69+). Dynamics in the M41+:M69+ ratio indicate that recently assimilated carbon is incorporated into the pyruvate carbon pool slowly across all CO2 treatments and is therefore accessible for isoprene synthesis at a slower rate when compared to substrates derived directly from photosynthesis. Analysis of the rates of change for individual masses indicated that the carbon pools in trees grown in sub-ambient CO2 (200 ppm) are labeled ~2 times faster than those of trees grown in ambient or elevated CO2. Analysis of the total isoprene emission rates between treatments

  4. Changes in concentration and (delta) 13C value of dissolved CH4, CO2 and organic carbon in rice paddies under ambient and elevated concentrations of atmospheric CO2

    International Nuclear Information System (INIS)

    Changes in concentration and (delta)13C value of dissolved CH4, CO2 and organic carbon (DOC) in floodwater and soil solution from a Japanese rice paddy were studied under ambient and elevated concentrations of atmospheric CO2 in controlled environment chambers. The concentrations of dissolved CH4 in floodwater increased with rice growth (with some fluctuation), while the concentrations of CO2 remained between 2.9 to 4.4 and 4.2 to 5.8 μg C mL-1 under conditions of ambient and elevated CO2 concentration, respectively. The amount of CH4 dissolved in soil solution under elevated CO2 levels was significantly lower than under ambient CO2 in the tillering stage, implying that the elevated CO2 treatment accelerated CH4 oxidation during the early stage of growth. However, during later stages of growth, production of CH4 increased and the amount of CH4 dissolved in soil solution under elevated CO2 levels was, on average, greater than that under ambient CO2 conditions. Significant correlation existed among the (delta)13C values of dissolved CH4, CO2, and DOC in floodwater (except for the samples taken immediately after pulse feeding with 13C enriched CO2), indicating that the origins and cycling of CH4, CO2 and DOC were related. There were also significant correlations among the (delta)13C values of CH4, CO2 and DOC in the soil solution. The turnover rate of CO2 in soil solution was most rapid in the panicle formation stage of rice growth and that of CH4 fastest in the grain filling stage. (Author)

  5. Changing Amazon biomass and the role of atmospheric CO2 concentration, climate, and land use

    Science.gov (United States)

    Almeida Castanho, Andrea D.; Galbraith, David; Zhang, Ke; Coe, Michael T.; Costa, Marcos H.; Moorcroft, Paul

    2016-01-01

    The Amazon tropical evergreen forest is an important component of the global carbon budget. Its forest floristic composition, structure, and function are sensitive to changes in climate, atmospheric composition, and land use. In this study biomass and productivity simulated by three dynamic global vegetation models (Integrated Biosphere Simulator, Ecosystem Demography Biosphere Model, and Joint UK Land Environment Simulator) for the period 1970-2008 are compared with observations from forest plots (Rede Amazónica de Inventarios Forestales). The spatial variability in biomass and productivity simulated by the DGVMs is low in comparison to the field observations in part because of poor representation of the heterogeneity of vegetation traits within the models. We find that over the last four decades the CO2 fertilization effect dominates a long-term increase in simulated biomass in undisturbed Amazonian forests, while land use change in the south and southeastern Amazonia dominates a reduction in Amazon aboveground biomass, of similar magnitude to the CO2 biomass gain. Climate extremes exert a strong effect on the observed biomass on short time scales, but the models are incapable of reproducing the observed impacts of extreme drought on forest biomass. We find that future improvements in the accuracy of DGVM predictions will require improved representation of four key elements: (1) spatially variable plant traits, (2) soil and nutrients mediated processes, (3) extreme event mortality, and (4) sensitivity to climatic variability. Finally, continued long-term observations and ecosystem-scale experiments (e.g. Free-Air CO2 Enrichment experiments) are essential for a better understanding of the changing dynamics of tropical forests.

  6. Forecasting global atmospheric CO2

    Directory of Open Access Journals (Sweden)

    A. Agustí-Panareda

    2014-05-01

    Full Text Available A new global atmospheric carbon dioxide (CO2 real-time forecast is now available as part of the pre-operational Monitoring of Atmospheric Composition and Climate – Interim Implementation (MACC-II service using the infrastructure of the European Centre for Medium-Range Weather Forecasts (ECMWF Integrated Forecasting System (IFS. One of the strengths of the CO2 forecasting system is that the land surface, including vegetation CO2 fluxes, is modelled online within the IFS. Other CO2 fluxes are prescribed from inventories and from off-line statistical and physical models. The CO2 forecast also benefits from the transport modelling from a state-of-the-art numerical weather prediction (NWP system initialized daily with a wealth of meteorological observations. This paper describes the capability of the forecast in modelling the variability of CO2 on different temporal and spatial scales compared to observations. The modulation of the amplitude of the CO2 diurnal cycle by near-surface winds and boundary layer height is generally well represented in the forecast. The CO2 forecast also has high skill in simulating day-to-day synoptic variability. In the atmospheric boundary layer, this skill is significantly enhanced by modelling the day-to-day variability of the CO2 fluxes from vegetation compared to using equivalent monthly mean fluxes with a diurnal cycle. However, biases in the modelled CO2 fluxes also lead to accumulating errors in the CO2 forecast. These biases vary with season with an underestimation of the amplitude of the seasonal cycle both for the CO2 fluxes compared to total optimized fluxes and the atmospheric CO2 compared to observations. The largest biases in the atmospheric CO2 forecast are found in spring, corresponding to the onset of the growing season in the Northern Hemisphere. In the future, the forecast will be re-initialized regularly with atmospheric CO2 analyses based on the assimilation of CO2 satellite retrievals, as they

  7. Coupling of surface temperatures and atmospheric CO_2 concentrations during the Palaeozoic era

    OpenAIRE

    Came, Rosemarie E.; Eiler, John M.; Veizer, Ján; Azmy, Karem; Brand, Uwe; Weidman, Christopher R.

    2007-01-01

    Atmospheric carbon dioxide concentrations seem to have been several times modern levels during much of the Palaeozoic era (543–248 million years ago), but decreased during the Carboniferous period to concentrations similar to that of today. Given that carbon dioxide is a greenhouse gas, it has been proposed that surface temperatures were significantly higher during the earlier portions of the Palaeozoic era. A reconstruction of tropical sea surface temperatures based on the δ^(18)O of carbona...

  8. Technical Note: Long-term memory effect in the atmospheric CO2 concentration at Mauna Loa

    Directory of Open Access Journals (Sweden)

    C. Varotsos

    2007-01-01

    Full Text Available The monthly mean values of the atmospheric carbon dioxide concentration derived from in-situ air samples collected at Mauna Loa Observatory, Hawaii, USA during 1958–2004 (the longest continuous record available in the world are analyzed by employing the detrended fluctuation analysis to detect scaling behavior in this time series. The main result is that the fluctuations of carbon dioxide concentrations exhibit long-range power-law correlations (long memory with lag times ranging from four months to eleven years, which correspond to 1/f noise. This result indicates that random perturbations in the carbon dioxide concentrations give rise to noise, characterized by a frequency spectrum following a power-law with exponent that approaches to one; the latter shows that the correlation times grow strongly. This feature is pointing out that a correctly rescaled subset of the original time series of the carbon dioxide concentrations resembles the original time series. Finally, the power-law relationship derived from the real measurements of the carbon dioxide concentrations could also serve as a tool to improve the confidence of the atmospheric chemistry-transport and global climate models.

  9. Technical Note: Long-term memory effect in the atmospheric CO2 concentration at Mauna Loa

    Directory of Open Access Journals (Sweden)

    M. Efstathiou

    2006-11-01

    Full Text Available The monthly mean values of the atmospheric carbon dioxide concentration derived from in-situ air samples collected at Mauna Loa Observatory, Hawaii, during 1958–2004 (the longest continuous record available in the world are analyzed by employing the detrended fluctuation analysis to detect scaling behavior in this time series. The main result is that the fluctuations of carbon dioxide concentrations exhibit long-range power-law correlations (long memory with lag times ranging from four months to eleven years, which correspond to 1/f noise. This result indicates that random perturbations in the carbon dioxide concentrations give rise to noise, characterized by a frequency spectrum following a power-law with exponent that approaches to one; the latter shows that the correlation times grow strongly. This feature is pointing out that a correctly rescaled subset of the original time series of the carbon dioxide concentrations resembles the original time series. Finally, the power-law relationship derived from the real measurements of the carbon dioxide concentrations could also serve as a tool to improve the confidence of the atmospheric chemistry-transport and global climate models.

  10. Carbon Dioxide Production Responsibility on the Basis of comparing in Situ and mean CO2 Atmosphere Concentration Data

    CERN Document Server

    Mavrodiev, S Cht; Vachev, B

    2008-01-01

    The method is proposed for estimation of regional CO2 and other greenhouses and pollutants production responcibility. The comparison of CO2 local emissions reduction data with world CO2 atmosphere data will permit easy to judge for overall effect in curbing not only global warming but also chemical polution.

  11. Passive CO2 concentration in higher plants.

    Science.gov (United States)

    Sage, Rowan F; Khoshravesh, Roxana

    2016-06-01

    Photorespiratory limitations on C3 photosynthesis are substantial in warm, low CO2 conditions. To compensate, certain plants evolved mechanisms to actively concentrate CO2 around Rubisco using ATP-supported CO2 pumps such as C4 photosynthesis. Plants can also passively accumulate CO2 without additional ATP expenditure by localizing the release of photorespired and respired CO2 around Rubisco that is diffusively isolated from peripheral air spaces. Passive accumulation of photorespired CO2 occurs when glycine decarboxylase is localized to vascular sheath cells in what is termed C2 photosynthesis, and through forming sheaths of chloroplasts around the periphery of mesophyll cells. The peripheral sheaths require photorespired CO2 to re-enter chloroplasts where it can be refixed. Passive accumulation of respiratory CO2 is common in organs such as stems, fruits and flowers, due to abundant heterotrophic tissues and high diffusive resistance along the organ periphery. Chloroplasts within these organs are able to exploit this high CO2 to reduce photorespiration. CO2 concentration can also be enhanced passively by channeling respired CO2 from roots and rhizomes into photosynthetic cells of stems and leaves via lacunae, aerenchyma and the xylem stream. Through passive CO2 concentration, C3 species likely improved their carbon economy and maintained fitness during episodes of low atmospheric CO2. PMID:27058940

  12. The sensitivity of stand-scale photosynthesis and transpiration to changes in atmospheric CO2 concentration and climate

    Directory of Open Access Journals (Sweden)

    B. Kruijt

    1999-01-01

    Full Text Available The 3-dimensional forest model MAESTRO was used to simulate daily and annual photosynthesis and transpiration fluxes of forest stands and the sensitivity of these fluxes to potential changes in atmospheric CO2 concentration ([CO2], temperature, water stress and phenology. The effects of possible feed-backs from increased leaf area and limitations to leaf nutrition were simulated by imposing changes in leaf area and nitrogen content. Two different tree species were considered: Picea sitchensis (Bong. Carr., a conifer with long needle longevity and large leaf area, and Betula pendula Roth., a broad-leaved deciduous species with an open canopy and small leaf area. Canopy photosynthetic production in trees was predicted to increase with atmospheric [CO2] and length of the growing season and to decrease with increased water stress. Associated increases in leaf area increased production further only in the B. pendula canopy, where the original leaf area was relatively small. Assumed limitations in N uptake affected B. pendula more than P. sitchensis. The effect of increased temperature was shown to depend on leaf area and nitrogen content. The different sensitivities of the two species were related to their very different canopy structure. Increased [CO2] reduced transpiration, but larger leaf area, early leaf growth, and higher temperature all led to increased water use. These effects were limited by feedbacks from soil water stress. The simulations suggest that, with the projected climate change, there is some increase in stand annual `water use efficiency', but the actual water losses to the atmosphere may not always decrease.

  13. Atmospheric CO2 concentrations and (delta)13C values across the Antarctic Circumpolar Current between New Zealand and Antarctica

    International Nuclear Information System (INIS)

    Measurements of atmospheric CO2 concentrations were repeatedly carried out on the vessel 'Italica' of the Italian National Research Program in Antarctica, during cruises from Italy to Antarctica. Discrete air samples were also collected in 4-L Pyrex flasks during these cruises in order to carry out (delta)13C analyses on atmospheric CO2. The results acquired between New Zealand and Antarctica are reported here. The mean growth rate of the CO2 concentration from 1996 to 2003 in this area of the Southern Oceans is of about 1.8 ppmv/yr, in good agreement with NOAA/CMDL measurements. The rates of increase from cruise to cruise are rather variable. From 1996-1997 to 1998-1999 cruise the yearly growth rate is 2.75 ppmv/yr, close to the large growth rates measured in several areas and mainly related to the most severe El Nino event of the last years. The other yearly growth rates are of about 1.3 and 2 ppmv for the periods 1998-1999 to 2001-2002 and 2001-2002 to 2003-2004, respectively. The large difference between these two values is probably related to the uncertainty on the only two 2001-2002 discrete measurements of CO2 concentration in this area. The measured (delta)13C values show two completely different distributions and a large interannual variability. The 1998-1999, 2002-2003, and 2003-2004 results obtained between about 55 deg S and 65 deg S across the Antarctic Polar Front show a marked negativization of up to more than 0.2% when compared to the background values. The results are related to local source regions of CO2, as frequently found in the Southern Ocean by several authors; the negative (delta)13C values are tentatively related to the possible contribution of different causes. Among them, the southward negative gradient of (delta)13C of the dissolved inorganic carbon, the contribution from upwelling deep waters and from subsurface processes between the Northern SubAntarctic Front and the Polar Front, and, partly, the contribution of CO2 of biogenic

  14. The last 41.000 years fluctuation in atmospheric CO2 concentration inferred from the changes in oxygen and carbon stable isotopes ratios of marine sediments

    International Nuclear Information System (INIS)

    The past atmospheric CO2 concentrations were reconstructed based on the results of measurements of stable oxygen and carbon isotopic ratios of fossil foraminifera and total organic carbon contained in marine sediment taken from the Okinawa Trough. East China Sea. In' this study, we utilized two models of Popp et al and Rau et al, for the reconstruction. The results show that the whole trends of the changes in CO2 concentrations are very similar, even when it is compared to the atmospheric CO2 concentration of air trapped in ice core from southern pole. Changes in atmospheric CO2 concentrations are interpreted as a consequence of fluctuation in ocean surface water utilization of CO2 by marine organism and those are closely related to glacial interglacial (cold-warm) fluctuations between maximum and minimum values through most Quaternary. (author)

  15. Effects of elevated atmospheric CO2 concentration on leaf dark respiration of Xanthium strumarium in light and in darkness

    OpenAIRE

    Wang, Xianzhong; Lewis, James D.; Tissue, David T.; Seemann, Jeffrey R.; Griffin, Kevin L.

    2001-01-01

    Leaf dark respiration (R) is an important component of plant carbon balance, but the effects of rising atmospheric CO2 on leaf R during illumination are largely unknown. We studied the effects of elevated CO2 on leaf R in light (RL) and in darkness (RD) in Xanthium strumarium at different developmental stages. Leaf RL was estimated by using the Kok method, whereas leaf RD was measured as the rate of CO2 efflux at zero light. Leaf RL and RD were sign...

  16. Control of atmospheric CO_2 concentrations by 2050: A calculation on the emission rights of different countries

    Institute of Scientific and Technical Information of China (English)

    DING ZhongLi; DUAN XiaoNan; GE QuanSheng; ZHANG ZhiQiang

    2009-01-01

    This paper is to provide quantitative data on some critical issues in anticipation of the forthcoming international negotiations in Denmark on the control of atmospheric CO_2 concentrations. Instead of letting only a small number of countries dominate a few controversial dialogues about emissions re-ductions, a comprehensive global system must be established based on emissions allowances for different countries, to realize the long-term goal of controlling global atmospheric CO_2 concentrations.That a system rooted in "cumulative emissions per capita," the best conception of the "common but differentiated responsibilities" principle affirmed by the Kyoto Protocol according to fundamental standards of fairness and justice, was demonstrated. Based on calculations of various countries' cu-mulative emissions per capita, estimates of their cumulative emissions from 1900 to 2005, and their annual emissions allowances into the future (2006-2050), a 470 ppmv atmospheric CO_2 concentration target was set. According to the following four objective indicators-total emissions allowance from 1900 to 2050, actual emissions from 1900 to 2005, emissions levels in 2005, and the average growth rate of emissions from 1996 to 2005-all countries and regions whose population was more than 300000 in 2005 were divided into four main groups: countries with emissions deficits, countries and regions needing to reduce their gross emissions, countries and regions needing to reduce their emissions growth rates, and countries that can maintain the current emissions growth rates. Based on this pro-posal, most G8 countries by 2005 had already expended their 2050 emissions allowances. The accu-mulated financial value based on emissions has reached more than 5.5 trillion US dollars (20 dollars per ton of CO_2). Even if these countries could achieve their ambitious emissions reduction targets in the future, their per capita emissions from 2006 to 2050 would still be much higher than those of de

  17. Control of atmospheric CO2 concentrations by 2050: A calculation on the emission rights of different countries

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    This paper is to provide quantitative data on some critical issues in anticipation of the forthcoming international negotiations in Denmark on the control of atmospheric CO2 concentrations. Instead of letting only a small number of countries dominate a few controversial dialogues about emissions reductions, a comprehensive global system must be established based on emissions allowances for different countries, to realize the long-term goal of controlling global atmospheric CO2 concentrations. That a system rooted in "cumulative emissions per capita," the best conception of the "common but differentiated responsibilities" principle affirmed by the Kyoto Protocol according to fundamental standards of fairness and justice, was demonstrated. Based on calculations of various countries’ cumulative emissions per capita, estimates of their cumulative emissions from 1900 to 2005, and their annual emissions allowances into the future (2006―2050), a 470 ppmv atmospheric CO2 concentration target was set. According to the following four objective indicators―total emissions allowance from 1900 to 2050, actual emissions from 1900 to 2005, emissions levels in 2005, and the average growth rate of emissions from 1996 to 2005―all countries and regions whose population was more than 300000 in 2005 were divided into four main groups: countries with emissions deficits, countries and regions needing to reduce their gross emissions, countries and regions needing to reduce their emissions growth rates, and countries that can maintain the current emissions growth rates. Based on this proposal, most G8 countries by 2005 had already expended their 2050 emissions allowances. The accu-mulated financial value based on emissions has reached more than 5.5 trillion US dollars (20 dollars per ton of CO2). Even if these countries could achieve their ambitious emissions reduction targets in the future, their per capita emissions from 2006 to 2050 would still be much higher than those of

  18. One-year spatial and temporal monitoring of concentration and carbon isotopic composition of atmospheric CO2 in a Wrocław (SW Poland) city area

    International Nuclear Information System (INIS)

    Highlights: • Seasonal variation in CO2 concentration and δ13C value in air urban area was noted. • Spatial distribution of CO2 in Wrocław indicate the anthropogenically changed areas. • Coal or diesel/gasoline dominant CO2 origin was indicated for heating seasons. • Soil respiration dominant biogenic CO2 origin was indicated for vegetative season. • Significant influence of newly opened highway on the atmospheric CO2 was observed. - Abstract: The main aim of this study was to assess the natural and anthropogenic contributions of CO2 in the urban atmosphere of Wrocław City (SW Poland) using combined quantitative (CO2 concentrations) and qualitative analysis (δ13C of CO2). Between 21 January 2011 and 22 December 2011, 17 sampling campaigns were performed at 3-week intervals and in total 255 samples were collected. The mean CO2 concentration was 469 ± 71 ppm and the mean δ13C(CO2) was −10.8 ± 1‰.The measured δ13C(CO2) values of major end-members for two winter heating seasons (−25.7‰ in January–March of 2011 and −27.6 ‰ in October–December of 2011) and for one vegetative season (−20.4‰ in April–September of 2011) suggest soil respiration as a main source of atmospheric CO2 during the vegetative season, and a very significant impact of fossil fuel combustion during the winter heating seasons. There were significant increases of CO2 concentrations at many sampling locations after the opening of a new motorway on 31 August 2011. The authors hypothesise that the new motorway contributes to the increase of CO2 across the city

  19. Increase of uncertainty in transient climate response to cumulative carbon emissions after stabilization of atmospheric CO2 concentration

    International Nuclear Information System (INIS)

    We analyzed a dataset from an experiment of an earth system model of intermediate complexity, focusing on the change in transient climate response to cumulative carbon emissions (TCRE) after atmospheric CO2 concentration was stabilized in the Representative Concentration Pathway (RCP) 4.5. We estimated the TCRE in 2005 at 0.3–2.4 K/TtC for an unconstrained case and 1.1–1.7 K/TtC when constrained with historical and present-day observational data, the latter result being consistent with other studies. The range of TCRE increased when the increase of CO2 concentration was moderated and then stabilized. This is because the larger (smaller) TCRE members yield even greater (less) TCRE. An additional experiment to assess the equilibrium state revealed significant changes in temperature and cumulative carbon emissions after 2300. We also found that variation of land carbon uptake is significant to the total allowable carbon emissions and subsequent change of the TCRE. Additionally, in our experiment, we revealed that equilibrium climate sensitivity (ECS), one of the 12 parameters perturbed in the ensemble experiment, has a strong positive relationship with the TCRE at the beginning of the stabilization and its subsequent change. We confirmed that for participant models in the Coupled Model Intercomparison Project Phase 5, ECS has a strong positive relationship with TCRE. For models using similar experimental settings, there is a positive relationship with TCRE for the start of the period of stabilization in CO2 concentration, and rate of change after stabilization. The results of this study are influential regarding the total allowable carbon emissions calculated from the TCRE and the temperature increase set as the mitigation target. (letter)

  20. Concentrations and (delta)13C values of atmospheric CO2 from oceanic atmosphere through time: polluted and non-polluted areas

    International Nuclear Information System (INIS)

    CO2 is one of the primary agents of global climate changes. The increase of atmospheric CO2 concentration is essentially related to human-induced emissions and, particularly, to the burning of fossil fuel whose (delta)13C values are quite negative. Consequently, an increase of the CO2 concentration in the atmosphere should be paralleled by a decrease of its (delta)13C. Continuous and/or spot measurements of CO2 concentrations were repeatedly carried out during the last decade and in the same period of the year along hemispheric courses from Italy to Antarctica on a vessel of the Italian National Research Program in Antarctica. During these expeditions, discrete air samples were also collected in 4-l Pyrex flasks in order to carry out precise carbon isotope analyses on atmospheric CO2 from different areas, including theoretically 'clean' open ocean areas, with the main purpose of comparing these open ocean results with the results obtained by the National Oceanic and Atmospheric Administration/World Meteorological Organization (NOAA/WMO) at land-based stations. According to the data obtained for these two variables, a relatively large atmospheric pollution is apparent in the Mediterranean area where the CO2 concentration has reached the value of 384 ppmv while quite negative (delta)13C values have been measured only occasionally. In this area, southerly winds probably help to reduce the effect of atmospheric pollution even though, despite a large variability of CO2 concentrations, these values are consistently higher than those measured in open ocean areas by a few ppmv to about 10 ppmv. A marked, though non-continuous, pollution is apparent in the area of the Bab-el-Mandeb strait where (delta)13C values considerably more negative than in the Central and Southern Red Sea were measured. The concentration of atmospheric CO2 over the Central Indian Ocean increased from about 361 ppmv at the end of 1996 to about 373 ppmv at the end of 2003 (mean growth rate of about 1

  1. Concentrations and δ13C values of atmospheric CO2 from oceanic atmosphere through time: polluted and non-polluted areas

    Science.gov (United States)

    Longinelli, Antonio; Lenaz, Renzo; Ori, Carlo; Selmo, Enrico

    2005-11-01

    CO2 is one of the primary agents of global climate changes. The increase of atmospheric CO2 concentration is essentially related to human-induced emissions and, particularly, to the burning of fossil fuel whose δ13C values are quite negative. Consequently, an increase of the CO2 concentration in the atmosphere should be paralleled by a decrease of its δ13C. Continuous and/or spot measurements of CO2 concentrations were repeatedly carried out during the last decade and in the same period of the year along hemispheric courses from Italy to Antarctica on a vessel of the Italian National Research Program in Antarctica. During these expeditions, discrete air samples were also collected in 4-l Pyrex flasks in order to carry out precise carbon isotope analyses on atmospheric CO2 from different areas, including theoretically 'clean' open ocean areas, with the main purpose of comparing these open ocean results with the results obtained by the National Oceanic and Atmospheric Administration/World Meteorological Organization (NOAA/WMO) at land-based stations. According to the data obtained for these two variables, a relatively large atmospheric pollution is apparent in the Mediterranean area where the CO2 concentration has reached the value of 384 ppmv while quite negative δ13C values have been measured only occasionally. In this area, southerly winds probably help to reduce the effect of atmospheric pollution even though, despite a large variability of CO2 concentrations, these values are consistently higher than those measured in open ocean areas by a few ppmv to about 10 ppmv. A marked, though non-continuous, pollution is apparent in the area of the Bab-el-Mandeb strait where δ13C values considerably more negative than in the Central and Southern Red Sea were measured. The concentration of atmospheric CO2 over the Central Indian Ocean increased from about 361 ppmv at the end of 1996 to about 373 ppmv at the end of 2003 (mean growth rate of about 1.7 ppmv yr1 in

  2. Development of a 2-micron Pulsed Differential Absorption Lidar for Atmospheric CO2 Concentration Measurement by Direct Detection Technique

    Science.gov (United States)

    Yu, J.; Singh, U. N.; Petros, M.; Bai, Y.

    2011-12-01

    Researchers at NASA Langley Research Center are developing a 2-micron Pulsed Differential Absorption Lidar instrument for ground and airborne measurements via direct detection method. This instrument will provide an alternate approach to measure atmospheric CO2 concentrations with significant advantages. A high energy pulsed approach provides high-precision measurement capbility by having high signal-to-noise level and unambiguously eliminates the contamination from aerosols and clouds that can bias the IPDA measurement. A key component of the CO2 DIAL system, transceiver, is an existing, airborne ready, robust hardware which can provide 250mJ at 10Hz with double pulse format specifically designed for DIAL instrument. The exact wavelengths of the transceiver are controlled by well defined CW seed laser source to provide the required injection source for generating on-and-off line wavelength pulses sequentially. The compact, rugged, highly reliable transceiver is based on the unique Ho:Tm:YLF high-energy 2-micron pulsed laser technology. All the optical mounts are custom designed and have space heritage. They are designed to be adjustable and lockable and hardened to withstand vibrations that can occur in airborne operation. For the direct detection lidar application, a large primary mirror size is preferred. A 14 inch diameter telescope will be developed for this program. The CO2 DIAL/IPDA system requires many electronic functions to operate. These include diode, RF, seed laser, and PZT drivers; injection seeding detection and control; detector power supplies; and analog inputs to sample various sensors. Under NASA Laser Risk Reduction Program (LRRP), a control unit Compact Laser Electronics (CLE), is developed for the controlling the coherent wind lidar transceiver. Significant modifications and additions are needed to update it for CO2 lidar controls. The data acquisition system was built for ground CO2 measurement demonstration. The software will be updated for

  3. Energyless CO2 Absorption, Generation, and Fixation Using Atmospheric CO2.

    Science.gov (United States)

    Inagaki, Fuyuhiko; Okada, Yasuhiko; Matsumoto, Chiaki; Yamada, Masayuki; Nakazawa, Kenta; Mukai, Chisato

    2016-01-01

    From an economic and ecological perspective, the efficient utilization of atmospheric CO2 as a carbon resource should be a much more important goal than reducing CO2 emissions. However, no strategy to harvest CO2 using atmospheric CO2 at room temperature currently exists, which is presumably due to the extremely low concentration of CO2 in ambient air (approximately 400 ppm=0.04 vol%). We discovered that monoethanolamine (MEA) and its derivatives efficiently absorbed atmospheric CO2 without requiring an energy source. We also found that the absorbed CO2 could be easily liberated with acid. Furthermore, a novel CO2 generator enabled us to synthesize a high value-added material (i.e., 2-oxazolidinone derivatives based on the metal catalyzed CO2-fixation at room temperature) from atmospheric CO2. PMID:26596773

  4. Effects of high atmospheric CO2 concentration on root hydraulic conductivity of conifers depend on species identity and inorganic nitrogen source

    International Nuclear Information System (INIS)

    We examined root hydraulic conductivity (Lp) responses of one-year-old seedlings of four conifers to the combined effects of elevated CO2 and inorganic nitrogen (N) sources. We found marked interspecific differences in Lp responses to high CO2 ranging from a 37% increase in P. abies to a 27% decrease in P. menziesii, but these effects depended on N source. The results indicate that CO2 effects on root water transport may be coupled to leaf area responses under nitrate (NO3-), but not ammonium (NH4+) dominated soils. To our knowledge, this is the first study that highlights the role of inorganic N source and species identity as critical factors that determine plant hydraulic responses to rising atmospheric CO2 levels. The results have important implications for understanding root biology in a changing climate and for models designed to predict feedbacks between rising atmospheric CO2, N deposition, and ecohydrology. - Highlights: → Root hydraulic conductivity (Lp) in conifers is affected by increased atmospheric CO2 levels. → This response depends on inorganic N source and species identity. → This is the first report of Lp responses to elevated CO2 and N source in multiple species. - Root water transport responses to rising atmospheric CO2 concentration depends on species identity and inorganic N sources.

  5. 大气CO2浓度非均匀动态分布条件下的气候模拟%Climate simulation for dynamic heterogeneous distribution of atmospheric CO2 concentration

    Institute of Scientific and Technical Information of China (English)

    杨成荫; 王汉杰; 韩士杰; 赵苏璇

    2012-01-01

    利用现有大气本底站的大气CO2浓度观测信息,综合考虑不同经济区划与土地覆盖类型对应的CO2浓度差异及其季节变化规律,构建模式区域内以月为单位的网格化大气CO2浓度非均匀动态分布数据模型.由此数据模型驱动RegCM4-CLM3.5区域气候模式运行,对东亚区2000年3月-2009年2月之间的气候变化特征进行了模拟,进而对大气CO2浓度非均匀动态分布可能引起的区域气候效应进行了初步研究.结果表明:目前气候模式中CO2浓度的常态均匀分布假设可能将温室效应夸大了10%左右.对大气CO2浓度非均匀动态分布影响气温变化的可能机制进行研究表明:CO2的自身效应(改变大气透射率)并不是导致Exp2试验温度降低的主要原因.大气CO2浓度的变化影响了大气与植物胞间CO2分压差,陆地植被通过改变气孔阻力适应这种变化,气孔阻力的变化直接影响到植物与大气间水分的交换,这种作用一方面通过蒸发冷却改变环境温度,另一方面,蒸发水分改变了近地面层湿度,进而水汽扩散到空中影响低云的分布.冬季,植物处于非生长季,对大气CO2浓度变化响应微弱,湿度和低云变化不明显;夏季,植物生长旺盛,由CO2生理学强迫激发的云反馈效应强烈,其效果是使中低云趋于增加,进而减弱了到达对流层低层的太阳短波辐射,造成温室效应减弱.%Based on the baseline concentration data of atmospheric CO2 observed from the GAW stations, considering the heterogeneous distributional characteristics of CO2 concentration among different economic regions and land use types, this paper constitutes a dynamical heterogeneous atmospheric CO2 concentration data set that varies monthly within a regional climate model domain around China. By running the RegCM4-CLM3. 5 regional climate model with the dynamic heterogeneous CO2 concentration data set, the climate change characteristics of the East Asia

  6. Saprobic microfungi under Lolium perenne and Trifolium repens at different fertilization intensities and elevated atmospheric CO2 concentration

    Czech Academy of Sciences Publication Activity Database

    Řezáčová, Veronika; Blum, H.; Hršelová, Hana; Gamper, H.; Gryndler, Milan

    2005-01-01

    Roč. 11, - (2005), s. 224-230. ISSN 1354-1013 R&D Projects: GA ČR GA526/00/1276; GA ČR GA526/03/0188; GA ČR GD206/03/H137 Institutional research plan: CEZ:AV0Z5020903 Keywords : carbon cycle * elevated CO2 * concentration Subject RIV: EE - Microbiology, Virology Impact factor: 4.075, year: 2005

  7. Dynamics of CO2 fluxes and concentrations during a shallow subsurface CO2 release

    Energy Technology Data Exchange (ETDEWEB)

    Lewicki, J.L.; Hilley, G.E.; Dobeck, L.; Spangler, L.

    2009-09-01

    A field facility located in Bozeman, Montana provides the opportunity to test methods to detect, locate, and quantify potential CO2 leakage from geologic storage sites. From 9 July to 7 August 2008, 0.3 t CO2 d{sup -1} were injected from a 100-m long, {approx}2.5 m deep horizontal well. Repeated measurements of soil CO2 fluxes on a grid characterized the spatio-temporal evolution of the surface leakage signal and quantified the surface leakage rate. Infrared CO2 concentration sensors installed in the soil at 30 cm depth at 0 to 10 m from the well and at 4 cm above the ground at 0 and 5 m from the well recorded surface breakthrough of CO2 leakage and migration of CO2 leakage through the soil. Temporal variations in CO2 concentrations were correlated with atmospheric and soil temperature, wind speed, atmospheric pressure, rainfall, and CO2 injection rate.

  8. Temperature and atmospheric CO2 concentration estimates through the PETM using triple oxygen isotope analysis of mammalian bioapatite

    Science.gov (United States)

    Gehler, Alexander; Gingerich, Philip D.; Pack, Andreas

    2016-07-01

    The Paleocene–Eocene Thermal Maximum (PETM) is a remarkable climatic and environmental event that occurred 56 Ma ago and has importance for understanding possible future climate change. The Paleocene–Eocene transition is marked by a rapid temperature rise contemporaneous with a large negative carbon isotope excursion (CIE). Both the temperature and the isotopic excursion are well-documented by terrestrial and marine proxies. The CIE was the result of a massive release of carbon into the atmosphere. However, the carbon source and quantities of CO2 and CH4 greenhouse gases that contributed to global warming are poorly constrained and highly debated. Here we combine an established oxygen isotope paleothermometer with a newly developed triple oxygen isotope paleo-CO2 barometer. We attempt to quantify the source of greenhouse gases released during the Paleocene–Eocene transition by analyzing bioapatite of terrestrial mammals. Our results are consistent with previous estimates of PETM temperature change and suggest that not only CO2 but also massive release of seabed methane was the driver for CIE and PETM.

  9. Temperature and atmospheric CO2 concentration estimates through the PETM using triple oxygen isotope analysis of mammalian bioapatite.

    Science.gov (United States)

    Gehler, Alexander; Gingerich, Philip D; Pack, Andreas

    2016-07-12

    The Paleocene-Eocene Thermal Maximum (PETM) is a remarkable climatic and environmental event that occurred 56 Ma ago and has importance for understanding possible future climate change. The Paleocene-Eocene transition is marked by a rapid temperature rise contemporaneous with a large negative carbon isotope excursion (CIE). Both the temperature and the isotopic excursion are well-documented by terrestrial and marine proxies. The CIE was the result of a massive release of carbon into the atmosphere. However, the carbon source and quantities of CO2 and CH4 greenhouse gases that contributed to global warming are poorly constrained and highly debated. Here we combine an established oxygen isotope paleothermometer with a newly developed triple oxygen isotope paleo-CO2 barometer. We attempt to quantify the source of greenhouse gases released during the Paleocene-Eocene transition by analyzing bioapatite of terrestrial mammals. Our results are consistent with previous estimates of PETM temperature change and suggest that not only CO2 but also massive release of seabed methane was the driver for CIE and PETM. PMID:27354522

  10. Leaf cavity CO2 concentrations and CO2 exchange in onion, Allium cepa L.

    Science.gov (United States)

    Byrd, G T; Loboda, T; Black, C C; Brown, R H

    1995-06-01

    Onion (Allium cepa L.) plants were examined to determine the photosynthetic role of CO2 that accumulates within their leaf cavities. Leaf cavity CO2 concentrations ranged from 2250 μL L(-1) near the leaf base to below atmospheric (CO2 concentrations with minimum values near midday and maximum values at night. Conductance to CO2 from the leaf cavity ranged from 24 to 202 μmol m(-2) s(-1) and was even lower for membranes of bulb scales. The capacity for onion leaves to recycle leaf cavity CO2 was poor, only 0.2 to 2.2% of leaf photosynthesis based either on measured CO2 concentrations and conductance values or as measured directly by (14)CO2 labeling experiments. The photosynthetic responses to CO2 and O2 were measured to determine whether onion leaves exhibited a typical C3-type response. A linear increase in CO2 uptake was observed in intact leaves up to 315 μL L(-1) of external CO2 and, at this external CO2 concentration, uptake was inhibited 35.4±0.9% by 210 mL L(-1) O2 compared to 20 mL L(-1) O2. Scanning electron micrographs of the leaf cavity wall revealed degenerated tissue covered by a membrane. Onion leaf cavity membranes apparently are highly impermeable to CO2 and greatly restrict the refixation of leaf cavity CO2 by photosynthetic tissue. PMID:24307095

  11. Effects of atmospheric CO2 enrichment on the growth and development of Hymenocallis littoralis (Amaryllidaceae) and the concentrations of several antineoplastic and antiviral constituents of its bulbs.

    Science.gov (United States)

    Idso, S B; Kimball, B A; Pettit Iii, G R; Garner, L C; Pettit, G R; Backhaus, R A

    2000-06-01

    Two 2-yr crops of tropical spider lily (Hymenocallis littoralis) plants were grown in field soil in clear-plastic-wall open-top enclosures in the Sonoran Desert environment of central Arizona. Half of the plants were exposed to ambient air of 400 ppm atmospheric CO(2) concentration and half of them were exposed to air of 700 ppm CO(2). This 75% increase in the air's CO(2) content resulted in a 48% increase in aboveground plant biomass and a 56% increase in belowground (bulb) biomass. It also increased the concentrations of five bulb constituents that have been demonstrated to possess anticancer and antiviral activities. Mean percentage increases in these concentrations were 6% for a two-constituent (1:1) mixture of 7-deoxynarciclasine and 7-deoxy-trans-dihydronarciclasine, 8% for pancratistatin, 8% for trans-dihydronarciclasine, and 28% for narciclasine, for a mean active ingredient percentage concentration increase of 12%. Combined with the 56% increase in bulb biomass, these percentage concentration increases resulted in a mean active ingredient increase of 75% for the 75% increase in the air's CO(2) concentration used in our experiments. PMID:10860907

  12. Searching for a Relationship Between Forest Water Use and Increasing Atmospheric CO2 Concentration with Long-Term Hydrologic Data from the Hubbard Brook Experimental Forest

    Energy Technology Data Exchange (ETDEWEB)

    Amthor, J.S.

    1998-11-01

    Increases in atmospheric C02 concentration from mid-1956 through mid-1997 were compared with hydrologic records from five forested, gaged watersheds in the Hubbard Brook Experimental Forest (HBEF) in New Hampshire, U.S.A. The purpose of the comparison was to assess whether a relationship between increasing atmospheric CO2 concentration and whole-ecosystem evapotranspiration (ET) could be determined. The HBEF is particularly well suited to this type of study because of the length of the hydrologic record and the physical properties of the watersheds. This analysis is based on HBEF water years (which begin 1 June and end the following 31 May) rather than calendar years. Hydrologic records from individual watersheds used in this analysis ranged from 28 to 41 water years. During the full 41-water-year period, it is estimated that water-year mean atmospheric CO2 concentration increased more than 15% (from about 314 to 363 ppm). In one south-facing watershed (i.e., HBEF watershed 3), there was a statistically significant negative relationship between atmospheric C02 concentration and ET. This translated into a nearly 77 rnndyear reduction in ET as a result of a 50 ppm increase in atmospheric C02 concentration, a result of practical significance. Evapotranspiration from the other watersheds was also negatively related to atmospheric CO2 concentration, but with smaller (and statistically insignificant) magnitudes. Evapotranspiration from the three south-facing (but not the two north-facing) watersheds included in the analysis was "abnormally" low during the most recent 2 years (i.e., water years beginning in 1995 and 1996), and this affected the trends in ET. This recent and abrupt, reduction in ET deserves further analysis, most importantly by an extension of the hydrologic record through continued long-term monitoring in the HBEF (which is ongoing). If ET remains relatively low during the coming years in south-facing watersheds, studies of the physical and/or biological

  13. Using an optimality model to understand medium and long-term responses of vegetation water use to elevated atmospheric CO2 concentrations

    Science.gov (United States)

    Schymanski, Stanislaus J.; Roderick, Michael L.; Sivapalan, Murugesu

    2015-01-01

    Vegetation has different adjustable properties for adaptation to its environment. Examples include stomatal conductance at short time scale (minutes), leaf area index and fine root distributions at longer time scales (days–months) and species composition and dominant growth forms at very long time scales (years–decades–centuries). As a result, the overall response of evapotranspiration to changes in environmental forcing may also change at different time scales. The vegetation optimality model simulates optimal adaptation to environmental conditions, based on the assumption that different vegetation properties are optimized to maximize the long-term net carbon profit, allowing for separation of different scales of adaptation, without the need for parametrization with observed responses. This paper discusses model simulations of vegetation responses to today's elevated atmospheric CO2 concentrations (eCO2) at different temporal scales and puts them in context with experimental evidence from free-air CO2 enrichment (FACE) experiments. Without any model tuning or calibration, the model reproduced general trends deduced from FACE experiments, but, contrary to the widespread expectation that eCO2 would generally decrease water use due to its leaf-scale effect on stomatal conductance, our results suggest that eCO2 may lead to unchanged or even increased vegetation water use in water-limited climates, accompanied by an increase in perennial vegetation cover. PMID:26019228

  14. Understanding urban atmospheric CO2: Challenges and Opportunities

    Science.gov (United States)

    Pataki, D. E.; Ehleringer, J. R.; Forster, C. B.; Klewicki, J. C.; Pardyjak, E. R.; Peterson, R. E.; Steenburgh, W. J.; Tyler, B. J.

    2004-12-01

    Many studies have shown that atmospheric CO2 concentrations are elevated far above ambient levels in cities due to strong local sources. Measurements of urban atmospheric CO2 mixing ratio, its isotopic composition, and its sources and sinks provide opportunities to understand the local carbon cycle and biogeochemistry of cities, which is increasingly important in studies of regional and global change as well as urban sustainability and planning. In an ongoing project in the Salt Lake Valley, Utah, measurements of CO2 mixing ratio and the isotopic composition of CO2 have shown that vehicle exhaust significantly elevates CO2 mixing ratios above ambient, particularly in the wintertime when temperature inversions create stable conditions. Natural gas combustion also makes a large contribution to CO2 mixing ratio in the winter, but becomes negligible in the summer. However, the urban "forest" in the Salt Lake Valley plays an active role in influencing CO2 mixing ratio during the spring, summer, and fall through photosynthesis and respiration. Atmospheric CO2 measurements in the Salt Lake Valley are also useful in that they correlate with air pollutants such as aerosols, particularly in the wintertime when CO2 sources are dominated by combustion. The relationship between CO2 mixing ratio and other pollutants varies as a function of fuel source (natural gas versus gasoline) and meteorological variables that affect atmospheric chemistry of reactive compounds; therefore, these relationships provide additional information about sources and sinks for atmospheric constituents. Finally, CO2 is a stable atmospheric tracer in that it does not undergo chemical transformations in the atmosphere. Measurements in the Salt Lake Valley showed that the temporal and spatial distribution of CO2 in the wintertime may provide information about atmospheric transport during complex cold pools events if mixing ratios are monitored at multiple locations. These results suggest that studies of

  15. Recent and projected increases in atmospheric CO2 concentration can enhance gene flow between wild and genetically altered rice (Oryza sativa.

    Directory of Open Access Journals (Sweden)

    Lewis H Ziska

    Full Text Available Although recent and projected increases in atmospheric carbon dioxide can alter plant phenological development, these changes have not been quantified in terms of floral outcrossing rates or gene transfer. Could differential phenological development in response to rising CO(2 between genetically modified crops and wild, weedy relatives increase the spread of novel genes, potentially altering evolutionary fitness? Here we show that increasing CO(2 from an early 20(th century concentration (300 µmol mol(-1 to current (400 µmol mol(-1 and projected, mid-21(st century (600 µmol mol(-1 values, enhanced the flow of genes from wild, weedy rice to the genetically altered, herbicide resistant, cultivated population, with outcrossing increasing from 0.22% to 0.71% from 300 to 600 µmol mol(-1. The increase in outcrossing and gene transfer was associated with differential increases in plant height, as well as greater tiller and panicle production in the wild, relative to the cultivated population. In addition, increasing CO(2 also resulted in a greater synchronicity in flowering times between the two populations. The observed changes reported here resulted in a subsequent increase in rice dedomestication and a greater number of weedy, herbicide-resistant hybrid progeny. Overall, these data suggest that differential phenological responses to rising atmospheric CO(2 could result in enhanced flow of novel genes and greater success of feral plant species in agroecosystems.

  16. Effects of high CO2 concentrations on ecophysiologically different microorganisms

    International Nuclear Information System (INIS)

    We investigated the effect of increasing CO2 concentrations on the growth and viability of ecophysiologically different microorganisms to obtain information for a leakage scenario of CO2 into shallow aquifers related to the capture and storage of CO2 in deep geological sections. CO2 concentrations in the gas phase varied between atmospheric conditions and 80% CO2 for the aerobic strains Pseudomonas putida F1 and Bacillus subtilis 168 and up to 100% CO2 for the anaerobic strains Thauera aromatica K172 and Desulfovibrio vulgaris Hildenborough. Increased CO2 concentrations caused prolonged lag-phases, and reduced growth rates and cell yields; the extent of this effect was proportional to the CO2 concentration. Additional experiments with increasing CO2 concentrations and increasing pressure (1–5000 kPa) simulated situations occurring in deep CO2 storage sites. Living cell numbers decreased significantly within 24 h at pressures ≥1000 kPa, demonstrating a severe lethal effect for the combination of high pressure and CO2. - Highlights: ► Influence of high CO2 concentration on ecophysiologically different (aerobic, nitrate-reducing, sulphate-reducing) microorganisms. ► Investigation of growth and viability of two aerobic and two anaerobic model organisms. ► CO2 treatment also at elevated pressure up to 5000 kPa. ► Reduction of growth and viability at high CO2 concentrations. ► Sterilization at high pressure and high CO2 concentrations. - Increased CO2 concentrations, combined also with high pressure, adversely affected the growth and viability of four ecophysiological different microorganisms.

  17. A role for atmospheric CO2 in preindustrial climate forcing

    NARCIS (Netherlands)

    Hoof, T.B. van; Wagner-Cremer, F.; Kürschner, W.M.; Visscher, H.

    2008-01-01

    Complementary to measurements in Antarctic ice cores, stomatal frequency analysis of leaves of land plants preserved in peat and lake deposits can provide a proxy record of preindustrial atmospheric CO2 concentration. CO2 trends based on leaf remains of Quercus robur (English oak) from the Netherlan

  18. A role for atmospheric CO2 in preindustrial climate forcing

    OpenAIRE

    Thomas B. Van Hoof; Wagner-Cremer, Friederike; Kürschner, Wolfram M.; Visscher, Henk

    2008-01-01

    Complementary to measurements in Antarctic ice cores, stomatal frequency analysis of leaves of land plants preserved in peat and lake deposits can provide a proxy record of preindustrial atmospheric CO2 concentration. CO2 trends based on leaf remains of Quercus robur (English oak) from the Netherlands support the presence of significant CO2 variability during the first half of the last millennium. The amplitude of the reconstructed multidecadal fluctuations, up to 34 parts per million by volu...

  19. Rising atmospheric CO2 is reducing the protein concentration of a floral pollen source essential for North American bees.

    Science.gov (United States)

    Ziska, Lewis H; Pettis, Jeffery S; Edwards, Joan; Hancock, Jillian E; Tomecek, Martha B; Clark, Andrew; Dukes, Jeffrey S; Loladze, Irakli; Polley, H Wayne

    2016-04-13

    At present, there is substantive evidence that the nutritional content of agriculturally important food crops will decrease in response to rising levels of atmospheric carbon dioxide, Ca However, whether Ca-induced declines in nutritional quality are also occurring for pollinator food sources is unknown. Flowering late in the season, goldenrod (Solidago spp.) pollen is a widely available autumnal food source commonly acknowledged by apiarists to be essential to native bee (e.g. Bombus spp.) and honeybee (Apis mellifera) health and winter survival. Using floral collections obtained from the Smithsonian Natural History Museum, we quantified Ca-induced temporal changes in pollen protein concentration of Canada goldenrod (Solidago canadensis), the most wide spread Solidago taxon, from hundreds of samples collected throughout the USA and southern Canada over the period 1842-2014 (i.e. a Ca from approx. 280 to 398 ppm). In addition, we conducted a 2 year in situtrial of S. Canadensis populations grown along a continuous Ca gradient from approximately 280 to 500 ppm. The historical data indicated a strong significant correlation between recent increases in Ca and reductions in pollen protein concentration (r(2)= 0.81). Experimental data confirmed this decrease in pollen protein concentration, and indicated that it would be ongoing as Ca continues to rise in the near term, i.e. to 500 ppm (r(2)= 0.88). While additional data are needed to quantify the subsequent effects of reduced protein concentration for Canada goldenrod on bee health and population stability, these results are the first to indicate that increasing Ca can reduce protein content of a floral pollen source widely used by North American bees. PMID:27075256

  20. Regional Ecosystem-Atmosphere CO2 Exchange Via Atmospheric Budgets

    Energy Technology Data Exchange (ETDEWEB)

    Davis, K J; Richardson, S J; Miles, N L

    2007-03-07

    are captured. Influence functions, derived using a Lagrangian Particle Dispersion model driven by the CSU Regional Atmospheric Modeling System and nudged to NCEP reanalysis meteorological fields, are used to determine source regions for the towers. The influence functions are combined with satellite vegetation observations to interpret the observed trends in CO2 concentration. Full inversions will combine these elements in a more formal analytic framework.

  1. Detection of CO2 leaks from carbon capture and storage sites with combined atmospheric CO2 and O-2 measurements

    NARCIS (Netherlands)

    van Leeuwen, Charlotte; Meijer, Harro A. J.

    2015-01-01

    This paper presents a transportable instrument that simultaneously measures the CO2 and (relative) O-2 concentration of the atmosphere with the purpose to aid in the detection of CO2 leaks from CCS sites. CO2 and O-2 are coupled in most processes on earth (e.g., photosynthesis, respiration and fossi

  2. Development of an atmospheric fossil fuel CO2 monitoring station

    International Nuclear Information System (INIS)

    Complete text of publication follows. The aim of the project supported by Hungarian NSF (ref No. F69029) is determination of atmospheric fossil fuel CO2 concentration in major cities or average industrial regions in Hungary using together measurement of CO2 mixing ratio and radiocarbon (14C) content of the air. For this aim we developed a high precision atmospheric CO2 monitoring station in ATOMKI (Figure 1.). The station's measuring system is based on an Ultramat 6F (Siemens) infrared gas analyser. To help continuous, unattended run and autocalibration we built up an automatic gas handling line for the analyzer. For radiocarbon measurements we applied an integrating sampling system. One was installed in Debrecen station and two independent 14CO2 sampling line were installed 400 km far from Debrecen at Hegyhatsal station as background references. During several tests of the measuring and sampling systems we demonstrated that uncertainty of individual CO2 mixing ratio results is less than 0.5 ppm and the applied radiocarbon sampling system developed by ATOMKI works with good reproducibility. In September and October of 2008 we measured the mixing ratio and radiocarbon content of atmospheric CO2 at Debrecen and the far rural reference station (Hegyhatsal) simultaneously. It was concluded that trends in CO2 mixing ratio variations in time are very similar at the three different sampling points (2 m above ground in Debrecen, 10 m and 115 m above ground in Hegyhatsal). Air quality in Debrecen during September of 2008 seemed to be relatively clear from the point of view of its CO2 content at least. When winter came in October, with lower outside temperature and less sunshine hours the CO2 content of air was increased in general at all the three sampling points, but this effect was more intensive closer to the ground level. According our radiocarbon observations it was clearly indicated that there was not significant amount of fossil fuel CO2 in the air of Debrecen during

  3. A joint effort to deliver satellite retrieved atmospheric CO2 concentrations for surface flux inversions: the ensemble median algorithm EMMA

    Directory of Open Access Journals (Sweden)

    R. Parker

    2013-02-01

    Full Text Available We analyze an ensemble of seven XCO2 retrieval algorithms for SCIAMACHY (scanning imaging absorption spectrometer of atmospheric chartography and GOSAT (greenhouse gases observing satellite. The ensemble spread can be interpreted as regional uncertainty and can help to identify locations for new TCCON (total carbon column observing network validation sites. Additionally, we introduce the ensemble median algorithm EMMA combining individual soundings of the seven algorithms into one new data set. The ensemble takes advantage of the algorithms' independent developments. We find ensemble spreads being often < 1 ppm but rising up to 2 ppm especially in the tropics and East Asia. On the basis of gridded monthly averages, we compare EMMA and all individual algorithms with TCCON and CarbonTracker model results (potential outliers, north/south gradient, seasonal (peak-to-peak amplitude, standard deviation of the difference. Our findings show that EMMA is a promising candidate for inverse modeling studies. Compared to CarbonTracker, the satellite retrievals find consistently larger north/south gradients (by 0.3–0.9 ppm and seasonal amplitudes (by 1.5–2.0 ppm.

  4. Stable isotope measurements of atmospheric CO2

    International Nuclear Information System (INIS)

    The measurement of stable carbon isotope ratios of atmospheric carbon dioxide, δ13CO2 are useful for partitioning surface-atmospheric fluxes into terrestrial and oceanic components. δC18OO also has potential for segregating photosynthetic and respiratory fluxes in terrestrial ecosystems. Here we describe in detail the techniques for making these measurements. The primary challenge for all of the techniques used to measure isotopes of atmospheric CO2 is to achieve acceptable accuracy and precision and to maintain them over the decades needed to observe carbon cycle variability. The keys to success such an approach are diligent intercalibrations of laboratories from around the world, as well as the use of multiple techniques such as dual inlet and GC-IRMS and the intercomparison of such measurements. We focus here on two laboratories, the Stable Isotope Lab at the Institute for Arctic and Alpine Research (INSTAAR) at the University of Colorado is described and the Commonwealth Scientific and Industrial Research Organisation - Atmospheric Research (CSIRO). Different approaches exist at other laboratories (e.g. programs operated by Scripps Institution of Oceanography (SIO) and The Center for Atmospheric and Oceanic Studies, Toboku University (TU)) however these are not discussed here. Finally, we also discuss the recently developed Gas Chromatography - Isotope Ratio Mass Spectrometry (GC-IRMS) technique which holds significant promise for measuring ultra-small samples of gas with good precision. (author)

  5. A 40-million-year history of atmospheric CO(2).

    Science.gov (United States)

    Zhang, Yi Ge; Pagani, Mark; Liu, Zhonghui; Bohaty, Steven M; Deconto, Robert

    2013-10-28

    The alkenone-pCO2 methodology has been used to reconstruct the partial pressure of ancient atmospheric carbon dioxide (pCO2) for the past 45 million years of Earth's history (Middle Eocene to Pleistocene epochs). The present long-term CO2 record is a composite of data from multiple ocean localities that express a wide range of oceanographic and algal growth conditions that potentially bias CO2 results. In this study, we present a pCO2 record spanning the past 40 million years from a single marine locality, Ocean Drilling Program Site 925 located in the western equatorial Atlantic Ocean. The trends and absolute values of our new CO2 record site are broadly consistent with previously published multi-site alkenone-CO2 results. However, new pCO2 estimates for the Middle Miocene are notably higher than published records, with average pCO2 concentrations in the range of 400-500 ppm. Our results are generally consistent with recent pCO2 estimates based on boron isotope-pH data and stomatal index records, and suggest that CO2 levels were highest during a period of global warmth associated with the Middle Miocene Climatic Optimum (17-14 million years ago, Ma), followed by a decline in CO2 during the Middle Miocene Climate Transition (approx. 14 Ma). Several relationships remain contrary to expectations. For example, benthic foraminiferal δ(18)O records suggest a period of deglaciation and/or high-latitude warming during the latest Oligocene (27-23 Ma) that, based on our results, occurred concurrently with a long-term decrease in CO2 levels. Additionally, a large positive δ(18)O excursion near the Oligocene-Miocene boundary (the Mi-1 event, approx. 23 Ma), assumed to represent a period of glacial advance and retreat on Antarctica, is difficult to explain by our CO2 record alone given what is known of Antarctic ice sheet history and the strong hysteresis of the East Antarctic Ice Sheet once it has grown to continental dimensions. We also demonstrate that in the

  6. Improved Instrumentation for the Detection of Atmospheric CO2 Concentration using an Airborne IPDA LIDAR for 2014 NASA ASCENDS Science Campaign

    Science.gov (United States)

    Allan, G. R.; Riris, H.; Hasselbrack, W. E.; Rodriguez, M.; Ramanathan, A. K.; Sun, X.; Mao, J.; Abshire, J. B.

    2014-12-01

    NASA-GSFC is developing a twin-channel, Integrated-Path, Differential Absorption (IPDA) lidar to measure atmospheric CO2 from space as a candidate for NASA's ASCENDS mission (Active Sensing of CO2 Emissions over Nights, Days, and Seasons). This lidar consists of two independent, tuned, pulsed transmitters on the same optical bench using a common 8" receiver telescope. The system measures CO2 abundance and O2 surface pressure in the same column to derive the dry volume mixing ratio (vmr). The system is being tested on an airborne platform up to altitudes of 13 Km. The lidar uses a cw scanning laser, externally pulsed and a fiber amplifier in a Master Oscillator Power Amplifier (MOPA) configuration to measure lineshape, range to scattering surfaces and backscatter profiles. The CO2 operates at 1572.335 nm. The O2 channel uses similar technology but frequency doubles to the O2 A-band absorption, around 765nm. Both lasers are scanned across the absorption feature measuring at a fixed number of discrete (~30) wavelengths per scan around ~300 scans/s. Each output pulse is slightly chirped 80%, linear over five decades is now used for CO2 channel. We have increased spatial resolution by an order of magnitude using 0.1s along track integration. The increased signal, negligible nonlinear response and increased spatial resolution will improve our CO2 retrievals. We will discuss the improvements and effects on the retrievals from the Summer 2014 ASCENDS Science campaign.

  7. Trend, seasonal and diurnal variations of atmospheric CO2 in Beijing

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The concentration of atmospheric CO2 in Beijing increased rapidly at a mean growth rate of 3.7%@a?1 from 1993 to 1995. After displaying a peak of (409.7±25.9) ?mol@mol?1 in 1995, it decreased slowly. Both the almost stable anthropogenic CO2 source and increasing biotic CO2 sink contribute to the drop of CO2 concentration from 1995 to 2000. The seasonal variation of CO2 concentration exhibits a clear cycle with a maximum in winter, averaging (426.8±20.6) ?mol@mol?1, and a minimum in summer, averaging (369.1±6.1) ?mol@mol?1. The seasonal variation of CO2 concentration is mainly controlled by phenology. The mean diurnal variation of atmospheric CO2 concentration for a year in Beijing is highly clear: daily maximum CO2 concentration usually occurs at night, but daily minimum CO2 concentration does in the daytime, with a mean diurnal difference more than 34.7 ?mol@mol?1. It has been revealed that the interannual variations of atmospheric CO2 concentration in winter and autumn regulated the interannual trend of atmospheric CO2, whereas the interannual variation of CO2 concentration in summer affected the general tendency of atmospheric CO2 in a less degree.

  8. A role for atmospheric CO2 in preindustrial climate forcing.

    Science.gov (United States)

    van Hoof, Thomas B; Wagner-Cremer, Friederike; Kürschner, Wolfram M; Visscher, Henk

    2008-10-14

    Complementary to measurements in Antarctic ice cores, stomatal frequency analysis of leaves of land plants preserved in peat and lake deposits can provide a proxy record of preindustrial atmospheric CO(2) concentration. CO(2) trends based on leaf remains of Quercus robur (English oak) from the Netherlands support the presence of significant CO(2) variability during the first half of the last millennium. The amplitude of the reconstructed multidecadal fluctuations, up to 34 parts per million by volume, considerably exceeds maximum shifts measured in Antarctic ice. Inferred changes in CO(2) radiative forcing are of a magnitude similar to variations ascribed to other mechanisms, particularly solar irradiance and volcanic activity, and may therefore call into question the concept of the Intergovernmental Panel on Climate Change, which assumes an insignificant role of CO(2) as a preindustrial climate-forcing factor. The stomata-based CO(2) trends correlate with coeval sea-surface temperature trends in the North Atlantic Ocean, suggesting the possibility of an oceanic source/sink mechanism for the recorded CO(2) changes. PMID:18838689

  9. Response of atmospheric CO2 to changes in land use

    International Nuclear Information System (INIS)

    This chapter examines how different histories of CO2 release from past changes in land use influence the simulation of past and future changes in atmospheric CO2. The authors first simulate past change in atmospheric CO2 using reconstructed histories of land-use CO2 release from a historical-ecological model of land-use change and CO2 release. They examine the impact of each history on the coincidence between simulated and observed atmospheric CO2. They then compare these CO2 release histories, and their contribution to coincidence or noncoincidence of simulation and observation, with histories reconstructed by deconvolution of the atmospheric CO2 record. They conclude by exploring the implications of these deconvolved reconstructions for the simulation of future changes in atmospheric CO2

  10. The effect of elevated atmospheric CO2 concentration on gross nitrogen and carbon dynamics in a permanent grassland: A field pulse-labeling study

    Science.gov (United States)

    Moser, Gerald; Gorenflo, André; Keidel, Lisa; Brenzinger, Kristof; Elias, Dafydd; McNamara, Niall; Maček, Irena; Vodnik, Dominik; Braker, Gesche; Schimmelpfennig, Sonja; Gerstner, Judith; Müller, Christoph

    2014-05-01

    To predict ecosystem reactions to elevated atmospheric CO2 (eCO2) it is essential to understand the interactions between plant carbon input, microbial community composition and activity and associated nutrient dynamics. Long-term observations (> 14 years) within the Giessen Free Air Carbon dioxide Enrichment (Giessen FACE) study on permanent grassland showed next to an enhanced biomass production an unexpected strong positive feedback effect on ecosystem respiration and nitrous oxide (N2O) production. The overall goal of this study is to understand the long-term effects of eCO2 and carbon input on microbial community composition and activity as well as the associated nitrogen dynamics, N2O production and plant N uptake in the Giessen FACE study on permanent grassland. A combination of 13CO2 pulse labelling with 15N tracing of 15NH4+ and 15NO3- was carried out in situ. Different fractions of soil organic matter (recalcitrant, labile SOM) and the various mineral N pools in the soil (NH4+, NO3-), gross N transformation rates, pool size dependent N2O and N2 emissions as well as N species dependent plant N uptake rates and the origin of the CO2 respiration have been quantified. Microbial analyses include exploring changes in the composition of microbial communities involved in the turnover of NH4+, NO3-, N2O and N2, i.e. ammonia oxidizing, denitrifying, and microbial communities involved in dissimilatory nitrate reduction to ammonia (DNRA). mRNA based analyses will be employed to comparably evaluate the long-term effects of eCO2 on the structure and abundance of these communities, while transcripts of these genes will be used to target the fractions of the communities which actively contribute to N transformations. We quantified the contribution of mycorrhizae on N2O emissions and observed the phenological development of the mycorrhizae after the labeling.

  11. Towards robust regional estimates of CO_2 sources and sinks using atmospheric transport models

    OpenAIRE

    Gurney, Kevin Robert; Randerson, James

    2002-01-01

    Information about regional carbon sources and sinks can be derived from variations in observed atmospheric CO_2 concentrations via inverse modelling with atmospheric tracer transport models. A consensus has not yet been reached regarding the size and distribution of regional carbon fluxes obtained using this approach, partly owing to the use of several different atmospheric transport models. Here we report estimates of surface–atmosphere CO_2 fluxes from an intercomparison of atmospheric CO_2...

  12. C4 Photosynthesis (The CO2-Concentrating Mechanism and Photorespiration).

    Science.gov (United States)

    Dai, Z.; Ku, MSB.; Edwards, G. E.

    1993-09-01

    Despite previous reports of no apparent photorespiration in C4 plants based on measurements of gas exchange under 2 versus 21% O2 at varying [CO2], photosynthesis in maize (Zea mays) shows a dual response to varying [O2]. The maximum rate of photosynthesis in maize is dependent on O2 (approximately 10%). This O2 dependence is not related to stomatal conductance, because measurements were made at constant intercellular CO2 concentration (Ci); it may be linked to respiration or pseudocyclic electron flow. At a given Ci, increasing [O2] above 10% inhibits both the rate of photosynthesis, measured under high light, and the maximum quantum yield, measured under limiting light ([phi]CO2). The dual effect of O2 is masked if measurements are made under only 2 versus 21% O2. The inhibition of both photosynthesis and [phi]CO2 by O2 (measured above 10% O2) with decreasing Ci increases in a very similar manner, characteristically of O2 inhibition due to photorespiration. There is a sharp increase in O2 inhibition when the Ci decreases below 50 [mu]bar of CO2. Also, increasing temperature, which favors photorespiration, causes a decrease in [phi]CO2 under limiting CO2 and 40% O2. By comparing the degree of inhibition of photosynthesis in maize with that in the C3 species wheat (Triticum aestivum) at varying Ci, the effectiveness of C4 photosynthesis in concentrating CO2 in the leaf was evaluated. Under high light, 30[deg]C, and atmospheric levels of CO2 (340 [mu]bar), where there is little inhibition of photosynthesis in maize by O2, the estimated level of CO2 around ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) in the bundle sheath compartment was 900 [mu]bar, which is about 3 times higher than the value around Rubisco in mesophyll cells of wheat. A high [CO2] is maintained in the bundle sheath compartment in maize until Ci decreases below approximately 100 [mu]bar. The results from these gas exchange measurements indicate that photorespiration occurs in maize but

  13. Tomato–Pseudomonas syringae interactions under elevated CO2 concentration: the role of stomata

    OpenAIRE

    Xin LI; Sun, Zenghui; Shao, Shujun; Zhang, Shuai; Ahammed, Golam Jalal; Zhang, Guanqun; Jiang, Yuping; Zhou, Jie; Xia, Xiaojian; Zhou, Yanhong; Yu, Jingquan; Shi, Kai

    2014-01-01

    Increasing atmospheric CO2 concentrations ([CO2]) in agricultural and natural ecosystems is known to reduce plant stomatal opening, but it is unclear whether these CO2-induced stomatal alterations are associated with foliar pathogen infections. In this study, tomato plants were grown under ambient and elevated [CO2] and inoculated with Pseudomonas syringae pv. tomato strain DC3000, a strain that is virulent on tomato plants. We found that elevated [CO2] enhanced tomato defence against P. syri...

  14. Analysis of Source and Concentration Variations of Atmospheric CO2 in East Asia in 1 994-201 0%1994-2010年东亚地区CO2浓度变化特征及成因分析

    Institute of Scientific and Technical Information of China (English)

    解淑艳; 王胜杰; 王瑞斌

    2014-01-01

    Based on observed atmospheric CO2 concentrations at 5 background stations in East Asia since 1 994,temporal and spatial variation characteristics and changesand impacts of the anthropogenic sourcesof atmospheric CO2 are analyzed.Results reveal that the annual average CO2 concentrations showed a clear upward trend,the concentration increased by 8.4% ~9.0% in 201 0 compared with 1 994.Monthly average CO2 concentrations exhibit strong seasonal variations.The higher values prefer to present in cold seasons such as winter and spring,while the lower values appear mostly in summer seasons in northern hemisphere.Reducing the fossil fuel consumption,increasing the forest coverage and improving the agricultural coverage will help reduce the mean CO2 concentration in the atmosphere.%在东亚地区选取5个大气本底观测站1994年以来观测的 CO2监测资料,分析了各站大气 CO2的时空变化特征,以及 CO2主要人为源的变化及其影响。结果表明,5个本底站大气 CO2年均值均呈明显升高趋势,2010年较1994年增长幅度为8.4%~9.0%;在北半球国家,CO2月均值有明显的季节变化,高值多出现在冬春等寒冷季节,低值多出现在夏季。减少化石燃料消耗量、增加森林覆盖率及农业覆盖率将对大气中 CO2有削减作用。

  15. Energy implications of future stabilization of atmospheric CO2 content

    International Nuclear Information System (INIS)

    The United Nations Framework Convention on Climate Change calls for ''stabilization of greenhouse-gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system...''. A standard baseline scenario that assumes no policy intervention to limit greenhouse-gas emissions has 10 TW (10 x 1012 watts) of carbon-emission-free power being produced by the year 2050, equivalent to the power provided by all today's energy sources combined. Here we employ a carbon-cycle/energy model to estimate the carbon-emission-free power needed for various atmospheric CO2 stabilization scenarios. We find that CO2 stabilization with continued economic growth will require innovative, cost-effective and carbon-emission-free technologies that can provide additional tens of terawatts of primary power in the coming decades, and certainly by the middle of the twenty-first century, even with sustained improvement in the economic productivity of primary energy. (author)

  16. Upconversion-based lidar measurements of atmospheric CO2

    DEFF Research Database (Denmark)

    Høgstedt, Lasse; Fix, Andreas; Wirth, Martin;

    2016-01-01

    For the first time an upconversion based detection scheme is demonstrated for lidar measurements of atmospheric CO2-concentrations, with a hard target at a range of 3 km and atmospheric backscatter from a range of similar to 450 m. The pulsed signals at 1572 nm are upconverted to 635 nm, and dete...... analyzed how the field-of-view of a receiver system, for long range detection, depends critically on the parameters for the nonlinear upconversion process, and how to optimize these parameters in future systems. (C) 2016 Optical Society of America...

  17. Biomass burial and storage to reduce atmospheric CO2

    Science.gov (United States)

    Zeng, N.

    2012-04-01

    To mitigate global climate change, a portfolio of strategies will be needed to keep the atmospheric CO2 concentration below a dangerous level. Here a carbon sequestration strategy is proposed in which certain dead or live trees are harvested via collection or selective cutting, then buried in trenches or stowed away in above-ground shelters. The largely anaerobic condition under a sufficiently thick layer of soil will prevent the decomposition of the buried wood. Because a large flux of CO2 is constantly being assimilated into the world's forests via photosynthesis, cutting off its return pathway to the atmosphere forms an effective carbon sink. It is estimated that a theoretical carbon sequestration potential for wood burial is 10 ± 5 GtC/y, but probably 1-3 GtC/y can be realized in practice. Burying wood has other benefits including minimizing CO2 source from deforestation, extending the lifetime of reforestation carbon sink, and reducing fire danger. There are possible environmental impacts such as nutrient lock-up which nevertheless appears manageable, but other environmental concerns and factors will likely set a limit so that only part of the full potential can be realized. Based on data from forest industry, the cost for wood burial is estimated to be 14/tCO2 (50/tC), lower than the typical cost for power plant CO2 capture with geological storage. The low cost for carbon sequestration with wood burial is possible because the technique uses the natural process of photosynthesis to remove carbon from the atmosphere. The technique is low tech, distributed, safe, and can be stopped at any time, thus an attractive option for large-scale implementation in a world-wide carbon market.

  18. 西安城区大气CO2浓度的变化特征及趋势研究%Study of Variation Characteristics and Trend of Atmospheric CO2 Concentration

    Institute of Scientific and Technical Information of China (English)

    王帆; 王照; 李文韬

    2015-01-01

    为了解西安市大气中CO2的特征,于东仪路烈士陵园对CO2进行了2011年~2013年的连续观测.结果表明,西安大气中CO2浓度的日变化大致呈现双峰趋势;同时,CO2浓度随季节变化明显,12月最高6~8月最低;2011~2013年间,CO2浓度和每年增幅均呈上升趋势.研究表明,西安大气中CO2主要来源于化石燃料燃烧等人为源,采暖季浓度明显高于非采暖季且日变化规律存在差异,机动车尾气的排放对CO2浓度每日的第二个峰值形成有重要影响.并采用SPSS软件对西安市2020年的CO2浓度做预测分析,其中私家车保有量和绿化面积对CO2浓度有直接影响.

  19. Constraints on the atmospheric CO2 deglacial rise based on its δ13CO2 evolution

    OpenAIRE

    Lourantou, A.; Lavric, J. V.; Köhler, Peter; Barnola, J.-M.; Michel, E.; Paillard, D.; D. Raynaud; Chappellaz, J.

    2009-01-01

    The analysis of air bubbles trapped in polar ice permits the reconstruction of atmospheric evolution of greenhouse gases, such as carbon dioxide (CO2 ), on various timescales. Within this study, the simultaneous analysis of the CO2 mixing ratio and its stable carbon isotope composition (δ 13 CO2 ) over the last two deglaciations allows us to better constrain the global carbon cycle. Based on the different isotopic signatures of the ocean and the terrestrial biosphere (major reservoirs re...

  20. Simulated effect of calcification feedback on atmospheric CO2 and ocean acidification

    Science.gov (United States)

    Zhang, Han; Cao, Long

    2016-02-01

    Ocean uptake of anthropogenic CO2 reduces pH and saturation state of calcium carbonate materials of seawater, which could reduce the calcification rate of some marine organisms, triggering a negative feedback on the growth of atmospheric CO2. We quantify the effect of this CO2-calcification feedback by conducting a series of Earth system model simulations that incorporate different parameterization schemes describing the dependence of calcification rate on saturation state of CaCO3. In a scenario with SRES A2 CO2 emission until 2100 and zero emission afterwards, by year 3500, in the simulation without CO2-calcification feedback, model projects an accumulated ocean CO2 uptake of 1462 PgC, atmospheric CO2 of 612 ppm, and surface pH of 7.9. Inclusion of CO2-calcification feedback increases ocean CO2 uptake by 9 to 285 PgC, reduces atmospheric CO2 by 4 to 70 ppm, and mitigates the reduction in surface pH by 0.003 to 0.06, depending on the form of parameterization scheme used. It is also found that the effect of CO2-calcification feedback on ocean carbon uptake is comparable and could be much larger than the effect from CO2-induced warming. Our results highlight the potentially important role CO2-calcification feedback plays in ocean carbon cycle and projections of future atmospheric CO2 concentrations.

  1. [Advances in research on CO2 concentrating mechanism of green algae].

    Science.gov (United States)

    Xia, Jianrong; Gao, Kunshan

    2002-11-01

    Unicellular green algae plays a key role in freshwater ecosystem, which possesses a CO2 concentrating mechanism that can increase the level of CO2 at the active site of ribulose bisphosphate carboxylase-oxygenase (Rubisco) by actively transporting inorganic carbon when adapted to low CO2 concentration. The mechanism results in an increase in photosynthetic rate, and a decrease in photorespiration. This mechanism and its environmental regulation such as light, temperature, CO2 concentration and nutrient are reviewed in this paper to enhance further studies on response of phytoplankton to elevated atmospheric CO2 concentration in China. PMID:12625019

  2. Towards robust regional estimates of CO2 sources and sinks using atmospheric transport models

    OpenAIRE

    Randerson, JT; Gurney, KR; Law, RM; Denning, AS; Rayner, PJ; Baker, D.; Bousquet, P.; Bruhwiler, L.; Chen, YH; Ciais, P.; Fan, S.; Fung, IY; Gloor, M.; Heimann, M.; Higuchi, K

    2002-01-01

    Information about regional carbon sources and sinks can be derived from variations in observed atmospheric CO2 concentrations via inverse modelling with atmospheric tracer transport models. A consensus has not yet been reached regarding the size and distribution of regional carbon fluxes obtained using this approach, partly owing to the use of several different atmospheric transport models(1-9). Here we report estimates of surface- atmosphere CO2 fluxes from an intercomparison of atmospheric ...

  3. The Global Land-Ocean Temperature Index in Relation to Sunspot Number, the Atlantic Multidecadal Oscillation Index, the Mauna Loa Atmospheric Concentration of CO2, and Anthropogenic Carbon Emissions

    Science.gov (United States)

    Wilson, Robert M.

    2013-01-01

    Global warming/climate change has been a subject of scientific interest since the early 19th century. In particular, increases in the atmospheric concentration of carbon dioxide (CO2) have long been thought to account for Earth's increased warming, although the lack of a dependable set of observational data was apparent as late as the mid 1950s. However, beginning in the late 1950s, being associated with the International Geophysical Year, the opportunity arose to begin accurate continuous monitoring of the Earth's atmospheric concentration of CO2. Consequently, it is now well established that the atmospheric concentration of CO2, while varying seasonally within any particular year, has steadily increased over time. Associated with this rising trend in the atmospheric concentration of CO2 is a rising trend in the surface-air and sea-surface temperatures (SSTs). This Technical Publication (TP) examines the statistical relationships between 10-year moving averages (10-yma) of the Global Land-Ocean Temperature Index (GLOTI), sunspot number (SSN), the Atlantic Multidecadal Oscillation (AMO) index, and the Mauna Loa CO2 (MLCO2) index for the common interval 1964-2006, where the 10-yma values are used to indicate trends in the data. Scatter plots using the 10-yma values between GLOTI and each of the other parameters are determined, both as single-variate and multivariate fits. Scatter plots are also determined for MLCO2 using single-variate and bivariate (BV) fits, based on the GLOTI alone and the GLOTI in combination with the AMO index. On the basis of the inferred preferential fits for MLCO2, estimates for MLCO2 are determined for the interval 1885-1964, thereby yielding an estimate of the preindustrial level of atmospheric concentration of CO2. Lastly, 10-yma values of MLCO2 are compared against 10-yma estimates of the total carbon emissions (TCE) to determine the likelihood that manmade sources of carbon emissions are indeed responsible for the recent warming now

  4. Atmospheric CO2 and climate: Importance of the transient response

    International Nuclear Information System (INIS)

    Preliminary studies suggest that the thermal inertia of the upper layers of the oceans, combined with vertical mixing of deeper oceanic waters, could delay the response of the globally averaged surface temperature to an increasing atmospheric CO2 concentration by a decade or so relative to equilibrium calculations. This study extends the global analysis of the transient response to zonal averages, using a hierarchy of simple energy balance models and vertical mixing assumptions for water exchange between upper and deeper oceanic layers. It is found that because of the latitudinal dependence of both thermal inertia and radiative and dynamic energy exchange mechanisms, the approach toward equilibrium of the surface temperature of various regions of the earth will be significantly different from the global average approach. This suggests that the actual time evolution of the horizontal surface temperature gradients--and any associated regional climatic anomalies-may well be significantly different from that suggested by equilibrium climatic modeling simulations (or those computed with a highly unrealistic geographic distribution of ocean thermal capacity). Also, the transient response as a function of latitude is significantly different between globally equivalent CO2 and solar constant focusing runs. It is suggested that the nature of the transient response is a major uncertainty in characterizing the CO2 problem and that study of this topic should become a major priority for future research. An appendix puts this issue in the context of the overall CO2 problem

  5. 太阳光谱对高分辨吸收光谱反演大气CO2浓度影响的研究%Study on the Effect of Solar Spectra on the Retrieval of Atmospheric CO2 Concentration Using High Resolution Absorption Spectra

    Institute of Scientific and Technical Information of China (English)

    胡振华; 黄腾; 王颖萍; 丁蕾; 郑海洋; 方黎

    2011-01-01

    以太阳光为辐射源的近红外波段高分辨率吸收光谱广泛应用于大气参数遥测.以CO2浓度反演为例,研究了太阳光谱分辨率的影响.利用美国AER公司编制的太阳光谱计算程序得到大气上界的理论计算太阳光谱作为辐射源,结合自行编制的高分辨率大气透过率模拟软件HRATS对大气中CO2平均浓度进行模拟反演.数值模拟计算结果表明,太阳光谱的准确度对浓度反演非常重要,特别是在超分辨光谱反演中异常重要,虽然反演浓度的偏差与观测分辨率没有明显的线性变化规律,但有趋势:观测分辨率的降低对太阳光谱分辨率的要求也降低,为了精确反演大气中CO2浓度,因此需要充分利用大气层顶的高分辨太阳辐射光谱数据.%Taking solar source as radiation in the near-infrared high-resolution absorption spectrum is widely used in remote sensing of atmospheric parameters. The present paper will take retrieval of the concentration of CO2 for example, and study the effect of solar spectra resolution. Retrieving concentrations of CO2 by using high resolution absorption spectra, a method which uses the program provided by AER to calculate the solar spectra at the top of atmosphere as radiation and combine with the HRATS (high resolution atmospheric transmission simulation) to simulate retrieving concentration of CO2. Numerical simulation shows that the accuracy of solar spectrum is important to retrieval, especially in the hyper-resolution spectral retrieavl, and the error of retrieval concentration has poor linear relation with the resolution of observation, but there is a tendency that the decrease in the resolution requires low resolution of solar spectrum. In order to retrieve the concentration of CO2 of atmosphere, the authors' should take full advantage of high-resolution solar spectrum at the top of atmosphere

  6. Regulation of senescence under elevated atmospheric CO2 via ubiquitin modification

    OpenAIRE

    Aoyama, Shoki; Lu, Yu; Yamaguchi, Junji; Sato, Takeo

    2014-01-01

    Elevated atmospheric CO2 concentration is a serious global environmental problem. Elevated CO2 affects plant growth by changing primary metabolism, closely related to carbon (C) and nitrogen (N) availability. Under sufficient N conditions, plant growth is dramatically promoted by elevated CO2. When N availability is limited, however, elevated CO2 disrupts the balance between cellular C and N (C/N). Disruption of the C/N balance is regarded as an important factor in plant growth defects. Here ...

  7. Long-term observations of atmospheric CO2 and carbon isotopes at continental sites in Germany

    OpenAIRE

    LEVIN Ingeborg; Graul, Rolf; Trivett, Neil

    1995-01-01

    A network for regional atmospheric CO2 observations had already been established in Germany by 1972, consisting of 5 stations with basically different characteristics: Westerland, a coastal station at the North Sea, 2 regional stations, Waldhof and Deuselbach, as well as 2 mountain stations, Brotjacklriegel at the eastern border of Germany and Schauinsland in the Black Forest. In addition to CO2 concentration observations, from 1977 onwards quasi-continuous 13CO2 and 14CO2 measurements were p...

  8. Long-term observations of atmospheric CO2 and carbon isotopes at continental sites in Germany

    OpenAIRE

    LEVIN Ingeborg; Graul, Rolf; TRIVETT, NEIL B. A.

    2011-01-01

    A network for regional atmospheric CO2 observations had already been established in Germany by 1972, consisting of 5 stations with basically different characteristics: Westerland, a coastal station at the North Sea, 2 regional stations, Waldhof and Deuselbach, as well as 2 mountain stations, Brotjacklriegel at the eastern boarder of Germany and Schauinsland in the Black Forest. In addition to CO2 concentration observations, from 1977 onwards quasi-continuous 13CO2 and 14CO2 measurements were ...

  9. Effects of Controlled Atmospheres with High-O2 or High-CO2 Concentrations on Postharvest Physiology and Storability of "Napoleon" Sweet Cherry%高O2或高CO2浓度气调贮藏对"那翁"甜樱桃采后生理和贮藏性的影响

    Institute of Scientific and Technical Information of China (English)

    姜爱丽; 田世平; 徐勇

    2002-01-01

    Sweet cherries ( Prunus avium L. cv. Napoleon) were stored in controlled atmospheres (CA) of high O2 (70% O2+0% CO2) or high CO2 (5% O2+10% CO2), in modified atmosphere package (MAP, (13%-18%) O2+(2%-4%) CO2) and in air (control) at 1 ℃ to investigate the effects of different O2 and CO2 concentrations on physiological properties, quality and storability of the fruits during storage. The results indicated that compared with other treatments, CA with high O2 concentration decreased fruit decay and ethanol content, but increased the accumulation of malondialdehyde (MDA) and stimulated browning. CA with high CO2 concentration inhibited polyphenol oxidase (PPO) activity, reduced MDA content, maintained vitamin C content and firmness, decreased fruit decay and browning. Soluble solids contents (SSC) were not significantly affected by different atmosphere treatments. "Napoleon" fruits stored in 5% O2+10% CO2 for as long as 80 d were of good quality, but only 40, 20 and 30 d stored in MAP, 70% O2+ 0% CO2 and air, respectively.%研究了甜樱桃品种"那翁" ( Prunus avium L. cv. Napoleon)在1 ℃的高O2 浓度气调(CA-I: 70% O2+0% CO2)、高CO2 浓度气调 (CA-II: 5% O2+10% CO2)、自发气调 (modified atmosphere package, MAP) 和普通冷藏条件下果实生理、品质、耐藏性的变化.结果表明:与其他处理相比,高O2 浓度的气调可以抑制果实腐烂、减少果肉中乙醇含量,但果实的丙二醛(MDA)含量迅速上升、褐变严重.高CO2浓度的气调能有效抑制MDA含量上升的速率和多酚氧化酶(PPO)活性,保持果实硬度和维生素C含量,减少果实腐烂和褐变,延长贮藏寿命.不同处理对果实可溶性固形物含量的影响不大."那翁" 甜樱桃在5% O2+10% CO2气调中贮藏80 d能保持果实固有的风味品质.在MAP下, 70% O2+0% CO2和普通冷藏中的适宜贮藏期分别为40 d、20 d和30 d.

  10. Future CO2 concentrations, though not warmer temperatures, enhance wheat photosynthesis temperature responses

    OpenAIRE

    Alonso, Aitor; Pérez, P.; Morcuende, R.; Martínez-Carrasco, R.

    2008-01-01

    The temperature dependence of C3 photosynthesis is known to vary according to the growth environment. Atmospheric CO2 concentration and temperature are predicted to increase with climate change. To test whether long-term growth in elevated CO2 and temperature modifies photosynthesis temperature response, wheat (Triticum aestivum L.) was grown in ambient CO2 (370 µmol mol-1) and elevated CO2 (700 µmol mol-1)combined with ambient and 4 ºC warmer temperatures, using temperature gradient ch...

  11. Characterization of YBCO superconductor sintered in CO2-containing atmosphere

    International Nuclear Information System (INIS)

    Stability of the YBCO superconductor toward reacting with CO2 in CO2/O2 gas mixtures during sintering was investigated as a function of the partial pressure of CO2 and temperature. Transport critical current density of the superconductor decreased drastically with increasing concentration of CO2 in the gas mixture. The microstructure and composition of the samples were investigated by transmission electron microscopy and energy-dispersive X-ray spectroscopy

  12. Dependence of global temperatures on atmospheric CO2 and solar irradiance

    OpenAIRE

    David J. Thomson

    1997-01-01

    Changes in global average temperatures and of the seasonal cycle are strongly coupled to the concentration of atmospheric CO2. I estimate transfer functions from changes in atmospheric CO2 and from changes in solar irradiance to hemispheric temperatures that have been corrected for the effects of precession. They show that changes from CO2 over the last century are about three times larger than those from changes in solar irradiance. The increase in global average ...

  13. Investigation into optimal CO2 concentration for CO2 capture from aluminium production

    OpenAIRE

    Mathisen, Anette; Sørensen, Henriette; Melaaen, Morten Christian; Müller, Gunn-Iren

    2013-01-01

    Capture of CO2 from aluminum production has been simulated using Aspen Plus and Aspen Hysys. The technology used for aluminum production is the Hall-Héroult and the current cell design necessitates that large amounts of false air is supplied to the cells. This results in a CO2 concentration in the process gas at around 1 vol%, which is considered uneconomical for CO2 capture. Therefore, the aim of this investigation is to evaluate the CO2 capture from aluminum production when the process g...

  14. Atmospheric CO2 and soil extracellular enzyme activity: A meta-analysis and CO2 gradient experiment

    Science.gov (United States)

    Rising atmospheric CO2 concentrations may alter carbon and nutrient cycling and microbial processes in terrestrial ecosystems. One of the primary ways that microbes interact with soil organic matter is through the production of extracellular enzymes, which break down large, complex organic molecules...

  15. How much has the increase in atmospheric CO2 directly affected past soybean production?

    Science.gov (United States)

    Sakurai, Gen; Iizumi, Toshichika; Nishimori, Motoki; Yokozawa, Masayuki

    2014-01-01

    Understanding the effects of climate change is vital for food security. Among the most important environmental impacts of climate change is the direct effect of increased atmospheric carbon dioxide concentration ([CO2]) on crop yields, known as the CO2 fertilization effect. Although several statistical studies have estimated past impacts of temperature and precipitation on crop yield at regional scales, the impact of past CO2 fertilization is not well known. We evaluated how soybean yields have been enhanced by historical atmospheric [CO2] increases in three major soybean-producing countries. The estimated average yields during 2002-2006 in the USA, Brazil, and China were 4.34%, 7.57%, and 5.10% larger, respectively, than the average yields estimated using the atmospheric [CO2] of 1980. Our results demonstrate the importance of considering atmospheric [CO2] increases in evaluations of the past effects of climate change on crop yields. PMID:24827887

  16. [Monitoring Atmospheric CO2 and delta(13)C (CO2) Background Levels at Shangdianzi Station in Beijing, China].

    Science.gov (United States)

    Xia, Ling-ju; Zhou, Ling-xi; Liu, Li-xin; Zhang, Gen

    2016-04-15

    The study presented time series of atmospheric CO2 concentrations from flask sampling at SDZ regional station in Beijing during 2007 and 2013, together with delta(13)CO2) values during 2009 and 2013. The "representative data" of CO2 and delta(13)C (CO2) were selected from the complete data for further analysis. Annual CO2 concentrations increased from 385.6 x 10(-6) in 2007 to 398.1 x 10(-6) in 2013, with an average growth rate of 2.0 x 10(-6) a(-1), while the delta(13)C values decreased from -8.38% per hundred in 2009 to -8.52% per hundred in 2013, with a mean growth rate of -0.03% per hundred x a(-1). The absolute increase of CO2 from 2007 to 2008 reached the lowest level during 2007 and 2013, possibly due to relatively less carbon emissions during the 2008 Olympic Games period. The peak-to-peak amplitudes of atmospheric CO2 and delta(13)C seasonal variations were 23. 9 x 10 -6 and 1. 03%o, respectively. The isotopic signatures of CO2 sources/sinks were also discussed in this study. The delta8 value for heating season I (Jan. 01-Mar. 14) was -21.30% per hundred, while -25.39% per hundred for heating season 11 (Nov. 15-Dec.31) , and for vegetative season (Mar. 15-Nov. 14) the delta(bio) value was estimated to be -21.28% per hundred, likely suggesting the significant impact of fossil fuel and corn straw combustions during winter heating season and biological activities during vegetative season. PMID:27548943

  17. Mesoscale modelling of atmospheric CO2 across Denmark

    DEFF Research Database (Denmark)

    Lansø, Anne Sofie

    2016-01-01

     have a significant impact on the annual air–sea CO2 exchange. A simulation with constant monthly fields of atmospheric CO2, reduced the winter release of CO2 for the six year period, resulting in an increase of 67% in the average annual uptake by the Baltic Sea and Danish inner waters. The inclusion of short......-term variability in surface water pCO2 was included, the annual uptake changed to an annual release of atmospheric CO2. Besides showing the impact of short-term variability in surface water pCO2, these simulations also showed that the choice of surface water pCO2 fields had a notable impact on the annual air–sea CO...... to take up an amount of CO2 that nearly corresponds to all the CO2 emitted by fossil fuel use in Denmark. However, the biospheric uptake might have been overestimated. The spatiotemporal resolution on land and sea has been greatly improved for the focus area during this study. The calculations...

  18. Dynamics of Soil Organic Carbon Under Uncertain Climate Change and Elevated Atmospheric CO2

    Institute of Scientific and Technical Information of China (English)

    LIN Zhong-Bing; ZHANG Ren-Duo

    2012-01-01

    Climate change and elevated atmospheric CO2 should affect the dynamics of soil organic carbon (SOC).SOC dynamics under uncertain patterns of climate warming and elevated atmospheric CO2 as well as with different soil erosion extents at Nelson Farm during 1998-2100 were simulated using stochastic modelling.Results based on numerous simulations showed that SOC decreased with elevated atmospheric temperature but increased with atmospheric CO2 concentration.Therefore,there was a counteract effect on SOC dynamics between climate warming and elevated CO2.For different soil erosion extents,warming 1 ℃ and elevated atmospheric CO2 resulted in SOC increase at least 15%,while warming 5 ℃ and elevated CO2 resulted in SOC decrease more than 29%.SOCpredictions with uncertainty assessment were conducted for different scenarios of soil erosion,climate change,and elevated CO2.Statistically,SOC decreased linearly with the probability.SOC also decreased with time and the degree of soil erosion.For example,in 2100 with a probability of 50%,SOC was 1617,1 167,and 892 g m-2,respectively,for no,minimum,and maximum soil erosion.Under climate warming 5 ℃ and elevated CO2,the soil carbon pools became a carbon source to the atmosphere (P > 95%).The results suggested that stochastic modelling could be a useful tool to predict future SOC dynamics under uncertain climate change and elevated CO2.

  19. 陆生植物气孔参数与大气CO2浓度变化%Relationship between stomata parameters of plants and atmospheric CO2 concentration change

    Institute of Scientific and Technical Information of China (English)

    郑淑霞; 上官周平

    2005-01-01

    陆生植物的起源与演化与全球气候和环境的变化密不可分,利用植物气孔参数(气孔密度和气孔指数)来指示或重建古大气CO2浓度变化是近年来全球变化研究的热点之一.就陆生植物气孔参数的研究进行了概述,对研究中存在的问题及其前景作了简要探讨,并对植物生物学方法在定量研究古气候和古环境变化的趋势进行了分析.

  20. Seasonal dynamics of soil CO2 efflux and soil profile CO2 concentrations in arboretum of Moscow botanical garden

    Science.gov (United States)

    Goncharova, Olga; Udovenko, Maria; Matyshak, Georgy

    2016-04-01

    To analyse and predict recent and future climate change on a global scale exchange processes of greenhouse gases - primarily carbon dioxide - over various ecosystems are of rising interest. In order to upscale land-use dependent sources and sinks of CO2, knowledge of the local variability of carbon fluxes is needed. Among terrestrial ecosystems, urban areas play an important role because most of anthropogenic emissions of carbon dioxide originate from these areas. On the other hand, urban soils have the potential to store large amounts of soil organic carbon and, thus, contribute to mitigating increases in atmospheric CO2 concentrations. Research objectives: 1) estimate the seasonal dynamics of carbon dioxide production (emission - closed chamber technique and profile concentration - soil air sampling tubes method) by soils of Moscow State University Botanical Garden Arboretum planted with Picea obovata and Pinus sylvestris, 1) identification the factors that control CO2 production. The study was conducted with 1-2 weeks intervals between October 2013 and November 2015 at two sites. Carbon dioxide soil surface efflux during the year ranged from 0 to 800 mgCO2/(m2hr). Efflux values above 0 mgCO2/(m2hr) was observed during the all cold period except for only 3 weeks. Soil CO2 concentration ranged from 1600-3000 ppm in upper 10-cm layer to 10000-40000 ppm at a depth of 60 cm. The maximum concentrations of CO2 were recorded in late winter and late summer. We associate it with high biological activity (both heterotrophic and autotrophic) during the summer, and with physical gas jamming in the winter. The high value of annual CO2 production of the studied soils is caused by high organic matter content, slightly alkaline reaction, good structure and texture of urban soils. Differences in soil CO2 production by spruce and pine urban forest soils (in the pine forest 1.5-2.0 times higher) are caused by urban soil profiles construction, but not temperature regimes. Seasonal

  1. Evaluation of terrestrial carbon cycle models with atmospheric CO2 measurements: Results from transient simulations considering increasing CO2, climate, and land-use effects

    Science.gov (United States)

    Dargaville, R.J.; Heimann, Martin; McGuire, A.D.; Prentice, I.C.; Kicklighter, D.W.; Joos, F.; Clein, J.S.; Esser, G.; Foley, J.; Kaplan, J.; Meier, R.A.; Melillo, J.M.; Moore, B., III; Ramankutty, N.; Reichenau, T.; Schloss, A.; Sitch, S.; Tian, H.; Williams, L.J.; Wittenberg, U.

    2002-01-01

    An atmospheric transport model and observations of atmospheric CO2 are used to evaluate the performance of four Terrestrial Carbon Models (TCMs) in simulating the seasonal dynamics and interannual variability of atmospheric CO2 between 1980 and 1991. The TCMs were forced with time varying atmospheric CO2 concentrations, climate, and land use to simulate the net exchange of carbon between the terrestrial biosphere and the atmosphere. The monthly surface CO2 fluxes from the TCMs were used to drive the Model of Atmospheric Transport and Chemistry and the simulated seasonal cycles and concentration anomalies are compared with observations from several stations in the CMDL network. The TCMs underestimate the amplitude of the seasonal cycle and tend to simulate too early an uptake of CO2 during the spring by approximately one to two months. The model fluxes show an increase in amplitude as a result of land-use change, but that pattern is not so evident in the simulated atmospheric amplitudes, and the different models suggest different causes for the amplitude increase (i.e., CO2 fertilization, climate variability or land use change). The comparison of the modeled concentration anomalies with the observed anomalies indicates that either the TCMs underestimate interannual variability in the exchange of CO2 between the terrestrial biosphere and the atmosphere, or that either the variability in the ocean fluxes or the atmospheric transport may be key factors in the atmospheric interannual variability.

  2. Implications of "peak oil" for atmospheric CO2 and climate

    CERN Document Server

    Kharecha, P A

    2007-01-01

    Peaking of global oil production may have a large effect on future atmospheric CO2 amount and climate change, depending upon choices made for subsequent energy sources. We suggest that, if estimates of oil and gas reserves by the Energy Information Administration are realistic, it is feasible to keep atmospheric CO2 from exceeding approximately 450 ppm, provided that future exploitation of the huge reservoirs of coal and unconventional fossil fuels incorporates carbon capture and sequestration. Existing coal-fired power plants, without sequestration, must be phased out before mid-century to achieve this limit on atmospheric CO2. We also suggest that it is important to "stretch" oil reserves via energy efficiency, thus avoiding the need to extract liquid fuels from coal or unconventional fossil fuels. We argue that a rising price on carbon emissions is probably needed to keep CO2 beneath the 450 ppm ceiling.

  3. Nitrogen and carbon cycling in a grassland community ecosystem as affected by elevated atmospheric CO2

    Science.gov (United States)

    Increasing global atmospheric CO2 concentration has led to concerns regarding its potential effects on terrestrial ecosystem and the long-term storage of C and N in soil. This study examined responses to elevated CO2 in a grass ecosystem invaded with a leguminous shrub Acacia farnesiana (L.) Willd (...

  4. Simulation of CO2 concentrations at Tsukuba tall tower using WRF-CO2 tracer transport model

    Indian Academy of Sciences (India)

    Srabanti Ballav; Prabir K Patra; Yousuke Sawa; Hidekazu Matsueda; Ahoro Adachi; Shigeru Onogi; Masayuki Takigawa; Utpal K De

    2016-02-01

    Simulation of carbon dioxide (CO2) at hourly/weekly intervals and fine vertical resolution at the continental or coastal sites is challenging because of coarse horizontal resolution of global transport models. Here the regional Weather Research and Forecasting (WRF) model coupled with atmospheric chemistry is adopted for simulating atmospheric CO2 (hereinafter WRF-CO2) in nonreactive chemical tracer mode. Model results at horizontal resolution of 27 × 27 km and 31 vertical levels are compared with hourly CO2 measurements from Tsukuba, Japan (36.05°N, 140.13°E) at tower heights of 25 and 200 m for the entire year 2002. Using the wind rose analysis, we find that the fossil fuel emission signal from the megacity Tokyo dominates the diurnal, synoptic and seasonal variations observed at Tsukuba. Contribution of terrestrial biosphere fluxes is of secondary importance for CO2 concentration variability. The phase of synoptic scale variability in CO2 at both heights are remarkably well simulated the observed data (correlation coefficient >0.70) for the entire year. The simulations of monthly mean diurnal cycles are in better agreement with the measurements at lower height compared to that at the upper height. The modelled vertical CO2 gradients are generally greater than the observed vertical gradient. Sensitivity studies show that the simulation of observed vertical gradient can be improved by increasing the number of vertical levels from 31 in the model WRF to 37 (4 below 200 m) and using the Mellor–Yamada–Janjic planetary boundary scheme. These results have large implications for improving transport model simulation of CO2 over the continental sites.

  5. Simulation of CO 2 concentrations at Tsukuba tall tower using WRF-CO 2 tracer transport model

    Science.gov (United States)

    Ballav, Srabanti; Patra, Prabir K.; Sawa, Yousuke; Matsueda, Hidekazu; Adachi, Ahoro; Onogi, Shigeru; Takigawa, Masayuki; de, Utpal K.

    2016-02-01

    Simulation of carbon dioxide (CO2) at hourly/weekly intervals and fine vertical resolution at the continental or coastal sites is challenging because of coarse horizontal resolution of global transport models. Here the regional Weather Research and Forecasting (WRF) model coupled with atmospheric chemistry is adopted for simulating atmospheric CO2 (hereinafter WRF-CO2) in nonreactive chemical tracer mode. Model results at horizontal resolution of 27 × 27 km and 31 vertical levels are compared with hourly CO2 measurements from Tsukuba, Japan (36.05°N, 140.13 oE) at tower heights of 25 and 200 m for the entire year 2002. Using the wind rose analysis, we find that the fossil fuel emission signal from the megacity Tokyo dominates the diurnal, synoptic and seasonal variations observed at Tsukuba. Contribution of terrestrial biosphere fluxes is of secondary importance for CO2 concentration variability. The phase of synoptic scale variability in CO2 at both heights are remarkably well simulated the observed data (correlation coefficient >0.70) for the entire year. The simulations of monthly mean diurnal cycles are in better agreement with the measurements at lower height compared to that at the upper height. The modelled vertical CO2 gradients are generally greater than the observed vertical gradient. Sensitivity studies show that the simulation of observed vertical gradient can be improved by increasing the number of vertical levels from 31 in the model WRF to 37 (4 below 200 m) and using the Mellor-Yamada-Janjic planetary boundary scheme. These results have large implications for improving transport model simulation of CO2 over the continental sites.

  6. Atmospheric CO2 capture by algae: Negative carbon dioxide emission path.

    Science.gov (United States)

    Moreira, Diana; Pires, José C M

    2016-09-01

    Carbon dioxide is one of the most important greenhouse gas, which concentration increase in the atmosphere is associated to climate change and global warming. Besides CO2 capture in large emission point sources, the capture of this pollutant from atmosphere may be required due to significant contribution of diffuse sources. The technologies that remove CO2 from atmosphere (creating a negative balance of CO2) are called negative emission technologies. Bioenergy with Carbon Capture and Storage may play an important role for CO2 mitigation. It represents the combination of bioenergy production and carbon capture and storage, keeping carbon dioxide in geological reservoirs. Algae have a high potential as the source of biomass, as they present high photosynthetic efficiencies and high biomass yields. Their biomass has a wide range of applications, which can improve the economic viability of the process. Thus, this paper aims to assess the atmospheric CO2 capture by algal cultures. PMID:27005790

  7. Nitrogen and Carbon Cycling in a Grassland Community Ecosystem as Affected by Elevated Atmospheric CO2

    OpenAIRE

    Torbert, H.A.; Johnson, H. B.; H. W. Polley

    2012-01-01

    Increasing global atmospheric carbon dioxide (CO2) concentration has led to concerns regarding its potential effects on terrestrial ecosystems and the long-term storage of carbon (C) and nitrogen (N) in soil. This study examined responses to elevated CO2 in a grass ecosystem invaded with a leguminous shrub Acacia farnesiana (L.) Willd (Huisache). Seedlings of Acacia along with grass species were grown for 13 months at CO2 concentrations of 385 (ambient), 690, and 980 μmol mol−1. Elevated CO2 ...

  8. Stability of CO_2 Atmospheres on Desiccated M Dwarf Exoplanets

    OpenAIRE

    Gao, Peter; Hu, Renyu; Robinson, Tyler D.; Li, Cheng; Yung, Yuk L.

    2015-01-01

    We investigate the chemical stability of CO2-dominated atmospheres of desiccated M dwarf terrestrial exoplanets using a 1-dimensional photochemical model. Around Sun-like stars, CO2 photolysis by Far-UV (FUV) radiation is balanced by recombination reactions that depend on water abundance. Planets orbiting M dwarf stars experience more FUV radiation, and could be depleted in water due to M dwarfs' prolonged, high-luminosity pre-main sequences (Luger & Barnes 2015). We show that, for water-depl...

  9. Halloysite Nanotubes Capturing Isotope Selective Atmospheric CO2

    OpenAIRE

    Subhra Jana; Sankar Das; Chiranjit Ghosh; Abhijit Maity; Manik Pradhan

    2015-01-01

    With the aim to capture and subsequent selective trapping of CO2, a nanocomposite has been developed through selective modification of the outer surface of the halloysite nanotubes (HNTs) with an organosilane to make the nanocomposite a novel solid-phase adsorbent to adsorb CO2 from the atmosphere at standard ambient temperature and pressure. The preferential adsorption of three major abundant isotopes of CO2 (12C16O2, 13C16O2, and 12C16O18O) from the ambient air by amine functionalized HNTs ...

  10. Rapid removal of atmospheric CO2 by urban soils

    OpenAIRE

    Washbourne, Carla-Leanne; Lopez-Capel, Elisa; Renforth, Phil; Ascough, Philippa L.; Manning, David A.C.

    2015-01-01

    The measured calcium carbonate content of soils to a depth of 100 mm at a large urban development site has increased over 18 months at a rate that corresponds to the sequestration of 85 t of CO2/ha (8.5 kg of CO2 m–2) annually. This is a consequence of rapid weathering of calcium silicate and hydroxide minerals derived from the demolition of concrete structures, which releases Ca that combines with CO2 ultimately derived from the atmosphere, precipitating as calcite. Stable isotope data confi...

  11. EFFECTS OF NITROGEN ON THE DRY MATTER ACCUMULATION,CARBON ANDNITROGEN METABOLISM OF WHEAT LEAVES UNDER ELEVATED ATMOSPHERIC CO2 CONCENTRATION%高浓度CO2下氮素对小麦叶片干物质积累及碳氮关系的影响

    Institute of Scientific and Technical Information of China (English)

    于显枫; 张绪成; 王红丽

    2012-01-01

    高大气CO2浓度下植物叶片干物质积累、碳氮关系和糖含量的变化对光合作用的适应性下调有重要的反馈作用,通过研究不同施氮量对高大气CO2浓度下植物叶片干物质积累、叶氮浓度和糖含量的影响,可进一步明确氮素对植物光合作用适应性下调的调控机制。以不同大气CO2浓度和氮素水平为处理条件,测定盆栽小麦拔节期叶片鲜重、干重、含水量、还原糖、可溶性糖、全氮含量,研究了氮素对长期高大气CO2浓度(760μmol.mol-1)下小麦叶片的干物质积累、糖含量及碳氮含量的影响。结果表明,大气CO2浓度升高使小麦叶片的鲜重和干重增加,含水量下降。大气CO2浓度升高使N0处理的小麦叶片还原糖含量下降,而可溶性糖含量显著升高;施氮后小麦叶片还原糖含量无显著变化,但可溶性糖含量降低。高大气CO2浓度条件下小麦叶片全氮含量下降,C/N比增加,而增施氮素后C/N比显著下降。可溶性糖含量和C/N比的下降有利于减轻同化物质对光合作用的反馈抑制,提高大气CO2浓度增高条件下小麦叶片的Pn。%The photosynthetic down-regulation in plant leaves under elevated atmospheric CO2 may be related to the changes of the relationship between nitrogen and carbon,and soluble sugars content in plant leaves.It is helped to investigate the effect of nitrogen application on the dry matter accumulation,foliar N concentration and soluble sugar content and determine the regulatory mechanism of nitrogen application on photosynthetic down-regulation under elevated atmospheric CO2 concentration.A pot experiment was conducted to wheat treated by different atmospheric CO2 concentrations and nitrogen application rates,the fresh weight,the dry weight,moisture content,foliar N concentration,reductive and soluble sugar content measured in this,to understand the effect of nitrogen application on the dry matter accumulation and nitrogen

  12. A regenerable solid amine CO2 concentrator for space station

    Science.gov (United States)

    Boehm, A. M.; Cusick, R. J.

    1982-01-01

    A regenerable solid amine CO2 control system, which employs water vapor for desorption, is being developed for potential use on long duration space missions. During cyclic operation, CO2 is first absorbed from the cabin atmosphere onto the granular amine. Steam is then used to heat the solid amine bed and desorb the CO2. This paper describes the solid amine system operation and application to the Shuttle Orbiter, Manned Space Platform (MSP) and Space Operations Center (SOC). The importance and interplay of system performance parameters are presented together with supporting data and design characteristics.

  13. First direct observation of the atmospheric CO2 year-to-year increase from space

    Directory of Open Access Journals (Sweden)

    M. Reuter

    2007-08-01

    Full Text Available The reliable prediction of future atmospheric CO2 concentrations and associated global climate change requires an adequate understanding of the CO2 sources and sinks. The sparseness of the existing surface measurement network limits current knowledge about the global distribution of CO2 surface fluxes. The retrieval of CO2 total vertical columns from satellite observations is predicted to improve this situation. Such an application however requires very high accuracy and precision. We report on retrievals of the column-averaged CO2 dry air mole fraction, denoted XCO2, from the near-infrared nadir spectral radiance and solar irradiance measurements of the SCIAMACHY satellite instrument between 2003 and 2005. We focus on northern hemispheric large scale CO2 features such as the CO2 seasonal cycle and show - for the first time - that the atmospheric annual increase of CO2 can be directly observed using satellite measurements of the CO2 total column. The satellite retrievals are compared with global XCO2 obtained from NOAA's CO2 assimilation system CarbonTracker taking into account the spatio-temporal sampling and altitude sensitivity of the satellite data. We show that the measured CO2 year-to-year increase agrees within about 1 ppm/year with CarbonTracker. We also show that the latitude dependent amplitude of the northern hemispheric CO2 seasonal cycle agrees with CarbonTracker within about 2 ppm with the retrieved amplitude being systematically larger. The analysis demonstrates that it is possible using satellite measurements of the CO2 total column to retrieve information on the atmospheric CO2 on the level of a few parts per million.

  14. Atmospheric CO2: principal control knob governing Earth's temperature.

    Science.gov (United States)

    Lacis, Andrew A; Schmidt, Gavin A; Rind, David; Ruedy, Reto A

    2010-10-15

    Ample physical evidence shows that carbon dioxide (CO(2)) is the single most important climate-relevant greenhouse gas in Earth's atmosphere. This is because CO(2), like ozone, N(2)O, CH(4), and chlorofluorocarbons, does not condense and precipitate from the atmosphere at current climate temperatures, whereas water vapor can and does. Noncondensing greenhouse gases, which account for 25% of the total terrestrial greenhouse effect, thus serve to provide the stable temperature structure that sustains the current levels of atmospheric water vapor and clouds via feedback processes that account for the remaining 75% of the greenhouse effect. Without the radiative forcing supplied by CO(2) and the other noncondensing greenhouse gases, the terrestrial greenhouse would collapse, plunging the global climate into an icebound Earth state. PMID:20947761

  15. Atmospheric Verification of Point Source Fossil Fuel CO2 Emissions

    Science.gov (United States)

    Turnbull, J. C.; Keller, E. D.; Norris, M. W.; Wiltshire, R.; Baisden, W. T.; Brailsford, G. W.; Bromley, T.

    2015-12-01

    Large point sources (electricity generation and large-scale industry) make up roughly one third of all fossil fuel CO2 (CO2ff) emissions. Currently, these emissions are determined from self-reported inventory data, and sometimes from smokestack emissions monitoring, and the uncertainty in emissions from individual power plants is about 20%. We examine the utility of atmospheric 14C measurements combined with atmospheric transport modelling as a tool for independently quantifying point source CO2ff emissions, to both improve the accuracy of the reported emissions and for verification as we move towards a regulatory environment. We use the Kapuni Gas Treatment Facility as a test case. It is located in rural New Zealand with no other significant fossil fuel CO2 sources nearby, and emits CO2ff at ~0.1 Tg carbon per year. We use several different sampling methods to determine the 14C and hence the CO2ff content downwind of the emission source: grab flask samples of whole air; absorption of CO2 into sodium hydroxide integrated over many hours; and plant material which faithfully records the 14C content of assimilated CO2. We use a plume dispersion model to compare the reported emissions with our observed CO2ff mole fractions. We show that the short-term variability in plume dispersion makes it difficult to interpret the grab flask sample results, whereas the variability is averaged out in the integrated samples and we obtain excellent agreement between the reported and observed emissions, indicating that the 14C method can reliably be used to evaluated point source emissions.

  16. Experimental and modeling study of NO emission under high CO2 concentration

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    An experimental and numerical study of the NOx formation and reduction process in a designed coal combustion furnace under both traditional air atmosphere and O2/CO2 atmosphere was conducted, in an attempt to explore the chemistry mechanism of the experimentally observed NOx suppression under high CO2 concentration atmospheres. A simplified ‘chemically oriented’ approach, computational fluid dynamics (CFD)-chemical kinetics modeling method, was validated and used to model the experimental process. The high CO2 concentration’s chemical effect on NO reduction has been studied, and the differences in NOx reaction behaviors between O2/CO2 atmosphere and air atmosphere were analyzed by detailed chemical kinetic model. On the basis of investigations through elementary chemical reactions, it can be concluded that high CO2 concentration plays an important role on NOx conversion process during oxy-fuel combustion. Moreover, the dominant reaction steps and the most important reactions for NO conversion under different atmospheres were discussed. Under O2/CO2 atmosphere, the main active sequence for NO reaction includes: NO→N→N2, and the main active path for NO reaction under air atmosphere is through N2→N→NO.

  17. Atmospheric column CO2 measurement from a new automatic ground-based sun photometer in Beijing from 2010 to 2012

    OpenAIRE

    Li, Z Q; Y. S. Xie; Gu, X. F.; D. H. Li; K. T. Li; Zhang, X. Y.; J. Wu; Xiong, W.

    2012-01-01

    Carbon dioxide is generally regarded as the most important greenhouse gas affecting global warming. Many researches have been conducted to measure atmospheric CO2 concentration, analyze CO2 variation on both seasonal and interannual scales and predict future CO2 tendencies. Among them, ground-based remote sensing observation of CO2 is the essential approach to provide validation data for satellite observation owning to its much higher accuracy and column CO2 measurement capability. Unlike the...

  18. Is there a decrease in the sink of atmospheric CO2 in the Nordic seas?

    International Nuclear Information System (INIS)

    It is well known that the seas off Norway sink a lot of carbon dioxide from the atmosphere, mainly because of the large heat loss from the sea in the area, which makes CO2 more soluble in the water. Whether this sink has increased after the industrial revolution and thereby contributes to slowing down the increase of atmospheric CO2 is uncertain. That is, it is uncertain whether there is a sink of anthropogenic CO2. There are indications that the opposite is true, that the sink of CO2 in this area has slowed down along with the rise in the concentration of atmospheric CO2. Storing of anthropogenic CO2, however, takes place at higher latitudes where deep-water formation occurs, such as in the Nordic seas, where water that is saturated with anthropogenic CO2 is transported down in the deep sea and becomes shielded from the atmosphere. Model calculations show that increased CO2 in the atmosphere will reduce the sink of this gas in the Nordic seas. This conclusion is supported by observations from the Barents Sea

  19. Differences between trends in atmospheric CO2 and the reported trends in anthropogenic CO2 emissions

    International Nuclear Information System (INIS)

    Averaged annual accumulation of CO2 in the atmosphere, dCa/dt, has been slowing from peak growth in 2002/2003 associated with anomalous climate-induced emissions at high northern latitudes. This slowing is widespread but determined with greatest certainty in the largest well-mixed portion of the global troposphere (30 deg S-90 deg S). We rely on atmospheric mixing for global integration and selection of atmospheric data for spatial representativeness. Prior to 2002/2003, after empirical adjustment for perturbations associated with ENSO and volcanic activity (EV), dCa/dt increases are well represented by linear regression, using direct monitoring records from 1990 or 1965, also from pre-industrial times using archived air. In contrast, modelled atmospheric trends due to reported emissions dCE/dt (assuming historically consistent oceanic and terrestrial uptake mechanisms), agree with dCa/dt or dCa/dt-EV up until 1990, are near-stable through the 1990s and increase by 29% between 2000 and 2008. Using atmospheric constraints based on trends in both dCa/dt-EV and interhemispheric gradient, the differences between trends in dCE/dt and atmospheric CO2 growth are most simply explained as an artefact of underestimating 1994-2003 emissions by around 6%. This is achieved with a near constant post-1965 airborne fraction; otherwise unusually complicated sink changes are required for the period.

  20. The extraction of CO2 from the atmosphere

    International Nuclear Information System (INIS)

    After having indicated some methods which are considered as ridiculous, hazardous or ethically questionable, the author first presents of method of extraction of CO2 from the atmosphere developed by a research team of the University of Calgary and applied by the Carbon Engineering Company. According to this concept, ambient air is circulated through an air-contactor in which air leaves its CO2 to a potassium hydroxide flow which transforms into potassium carbonate. This hydroxide is then re-generated by exchange with calcium hydroxide. The thus formed calcium carbonate is finally thermally decomposed to release CO2. He also presents the BECCS (Bio-energy with carbon capture and storage) which has been put forward by the IPCC, evokes the cost of the extracted ton of CO2 and the arguments of the opponents to this method

  1. Rapid Removal of Atmospheric CO2 by Urban Soils.

    Science.gov (United States)

    Washbourne, Carla-Leanne; Lopez-Capel, Elisa; Renforth, Phil; Ascough, Philippa L; Manning, David A C

    2015-05-01

    The measured calcium carbonate content of soils to a depth of 100 mm at a large urban development site has increased over 18 months at a rate that corresponds to the sequestration of 85 t of CO2/ha (8.5 kg of CO2 m(-2)) annually. This is a consequence of rapid weathering of calcium silicate and hydroxide minerals derived from the demolition of concrete structures, which releases Ca that combines with CO2 ultimately derived from the atmosphere, precipitating as calcite. Stable isotope data confirm an atmospheric origin for carbonate carbon, and 14C dating indicates the predominance of modern carbon in the pedogenic calcite. Trial pits show that carbonation extends to depths of ≥1 m. Work at other sites shows that the occurrence of pedogenic carbonates is widespread in artificially created urban soils containing Ca and Mg silicate minerals. Appropriate management of fewer than 12000 ha of urban land to maximize calcite precipitation has the potential to remove 1 million t of CO2 from the atmosphere annually. The maximal global potential is estimated to be approximately 700-1200 Mt of CO2 per year (representing 2.0-3.7% of total emissions from fossil fuel combustion) based on current rates of production of industry-derived Ca- and Mg-bearing materials. PMID:25837769

  2. Sensitivity Analysis for Atmospheric Infrared Sounder (AIRS) CO2 Retrieval

    Science.gov (United States)

    Gat, Ilana

    2012-01-01

    The Atmospheric Infrared Sounder (AIRS) is a thermal infrared sensor able to retrieve the daily atmospheric state globally for clear as well as partially cloudy field-of-views. The AIRS spectrometer has 2378 channels sensing from 15.4 micrometers to 3.7 micrometers, of which a small subset in the 15 micrometers region has been selected, to date, for CO2 retrieval. To improve upon the current retrieval method, we extended the retrieval calculations to include a prior estimate component and developed a channel ranking system to optimize the channels and number of channels used. The channel ranking system uses a mathematical formalism to rapidly process and assess the retrieval potential of large numbers of channels. Implementing this system, we identifed a larger optimized subset of AIRS channels that can decrease retrieval errors and minimize the overall sensitivity to other iridescent contributors, such as water vapor, ozone, and atmospheric temperature. This methodology selects channels globally by accounting for the latitudinal, longitudinal, and seasonal dependencies of the subset. The new methodology increases accuracy in AIRS CO2 as well as other retrievals and enables the extension of retrieved CO2 vertical profiles to altitudes ranging from the lower troposphere to upper stratosphere. The extended retrieval method for CO2 vertical profile estimation using a maximum-likelihood estimation method. We use model data to demonstrate the beneficial impact of the extended retrieval method using the new channel ranking system on CO2 retrieval.

  3. Covariation of deep Southern Ocean oxygenation and atmospheric CO2 through the last ice age.

    Science.gov (United States)

    Jaccard, Samuel L; Galbraith, Eric D; Martínez-García, Alfredo; Anderson, Robert F

    2016-02-11

    No single mechanism can account for the full amplitude of past atmospheric carbon dioxide (CO2) concentration variability over glacial-interglacial cycles. A build-up of carbon in the deep ocean has been shown to have occurred during the Last Glacial Maximum. However, the mechanisms responsible for the release of the deeply sequestered carbon to the atmosphere at deglaciation, and the relative importance of deep ocean sequestration in regulating millennial-timescale variations in atmospheric CO2 concentration before the Last Glacial Maximum, have remained unclear. Here we present sedimentary redox-sensitive trace-metal records from the Antarctic Zone of the Southern Ocean that provide a reconstruction of transient changes in deep ocean oxygenation and, by inference, respired carbon storage throughout the last glacial cycle. Our data suggest that respired carbon was removed from the abyssal Southern Ocean during the Northern Hemisphere cold phases of the deglaciation, when atmospheric CO2 concentration increased rapidly, reflecting--at least in part--a combination of dwindling iron fertilization by dust and enhanced deep ocean ventilation. Furthermore, our records show that the observed covariation between atmospheric CO2 concentration and abyssal Southern Ocean oxygenation was maintained throughout most of the past 80,000 years. This suggests that on millennial timescales deep ocean circulation and iron fertilization in the Southern Ocean played a consistent role in modifying atmospheric CO2 concentration. PMID:26840491

  4. Water loss from terrestrial planets with CO2-rich atmospheres

    International Nuclear Information System (INIS)

    Water photolysis and hydrogen loss from the upper atmospheres of terrestrial planets is of fundamental importance to climate evolution but remains poorly understood in general. Here we present a range of calculations we performed to study the dependence of water loss rates from terrestrial planets on a range of atmospheric and external parameters. We show that CO2 can only cause significant water loss by increasing surface temperatures over a narrow range of conditions, with cooling of the middle and upper atmosphere acting as a bottleneck on escape in other circumstances. Around G-stars, efficient loss only occurs on planets with intermediate CO2 atmospheric partial pressures (0.1-1 bar) that receive a net flux close to the critical runaway greenhouse limit. Because G-star total luminosity increases with time but X-ray and ultraviolet/ultravoilet luminosity decreases, this places strong limits on water loss for planets like Earth. In contrast, for a CO2-rich early Venus, diffusion limits on water loss are only important if clouds caused strong cooling, implying that scenarios where the planet never had surface liquid water are indeed plausible. Around M-stars, water loss is primarily a function of orbital distance, with planets that absorb less flux than ∼270 W m–2 (global mean) unlikely to lose more than one Earth ocean of H2O over their lifetimes unless they lose all their atmospheric N2/CO2 early on. Because of the variability of H2O delivery during accretion, our results suggest that many 'Earth-like' exoplanets in the habitable zone may have ocean-covered surfaces, stable CO2/H2O-rich atmospheres, and high mean surface temperatures.

  5. Water loss from terrestrial planets with CO2-rich atmospheres

    OpenAIRE

    Wordsworth, Robin; Pierrehumbert, Raymond

    2013-01-01

    Water photolysis and hydrogen loss from the upper atmospheres of terrestrial planets is of fundamental importance to climate evolution but remains poorly understood in general. Here we present a range of calculations we performed to study the dependence of water loss rates from terrestrial planets on a range of atmospheric and external parameters. We show that CO2 can only cause significant water loss by increasing surface temperatures over a narrow range of conditions, with cooling of the mi...

  6. Module for measurement of CO2 concentration in exhaled air

    Science.gov (United States)

    Puton, Jaroslaw; Palko, Tadeusz; Knap, Andrzej; Jasek, Krzysztof; Siodlowski, Boguslaw

    2003-09-01

    The objective of this work consists in working out of a detection module for capnography (carbon dioxide concentration measurement in anaesthesiology and intensive care). The principle of operation of the module consists of the NDIR method. The basic assumption for construction of this model was using of directly modulated thermal IR source in it. A few models of IR sources were worked out. Their heaters were made from thick platinum layers and foil. Limits of modulation frequency for IR sources were greater than 30 Hz. The detection module consists of an optical part, analogue electronics and microprocessor system with a suitable program. The time dependent concentration of CO2, end tidal concentration of CO2, mean concentration of N2O and breath frequency are output values of the detection module. Measurements are executed 30 times per second. The accuracy of CO2 concentration measurement equals to 5%.

  7. Tropical epiphytes in a CO 2-rich atmosphere

    Science.gov (United States)

    Monteiro, José Alberto Fernandez; Zotz, Gerhard; Körner, Christian

    2009-01-01

    We tested the effect on epiphyte growth of a doubling of pre-industrial CO 2 concentration (280 vs. 560 ppm) combined with two light (three fold) and two nutrition (ten fold) treatments under close to natural humid conditions in daylight growth cabinets over 6 months. Across co-treatments and six species, elevated CO 2 increased relative growth rates by only 6% ( p = 0.03). Although the three C3 species, on average, grew 60% faster than the three CAM species, the two groups did not significantly differ in their CO 2 response. The two Orchidaceae, Bulbophyllum (CAM) and Oncidium (C3) showed no CO 2 response, and three out of four Bromeliaceae showed a positive one: Aechmea (CAM, +32% p = 0.08), Catopsis (C3, +11% p = 0.01) and Vriesea (C3, +4% p = 0.02). In contrast, the representative of the species-rich genus Tillandsia (CAM), which grew very well under experimental conditions, showed no stimulation. On average, high light increased growth by 21% and high nutrients by 10%. Interactions between CO 2, light and nutrient treatments (low vs. high) were inconsistent across species. CO 2 responsive taxa such as Catopsis, could accelerate tropical forest dynamics and increase branch breakage, but overall, the responses to doubling CO 2 of these epiphytes was relatively small and the responses were taxa specific.

  8. Algal constraints on the Cenozoic history of atmospheric CO2?

    Directory of Open Access Journals (Sweden)

    R. E. M. Rickaby

    2007-01-01

    Full Text Available An urgent question for future climate, in light of increased burning of fossil fuels, is the temperature sensitivity of the climate system to atmospheric carbon dioxide (pCO2. To date, no direct proxy for past levels of pCO2 exists beyond the reach of the polar ice core records. We propose a new methodology for placing an upper constraint on pCO2 over the Cenozoic based on the living geological record. Specifically, our premise is that the contrasting calcification tolerance of various extant species of coccolithophore to raised pCO2 reflects an "evolutionary memory" of past atmospheric composition. The different times of first emergence of each morphospecies allows an upper constraint of past pCO2 to be placed on Cenozoic timeslices. Further, our hypothesis has implications for the response of marine calcifiers to ocean acidification. Geologically "ancient" species, which have survived large changes in ocean chemistry, are likely more resilient to predicted acidification.

  9. Effects of Atmospheric CO2 Enrichment on Soil CO2 Efflux in a Young Longleaf Pine System

    Directory of Open Access Journals (Sweden)

    G. Brett Runion

    2012-01-01

    Full Text Available The southeastern landscape is composed of agricultural and forest systems that can store carbon (C in standing biomass and soil. Research is needed to quantify the effects of elevated atmospheric carbon dioxide (CO2 on terrestrial C dynamics including CO2 release back to the atmosphere and soil sequestration. Longleaf pine savannahs are an ecologically and economically important, yet understudied, component of the southeastern landscape. We investigated the effects of ambient and elevated CO2 on soil CO2 efflux in a young longleaf pine system using a continuous monitoring system. A significant increase (26.5% in soil CO2 efflux across 90 days was observed under elevated CO2; this occurred for all weekly and daily averages except for two days when soil temperature was the lowest. Soil CO2 efflux was positively correlated with soil temperature with a trend towards increased efflux response to temperature under elevated CO2. Efflux was negatively correlated with soil moisture and was best represented using a quadratic relationship. Soil CO2 efflux was not correlated with root biomass. Our data indicate that, while elevated CO2 will increase feedback of CO2 to the atmosphere via soil efflux, terrestrial ecosystems will remain potential sinks for atmospheric CO2 due to greater biomass production and increased soil C sequestration.

  10. Chemical transport modeling of potential atmospheric CO2 sinks

    International Nuclear Information System (INIS)

    The potential for carbon dioxide (CO2) sequestration via engineered chemical sinks is investigated using a three dimensional chemical transport model (CTM). Meteorological and chemical constraints for flat or vertical systems that would absorb CO2 from the atmosphere, as well as an example chemical system of calcium hydroxide (Ca(OH)2) proposed by Elliott et al. [Compensation of atmospheric CO2 buildup through engineered chemical sinkage, Geophys. Res. Lett. 28 (2001) 1235] are reviewed. The CTM examines land based deposition sinks, with 4ox5o latitude/longitude resolution at various locations, and deposition velocities (v). A maximum uptake of ∼20 Gton (1015 g) C yr-1 is attainable with v>5 cm s -1 at a mid-latitude site. The atmospheric increase of CO2 (3 Gton yr-1) can be balanced by an engineered sink with an area of no more than 75,000 km2 at v of 1 cm s-1. By building the sink upwards or splitting this area into narrow elements can reduce the active area by more than an order of magnitude as discussed in Dubey at el. [31]. (author)

  11. Estimating the amount of (co2)-c-14 in the atmosphere during the holocene and glacial periods

    Czech Academy of Sciences Publication Activity Database

    Světlík, Ivo; Povinec, P. P.; Pachnerová Brabcová, Kateřina; Fejgl, M.; Tomášková, Lenka; Turek, Karel

    2013-01-01

    Roč. 55, 2-3 (2013), s. 1546-1555. ISSN 0033-8222 Institutional support: RVO:61389005 Keywords : atmospheric 14CO2 * activity concentration of 14CO2 * deglacial CO2 rise Subject RIV: DD - Geochemistry Impact factor: 1.037, year: 2013

  12. A review of elevated atmospheric CO2 effects on plant growth and water relations: implications for horticulture

    Science.gov (United States)

    Empirical records provide incontestable evidence for the global rise in CO2 concentration in the earth's atmosphere. Plant growth can be stimulated by elevation of CO2; photosynthesis increases and economic yield is often enhanced. The application of more CO2 can increase plant water use efficiency ...

  13. Operational constraints and strategies for systems to effect the sustainable, solar-driven reduction of atmospheric CO_2

    OpenAIRE

    Chen, Yikai; Lewis, Nathan S.; Xiang, Chengxiang

    2015-01-01

    The operational constraints for a 6-electron/6-proton CO_2 reduction system that operates at the concentration of CO_2 in the current atmosphere (p_(CO_2) = 400 ppm) have been evaluated on a variety of scale lengths that span from laboratory scale to global scale. Due to the low concentration of CO_2 in the atmosphere, limitations due to mass transport of CO_2 from the tropopause have been evaluated through five different regions, each with different characteristic length scales: the troposph...

  14. Climate change and agroecosystems: the effect of elevated atmospheric CO2 and temperature on crop growth, development, and yield

    Directory of Open Access Journals (Sweden)

    Streck Nereu Augusto

    2005-01-01

    Full Text Available The amount of carbon dioxide (CO2 of the Earths atmosphere is increasing, which has the potential of increasing greenhouse effect and air temperature in the future. Plants respond to environment CO2 and temperature. Therefore, climate change may affect agriculture. The purpose of this paper was to review the literature about the impact of a possible increase in atmospheric CO2 concentration and temperature on crop growth, development, and yield. Increasing CO2 concentration increases crop yield once the substrate for photosynthesis and the gradient of CO2 concentration between atmosphere and leaf increase. C3 plants will benefit more than C4 plants at elevated CO2. However, if global warming will take place, an increase in temperature may offset the benefits of increasing CO2 on crop yield.

  15. Climate Sensitivity, Sea Level, and Atmospheric CO2

    CERN Document Server

    Hansen, James; Russell, Gary; Kharecha, Pushker

    2012-01-01

    Cenozoic temperature, sea level and CO2 co-variations provide insights into climate sensitivity to external forcings and sea level sensitivity to climate change. Pleistocene climate oscillations imply a fast-feedback climate sensitivity 3 {\\pm} 1 {\\deg}C for 4 W/m2 CO2 forcing for the average of climate states between the Holocene and Last Glacial Maximum (LGM), the error estimate being large and partly subjective because of continuing uncertainty about LGM global surface climate. Slow feedbacks, especially change of ice sheet size and atmospheric CO2, amplify total Earth system sensitivity. Ice sheet response time is poorly defined, but we suggest that hysteresis and slow response in current ice sheet models are exaggerated. We use a global model, simplified to essential processes, to investigate state-dependence of climate sensitivity, finding a strong increase in sensitivity when global temperature reaches early Cenozoic and higher levels, as increased water vapor eliminates the tropopause. It follows that...

  16. Water loss from terrestrial planets with CO2-rich atmospheres

    CERN Document Server

    Wordsworth, Robin

    2013-01-01

    Water photolysis and hydrogen loss from the upper atmospheres of terrestrial planets is of fundamental importance to climate evolution but remains poorly understood in general. Here we present a range of calculations we performed to study the dependence of water loss rates from terrestrial planets on atmospheric composition (CO2 and N2 levels), planetary mass, and external parameters (stellar spectrum, orbital distance and impacts). From coupled 1D climate and escape modeling, we show that CO2 can only cause significant water loss by increasing surface temperatures over a narrow range of conditions, with cooling of the middle and upper atmosphere acting as a bottleneck on escape in other circumstances. Around G-stars, efficient loss only occurs on planets with intermediate CO2 atmospheric partial pressures (0.1 to 1 bar) that receive a net flux close to the critical runaway greenhouse limit. Because G-star total luminosity increases with time but XUV/UV luminosity decreases, this places strong limits on moist...

  17. Effect of elevated atmospheric CO2 and vegetation type on microbiota associated with decomposing straw

    DEFF Research Database (Denmark)

    Frederiksen, Helle B.; Ronn, R.; Christensen, S.

    2001-01-01

    Straw from wheat plants grown at ambient and elevated atmospheric CO2 concentrations was placed in litterbags in a grass fallow field and a wheat field. The CO2 treatment induced an increase in straw concentration of ash-free dry mass from 84% to 93% and a decrease in nitrogen concentration from 0...... and 3.40 vs. 2.67% AFDM per litterbag when buried in the wheat field). The immobilization of nitrogen during decomposition was significantly higher in the ambient straw, and there was a significant negative correlation between the content of organic matter remaining per litterbag and the nitrogen...... concentration in the recovered straw samples. After five months of decomposition, hyphal biomass was significantly lower in straw from plants grown at elevated CO2 (-30% and -13% in the fallow and wheat field, respectively). Bacterial biomass was not significantly affected by the CO2 induced changes in the...

  18. Rising CO2 concentrations affect settlement behaviour of larval damselfishes

    Science.gov (United States)

    Devine, B. M.; Munday, P. L.; Jones, G. P.

    2012-03-01

    Reef fish larvae actively select preferred benthic habitat, relying on olfactory, visual and acoustic cues to discriminate between microhabitats at settlement. Recent studies show exposure to elevated carbon dioxide (CO2) impairs olfactory cue recognition in larval reef fishes. However, whether this alters the behaviour of settling fish or disrupts habitat selection is unknown. Here, the effect of elevated CO2 on larval behaviour and habitat selection at settlement was tested in three species of damselfishes (family Pomacentridae) that differ in their pattern of habitat use: Pomacentrus amboinensis (a habitat generalist), Pomacentrus chrysurus (a rubble specialist) and Pomacentrus moluccensis (a live coral specialist). Settlement-stage larvae were exposed to current-day CO2 levels or CO2 concentrations that could occur by 2100 (700 and 850 ppm) based on IPCC emission scenarios. First, pair-wise choice tests were performed using a two-channel flume chamber to test olfactory discrimination between hard coral, soft coral and coral rubble habitats. The habitat selected by settling fish was then compared among treatments using a multi-choice settlement experiment conducted overnight. Finally, settlement timing between treatments was compared across two lunar cycles for one of the species, P. chrysurus. Exposure to elevated CO2 disrupted the ability of larvae to discriminate between habitat odours in olfactory trials. However, this had no effect on the habitats selected at settlement when all sensory cues were available. The timing of settlement was dramatically altered by CO2 exposure, with control fish exhibiting peak settlement around the new moon, whereas fish exposed to 850 ppm CO2 displaying highest settlement rates around the full moon. These results suggest larvae can rely on other sensory information, such as visual cues, to compensate for impaired olfactory ability when selecting settlement habitat at small spatial scales. However, rising CO2 could cause larvae

  19. Can the envisaged reductions of fossil fuel CO2 emissions be detected by atmospheric observations?

    OpenAIRE

    Levin, Ingeborg; Rödenbeck, Christian

    2007-01-01

    The lower troposphere is an excellent receptacle, which integrates anthropogenic greenhouse gases emissions over large areas. Therefore, atmospheric concentration observations over populated regions would provide the ultimate proof if sustained emissions changes have occurred. The most important anthropogenic greenhouse gas, carbon dioxide (CO2), also shows large natural concentration variations, which need to be disentangled from anthropogenic signals to assess changes in associated emission...

  20. Optimization of the seasonal cycles of simulated CO2 flux by fitting simulated atmospheric CO2 to observed vertical profiles

    Directory of Open Access Journals (Sweden)

    S. Maksyutov

    2009-06-01

    Full Text Available An inverse of a combination of atmospheric transport and flux models was used to optimize model parameters of the Carnegie-Ames-Stanford Approach (CASA terrestrial ecosystem model. The method employed in the present study is based on minimizing an appropriate cost function (i.e. the weighted differences between the simulated and observed seasonal cycles of CO2 concentrations. We tried to reduce impacts that the inaccuracy of a vertical mixing in a transport model has on the simulated amplitudes of seasonal cycles of carbon flux by using airborne observations of CO2 vertical profile aggregated to a partial column. Effect of the vertical mixing on optimized NEP was evaluated by carrying out 2 sets of inverse calculations: one with partial-column concentration data from 15 locations and another with near-surface CO2 concentration data from the same 15 locations. We found that the values of simulated growing season net flux (GSNF and net primary productivity (NPP are affected by the rate of vertical mixing in a transport model used in the optimization. Optimized GSNF and NPP are higher when optimized with partial column data as compared to the case with near-surface data only due to the weak vertical mixing in the transport model used in this study.

  1. Optimization of the seasonal cycles of simulated CO2 flux by fitting simulated atmospheric CO2 to observed vertical profiles

    Science.gov (United States)

    Nakatsuka, Y.; Maksyutov, S.

    2009-06-01

    An inverse of a combination of atmospheric transport and flux models was used to optimize model parameters of the Carnegie-Ames-Stanford Approach (CASA) terrestrial ecosystem model. The method employed in the present study is based on minimizing an appropriate cost function (i.e. the weighted differences between the simulated and observed seasonal cycles of CO2 concentrations). We tried to reduce impacts that the inaccuracy of a vertical mixing in a transport model has on the simulated amplitudes of seasonal cycles of carbon flux by using airborne observations of CO2 vertical profile aggregated to a partial column. Effect of the vertical mixing on optimized NEP was evaluated by carrying out 2 sets of inverse calculations: one with partial-column concentration data from 15 locations and another with near-surface CO2 concentration data from the same 15 locations. We found that the values of simulated growing season net flux (GSNF) and net primary productivity (NPP) are affected by the rate of vertical mixing in a transport model used in the optimization. Optimized GSNF and NPP are higher when optimized with partial column data as compared to the case with near-surface data only due to the weak vertical mixing in the transport model used in this study.

  2. Estimates of CO2 traffic emissions from mobile concentration measurements

    Science.gov (United States)

    Maness, H. L.; Thurlow, M. E.; McDonald, B. C.; Harley, R. A.

    2015-03-01

    We present data from a new mobile system intended to aid in the design of upcoming urban CO2-monitoring networks. Our collected data include GPS probe data, video-derived traffic density, and accurate CO2 concentration measurements. The method described here is economical, scalable, and self-contained, allowing for potential future deployment in locations without existing traffic infrastructure or vehicle fleet information. Using a test data set collected on California Highway 24 over a 2 week period, we observe that on-road CO2 concentrations are elevated by a factor of 2 in congestion compared to free-flow conditions. This result is found to be consistent with a model including vehicle-induced turbulence and standard engine physics. In contrast to surface concentrations, surface emissions are found to be relatively insensitive to congestion. We next use our model for CO2 concentration together with our data to independently derive vehicle emission rate parameters. Parameters scaling the leading four emission rate terms are found to be within 25% of those expected for a typical passenger car fleet, enabling us to derive instantaneous emission rates directly from our data that compare generally favorably to predictive models presented in the literature. The present results highlight the importance of high spatial and temporal resolution traffic data for interpreting on- and near-road concentration measurements. Future work will focus on transport and the integration of mobile platforms into existing stationary network designs.

  3. Effect of elevated CO2 concentration: Acclimation of Rubisco

    Czech Academy of Sciences Publication Activity Database

    Urban, Otmar; Šprtová, Miroslava

    Volume 1. 1. Brno : Global Change Research Centre, Academy of Sciences of the Czech Republic, v. v. i, 2015 - (Urban, O.; Klem, K.), s. 78-88 ISBN 978-80-87902-14-1 R&D Projects: GA MŠk(CZ) LO1415 Institutional support: RVO:67179843 Keywords : CO2 concentration * Rubisco * acclimation Subject RIV: EH - Ecology, Behaviour

  4. The Dependence of Plant δ13C on Atmospheric pCO2

    Science.gov (United States)

    Jahren, H.; Schubert, B.

    2011-12-01

    Numerous studies on multicellular plants have reported increasing carbon isotope fractionation in leaf tissue with increasing concentrations of atmospheric carbon dioxide (pCO2), but the magnitude of the effect is highly variable (i.e., 0.62 to 2.7 % per 100 ppm CO2). The majority of these experiments tested only small differences in CO2 levels (Raphanus sativus plants grown under controlled light, water, and temperature conditions, and varying the pCO2 concentrations across a trajectory of 17 different pCO2 levels ranging from 370 to 4200 ppm. From this large dataset, we show that the carbon isotope discrimination [Δδ13C = (δ13CCO2 - δ13Cplant) / (1000 + δ13Cplant)] is indeed a function of pCO2, however, the relationship is hyperbolic, rather than linear, as is typically assumed. Across the small changes in pCO2 previously studied the response appears linear, however, our expanded dataset clearly shows that increases in Δδ13C level off at high pCO2, which is consistent with the ultimate control over fractionation being the activity of Rubisco as the concentration of pCO2 inside the leaf approaches the pCO2 level outside the leaf. The hyperbolic relationship we have quantified using published and new data is extremely robust (R2 = 0.90, n = 26, P < 0.0001), and evident in n-alkanes as well as bulk tissue, suggesting the potential for application to fossil plant materials in order to reconstruct pCO2 across critical intervals.

  5. Overlapping effect of atmospheric H2O, CO2 and 03 on the CO2 radiative effect

    OpenAIRE

    Wang, Wei-Chyung; Ryan, P. Barry

    2011-01-01

    The effect of overlapping of atmospheric HThe effect of overlapping of atmospheric H2O, CO2 and 03 absorption bands on the radiation budget perturbation caused by CO2 doubling is investigated. Since the effect depends on the amount of gases in the atmosphere as well as on the strength of the absorption bands, we examine the effect associated with the variation of gas abundance using a narrow band representation for the absorption bands. This band representation allows for the absorption band ...

  6. Advances on the Responses of Root Dynamics to Increased Atmospheric CO2 and Global Climate Change

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Plant roots dynamics responses to elevated atmospheric CO2 concentration, increased temperature and changed precipitation can be a key link between plant growth and long-term changes in soil organic matter and ecosystem carbon balance. This paper reviews some experiments and hypotheses developed in this area, which mainly include plant fine roots growth, root turnover, root respiration and other root dynamics responses to elevated CO2 and global climate change. Some recent new methods of studying root systems were also discussed and summarized. It holds herein that the assemblage of information about root turnover patterns, root respiration and other dynamic responses to elevated atmospheric CO2 and global climatic change can help to better understand and explore some new research areas. In this paper, some research challenges in the plant root responses to the elevated CO2 and other environmental factors during global climate change were also demonstrated.

  7. 晚白垩世(80Ma)CO_2浓度对东亚气候影响的数值模拟%MODELING IMPACTS OF ATMOSPHERIC CO_2 CONCENTRATION ON EAST ASIAN CLIMATE DURING THE LATE CRETACEOUS(80Ma)

    Institute of Scientific and Technical Information of China (English)

    陈军明; 赵平; 王成善; 黄永建

    2009-01-01

    利用美国国家大气研究中心(NCAR)的CCSM2.0全球气候系统模式,并结合重建的古地理资料,研究了晚白垩世(80Ma)东亚气候特征以及CO_2浓度变化对东亚气候的影响.模拟结果表明:与现代气候比较,晚白垩纪时期的东亚大陆冬季风和夏季风都偏强,具有同步变化的特点,并且中高纬度年平均地表气温明显增加,而低纬度地区有所下降,年降水变化的区域性特征明显;就年平均而言,在30°~40°N的内陆地区地面净失去水分、变干燥,而在低纬度、大陆东岸以及高纬度地区,地表获得水分、变湿润.晚白垩纪CO_2浓度变化对大气辐射和大气热状况的影响是复杂的;降低CO_2浓度可以导致东亚地区气候显著变化,冬季东亚中纬度地区大陆降温比其附近的海洋大,太平洋中高纬度的低压系统加强,因而造成东亚冬季风偏强;而在夏季,中纬度大陆地区降温幅度大于海洋,西太平洋副热带高压减弱,因而夏季风减弱.对应于较低的CO_2浓度,年降水量在东亚及其沿岸的中、低纬度大部分地区显著减少,在东亚高纬度的大陆和海洋上降水的减少幅度不大,而在30°N附近亚洲大陆中部和东部的一些地区降水有所增加;总体上,地表水分收支在东亚大陆的东部都是以负值为主,地面净失去水分、变干燥,其中30°N以南的大陆沿岸最显著;而在东亚大陆的内陆地区,水分收支差异以0~0.5mm/天的正值为主,东亚大陆的东部是以地面净得到水分、变潮湿为主.%In this paper,the characteristics of the East Asian climate and the impacts of atmospheric CO_2 concentration variation on the East Asian climate were examined by using the Community Climate System Model version 2 (CCSM 2.0)developed by the National Center for Atmospheric Research (NCAR)as well as the reconstructed paleogeographic data of the Late Cretaceous (80Ma). The simulation results show that the winter and

  8. Atmospheric radon, CO2 and CH4 dynamics in an Australian coal seam gas field

    Science.gov (United States)

    Tait, D. R.; Santos, I. R.; Maher, D. T.

    2013-12-01

    Atmospheric radon (222Rn), carbon dioxide (CO2), and methane concentrations (CH4) as well as carbon stable isotope ratios (δ13C) were used to gain insight into atmospheric chemistry within an Australian coal seam gas (CSG) field (Surat Basin, Tara region, Queensland). A˜3 fold increase in maximum 222Rn concentration was observed inside the gas field compared to outside of it. There was a significant relationship between maximum and average 222Rn concentrations and the number of gas wells within a 2 km to 4 km radius of the sampling sites (n = 5 stations; p gas field related to point sources (well heads, pipelines, etc.) and diffse soil sources due to changes in the soil structural and hydrological characteristics. A rapid qualitative assessment of CH4 and CO2 concentration, and carbon isotopes using a mobile cavity ring-down spectrometer system showed a widespread enrichment of both CH4 and CO2 within the production gas field. Concentrations of CH4 and CO2 were as high as 6.89 ppm and 541 ppm respectively compared average concentrations of 1.78 ppm (CH4) and 388 ppm (CO2) outside the gas field. The δ13C values showed distinct differences between areas inside and outside the production field with the δ13C value of the CH4 source within the field matching that of the methane in the CSG.

  9. Modeling The Anthropogenic CO2 Footprint in Europe Using a High Resolution Atmospheric Model

    Science.gov (United States)

    Liu, Yu; Gruber, Nicolas; Brunner, Dominik

    2015-04-01

    The localized nature of most fossil fuel emission sources leaves a distinct footprint on atmospheric CO2 concentrations, yet to date, most studies have used relatively coarse atmospheric transport models to simulate this footprint, causing an excess amount of spatial smoothing. In addition, most studies have considered only monthly variations in emissions, neglecting their substantial diurnal and weekly fluctuations. With the fossil fuel emission fluxes dominating the carbon balance in Europe and many other industrialized countries, it is paramount to simulate the fossil fuel footprint in atmospheric CO2 accurately in time and space in order to discern the footprint of the terrestrial biosphere. Furthermore, a good understanding of the fossil fuel footprint also provides the opportunity to monitor and verify any change in fossil fuel emission. We use here a high resolution (7 km) atmospheric model setup for central Europe based on the operational weather forecast model COSMO and simulate the atmospheric CO2 concentrations separately for 5 fossil fuel emission sectors (i.e., power generation, heating, transport, industrial processes, and rest), and for 10 different country-based regions. The emissions were based on high-resolution emission inventory data (EDGAR(10km) and MeteoTest(500m)), to which we have added detailed time functions for each process and country. The total anthropogenic CO2 footprint compares well with observational estimates based on radiocarbon (C14) and CO for a number of sites across Europe, providing confidence in the emission inventory and atmospheric transport. Despite relatively rapid atmospheric mixing, the fossil fuel footprint shows strong annual mean structures reflecting the point-source nature of most emissions. Among all the processes, the emissions from power plants dominates the fossil fuel footprint, followed by industry, while traffic emissions are less distinct, largely owing to their spatially more distributed nature. However

  10. Root damage by insects reverses the effects of elevated atmospheric CO2 on Eucalypt seedlings.

    Directory of Open Access Journals (Sweden)

    Scott N Johnson

    Full Text Available Predicted increases in atmospheric carbon dioxide (CO2 are widely anticipated to increase biomass accumulation by accelerating rates of photosynthesis in many plant taxa. Little, however, is known about how soil-borne plant antagonists might modify the effects of elevated CO2 (eCO2, with root-feeding insects being particularly understudied. Root damage by insects often reduces rates of photosynthesis by disrupting root function and imposing water deficits. These insects therefore have considerable potential for modifying plant responses to eCO2. We investigated how root damage by a soil-dwelling insect (Xylotrupes gideon australicus modified the responses of Eucalyptus globulus to eCO2. eCO2 increased plant height when E. globulus were 14 weeks old and continued to do so at an accelerated rate compared to those grown at ambient CO2 (aCO2. Plants exposed to root-damaging insects showed a rapid decline in growth rates thereafter. In eCO2, shoot and root biomass increased by 46 and 35%, respectively, in insect-free plants but these effects were arrested when soil-dwelling insects were present so that plants were the same size as those grown at aCO2. Specific leaf mass increased by 29% under eCO2, but at eCO2 root damage caused it to decline by 16%, similar to values seen in plants at aCO2 without root damage. Leaf C:N ratio increased by >30% at eCO2 as a consequence of declining leaf N concentrations, but this change was also moderated by soil insects. Soil insects also reduced leaf water content by 9% at eCO2, which potentially arose through impaired water uptake by the roots. We hypothesise that this may have impaired photosynthetic activity to the extent that observed plant responses to eCO2 no longer occurred. In conclusion, soil-dwelling insects could modify plant responses to eCO2 predicted by climate change plant growth models.

  11. Improving the Ginkgo CO2 barometer: Implications for the early Cenozoic atmosphere

    Science.gov (United States)

    Barclay, Richard S.; Wing, Scott L.

    2016-04-01

    Stomatal properties of fossil Ginkgo have been used widely to infer the atmospheric concentration of CO2 in the geological past (paleo-pCO2). Many of these estimates of paleo-pCO2 have relied on the inverse correlation between pCO2 and stomatal index (SI - the proportion of epidermal cells that are stomata) observed in recent Ginkgo biloba, and therefore depend on the accuracy of this relationship. The SI - pCO2 relationship in G. biloba has not been well documented, however. Here we present new measurements of SI for leaves of G. biloba that grew under pCO2 from 290 to 430 ppm. We prepared and imaged all specimens using a consistent procedure and photo-documented each count. As in prior studies, we found a significant inverse relationship between SI and pCO2, however, the relationship is more linear, has a shallower slope, and a lower correlation coefficient than previously reported. We examined leaves of G. biloba grown under pCO2 of 1500 ppm, but found they had highly variable SI and a large proportion of malformed stomata. We also measured stomatal dimensions, stomatal density, and the carbon isotope composition of G. biloba leaves in order to test a mechanistic model for inferring pCO2. This model overestimated observed pCO2, performing less well than the SI method between 290 and 430 ppm. We used our revised SI-pCO2 response curve, and new observations of selected fossils, to estimate late Cretaceous and Cenozoic pCO2 from fossil Ginkgo adiantoides. All but one of the new estimates is below 800 ppm, and together they show little long-term change in pCO2 or relation to global temperature. The low Paleogene pCO2 levels indicated by the Ginkgo SI proxy are not consistent with the high pCO2 inferred by some climate and carbon cycle models. We cannot currently resolve the discrepancy, but greater agreement between proxy data and models may come from a better understanding of the stomatal response of G. biloba to elevated pCO2, better counts and measurements of

  12. Atmospheric CO2 fertilization effects on biomass yields of 10 crops in northern Germany

    Directory of Open Access Journals (Sweden)

    Jan F. Degener

    2015-07-01

    Full Text Available The quality and quantity of the influence that atmospheric CO2 has on cropgrowth is still a matter of debate. This study's aim is to estimate if CO2 will have an effect on biomass yields at all, to quantify and spatially locate the effects and to explore if an elevated photosynthesis rate or water-use-efficiency is predominantly responsible. This study uses a numerical carbon based crop model (BioSTAR to estimate biomass yields within theadministrative boundaries of Niedersachsen in Northern Germany. 10 crops are included (winter grains: wheat, barley,rye, triticale - early, medium, late maize variety - sunflower, sorghum, spring wheat, modeled annuallyfor the entire 21st century on 91,014 separate sites. Modeling was conducted twice, once with an annually adaptedCO2 concentration according to the SRES-A1B scenario and once with a fixed concentration of 390 ppm to separate the influence of CO2 from that of the other input variables.Rising CO2 concentrations will play a central role in keeping future yields of all crops above or aroundtoday's level. Differences in yields between modeling with fixed or adapted CO2 can be as high as60 % towards the century's end. Generally yields will increase when CO2 rises and decline whenit is kept constant. As C4-crops are equivalently affected it is presumed that anelevated efficiency in water use is the main responsible factor for all plants.

  13. Evaluating calibration strategies for isotope ratio infrared spectroscopy for atmospheric 13CO2 / 12CO2 measurement

    Directory of Open Access Journals (Sweden)

    X.-F. Wen

    2013-06-01

    Full Text Available Isotope ratio infrared spectroscopy (IRIS provides an in situ technique for measuring δ13C in atmospheric CO2. A number of methods have been proposed for calibrating the IRIS measurements, but few studies have systematically evaluated their accuracy for atmospheric applications. In this study, we carried out laboratory and ambient measurements with two commercial IRIS analyzers and compared the accuracy of four calibration strategies. We found that calibration based on the 12C and 13C mixing ratios (Bowling et al., 2003 and on linear interpolation of the measured delta using the mixing ratio of the major isotopologue (Lee et al., 2005 yielded accuracy better than 0.06‰. Over a 7-day atmospheric measurement in Beijing, the two analyzers agreed to within −0.02 ± 0.18‰ after proper calibration. However, even after calibration the difference between the two analyzers showed a slight correlation with concentration, and this concentration dependence propagated through the Keeling analysis, resulting in a much larger difference of 2.44‰ for the Keeling intercept. The high sensitivity of the Keeling analysis to the concentration dependence underscores the challenge of IRIS for atmospheric research.

  14. Evaluating calibration strategies for isotope ratio infrared spectroscopy for atmospheric 13CO2/12CO2 measurement

    Directory of Open Access Journals (Sweden)

    X. Lee

    2013-01-01

    Full Text Available Isotope ratio infrared spectroscopy (IRIS provides an in-situ technique for measuring δ13C in atmospheric CO2. A number of methods have been proposed for calibrating the IRIS measurements, but few studies have systematically evaluated their accuracy for atmospheric applications. In this study, we carried out laboratory and ambient measurements with two commercial IRIS analyzers and compared the accuracy of four calibration strategies. We found that calibration based on the 12C and 13C mixing ratios (Bowling et al., 2003 and that based on linear interpolation of the measured delta using the mixing ratio of the major isotopologue (Lee et al., 2005 yielded accuracy better than 0.06‰. Over a 7-day atmospheric measurement in Beijing, the two analyzers differed by 9.44 ± 1.65‰ (mean ± 1 standard deviation of hourly values before calibration and agreed to within −0.02 ± 0.18‰ after properly calibration. However, even after calibration the difference between the two analyzers showed a slight correlation with concentration, and this concentration dependence propagated through the Keeling analysis resulting in a much larger difference of 2.44‰ for the Keeling intercept. The high sensitivity of the Keeling analysis to the concentration dependence underscores the challenge of IRIS for atmospheric research.

  15. Evaluating calibration strategies for isotope ratio infrared spectroscopy for atmospheric 13CO2 / 12CO2 measurement

    Science.gov (United States)

    Wen, X.-F.; Meng, Y.; Zhang, X.-Y.; Sun, X.-M.; Lee, X.

    2013-06-01

    Isotope ratio infrared spectroscopy (IRIS) provides an in situ technique for measuring δ13C in atmospheric CO2. A number of methods have been proposed for calibrating the IRIS measurements, but few studies have systematically evaluated their accuracy for atmospheric applications. In this study, we carried out laboratory and ambient measurements with two commercial IRIS analyzers and compared the accuracy of four calibration strategies. We found that calibration based on the 12C and 13C mixing ratios (Bowling et al., 2003) and on linear interpolation of the measured delta using the mixing ratio of the major isotopologue (Lee et al., 2005) yielded accuracy better than 0.06‰. Over a 7-day atmospheric measurement in Beijing, the two analyzers agreed to within -0.02 ± 0.18‰ after proper calibration. However, even after calibration the difference between the two analyzers showed a slight correlation with concentration, and this concentration dependence propagated through the Keeling analysis, resulting in a much larger difference of 2.44‰ for the Keeling intercept. The high sensitivity of the Keeling analysis to the concentration dependence underscores the challenge of IRIS for atmospheric research.

  16. Kinetic study of the thermal decomposition process of calcite particles in air and CO2 atmosphere

    OpenAIRE

    Escardino Benlloch, Agustín; García Ten, Francisco Javier; Feliu Mingarro, Carlos; Saburit Llaudis, Alejandro; Cantavella Soler, Vicente

    2013-01-01

    The thermal decomposition process of calcite particles (0.45–3.60 mm average diameter), made up of porous agglomerates of very small CaCO3 microcrystals, was studied in the 975–1216 K temperature range. The experiments were carried out under isothermal conditions in air atmosphere, in CO2 atmosphere, as well as in a gas stream comprising different concentrations of air and CO2. An equation is proposed that relates the calcite conversion degree to both reaction time and operating condition...

  17. Atmospheric CO2 enrichment alters energy assimilation, investment and allocation in Xanthium strumarium.

    Science.gov (United States)

    Nagel, Jennifer M; Wang, Xianzhong; Lewis, James D; Fung, Howard A; Tissue, David T; Griffin, Kevin L

    2005-05-01

    Energy-use efficiency and energy assimilation, investment and allocation patterns are likely to influence plant growth responses to increasing atmospheric CO2 concentration ([CO2]). Here, we describe the influence of elevated [CO2] on energetic properties as a mechanism of growth responses in Xanthium strumarium. Individuals of X. strumarium were grown at ambient or elevated [CO2] and harvested. Total biomass and energetic construction costs (CC) of leaves, stems, roots and fruits and percentage of total biomass and energy allocated to these components were determined. Photosynthetic energy-use efficiency (PEUE) was calculated as the ratio of total energy gained via photosynthetic activity (Atotal) to leaf CC. Elevated [CO2] increased leaf Atotal, but decreased CC per unit mass of leaves and roots. Consequently, X. strumarium individuals produced more leaf and root biomass at elevated [CO2] without increasing total energy investment in these structures (CCtotal). Whole-plant biomass was associated positively with PEUE. Whole-plant construction required 16.1% less energy than modeled whole-plant energy investment had CC not responded to increased [CO2]. As a physiological mechanism affecting growth, altered energetic properties could positively influence productivity of X. strumarium, and potentially other species, at elevated [CO2]. PMID:15819914

  18. Changes in calcification of coccoliths under stable atmospheric CO2

    DEFF Research Database (Denmark)

    Berger, C.; Meier, K. J. S.; Kinkel, H.;

    2014-01-01

    The response of coccolithophore calcification to ocean acidification has been studied in culture experiments as well as in present and past oceans. The response, however, is different between species and strains, and for the relatively small carbonate chemistry changes observed in natural...... North Atlantic Ocean. The pre-industrial Holocene, with its predominantly stable atmospheric CO2, provides the conditions for such a comprehensive analysis. For an analysis on changes in major components of Holocene coccolithophores under natural conditions, the family Noelaerhabdaceae was selected...

  19. Radon and CO2 concentration screening in Bulgarian caves

    Czech Academy of Sciences Publication Activity Database

    Turek, Ondřej; Stefanov, P.; Světlík, Ivo; Orčíková, Hana; Šimek, Pavel; Kořínková, Tereza

    Sofia: TepApt, 2015, s. 32-43. ISBN 978-954-9531-26-8. [International Scientific and Practical Conference - PROTECTED KARST TERRITORIES - EDUCATION AND TRAINING. Sofia (BG), 23.09.2015-26.09.2015] Institutional support: RVO:61389005 Keywords : Bulgarian karst * 222Rn monitoring * track etch detectors * Radon activity concentration * CO2 mixing ratio * seasional variability * effective dose Subject RIV: DO - Wilderness Conservation

  20. Effects of Temperature Rise and Increase in CO2 Concentration on Simulated Wheat Yields in Europe

    NARCIS (Netherlands)

    Nonhebel, Sanderine

    1996-01-01

    A crop-growth-simulation model based on SUCROS87 was used to study effects of temperature rise and increase of atmospheric CO2 concentration on wheat yields in several regions in Europe. The model simulated potential and water-limited crop production (growth with ample supply of nutrients and in the

  1. Effects of Atmospheric CO2 Enrichment on Soil CO2 Efflux in a Young Longleaf Pine System

    OpenAIRE

    G. Brett Runion; J. R. Butnor; Prior, S. A.; Mitchell, R. J.; Rogers, H. H.

    2012-01-01

    The southeastern landscape is composed of agricultural and forest systems that can store carbon (C) in standing biomass and soil. Research is needed to quantify the effects of elevated atmospheric carbon dioxide (CO2) on terrestrial C dynamics including CO2 release back to the atmosphere and soil sequestration. Longleaf pine savannahs are an ecologically and economically important, yet understudied, component of the southeastern landscape. We investigated the effects of ambient and elevated C...

  2. Development of a mobile and high-precision atmospheric CO2 monitoring station

    Science.gov (United States)

    Molnár, M.; Haszpra, L.; Major, I.; Svingor, É.; Veres, M.

    2009-04-01

    Nowadays one of the most burning questions for the science is the rate and the reasons of the recent climate change. Greenhouse gases (GHG), mainly CO2 and CH4 in the atmosphere could affect the climate of our planet. However, the relation between the amount of atmospheric GHG and the climate is complex, full with interactions and feedbacks partly poorly known even by now. The only way to understand the processes, to trace the changes, to develop and validate mathematical models for forecasts is the extensive, high precision, continuous monitoring of the atmosphere. Fossil fuel CO2 emissions are a major component of the European carbon budget. Separation of the fossil fuel signal from the natural biogenic one in the atmosphere is, therefore, a crucial task for quantifying exchange flux of the continental biosphere through atmospheric observations and inverse modelling. An independent method to estimate trace gas emissions is the top-down approach, using atmospheric CO2 concentration measurements combined with simultaneous radiocarbon (14C) observations. As adding fossil fuel CO2 to the atmosphere, therefore, leads not only to an increase in the CO2 content of the atmosphere but also to a decrease in the 14C/12C ratio in atmospheric CO2. The ATOMKI has more than two decade long experience in atmospheric 14CO2 monitoring. As a part of an ongoing research project being carried out in Hungary to investigate the amount and temporal and spatial variations of fossil fuel CO2 in the near surface atmosphere we developed a mobile and high-precision atmospheric CO2 monitoring station. We describe the layout and the operation of the measuring system which is designed for the continuous, unattended monitoring of CO2 mixing ratio in the near surface atmosphere based on an Ultramat 6F (Siemens) infrared gas analyser. In the station one atmospheric 14CO2 sampling unit is also installed which is developed and widely used since more than one decade by ATOMKI. Mixing ratio of CO2 is

  3. Regional scale variations of atmospheric CO2 and CH4 from satellite observation

    International Nuclear Information System (INIS)

    To identify the sources, sinks and changes of atmospheric CO2 and CH4, this study investigates the spatio-temporal changes of atmospheric CO2 and CH4 concentration on the regional scale by the satellite observations. In this paper, choosing the land region of China as the study area, we investigate the spatio-temporal changes of atmospheric CO2 and CH4 concentrations using the data of the CO2 dry air mixing ratio (XCO2), and the CH4 dry air mixing ratio (XCH4), retrieved by the Greenhouse Gases Observing Satellite (GOSAT) from Jan. 2010 to Dec. 2012. The results show that (1) both XCO2 and XCH4 show higher concentrations in southeastern regions than that in the northwestern, and tend to yearly increasing from 2010 to 2013; (2) XCO2 shows obvious seasonal change with higher values in the spring than that in summer. The seasonal peak-to-peak amplitude is 8 ppm and the annual growth is about 2 ppm. XCH4, however, does not show a seasonal change; (3) With regard to different land-use backgrounds, XCO2 shows larger concentrations over the areas of urban agglomeration than that over the grasslands and deserts, and XCH4 shows lower concentrations over deserts than that over the Yangtze River Delta region and Sichuan Basin

  4. Regional impacts of climate change and atmospheric CO2 on future ocean carbon uptake: a multi model linear feedback analysis

    International Nuclear Information System (INIS)

    The increase in atmospheric CO2 over this century depends on the evolution of the oceanic air-sea CO2 uptake, which will be driven by the combined response to rising atmospheric CO2 itself and climate change. Here, the future oceanic CO2 uptake is simulated using an ensemble of coupled climate-carbon cycle models. The models are driven by CO2 emissions from historical data and the Special Report on Emissions Scenarios (SRES) A2 high-emission scenario. A linear feedback analysis successfully separates the regional future (2010-2100) oceanic CO2 uptake into a CO2-induced component, due to rising atmospheric CO2 concentrations, and a climate-induced component, due to global warming. The models capture the observation based magnitude and distribution of anthropogenic CO2 uptake. The distributions of the climate-induced component are broadly consistent between the models, with reduced CO2 uptake in the sub polar Southern Ocean and the equatorial regions, owing to decreased CO2 solubility; and reduced CO2 uptake in the mid-latitudes, owing to decreased CO2 solubility and increased vertical stratification. The magnitude of the climate-induced component is sensitive to local warming in the southern extra-tropics, to large freshwater fluxes in the extra-tropical North Atlantic Ocean, and to small changes in the CO2 solubility in the equatorial regions. In key anthropogenic CO2 uptake regions, the climate-induced component offsets the CO2- induced component at a constant proportion up until the end of this century. This amounts to approximately 50% in the northern extra-tropics and 25% in the southern extra-tropics and equatorial regions. Consequently, the detection of climate change impacts on anthropogenic CO2 uptake may be difficult without monitoring additional tracers, such as oxygen. (authors)

  5. Regional impacts of climate change and atmospheric CO2 on future ocean carbon uptake: a multi model linear feedback analysis

    International Nuclear Information System (INIS)

    The increase in atmospheric CO2 over this century depends on the evolution of the oceanic air-sea CO2 uptake, which will be driven by the combined response to rising atmospheric CO2 itself and climate change. Here, the future oceanic CO2 uptake is simulated using an ensemble of coupled climate-carbon cycle models. The models are driven by CO2 emissions from historical data and the Special Report on Emissions Scenarios (SRES) A2 high-emission scenario. A linear feedback analysis successfully separates the regional future (2010-2100) oceanic CO2 uptake into a CO2-induced component, due to rising atmospheric CO2 concentrations, and a climate-induced component, due to global warming. The models capture the observation based magnitude and distribution of anthropogenic CO2 uptake. The distributions of the climate-induced component are broadly consistent between the models, with reduced CO2 uptake in the sub-polar Southern Ocean and the equatorial regions, owing to decreased CO2 solubility; and reduced CO2 uptake in the mid latitudes, owing to decreased CO2 solubility and increased vertical stratification. The magnitude of the climate-induced component is sensitive to local warming in the southern extra tropics, to large freshwater fluxes in the extra tropical North Atlantic Ocean, and to small changes in the CO2 solubility in the equatorial regions. In key anthropogenic CO2 uptake regions, the climate-induced component offsets the CO2- induced component at a constant proportion up until the end of this century. This amounts to approximately 50% in the northern extra tropics and 25% in the southern extra tropics and equatorial regions. Consequently, the detection of climate change impacts on anthropogenic CO2 uptake may be difficult without monitoring additional tracers, such as oxygen. (authors)

  6. Effect of elevated CO2 concentration on photosynthetic characteristics of hyperaccumulator Sedum alfredii under cadmium stress

    Institute of Scientific and Technical Information of China (English)

    Tingqiang Li; Qi Tao; Zhenzhen Di; Fan Lu; Xiaoe Yang

    2015-01-01

    The combined effects of elevated CO2 and cadmi-um (Cd) on photosynthetic rate, chlorophyl fluorescence and Cd accumulation in hyperaccumulator Sedum alfredi Hance were investigated to predict plant growth under Cd stress with rising atmospheric CO2 concentration. Both pot and hydroponic experiments were conducted and the plants were grown under ambient (350 mL L?1) or elevated (800 mL L?1) CO2. Elevated CO2 significantly (P<0.05) increased Pn (105%–149%), Pnmax (38.8%–63.0%) and AQY (20.0%–34.8%) of S. alfredii in al the Cd treatments, but reduced chlorophyl concentra-tion, dark respiration and photorespiration. After 10 days growth in medium with 50 mM Cd under elevated CO2, PSII activities were significantly enhanced (P<0.05) with Pm, Fv/Fm, F(II) and qP increased by 66.1%, 7.5%, 19.5% and 16.4%, respectively, as compared with ambient-grown plants. Total Cd uptake in shoot of S. alfredi grown under elevated CO2 was increased by 44.1%–48.5%, which was positively correlated with the increase in Pn. These results indicate that elevated CO2 promoted the growth of S. alfredi due to increased photosynthetic carbon uptake rate and photosynthetic light-use efficiency, and showed great potential to improve the phytoextraction of Cd by S. alfredi .

  7. Effect of elevated CO2 concentration on photosynthetic characteristics of hyperaccumulator Sedum alfredii under cadmium stress.

    Science.gov (United States)

    Li, Tingqiang; Tao, Qi; Di, Zhenzhen; Lu, Fan; Yang, Xiaoe

    2015-07-01

    The combined effects of elevated CO2 and cadmium (Cd) on photosynthetic rate, chlorophyll fluorescence and Cd accumulation in hyperaccumulator Sedum alfredii Hance were investigated to predict plant growth under Cd stress with rising atmospheric CO2 concentration. Both pot and hydroponic experiments were conducted and the plants were grown under ambient (350 µL L(-1)) or elevated (800 µL L(-1)) CO2 . Elevated CO2 significantly (P < 0.05) increased Pn (105%-149%), Pnmax (38.8%-63.0%) and AQY (20.0%-34.8%) of S. alfredii in all the Cd treatments, but reduced chlorophyll concentration, dark respiration and photorespiration. After 10 days growth in medium with 50 µM Cd under elevated CO2 , PSII activities were significantly enhanced (P < 0.05) with Pm, Fv/Fm, Φ(II) and qP increased by 66.1%, 7.5%, 19.5% and 16.4%, respectively, as compared with ambient-grown plants. Total Cd uptake in shoot of S. alfredii grown under elevated CO2 was increased by 44.1%-48.5%, which was positively correlated with the increase in Pn. These results indicate that elevated CO2 promoted the growth of S. alfredii due to increased photosynthetic carbon uptake rate and photosynthetic light-use efficiency, and showed great potential to improve the phytoextraction of Cd by S. alfredii. PMID:25370532

  8. VARIABILITY OF ATMOSPHERIC CO2 OVER INDIA AND SURROUNDING OCEANS AND CONTROL BY SURFACE FLUXES

    Directory of Open Access Journals (Sweden)

    R. K. Nayak

    2012-08-01

    Full Text Available In the present study, seasonal and inter-annual variability of atmospheric CO2 concentration over India and surrounding oceans during 2002–2010 derived from Atmospheric InfrarRed Sounder observation and their relation with the natural flux exchanges over terrestrial Indian and surrounding oceans were analyzed. The natural fluxes over the terrestrial Indian in the form of net primary productivity (NPP were simulated based on a terrestrial biosphere model governed by time varying climate parameters (solar radiation, air temperature, precipitation etc and satellite greenness index together with the land use land cover and soil attribute maps. The flux exchanges over the oceans around India (Tropical Indian Ocean: TIO were calculated based on a empirical model of CO2 gas dissolution in the oceanic water governed by time varying upper ocean parameters such as gradient of partial pressure of CO2 between ocean and atmosphere, winds, sea surface temperature and salinity. Comparison between the variability of atmospheric CO2 anomaly with the anomaly of surface fluxes over India and surrounding oceans suggests that biosphere uptake over India and oceanic uptake over the south Indian Ocean could play positive role on the control of seasonal variability of atmospheric carbon dioxide growth rate. On inter-annual scale, flux exchanges over the tropical north Indian Ocean could play positive role on the control of atmospheric carbon dioxide growth rate.

  9. Variability of Atmospheric CO2 Over India and Surrounding Oceans and Control by Surface Fluxes

    Science.gov (United States)

    Nayak, R. K.; Dadhwal, V. K.; Majumdar, A.; Patel, N. R.; Dutt, C. B. S.

    2011-08-01

    In the present study, seasonal and inter-annual variability of atmospheric CO2 concentration over India and surrounding oceans during 2002-2010 derived from Atmospheric InfrarRed Sounder observation and their relation with the natural flux exchanges over terrestrial Indian and surrounding oceans were analyzed. The natural fluxes over the terrestrial Indian in the form of net primary productivity (NPP) were simulated based on a terrestrial biosphere model governed by time varying climate parameters (solar radiation, air temperature, precipitation etc) and satellite greenness index together with the land use land cover and soil attribute maps. The flux exchanges over the oceans around India (Tropical Indian Ocean: TIO) were calculated based on a empirical model of CO2 gas dissolution in the oceanic water governed by time varying upper ocean parameters such as gradient of partial pressure of CO2 between ocean and atmosphere, winds, sea surface temperature and salinity. Comparison between the variability of atmospheric CO2 anomaly with the anomaly of surface fluxes over India and surrounding oceans suggests that biosphere uptake over India and oceanic uptake over the south Indian Ocean could play positive role on the control of seasonal variability of atmospheric carbon dioxide growth rate. On inter-annual scale, flux exchanges over the tropical north Indian Ocean could play positive role on the control of atmospheric carbon dioxide growth rate.

  10. Radiative transfer in CO2-rich atmospheres: 1. Collisional line mixing implies a colder early Mars

    Science.gov (United States)

    Ozak, N.; Aharonson, O.; Halevy, I.

    2016-06-01

    Fast and accurate radiative transfer methods are essential for modeling CO2-rich atmospheres, relevant to the climate of early Earth and Mars, present-day Venus, and some exoplanets. Although such models already exist, their accuracy may be improved as better theoretical and experimental constraints become available. Here we develop a unidimensional radiative transfer code for CO2-rich atmospheres, using the correlated k approach and with a focus on modeling early Mars. Our model differs from existing models in that it includes the effects of CO2 collisional line mixing in the calculation of the line-by-line absorption coefficients. Inclusion of these effects results in model atmospheres that are more transparent to infrared radiation and, therefore, in colder surface temperatures at radiative-convective equilibrium, compared with results of previous studies. Inclusion of water vapor in the model atmosphere results in negligible warming due to the low atmospheric temperatures under a weaker early Sun, which translate into climatically unimportant concentrations of water vapor. Overall, the results imply that sustained warmth on early Mars would not have been possible with an atmosphere containing only CO2 and water vapor, suggesting that other components of the early Martian climate system are missing from current models or that warm conditions were not long lived.

  11. Recent advances in developing COS as a tracer of Biosphere-atmosphere exchange of CO2

    Science.gov (United States)

    Asaf, D.; Stimler, K.; Yakir, D.

    2012-04-01

    Potential use of COS as tracer of CO2 flux into vegetation, based on its co-diffusion with CO2 into leaves without outflux, stimulated research on COS-CO2 interactions. Atmospheric measurements by NOAA in recent years, across a global latitudinal transect, indicated a ratio of the seasonal drawdowns in COS and CO2 (normalized to their respective ambient concentrations) of about 6. We carried out leaf-scale gas exchange measurements of COS and CO2 in 22 plant species of deciduous, evergreen trees, grasses, and shrubs, under a range of light intensities and ambient COS concentrations (using mid IR laser spectroscopy). A narrow range in the normalized ratio of the net uptake rates of COS and CO2 (termed leaf relative uptake; LRU) was observed with a mean value of 1.61±0.26. These results reflect the dominance of stomatal conductance over both COS and CO2 uptake, imposing a relatively constant ratio between the two fluxes, except under low light conditions when CO2, but not COS, metabolism is light limited. A relatively constant ratio under common ambient conditions will facilitate the application of COS as a tracer of gross photosynthesis from leaf to global scales. We also report first eddy flux measurements of COS/CO2 at the ecosystem scales. Preliminarily results indicate a ratio of the COS flux, Fcos, to net ecosystem CO2 exchange, NEE, of 3-5 (termed ecosystem relative uptake; ERU). Combining measurements of COS and CO2 and the new information on their ratios at different scales should permit the direct estimation of gross CO2 uptake, GPP, by land ecosystems according to: GPP=NEE*ERU/LRU. In addition, we show that COS effect on stomatal conductance may require a special attention. Increasing COS concentrations between 250 and 2800 pmol mol-1 (enveloping atmospheric levels) stimulate stomatal conductance. It seems likely that the stomata are responding to H2S produced in the leaves from COS.

  12. Does Size Matter? Atmospheric CO2 May Be a Stronger Driver of Stomatal Closing Rate Than Stomatal Size in Taxa That Diversified under Low CO2.

    Science.gov (United States)

    Elliott-Kingston, Caroline; Haworth, Matthew; Yearsley, Jon M; Batke, Sven P; Lawson, Tracy; McElwain, Jennifer C

    2016-01-01

    One strategy for plants to optimize stomatal function is to open and close their stomata quickly in response to environmental signals. It is generally assumed that small stomata can alter aperture faster than large stomata. We tested the hypothesis that species with small stomata close faster than species with larger stomata in response to darkness by comparing rate of stomatal closure across an evolutionary range of species including ferns, cycads, conifers, and angiosperms under controlled ambient conditions (380 ppm CO2; 20.9% O2). The two species with fastest half-closure time and the two species with slowest half-closure time had large stomata while the remaining three species had small stomata, implying that closing rate was not correlated with stomatal size in these species. Neither was response time correlated with stomatal density, phylogeny, functional group, or life strategy. Our results suggest that past atmospheric CO2 concentration during time of taxa diversification may influence stomatal response time. We show that species which last diversified under low or declining atmospheric CO2 concentration close stomata faster than species that last diversified in a high CO2 world. Low atmospheric [CO2] during taxa diversification may have placed a selection pressure on plants to accelerate stomatal closing to maintain adequate internal CO2 and optimize water use efficiency. PMID:27605929

  13. The persistent and pernicious myth of the early CO2-N2 atmospheres of terrestrial planets

    Science.gov (United States)

    Shaw, G. H.

    2009-12-01

    The accepted model for early atmospheres of terrestrial planets has settled on a CO2-N2 composition. Unfortunately, while it is largely based on a brilliant geological analysis by Rubey, there is no compelling evidence whatsoever for such a composition as the first “permanent” atmosphere for Earth or any other planet. In fact, geological discoveries of the past 50+ years reveal several problems with a CO2-N2 atmosphere, some of which Rubey recognized in his own analysis. He clearly addressed the problem of timing of degassing, concluding that early massive degassing of CO2 would produce readily observed and profound effects, which are not evident. Modeling and constraints on the timing of planetary accretion and core formation indicate massive early degassing. If early degassing emitted CO2-N2, the effects are concealed. Plate tectonic recycling is not a solution, as conditions would have persisted beyond the time of the earliest rocks, which do not show the effects. Attempts to return degassed CO2 to the mantle are not only ad hoc, but inconsistent with early thermal structure of the Earth. Second, production of prebiotic organic compounds from a CO2-N2 atmosphere has been a nagging problem. At best this has been addressed by invoking hydrogen production from the mantle to provide reducing capacity. While hydrogen may be emitted in volcanic eruptions, it is exceedingly difficult to imagine this process generating enough organics to yield high concentrations in a global ocean. The recent fashion of invoking organic synthesis at deep-sea vents suffers from the same problem: how to achieve sufficient concentrations of organics in a global ocean by abiotic synthesis when hydrothermal activity stirs the solution and carries the prebiotic products off to great dilution? Suggesting life began at deep-sea vents, and continues to carry on chemosynthesis there, begs the question. Unless you get high enough concentrations of prebiotics by abiotic processes, you simply

  14. Exchanges of Atmospheric CO2 and 13CO2 with the Terrestrial Biosphere and Oceans from 1978 to 2000. II. A Three-Dimensional Tracer Inversion Model to Deduce Regional Fluxes

    OpenAIRE

    Piper, Stephen C; Keeling, Charles D.; HEIMANN Martin; Stewart, Elisabeth F

    2001-01-01

    A three-dimensional tracer inversion model is described that couples atmospheric CO2 transport with prescribed and adjustable source/sink components of the global car- bon cycle to predict atmospheric CO2 concentration and 13C/12C isotopic ratio taking account of exchange fluxes of atmospheric CO2 with the terrestrial biosphere and the oceans. Industrial CO2 emissions are prescribed from fuel production data. Transport of CO2 is prescribed by a model, TM2, that employs 9 vertical levels from ...

  15. Plant growth and leaf-spot severity on eucalypt at different CO2 concentrations in the air

    Directory of Open Access Journals (Sweden)

    Carlos Eduardo Oliveira da Silva

    2014-03-01

    Full Text Available The objective of this work was to evaluate the effects of increased air-CO2 concentration on plant growth and on leaf-spot caused by Cylindrocladium candelabrum in Eucalyptus urophylla. Seedlings were cultivated for 30 days at 451, 645, 904, and 1,147 µmol mol-1 CO2 ; then, they were inoculated with the pathogen and kept under the same conditions for seven days. Increased CO2 concentration increased plant height and shoot dry matter mass, and decreased disease incidence and severity. Stem diameter was not affected by the treatments. Increased concentrations of atmospheric CO2 favorably affect eucalypt growth and reduce leaf-spot severity.

  16. Long-term response of oceans to CO2 removal from the atmosphere

    Science.gov (United States)

    Mathesius, Sabine; Hofmann, Matthias; Caldeira, Ken; Schellnhuber, Hans Joachim

    2015-12-01

    Carbon dioxide removal (CDR) from the atmosphere has been proposed as a measure for mitigating global warming and ocean acidification. To assess the extent to which CDR might eliminate the long-term consequences of anthropogenic CO2 emissions in the marine environment, we simulate the effect of two massive CDR interventions with CO2 extraction rates of 5 GtC yr-1 and 25 GtC yr-1, respectively, while CO2 emissions follow the extended RCP8.5 pathway. We falsify two hypotheses: the first being that CDR can restore pre-industrial conditions in the ocean by reducing the atmospheric CO2 concentration back to its pre-industrial level, and the second being that high CO2 emissions rates (RCP8.5) followed by CDR have long-term oceanic consequences that are similar to those of low emissions rates (RCP2.6). Focusing on pH, temperature and dissolved oxygen, we find that even after several centuries of CDR deployment, past CO2 emissions would leave a substantial legacy in the marine environment.

  17. On the development of a methodology for extensive in-situ and continuous atmospheric CO2 monitoring

    Science.gov (United States)

    Wang, K.; Chang, S.; Jhang, T.

    2010-12-01

    Carbon dioxide is recognized as the dominating greenhouse gas contributing to anthropogenic global warming. Stringent controls on carbon dioxide emissions are viewed as necessary steps in controlling atmospheric carbon dioxide concentrations. From the view point of policy making, regulation of carbon dioxide emissions and its monitoring are keys to the success of stringent controls on carbon dioxide emissions. Especially, extensive atmospheric CO2 monitoring is a crucial step to ensure that CO2 emission control strategies are closely followed. In this work we develop a methodology that enables reliable and accurate in-situ and continuous atmospheric CO2 monitoring for policy making. The methodology comprises the use of gas filter correlation (GFC) instrument for in-situ CO2 monitoring, the use of CO2 working standards accompanying the continuous measurements, and the use of NOAA WMO CO2 standard gases for calibrating the working standards. The use of GFC instruments enables 1-second data sampling frequency with the interference of water vapor removed from added dryer. The CO2 measurements are conducted in the following timed and cycled manner: zero CO2 measurement, two standard CO2 gases measurements, and ambient air measurements. The standard CO2 gases are calibrated again NOAA WMO CO2 standards. The methodology is used in indoor CO2 measurements in a commercial office (about 120 people working inside), ambient CO2 measurements, and installed in a fleet of in-service commercial cargo ships for monitoring CO2 over global marine boundary layer. These measurements demonstrate our method is reliable, accurate, and traceable to NOAA WMO CO2 standards. The portability of the instrument and the working standards make the method readily applied for large-scale and extensive CO2 measurements.

  18. CO2 and HCO3- uptake in marine diatoms acclimated to different CO2 concentrations.

    OpenAIRE

    Burkhardt, S.; Amoroso, G.; Riebesell, Ulf

    2001-01-01

    Rates of cellular uptake of CO2 and HCO3- during steady-state photosynthesis were measured in the marine diatoms Thalassiosira weissflogii and Phaeodactylum tricornutum, acclimated to CO2 partial pressures of 36, 180, 360, and 1,800 ppmv. In addition, in vivo activity of extracellular (eCA) and intracellular (iCA) carbonic anhydrase was determined in relation to CO2 availability. Both species responded to diminishing CO2 supply with an increase in eCA and iCA activity. In P. tricornutum, eCA ...

  19. Dispersive infrared spectroscopy measurements of atmospheric CO2 using a Fabry–Pérot interferometer sensor

    International Nuclear Information System (INIS)

    In this paper, we present the first dispersive infrared spectroscopic (DIRS) measurement of atmospheric carbon dioxide (CO2) using a new scanning Fabry–Pérot interferometer (FPI) sensor. The sensor measures the optical spectra in the mid infrared (3900 nm to 5220 nm) wavelength range with full width half maximum (FWHM) spectral resolution of 78.8 nm at the CO2 absorption band (∼ 4280 nm) and sampling resolution of 20 nm. The CO2 concentration is determined from the measured optical absorption spectra by fitting it to the CO2 reference spectrum. Interference from other major absorbers in the same wavelength range, e.g., carbon monoxide (CO) and water vapor (H2O), was taken out by including their reference spectra in the fit as well. The detailed descriptions of the instrumental setup, the retrieval procedure, a modeling study for error analysis as well as laboratory validation using standard gas concentrations are presented. An iterative algorithm to account for the non-linear response of the fit function to the absorption cross sections due to the broad instrument function was developed and tested. A modeling study of the retrieval algorithm showed that errors due to instrument noise can be considerably reduced by using the dispersive spectral information in the retrieval. The mean measurement error of the prototype DIRS CO2 measurement for 1 minute averaged data is about ± 2.5 ppmv, and down to ± 0.8 ppmv for 10 minute averaged data. A field test of atmospheric CO2 measurements were carried out in an urban site in Hong Kong for a month and compared to a commercial non-dispersive infrared (NDIR) CO2 analyzer. 10 minute averaged data shows good agreement between the DIRS and NDIR measurements with Pearson correlation coefficient (R) of 0.99. This new method offers an alternative approach of atmospheric CO2 measurement featuring high accuracy, correction of non-linear absorption and interference of water vapor. - Highlights: • Dispersive infrared

  20. Antarctic ice sheet sensitivity to atmospheric CO2 variations in the early to mid-Miocene

    Science.gov (United States)

    Levy, Richard; Harwood, David; Florindo, Fabio; Sangiorgi, Francesca; Tripati, Robert; von Eynatten, Hilmar; Gasson, Edward; Kuhn, Gerhard; Tripati, Aradhna; DeConto, Robert; Fielding, Christopher; Field, Brad; Golledge, Nicholas; McKay, Robert; Naish, Timothy; Olney, Matthew; Pollard, David; Schouten, Stefan; Talarico, Franco; Warny, Sophie; Willmott, Veronica; Acton, Gary; Panter, Kurt; Paulsen, Timothy; Taviani, Marco; SMS Science Team; Acton, Gary; Askin, Rosemary; Atkins, Clifford; Bassett, Kari; Beu, Alan; Blackstone, Brian; Browne, Gregory; Ceregato, Alessandro; Cody, Rosemary; Cornamusini, Gianluca; Corrado, Sveva; DeConto, Robert; Del Carlo, Paola; Di Vincenzo, Gianfranco; Dunbar, Gavin; Falk, Candice; Field, Brad; Fielding, Christopher; Florindo, Fabio; Frank, Tracy; Giorgetti, Giovanna; Grelle, Thomas; Gui, Zi; Handwerger, David; Hannah, Michael; Harwood, David M.; Hauptvogel, Dan; Hayden, Travis; Henrys, Stuart; Hoffmann, Stefan; Iacoviello, Francesco; Ishman, Scott; Jarrard, Richard; Johnson, Katherine; Jovane, Luigi; Judge, Shelley; Kominz, Michelle; Konfirst, Matthew; Krissek, Lawrence; Kuhn, Gerhard; Lacy, Laura; Levy, Richard; Maffioli, Paola; Magens, Diana; Marcano, Maria C.; Millan, Cristina; Mohr, Barbara; Montone, Paola; Mukasa, Samuel; Naish, Timothy; Niessen, Frank; Ohneiser, Christian; Olney, Mathew; Panter, Kurt; Passchier, Sandra; Patterson, Molly; Paulsen, Timothy; Pekar, Stephen; Pierdominici, Simona; Pollard, David; Raine, Ian; Reed, Joshua; Reichelt, Lucia; Riesselman, Christina; Rocchi, Sergio; Sagnotti, Leonardo; Sandroni, Sonia; Sangiorgi, Francesca; Schmitt, Douglas; Speece, Marvin; Storey, Bryan; Strada, Eleonora; Talarico, Franco; Taviani, Marco; Tuzzi, Eva; Verosub, Kenneth; von Eynatten, Hilmar; Warny, Sophie; Wilson, Gary; Wilson, Terry; Wonik, Thomas; Zattin, Massimiliano

    2016-03-01

    Geological records from the Antarctic margin offer direct evidence of environmental variability at high southern latitudes and provide insight regarding ice sheet sensitivity to past climate change. The early to mid-Miocene (23-14 Mya) is a compelling interval to study as global temperatures and atmospheric CO2 concentrations were similar to those projected for coming centuries. Importantly, this time interval includes the Miocene Climatic Optimum, a period of global warmth during which average surface temperatures were 3-4 °C higher than today. Miocene sediments in the ANDRILL-2A drill core from the Western Ross Sea, Antarctica, indicate that the Antarctic ice sheet (AIS) was highly variable through this key time interval. A multiproxy dataset derived from the core identifies four distinct environmental motifs based on changes in sedimentary facies, fossil assemblages, geochemistry, and paleotemperature. Four major disconformities in the drill core coincide with regional seismic discontinuities and reflect transient expansion of grounded ice across the Ross Sea. They correlate with major positive shifts in benthic oxygen isotope records and generally coincide with intervals when atmospheric CO2 concentrations were at or below preindustrial levels (˜280 ppm). Five intervals reflect ice sheet minima and air temperatures warm enough for substantial ice mass loss during episodes of high (˜500 ppm) atmospheric CO2. These new drill core data and associated ice sheet modeling experiments indicate that polar climate and the AIS were highly sensitive to relatively small changes in atmospheric CO2 during the early to mid-Miocene.

  1. The paper trail of the 13C of atmospheric CO2 since the industrial revolution period

    International Nuclear Information System (INIS)

    The 13C concentration in atmospheric CO2 has been declining over the past 150 years as large quantities of 13C-depleted CO2 from fossil fuel burning are added to the atmosphere. Deforestation and other land use changes have also contributed to the trend. Looking at the 13C variations in the atmosphere and in annual growth rings of trees allows us to estimate CO2 uptake by land plants and the ocean, and assess the response of plants to climate. Here I show that the effects of the declining 13C trend in atmospheric CO2 are recorded in the isotopic composition of paper used in the printing industry, which provides a well-organized archive and integrated material derived from trees' cellulose. 13C analyses of paper from two European and two American publications showed, on average, a - 1.65 ± 1.00 per mille trend between 1880 and 2000, compared with - 1.45 and - 1.57 per mille for air and tree-ring analyses, respectively. The greater decrease in plant-derived 13C in the paper we tested than in the air is consistent with predicted global-scale increases in plant intrinsic water-use efficiency over the 20th century. Distinct deviations from the atmospheric trend were observed in both European and American publications immediately following the World War II period.

  2. Effect of CO2 on Atmospheric Corrosion of UNS G10190 Steel under Thin Electrolyte Film

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The atmospheric corrosion of UNS G10190 steel under a thin electrolyte film in the atmosphere polluted by CO2 has been studied in the lab using an atmospheric corrosion monitor(ACM) in combination with XRD and SEM observations of the surface of steel. The ACM study indicated that the corrosion rate of the steel increased with increasing carbon dioxide concentration. The XRD and SEM observations showed that no carbonate was found in the corrosion product on the steel surface. The corrosion product consisted of two layers, i. e., inner and outer layer. From the experimental results, it was concluded that CO2 played an enhancing role in the atmospheric corrosion of UNS G10190 steel. The film of the corrosion product showed slight protection.

  3. Impact of oceanic circulation changes on the CO2 concentration during past interglacials

    Science.gov (United States)

    Bouttes, Nathaelle; Swingedouw, Didier; Crosta, Xavier; Fernanda Sanchez Goñi, Maria; Roche, Didier

    2016-04-01

    Interglacials before the Mid-Bruhnes Event (around 430 kyrs BP) were characterized by colder temperature in Antarctica, lower sea level and lower atmospheric CO2 compared to the more recent interglacials. Recent climate simulations have shown that the climate of the interglacials before and after the MBE can only be reproduced when taking into account changes in orbital parameters and atmospheric CO2 concentrations (Yin and Berger, 2010; Yin and Berger, 2012). Indeed, interglacial atmospheric CO2 concentrations were ~250 ppm and ~280 ppm prior and after the MBE, respectively. Yet, the cause for this change in atmospheric CO2 remains mainly unknown. climate simulations suggest that oceanic circulation was different during the interglacials due to the different climate states (Yin, 2013). The changes of oceanic circulation could have modified the carbon cycle: a more sluggish circulation would lead to greater carbon sequestration in the deep ocean and, subsequently, a decrease of atmospheric CO2. However, the impact of oceanic circulation changes on the carbon cycle during the interglacials of the last 800 kyrs has never been tested in coupled carbon-climate models. Here, we evaluate the role of ocean circulation changes on the carbon cycle during interglacials by using the intermediate complexity model iLOVECLIM (Goosse et al., 2010 ; Bouttes et al., 2015). This model includes a carbon cycle module on land and in the ocean and simulates carbon isotopes. The interglacial simulations are forced with orbital parameters, ice sheets and CO2 concentrations from data reconstructions. The model computes carbon fluxes between the reservoirs and an atmospheric CO2 that is distinct from the one used as a forcing. We will present simulations from this climate model for different interglacial periods of the last 800 000 years and use model-data comparison to analyse and evaluate the changes in the carbon cycle, including CO2. References Bouttes, N. et al. (2015), Geosci. Model

  4. Characteristics of coupled atmosphere-ocean CO2 sensitivity experiments with different ocean formulations

    International Nuclear Information System (INIS)

    The Community Climate Model at the National Center for Atmospheric Research has been coupled to a simple mixed-layer ocean model and to a coarse-grid ocean general circulation model (OGCM). This paper compares the responses of simulated climate to increases of atmospheric carbon dioxide (CO2) in these two coupled models. Three types of simulations were run: (1) control runs with both ocean models, with CO2 held constant at present-day concentrations, (2) instantaneous doubling of atmospheric CO2 (from 330 to 660 ppm) with both ocean models, and (3) a gradually increasing (transient) CO2 concentration starting at 330 ppm and increasing linearly at 1% per year, with the OGCM. The mixed-layer and OGCM cases exhibit increases of 3.5 C and 1.6 C, respectively, in globally averaged surface air temperature for the instantaneous doubling cases. The transient-forcing case warms 0.7 C by the end of 30 years. The mixed-layer ocean yields warmer-than-observed tropical temperatures and colder-than-observed temperatures in the higher latitudes. The coarse-grid OGCM simulates lower-than-observed sea surface temperatures (SSTs) in the tropics and higher-than-observed SSTs and reduced sea-ice extent at higher latitudes. Sensitivity in the OGCM after 30 years is much lower than in simulations with the same atmosphere coupled to a 50-m slab-ocean mixed layer. The OGCM simulates a weaker thermohaline circulation with doubled CO2 as the high-latitude ocean-surface layer warms and freshens and the westerly wind stress decreases. Convective overturning in the OGCM decreases substantially with CO2 warming

  5. Characteristics of coupled atmosphere-ocean CO2 sensitivity experiments with different ocean formulations

    International Nuclear Information System (INIS)

    The Community Climate Model at the National Center for Atmospheric Research has been coupled to a simple mixed-layer ocean model and to a coarse-grid ocean general circulation model (OGCM). This paper compares the responses of simulated climate to increases of atmospheric carbon dioxide (CO2) in these two coupled models. Three types of simulations were run: (1) control runs with both ocean models, with CO2 held constant at present-day concentrations, (2) instantaneous doubling of atmospheric CO2 (from 330 to 660 ppm) with both ocean models, and (3) a gradually increasing (transient) CO2 concentration starting at 330 ppm and increasing linearly at 1% per year, with the OGCM. The mixed-layer and OGCM cases exhibit increases of 3.5 C and 1.6 C, respectively, in globally averaged surface air temperature for the instantaneous doubling cases. The transient-forcing case warms 0.7 C by the end of 30 years. The mixed-layer ocean yields warmer-than-observed tropical temperatures and colder-than-observed temperatures in the higher latitudes. The coarse-grid OGCM simulates lower-than-observed sea surface temperatures (SSTs) in the tropics and higher-than-observed SSTs and reduced sea-ice extent at higher latitudes. Sensitivity in the OGCM after 30 years is much lower than in simulations with the same atmosphere coupled to a 50-m slab-ocean mixed layer. The OGCM simulates a weaker thermohaline circulation with doubled CO2 as the high-latitude ocean-surface layer warms and freshens and the westerly wind stress decreases. Convective overturning in the OGCM decreases substantially with CO2 warming. 46 refs.; 20 figs.; 1 tab

  6. Effects of doubled CO2 concentration on leaf photosynthesis, transpiration and water use efficiency of eight crop species

    OpenAIRE

    Wang, Jian-Lin; WEN Xue-Fa; ZHAO Feng-Hua; FANG Quan-Xiao; YANG Xin-Min

    2012-01-01

    Aims Our objective was to elucidate the response of crop photosynthesis, transpiration and water use efficiency to atmospheric CO2 concentration. This has great significance to predicting crop productivity and water-demand changes under increasing atmospheric CO2 concentration.Methods The photosynthesis rate, transpiration rate and water use efficiency of eight crops (soybean (Glycine max), sweet potato (Ipomoea batatas), peanut (Arachis hypogaea), rice (Oryza sativa), cotton (Gossypium hirsu...

  7. Rapid atmospheric CO2 changes associated with the 8,200-years-B.P. cooling event

    NARCIS (Netherlands)

    Wagner, F.; Aaby, B.; Visscher, H.

    2002-01-01

    By applying the inverse relation between numbers of leaf stomata and atmospheric CO2 concentration, stomatal frequency analysis of fossil birch leaves from lake deposits in Denmark reveals a century-scale CO2 change during the prominent Holocene cooling event that occurred in the North Atlantic regi

  8. Development and consequences of atmospheric CO2 pollution

    International Nuclear Information System (INIS)

    The consequences of the use of fossil fuels and a number of trace gases have changed the composition of the atmosphere and, in this way, the radiation balance within the atmosphere. The influence on the climate of the rising atmospheric content of carbon dioxide (CO2) has become an important problem, which constitutes the background to energy policy. This problem has become more and more topical and multi-faceted over the past decade. Extreme climatic anomalies occur in various regions of the earth, which had not previously been experienced in this intensity in our century. Even more extreme weather and climatic events must be expected to occur in the future. From the most recent data climatologists conclude that the development will be different than had initially been assumed. For instance, the role of water vapor seems to have been underestimated. A change in climate, starting from the tropics, seems to be under way. The modeling results, which must be used as a starting point for specific predictions in any field, are still highly contradictory and do not at present permit a forecast to be made for a region such as Central Europe. It can only be said with some reliability that the process of warming up will continue, perhaps even at an increasing pace. (orig.)

  9. Diurnal variation of CO2 concentration, Δ14C and δ13C in an urban forest: estimate of the anthropogenic and biogenic CO2 contributions

    OpenAIRE

    Takahashi, Hiroshi A.; Konohira, Eiichi; HIYAMA, TETSUYA; MINAMI, Masayo; Nakamura, Toshio; YOSHIDA, Naohiro

    2002-01-01

    Diurnal variation in the atmospheric CO2 concentration and the carbon isotopic composition (Δ14C and δ13C) was measured in a forest in an urban area on 9 February 1999. The carbon isotope approach used in the present study differentiated between the quantitative contributions from anthropogenic and biogenic CO2 sources in the urban atmosphere. The anthropogenic (fossil fuel) and biogenic (soil respiration) contributions was estimated, and they ranged from 1 to 16% and from 2 to 8% of the tota...

  10. Glyphosate Resistance of C3 and C4 Weeds under Rising Atmospheric CO2

    Science.gov (United States)

    Fernando, Nimesha; Manalil, Sudheesh; Florentine, Singarayer K.; Chauhan, Bhagirath S.; Seneweera, Saman

    2016-01-01

    The present paper reviews current knowledge on how changes of plant metabolism under elevated CO2 concentrations (e[CO2]) can affect the development of the glyphosate resistance of C3 and C4 weeds. Among the chemical herbicides, glyphosate, which is a non-selective and post-emergence herbicide, is currently the most widely used herbicide in global agriculture. As a consequence, glyphosate resistant weeds, particularly in major field crops, are a widespread problem and are becoming a significant challenge to future global food production. Of particular interest here it is known that the biochemical processes involved in photosynthetic pathways of C3 and C4 plants are different, which may have relevance to their competitive development under changing environmental conditions. It has already been shown that plant anatomical, morphological, and physiological changes under e[CO2] can be different, based on (i) the plant’s functional group, (ii) the available soil nutrients, and (iii) the governing water status. In this respect, C3 species are likely to have a major developmental advantage under a CO2 rich atmosphere, by being able to capitalize on the overall stimulatory effect of e[CO2]. For example, many tropical weed grass species fix CO2 from the atmosphere via the C4 photosynthetic pathway, which is a complex anatomical and biochemical variant of the C3 pathway. Thus, based on our current knowledge of CO2 fixing, it would appear obvious that the development of a glyphosate-resistant mechanism would be easier under an e[CO2] in C3 weeds which have a simpler photosynthetic pathway, than for C4 weeds. However, notwithstanding this logical argument, a better understanding of the biochemical, genetic, and molecular measures by which plants develop glyphosate resistance and how e[CO2] affects these measures will be important before attempting to innovate sustainable technology to manage the glyphosate-resistant evolution of weeds under e[CO2]. Such information will be

  11. Glyphosate Resistance of C3 and C4 Weeds under Rising Atmospheric CO2.

    Science.gov (United States)

    Fernando, Nimesha; Manalil, Sudheesh; Florentine, Singarayer K; Chauhan, Bhagirath S; Seneweera, Saman

    2016-01-01

    The present paper reviews current knowledge on how changes of plant metabolism under elevated CO2 concentrations (e[CO2]) can affect the development of the glyphosate resistance of C3 and C4 weeds. Among the chemical herbicides, glyphosate, which is a non-selective and post-emergence herbicide, is currently the most widely used herbicide in global agriculture. As a consequence, glyphosate resistant weeds, particularly in major field crops, are a widespread problem and are becoming a significant challenge to future global food production. Of particular interest here it is known that the biochemical processes involved in photosynthetic pathways of C3 and C4 plants are different, which may have relevance to their competitive development under changing environmental conditions. It has already been shown that plant anatomical, morphological, and physiological changes under e[CO2] can be different, based on (i) the plant's functional group, (ii) the available soil nutrients, and (iii) the governing water status. In this respect, C3 species are likely to have a major developmental advantage under a CO2 rich atmosphere, by being able to capitalize on the overall stimulatory effect of e[CO2]. For example, many tropical weed grass species fix CO2 from the atmosphere via the C4 photosynthetic pathway, which is a complex anatomical and biochemical variant of the C3 pathway. Thus, based on our current knowledge of CO2 fixing, it would appear obvious that the development of a glyphosate-resistant mechanism would be easier under an e[CO2] in C3 weeds which have a simpler photosynthetic pathway, than for C4 weeds. However, notwithstanding this logical argument, a better understanding of the biochemical, genetic, and molecular measures by which plants develop glyphosate resistance and how e[CO2] affects these measures will be important before attempting to innovate sustainable technology to manage the glyphosate-resistant evolution of weeds under e[CO2]. Such information will be of

  12. Agricultural Green Revolution as a driver of increasing atmospheric CO2 seasonal amplitude

    Science.gov (United States)

    Zeng, Ning; Zhao, Fang; Collatz, George J.; Kalnay, Eugenia; Salawitch, Ross J.; West, Tristram O.; Guanter, Luis

    2014-11-01

    The atmospheric carbon dioxide (CO2) record displays a prominent seasonal cycle that arises mainly from changes in vegetation growth and the corresponding CO2 uptake during the boreal spring and summer growing seasons and CO2 release during the autumn and winter seasons. The CO2 seasonal amplitude has increased over the past five decades, suggesting an increase in Northern Hemisphere biospheric activity. It has been proposed that vegetation growth may have been stimulated by higher concentrations of CO2 as well as by warming in recent decades, but such mechanisms have been unable to explain the full range and magnitude of the observed increase in CO2 seasonal amplitude. Here we suggest that the intensification of agriculture (the Green Revolution, in which much greater crop yield per unit area was achieved by hybridization, irrigation and fertilization) during the past five decades is a driver of changes in the seasonal characteristics of the global carbon cycle. Our analysis of CO2 data and atmospheric inversions shows a robust 15 per cent long-term increase in CO2 seasonal amplitude from 1961 to 2010, punctuated by large decadal and interannual variations. Using a terrestrial carbon cycle model that takes into account high-yield cultivars, fertilizer use and irrigation, we find that the long-term increase in CO2 seasonal amplitude arises from two major regions: the mid-latitude cropland between 25° N and 60° N and the high-latitude natural vegetation between 50° N and 70° N. The long-term trend of seasonal amplitude increase is 0.311 +/- 0.027 per cent per year, of which sensitivity experiments attribute 45, 29 and 26 per cent to land-use change, climate variability and change, and increased productivity due to CO2 fertilization, respectively. Vegetation growth was earlier by one to two weeks, as measured by the mid-point of vegetation carbon uptake, and took up 0.5 petagrams more carbon in July, the height of the growing season, during 2001-2010 than in 1961

  13. Development of concepts to assess, monitor and evaluate increased CO2 concentrations arising from potential leakages of CCS sites

    OpenAIRE

    Schulz, Alexandra

    2013-01-01

    Increasing CO2 concentrations in the atmosphere make it necessary to reduce the anthropogenic greenhouse gas emission. One option is the capture and storage of CO2 in the deep underground. If leakages from these storage reservoirs occur, monitoring methods need to be available for early detection. Stable carbon isotopes were used to test an early warning monitoring approach during a field experiment, where 800 kg of CO2 were injected in the underground. Additionally, the influence of increase...

  14. Decarbonization and the time-delay between peak CO2 emissions and concentrations

    CERN Document Server

    Seshadri, Ashwin K

    2015-01-01

    Carbon-dioxide (CO2) is the main contributor to anthropogenic global warming, and the timing of its peak concentration in the atmosphere is likely to govern the timing of maximum radiative forcing. While dynamics of atmospheric CO2 is governed by multiple time-constants, we idealize this by a single time-constant to consider some of the factors describing the time-delay between peaks in CO2 emissions and concentrations. This time-delay can be understood as the time required to bring CO2 emissions down from its peak to a small value, and is governed by the rate of decarbonizaton of economic activity. This decarbonization rate affects how rapidly emissions decline after having achieved their peak, and a rapid decline in emissions is essential for limiting peak radiative forcing. Long-term mitigation goals for CO2 should therefore consider not only the timing of peak emissions, but also the rate of decarbonization. We discuss implications for mitigation of the fact that the emissions peak corresponds to small bu...

  15. Time-dependent atmospheric CO2 inversions based on interannually varying tracer transport

    International Nuclear Information System (INIS)

    The use of inverse calculations to estimate surface CO2 fluxes from atmospheric concentration measurements has gained large attention in recent years. The success of an inversion will, among other factors, depend strongly on how realistically atmospheric tracer transport is represented by the employed transport model, as it links surface CO2 fluxes to modelled concentrations at the location of measurement stations. We present sensitivity studies demonstrating that transport modelling should be based on interannually varying meteorology, as compared to the traditional use of repeating a single year's winds only. Moreover, we propose an improved procedure of representing the concentration sampling in the model, which allows consistency with the measurements and uses their information content more efficiently. In further sensitivity tests, we estimate the effect of different spatial transport model resolutions and different meteorological driver data sets. Finally, we assess the quality of the inversion results with the help of independent measurements and flux estimates, and preliminarily discuss some of the resulting features

  16. Abiotic formation of O2 and O3 in high-CO2 terrestrial atmospheres

    CERN Document Server

    Segura, A; Kasting, J F; Crisp, D; Cohen, M

    2007-01-01

    Previous research has indicated that high amounts of ozone (O3) and oxygen (O2) may be produced abiotically in atmospheres with high concentrations of CO2. The abiotic production of these two gases, which are also characteristic of photosynthetic life processes, could pose a potential "false-positive" for remote-sensing detection of life on planets around other stars.We show here that such false positives are unlikely on any planet that possesses abundant liquid water, as rainout of oxidized species onto a reduced planetary surface should ensure that atmospheric H2 concentrations remain relatively high, and that O2 and O3 remain low. Our aim is to determine the amount of O3 and O2 formed in a high CO2 atmosphere for a habitable planet without life. We use a photochemical model that considers hydrogen (H2) escape and a detailed hydrogen balance to calculate the O2 and O3 formed on planets with 0.2 of CO2 around the Sun, and 0.02, 0.2 and 2 bars of CO2 around a young Sun-like star with higher UV radiation. The ...

  17. Enhanced photosynthetic efficiency in trees world-wide by rising atmospheric CO2 levels

    Science.gov (United States)

    Ehlers, Ina; Wieloch, Thomas; Groenendijk, Peter; Vlam, Mart; van der Sleen, Peter; Zuidema, Pieter A.; Robertson, Iain; Schleucher, Jürgen

    2014-05-01

    The atmospheric CO2 concentration is increasing rapidly due to anthropogenic emissions but the effect on the Earth's biosphere is poorly understood. The ability of the biosphere to fix CO2 through photosynthesis will determine future atmospheric CO2 concentrations as well as future productivity of crops and forests. Manipulative CO2 enrichment experiments (e.g. FACE) are limited to (i) short time spans, (ii) few locations and (iii) large step increases in [CO2]. Here, we apply new stable isotope methodology to tree-ring archives, to study the effect of increasing CO2 concentrations retrospectively during the past centuries. We cover the whole [CO2] increase since industrialization, and sample trees with global distribution. Instead of isotope ratios of whole molecules, we use intramolecular isotope distributions, a new tool for tree-ring analysis with decisive advantages. In experiments on annual plants, we have found that the intramolecular distribution of deuterium (equivalent to ratios of isotopomer abundances) in photosynthetic glucose depends on growth [CO2] and reflects the metabolic flux ratio of photosynthesis to photorespiration. By applying this isotopomer methodology to trees from Oak Ridge FACE experiment, we show that this CO2 response is present in trees on the leaf level. This CO2 dependence constitutes a physiological signal, which is transferred to the wood of the tree rings. In trees from 13 locations on all continents the isotopomer ratio of tree-ring cellulose is correlated to atmospheric [CO2] during the past 200 years. The shift of the isotopomer ratio is universal for all 12 species analyzed, including both broad-leafed trees and conifers. Because the trees originate from sites with widely differing D/H ratios of precipitation, the generality of the response demonstrates that the signal is independent of the source isotope ratio, because it is encoded in an isotopomer abundance ratio. This decoupling of climate signals and physiological

  18. Temporal variations of atmospheric CO2 and CO at Ahmedabad in western India

    Science.gov (United States)

    Chandra, Naveen; Lal, Shyam; Venkataramani, S.; Patra, Prabir K.; Sheel, Varun

    2016-05-01

    About 70 % of the anthropogenic carbon dioxide (CO2) is emitted from the megacities and urban areas of the world. In order to draw effective emission mitigation policies for combating future climate change as well as independently validating the emission inventories for constraining their large range of uncertainties, especially over major metropolitan areas of developing countries, there is an urgent need for greenhouse gas measurements over representative urban regions. India is a fast developing country, where fossil fuel emissions have increased dramatically in the last three decades and are predicted to continue to grow further by at least 6 % per year through to 2025. The CO2 measurements over urban regions in India are lacking. To overcome this limitation, simultaneous measurements of CO2 and carbon monoxide (CO) have been made at Ahmedabad, a major urban site in western India, using a state-of-the-art laser-based cavity ring down spectroscopy technique from November 2013 to May 2015. These measurements enable us to understand the diurnal and seasonal variations in atmospheric CO2 with respect to its sources (both anthropogenic and biospheric) and biospheric sinks. The observed annual average concentrations of CO2 and CO are 413.0 ± 13.7 and 0.50 ± 0.37 ppm respectively. Both CO2 and CO show strong seasonality with lower concentrations (400.3 ± 6.8 and 0.19 ± 0.13 ppm) during the south-west monsoon and higher concentrations (419.6 ± 22.8 and 0.72 ± 0.68 ppm) during the autumn (SON) season. Strong diurnal variations are also observed for both the species. The common factors for the diurnal cycles of CO2 and CO are vertical mixing and rush hour traffic, while the influence of biospheric fluxes is also seen in the CO2 diurnal cycle. Using CO and CO2 covariation, we differentiate the anthropogenic and biospheric components of CO2 and found significant contributions of biospheric respiration and anthropogenic emissions in the late night (00:00-05:00 h, IST

  19. A field and laboratory method for monitoring the concentration and isotopic composition of soil CO2.

    Science.gov (United States)

    Breecker, Dan; Sharp, Zachary D

    2008-01-01

    The stable isotope composition of nmol size gas samples can be determined accurately and precisely using continuous flow isotope ratio mass spectrometry (IRMS). We have developed a technique that exploits this capability in order to measure delta13C and delta18O values and, simultaneously, the concentration of CO2 in sub-mL volume soil air samples. A sampling strategy designed for monitoring CO2 profiles at particular locations of interest is also described. This combined field and laboratory technique provides several advantages over those previously reported: (1) the small sample size required allows soil air to be sampled at a high spatial resolution, (2) the field setup minimizes sampling times and does not require powered equipment, (3) the analytical method avoids the introduction of air (including O2) into the mass spectrometer thereby extending filament life, and (4) pCO2, delta13C and delta18O are determined simultaneously. The reproducibility of measurements of CO2 in synthetic tank air using this technique is: +/-0.08 per thousand (delta13C), +/-0.10 per thousand (delta18O), and +/-0.7% (pCO2) at 5550 ppm. The reproducibility for CO2 in soil air is estimated as: +/-0.06 per thousand (delta13C), +/-0.06 per thousand (delta18O), and +/-1.6% (pCO2). Monitoring soil CO2 using this technique is applicable to studies concerning soil respiration and ecosystem gas exchange, the effect of elevated atmospheric CO2 (e.g. free air carbon dioxide enrichment) on soil processes, soil water budgets including partitioning evaporation from transpiration, pedogenesis and weathering, diffuse solid-earth degassing, and the calibration of speleothem and pedogenic carbonate delta13C values as paleoenvironmental proxies. PMID:18186546

  20. Elevated CO2 significantly delays reproductive development of soybean under Free-Air Concentration Enrichment (FACE).

    Science.gov (United States)

    Castro, Joseph C; Dohleman, Frank G; Bernacchi, Carl J; Long, Stephen P

    2009-01-01

    The effect of rising atmospheric concentration of carbon dioxide [CO(2)] on the reproductive development of soybean (Glycine max. Merr) has not been evaluated under open-air field conditions. Soybeans grown under Free-Air CO(2) Enrichment (FACE) exhibit warmer canopies due to decreased latent heat loss because of decreased stomatal conductance. According to development models based on accumulated thermal time, or growing degree days ( degrees Cd), increased canopy temperature should accelerate development. The SoyFACE research facility (Champaign, Illinois, USA) was used to test the hypothesis that development is accelerated in soybean when grown in [CO(2)] elevated to 548 micromol mol(-1). Canopy temperature was measured continuously with infrared thermometry, and used in turn to calculate GDD. Opposite to expectation, elevated [CO(2)], while increasing canopy temperature, delayed reproductive development by up to 3 days (P <0.05). Soybean grown in elevated [CO(2)] required approximately 49 degrees Cd more GDD (P <0.05) to complete full bloom stage (R2) and approximately 52 degrees Cd more GDD (P <0.05) to complete the beginning seed (R5) stage, but needed approximately 46 degrees Cd fewer GDD (P <0.05) to complete seed filling (R6). Soybeans grown in elevated [CO(2)] produced significantly more nodes (P <0.01) on the main stem than those grown under current [CO(2)]. This may explain the delay in completion of reproductive development and final maturation of the crop under elevated [CO(2)]. These results show a direct effect of rising [CO(2)] on plant development that will affect both projections of grain supply and may be significant to other species including those in natural communities. PMID:19561049

  1. Stable isotope ratios of atmospheric CO_{2} and CH_{4} over Siberia measured at ZOTTO

    Science.gov (United States)

    Timokhina, Anastasiya; Prokushkin, Anatily; Lavric, Jost; Heimann, Martin

    2016-04-01

    The boreal and arctic zones of Siberia housing the large amounts of carbon stored in the living biomass of forests and wetlands, as well as in soils and specifically permafrost, play a crucial role in earth's global carbon cycle. The long-term studies of greenhouse gases (GHG) concentrations are important instruments to analyze the response of these systems to climate warming. In parallel to GHG observations, the measurements of their stable isotopic composition can provide useful information for distinguishing contribution of individual GHG source to their atmospheric variations, since each source has its own isotopic signature. In this study we report first results of laboratory analyses of the CO2 and CH4 concentrations, the stable isotope ratio of δ13C-CO2, δ18O-CO2, δ13C-CH4, δD-CH4 measured in one-liter glass flasks which were obtained from 301 height of ZOTTO (Zotino Tall Tower Observatory, near 60° N, 90° E, about 20 km west of the Yenisei River) during 2008 - 2013 and 2010 - 2013 for stable isotope composition of CO2 and CH4. The magnitudes of δ13C-CO2 and δ18O-CO2 in a seasonal cycle are -1.4±0.1‰ (-7.6 - -9.0‰) and -2.2±0.2‰ (-0.1 - -2.3‰), respectively. The δ13C-CO2 seasonal pattern opposes the CO2 concentrations, with a gradual enrichment in heavy isotope occurring during May - July, reflecting its discrimination in photosynthesis, and further depletion in August - September as photosynthetic activity decreases comparatively to ecosystem respiration. Relationship between the CO2 concentrations and respective δ13C-CO2 (Keeling plot) reveals isotopic source signature for growing season (May - September) -27.3±1.4‰ and -30.4±2.5‰ for winter (January - March). The behavior of δ18O-CO2 associated with both high photosynthetic rate in the June (enrichment of atmospheric CO2 by 18O as consequence of CO2 equilibrium with "heavy" leaf water) and respiratory activity of forest floor in June - October (depletion of respired CO2 by 18O

  2. Atmospheric Variability of CO2 impact on space observation Requirements

    Science.gov (United States)

    Swanson, A. L.; Sen, B.; Newhart, L.; Segal, G.

    2009-12-01

    If International governments are to reduce GHG levels by 80% by 2050, as recommended by most scientific bodies concerned with avoiding the most hazardous changes in climate, then massive investments in infrastructure and new technology will be required over the coming decades. Such an investment will be a huge commitment by governments and corporations, and while it will offer long-term dividends in lower energy costs, a healthier environment and averted additional global warming, the shear magnitude of upfront costs will drive a call for a monitoring and verification system. Such a system will be required to offer accountability to signatories of governing bodies, as well as, for the global public. Measuring the average global distribution of CO2 is straight forward, as exemplified by the long running station measurements managed by NOAA’s Global Monitoring Division that includes the longterm Keeling record. However, quantifying anthropogenic and natural source/sink distributions and atmospheric mixing have been much more difficult to constrain. And, yet, an accurate accounting of all anthropogenic source strengths is required for Global Treaty verification. The only way to accurately assess Global GHG emissions is to construct an integrated system of ground, air and space based observations with extensive chemical modeling capabilities. We look at the measurement requirements for the space based component of the solutions. To determine what space sensor performance requirements for ground resolution, coverage, and revisit, we have analyzed regional CO2 distributions and variability using NASA and NOAA aircraft flight campaigns. The results of our analysis are presented as variograms showing average spatial variability over several Northern Hemispheric regions. There are distinct regional differences with the starkest contrast between urban versus rural and Coastal Asia versus Coastal US. The results suggest specific consequences on what spatial and temporal

  3. Analysis of atmospheric CO2 growth rates at Mauna Loa using CO2 fluxes derived from an inverse model

    International Nuclear Information System (INIS)

    Carbon dioxide (CO2) growth rates are estimated for a period 1959-2004 from atmospheric CO2 measurements at Mauna Loa by the Scripps Institute of Oceanography. Only during a few short periods, 1965-1966, 1972-1973, 1987-1988 and 1997-1998, in the last 45 yr have growth rates of atmospheric CO2 been of a similar magnitude or higher than that due to the total emission from burning of fossil fuels. Using results from a time-dependent inverse (TDI) model, based on observations of atmospheric CO2 at 87 stations, we establish that El Nino-induced climate variations in the tropics and large-scale forest fires in the boreal regions are the main causes of anomalous growth rates of atmospheric CO2. The high growth rate of 2.8 ppm/yr in 2002 can be predicted fairly successfully by using the correlations between (1) the peak-to-trough amplitudes in the El Nino Southern Oscillation (ENSO) index and tropical flux anomaly, and (2) anomalies in CO2 flux and area burned by fire from the boreal regions. We suggest that the large interannual changes in CO2 growth rates can mostly be explained by natural climate variability. Our analysis also shows that the decadal average growth rate, linked primarily to human activity, has fluctuated around an all-time high value of 1.5 ppm/yr over the past 20 yr. A statistical model analysis is performed to identify the regions which have the maximum influence on the observed growth rate anomaly at Mauna Loa

  4. Atmospheric inversion for cost effective quantification of city CO2 emissions

    Science.gov (United States)

    Wu, L.; Broquet, G.; Ciais, P.; Bellassen, V.; Vogel, F.; Chevallier, F.; Xueref-Remy, I.; Wang, Y.

    2015-11-01

    Cities, currently covering only a very small portion (CO2, and are associated with 71-76 % of CO2 emissions from global final energy use. Although many cities have set voluntary climate plans, their CO2 emissions are not evaluated by Monitoring, Reporting and Verification (MRV) procedures that play a key role for market- or policy-based mitigation actions. Here we propose a monitoring tool that could support the development of such procedures at the city scale. It is based on an atmospheric inversion method that exploits inventory data and continuous atmospheric CO2 concentration measurements from a network of stations within and around cities to estimate city CO2 emissions. We examine the cost-effectiveness and the performance of such a tool. The instruments presently used to measure CO2 concentrations at research stations are expensive. However, cheaper sensors are currently developed and should be useable for the monitoring of CO2 emissions from a megacity in the near-term. Our assessment of the inversion method is thus based on the use of several types of hypothetical networks, with a range of numbers of sensors sampling at 25 m a.g.l. The study case for this assessment is the monitoring of the emissions of the Paris metropolitan area (~ 12 million inhabitants and 11.4 Tg C emitted in 2010) during the month of January 2011. The performance of the inversion is evaluated in terms of uncertainties in the estimates of total and sectoral CO2 emissions. These uncertainties are compared to a notional ambitious target to diagnose annual total city emissions with an uncertainty of 5 % (2-sigma). We find that, with 10 stations only, which is the typical size of current pilot networks that are deployed in some cities, the uncertainty for the 1-month total city CO2 emissions is significantly reduced by the inversion by ~ 42 % but still corresponds to an annual uncertainty that is two times larger than the target of 5 %. By extending the network from 10 to 70 stations, the

  5. Regional disparities in the beneficial effects of rising CO2 concentrations on crop water productivity

    Science.gov (United States)

    Deryng, Delphine; Elliott, Joshua; Folberth, Christian; Müller, Christoph; Pugh, Thomas A. M.; Boote, Kenneth J.; Conway, Declan; Ruane, Alex C.; Gerten, Dieter; Jones, James W.; Khabarov, Nikolay; Olin, Stefan; Schaphoff, Sibyll; Schmid, Erwin; Yang, Hong; Rosenzweig, Cynthia

    2016-08-01

    Rising atmospheric CO2 concentrations ([CO2]) are expected to enhance photosynthesis and reduce crop water use. However, there is high uncertainty about the global implications of these effects for future crop production and agricultural water requirements under climate change. Here we combine results from networks of field experiments and global crop models to present a spatially explicit global perspective on crop water productivity (CWP, the ratio of crop yield to evapotranspiration) for wheat, maize, rice and soybean under elevated [CO2] and associated climate change projected for a high-end greenhouse gas emissions scenario. We find CO2 effects increase global CWP by 10[047]%-27[737]% (median[interquartile range] across the model ensemble) by the 2080s depending on crop types, with particularly large increases in arid regions (by up to 48[25;56]% for rainfed wheat). If realized in the fields, the effects of elevated [CO2] could considerably mitigate global yield losses whilst reducing agricultural consumptive water use (4-17%). We identify regional disparities driven by differences in growing conditions across agro-ecosystems that could have implications for increasing food production without compromising water security. Finally, our results demonstrate the need to expand field experiments and encourage greater consistency in modelling the effects of rising [CO2] across crop and hydrological modelling communities.

  6. Separation of biospheric and fossil fuel fluxes of CO2 by atmospheric inversion of CO2 and 14CO2 measurements: Observation System Simulations

    Science.gov (United States)

    Basu, Sourish; Bharat Miller, John; Lehman, Scott

    2016-05-01

    National annual total CO2 emissions from combustion of fossil fuels are likely known to within 5-10 % for most developed countries. However, uncertainties are inevitably larger (by unknown amounts) for emission estimates at regional and monthly scales, or for developing countries. Given recent international efforts to establish emission reduction targets, independent determination and verification of regional and national scale fossil fuel CO2 emissions are likely to become increasingly important. Here, we take advantage of the fact that precise measurements of 14C in CO2 provide a largely unbiased tracer for recently added fossil-fuel-derived CO2 in the atmosphere and present an atmospheric inversion technique to jointly assimilate observations of CO2 and 14CO2 in order to simultaneously estimate fossil fuel emissions and biospheric exchange fluxes of CO2. Using this method in a set of Observation System Simulation Experiments (OSSEs), we show that given the coverage of 14CO2 measurements available in 2010 (969 over North America, 1063 globally), we can recover the US national total fossil fuel emission to better than 1 % for the year and to within 5 % for most months. Increasing the number of 14CO2 observations to ˜ 5000 per year over North America, as recently recommended by the National Academy of Science (NAS) (Pacala et al., 2010), we recover monthly emissions to within 5 % for all months for the US as a whole and also for smaller, highly emissive regions over which the specified data coverage is relatively dense, such as for the New England states or the NY-NJ-PA tri-state area. This result suggests that, given continued improvement in state-of-the art transport models, a measurement program similar in scale to that recommended by the NAS can provide for independent verification of bottom-up inventories of fossil fuel CO2 at the regional and national scale. In addition, we show that the dual tracer inversion framework can detect and minimize biases in

  7. Atmospheric inversion for cost effective quantification of city CO2 emissions

    Directory of Open Access Journals (Sweden)

    L. Wu

    2015-11-01

    Full Text Available Cities, currently covering only a very small portion (2, and are associated with 71–76 % of CO2 emissions from global final energy use. Although many cities have set voluntary climate plans, their CO2 emissions are not evaluated by Monitoring, Reporting and Verification (MRV procedures that play a key role for market- or policy-based mitigation actions. Here we propose a monitoring tool that could support the development of such procedures at the city scale. It is based on an atmospheric inversion method that exploits inventory data and continuous atmospheric CO2 concentration measurements from a network of stations within and around cities to estimate city CO2 emissions. We examine the cost-effectiveness and the performance of such a tool. The instruments presently used to measure CO2 concentrations at research stations are expensive. However, cheaper sensors are currently developed and should be useable for the monitoring of CO2 emissions from a megacity in the near-term. Our assessment of the inversion method is thus based on the use of several types of hypothetical networks, with a range of numbers of sensors sampling at 25 m a.g.l. The study case for this assessment is the monitoring of the emissions of the Paris metropolitan area (~ 12 million inhabitants and 11.4 Tg C emitted in 2010 during the month of January 2011. The performance of the inversion is evaluated in terms of uncertainties in the estimates of total and sectoral CO2 emissions. These uncertainties are compared to a notional ambitious target to diagnose annual total city emissions with an uncertainty of 5 % (2-sigma. We find that, with 10 stations only, which is the typical size of current pilot networks that are deployed in some cities, the uncertainty for the 1-month total city CO2 emissions is significantly reduced by the inversion by ~ 42 % but still corresponds to an annual uncertainty that is two times larger than the target of 5 %. By extending the network from 10 to

  8. Elevated atmospheric CO2 increases microbial growth rates and enzymes activity in soil

    Science.gov (United States)

    Blagodatskaya, Evgenia; Blagodatsky, Sergey; Dorodnikov, Maxim; Kuzyakov, Yakov

    2010-05-01

    Increasing the belowground translocation of assimilated carbon by plants grown under elevated CO2 can cause a shift in the structure and activity of the microbial community responsible for the turnover of organic matter in soil. We investigated the long-term effect of elevated CO2 in the atmosphere on microbial biomass and specific growth rates in root-free and rhizosphere soil. The experiments were conducted under two free air carbon dioxide enrichment (FACE) systems: in Hohenheim and Braunschweig, as well as in the intensively managed forest mesocosm of the Biosphere 2 Laboratory (B2L) in Oracle, AZ. Specific microbial growth rates (μ) were determined using the substrate-induced respiration response after glucose and/or yeast extract addition to the soil. We evaluated the effect of elevated CO2 on b-glucosidase, chitinase, phosphatase, and sulfatase to estimate the potential enzyme activity after soil amendment with glucose and nutrients. For B2L and both FACE systems, up to 58% higher μ were observed under elevated vs. ambient CO2, depending on site, plant species and N fertilization. The μ-values increased linearly with atmospheric CO2 concentration at all three sites. The effect of elevated CO2 on rhizosphere microorganisms was plant dependent and increased for: Brassica napus=Triticum aestivumCO2 was smoothed on rich vs. simple substrate. So, the r/K strategies ratio can be better revealed by studying growth on simple (glucose) than on rich substrate mixtures (yeast extract). After adding glucose, enzyme activities under elevated CO2 were

  9. Chemical effects of a high CO2 concentration in oxy-fuel combustion of methane

    DEFF Research Database (Denmark)

    Glarborg, Peter; Bentzen, L.L.B.

    2008-01-01

    The oxidation of methane in an atmospheric-pres sure flow reactor has been studied experimentally under highly diluted conditions in N-2 and CO2, respectively. The stoichiometry was varied from fuel-lean to fuel-rich, and the temperatures covered the range 1200-1800 K. The results were interpreted...... in terms of a detailed chemical kinetic mechanism for hydrocarbon oxidation. On the basis of results of the present study, it can be expected that oxy-fuel combustion will lead to strongly increased CO concentrations in the near-burner region. The CO2 present will compete with O-2 for atomic hydrogen...... consuming CO2. The high local CO levels may have implications for near-burner corrosion and stagging, but increased problems with CO emission in oxy-fuel combustion are not anticipated....

  10. Response of leaf litter decomposition to rises in atmospheric CO2 and temperature

    Science.gov (United States)

    Hammrich, A.; Flury, S.; Gessner, M. O.

    2007-05-01

    Atmospheric concentrations of CO2 have considerably increased in the last century and are expected to rise further. Elevated CO2 concentrations not only increase global temperature but also have potential to change plant litter quality, for example by increasing lignin content, changing C:N ratios and altering tannin contents. These chemical changes may interact with increased temperature to alter litter decomposition. To test whether changes in litter quality and warming affect decomposition, we conducted a field experiment with leaf litter collected from six species of mature deciduous trees exposed to either ambient or elevated CO2 levels. We used a set of 16 enclosures installed in four blocks in a freshwater marsh in a prealpine lake to test for the effects of CO2-mediated litter quality and temperature and the interaction of both factors. We measured leaf mass loss of the twelve litter types in control and heated enclosures (4 °C above ambient) and also in the open marsh. In contrast to expectations, species decomposing at low (oak and beech) and medium (hornbeam and maple) rates showed faster mass loss when leaves were grown under elevated CO2 conditions, whereas fast-decomposing species (cherry and basswood) showed no clear response. The accelerated decomposition of CO2-enriched litter could be due to higher amounts of nonstructural carbohydrates, which may have been either leached or readily degraded. Warming had a surprisingly small influence on mass loss of the tested litter species, and interactive effects were weak. These results suggest that direct and indirect effects of elevated CO2 levels on litter decomposition may not be readily predictable from first principles.

  11. Elevated atmospheric CO2 alters the arthropod community in a forest understory

    Science.gov (United States)

    Hamilton, Jason; Zangerl, Arthur R.; Berenbaum, May R.; Sparks, Jed P.; Elich, Lauren; Eisenstein, Alissa; DeLucia, Evan H.

    2012-08-01

    The objective of this study was to determine the extent to which overall population sizes and community composition of arthropods in a naturally occurring forest understory are altered by elevated CO2. The Free Air Concentration Enrichment (FACE) method was used to fumigate large, replicated plots in the Piedmont region of North Carolina, USA to achieve the CO2 concentration predicted for 2050 (˜580 μl l-1). In addition, the extent to which unrestricted herbivorous arthropods were spatially delimited in their resource acquisition was determined. Stable isotope data for spiders (δ13C and δ15N) were collected in ambient and elevated CO2 plots and analyzed to determine whether their prey species moved among plots. Elevated CO2 had no effect on total arthropod numbers but had a large effect on the composition of the arthropod community. Insects collected in our samples were identified to a level that allowed for an assignment of trophic classification (generally to family). For the groups of insects sensitive to atmospheric gas composition, there was an increase in the numbers of individuals collected in primarily predaceous orders (Araneae and Hymenoptera; from 60% to more than 150%) under elevated CO2 and a decrease in the numbers in primarily herbivorous orders (Lepidoptera and Coleoptera; from -30 to -45%). Isotopic data gave no indication that the treatment plots represented a "boundary" to the movement of insects or that there were distinct and independent insect populations inside and outside the treatment plots. A simple two-ended mixing model estimates 55% of the carbon and nitrogen in spider biomass originated external to the elevated CO2 plots. In addition to changes in insect performance, decreases in herbivorous arthropods and increases in predaceous arthropods may also be factors involved in reduced herbivory under elevated CO2 in this forest.

  12. A high precision mass spectrometry method for measuring O2/N2 ratios and CO2 concentrations in air

    International Nuclear Information System (INIS)

    A full, detailed understanding of the global carbon budget is needed for robust modelling of global climate and environmental change. Since the industrial revolution the carbon cycle has been shifted from a steady state in which removal of CO2 from the atmosphere through photosynthesis is balanced by its addition through respiration. Currently increased respiration due to deforestation, modern agricultural practises and the burning of fossil fuels dominates photosynthesis resulting in modern atmospheric CO2 concentrations some 32% higher than the year 1800 levels. However, the CO2 concentration rises are lower than expected from known fossil fuel combustion inventories. A significant proportion of the excess CO2 is taken up by the oceans, however a missing carbon sink must still be invoked to account for the difference between measured and expected CO2 rises. A global greening as a result of increased photosynthesis is required to close the circle

  13. Carbon-13 isotope composition of the mean CO2 source in the urban atmosphere of Krakow, southern Poland

    Science.gov (United States)

    Zimnoch, Miroslaw; Jasek, Alina; Rozanski, Kazimierz

    2014-05-01

    Quantification of carbon emissions in urbanized areas constitutes an important part of the current research on the global carbon cycle. As the carbon isotopic composition of atmospheric carbon dioxide can serve as a fingerprint of its origin, systematic observations of δ13CO2 and/or Δ14CO2, combined with atmospheric CO2mixing ratio measurements can be used to better constrain the urban sources of this gas. Nowadays, high precision optical analysers based on absorption of laser radiation in the cavity allow a real-time monitoring of atmospheric CO2 concentration and its 13CO2/12CO2 ratio, thus enabling better quantification of the contribution of different anthropogenic and natural sources of this gas to the local atmospheric CO2load. Here we present results of a 2-year study aimed at quantifying carbon isotopic signature of the mean CO2 source and its seasonal variability in the urban atmosphere of Krakow, southern Poland. The Picarro G2101-i CRDS isotopic analyser system for CO2and 13CO2/12CO2 mixing ratio measurements has been installed at the AGH University of Science and Technology campus in July 2011. Air inlet was located at the top of a 20m tower mounted on the roof of the faculty building (ca. 42m a.g.l.), close to the city centre. While temporal resolution of the analyser is equal 1s, a 2-minute moving average was used for calculations of δ13CO2 and CO2 mixing ratio to reduce measurement uncertainty. The measurements were calibrated against 2 NOAA (National Oceanic and Atmospheric Administration) primary standard tanks for CO2 mixing ratio and 1 JRAC (Jena Reference Air Cylinder) isotope primary standard for δ13C. A Keeling approach based on two-component mass and isotope balance was used to derive daily mean isotopic signatures of local CO2 from individual measurements of δ13CO2 and CO2 mixing ratios. The record covers a 2-year period, from July 2011 to July 2013. It shows a clear seasonal pattern, with less negative and less variable δ13CO2 values

  14. 3D modelling of the early Martian Climate under a denser CO2 atmosphere: Temperatures and CO2 ice clouds

    CERN Document Server

    Forget, Francois; Millour, Ehouarn; Madeleine, Jean-Baptiste; Kerber, Laura; Leconte, Jeremy; Marcq, Emmanuel; Haberle, Robert M

    2012-01-01

    On the basis of geological evidence, it is often stated that the early martian climate was warm enough for liquid water to flow on the surface thanks to the greenhouse effect of a thick atmosphere. We present 3D global climate simulations of the early martian climate performed assuming a faint young sun and a CO2 atmosphere with pressure between 0.1 and 7 bars. The model includes a detailed radiative transfer model using revised CO2 gas collision induced absorption properties, and a parameterisation of the CO2 ice cloud microphysical and radiative properties. A wide range of possible climates is explored by using various values of obliquities, orbital parameters, cloud microphysic parameters, atmospheric dust loading, and surface properties. Unlike on present day Mars, for pressures higher than a fraction of a bar, surface temperatures vary with altitude because of the adiabatic cooling and warming of the atmosphere when it moves vertically. In most simulations, CO2 ice clouds cover a major part of the planet...

  15. Measurement of Ecosystem-Atmosphere Exchange of Isotopic CO2 Using Fourier Transform Infrared (FTIR) Spectroscopy

    Science.gov (United States)

    Cambaliza, M. O.; Mount, G.; Lamb, B.; Westberg, H.; Gibson, R.

    2005-12-01

    Analysis of the isotopic content of atmospheric carbon dioxide provides a wealth of information about the complex interaction between the biosphere and the atmosphere. Traditionally, the isotopic content of atmospheric CO2 has been determined by taking grab samples from field sites followed by laboratory mass spectrometry analysis. This procedure severely limits the duration and frequency of measurements. In this work, we investigate the performance of a measurement method that is based on Fourier Transform Infrared (FTIR) spectroscopy. The FTIR separately measures the concentrations of the 12CO2 and 13CO2 isotopomers of carbon dioxide at approximately one minute intervals with very high signal-to-noise ratio using molecular absorption in a 1-meter cell in the 2100 to 2600 cm-1 region of the isotopic vibration-rotation bands. δ13C values are determined with a precision of approximately 0.7‰ every minute, with higher precision obtained by averaging the short integrations. The FTIR system also measures CO2 flux using the disjunct eddy covariance technique, so the net ecosystem exchange (NEE) and isoflux can also be measured, potentially allowing for the partitioning of the NEE into its photosynthetic and respiratory components. First scientific results from this new instrument are presented from two field campaigns conducted in summer 2005 in a poplar forest near Boardman, Oregon. A 25-m tower was used with air inlets at 0.3, 4.1, 7.5, 10.8, 14.0, and 20.6 meters above the ground. These were switched sequentially into the instrument to achieve height resolution in the canopy, or were kept at constant height. Canopy height was 13 meters. Carbon dioxide concentrations are measured to a precision of about 0.7 ppmv from a one-minute integration with higher precisions obtained from time averaging. CO2 isotopic concentrations were measured with a precision of about 2 ppmv/minute. In this work, we present results of temporal and vertical variations of CO2 concentrations

  16. A proposed potential role for increasing atmospheric CO2 as a promoter of weight gain and obesity

    DEFF Research Database (Denmark)

    Hersoug, Lars-Georg; Sjödin, Anders Mikael; Astrup, A

    2012-01-01

    Human obesity has evolved into a global epidemic. Interestingly, a similar trend has been observed in many animal species, although diet composition, food availability and physical activity have essentially remained unchanged. This suggests a common factor-potentially an environmental factor...... affecting all species. Coinciding with the increase in obesity, atmospheric CO2 concentration has increased more than 40%. Furthermore, in modern societies, we spend more time indoors, where CO2 often reaches even higher concentrations. Increased CO2 concentration in inhaled air decreases the pH of blood...

  17. Impact of elevated CO2 concentration on dynamics of leaf photosynthesis in Fagus sylvatica is modulated by sky conditions

    International Nuclear Information System (INIS)

    It has been suggested that atmospheric CO2 concentration and frequency of cloud cover will increase in future. It remains unclear, however, how elevated CO2 influences photosynthesis under complex clear versus cloudy sky conditions. Accordingly, diurnal changes in photosynthetic responses among beech trees grown at ambient (AC) and doubled (EC) CO2 concentrations were studied under contrasting sky conditions. EC stimulated the daily sum of fixed CO2 and light use efficiency under clear sky. Meanwhile, both these parameters were reduced under cloudy sky as compared with AC treatment. Reduction in photosynthesis rate under cloudy sky was particularly associated with EC-stimulated, xanthophyll-dependent thermal dissipation of absorbed light energy. Under clear sky, a pronounced afternoon depression of CO2 assimilation rate was found in sun-adapted leaves under EC compared with AC conditions. This was caused in particular by stomata closure mediated by vapour pressure deficit. -- Highlights: • Sky conditions affect the relative impact of elevated CO2 on photosynthesis. • Cloudy skies reduce light use efficiency and carbon gain when CO2 is elevated. • Stimulation of photosynthesis by high CO2 may decline with increasing cloud cover. • High CO2 leads to marked afternoon photosynthesis depression in sun-adapted leaves. -- The stimulatory effect of elevated CO2 concentration on photosynthetic carbon assimilation can be expected to diminish as cloud cover increases

  18. Changes in the salinity tolerance of sweet pepper plants as affected by nitrogen form and high CO2 concentration.

    Science.gov (United States)

    Piñero, María C; Pérez-Jiménez, Margarita; López-Marín, Josefa; Del Amor, Francisco M

    2016-08-01

    The assimilation and availability of nitrogen in its different forms can significantly affect the response of primary productivity under the current atmospheric alteration and soil degradation. An elevated CO2 concentration (e[CO2]) triggers changes in the efficiency and efficacy of photosynthetic processes, water use and product yield, the plant response to stress being altered with respect to ambient CO2 conditions (a[CO2]). Additionally, NH4(+) has been related to improved plant responses to stress, considering both energy efficiency in N-assimilation and the overcoming of the inhibition of photorespiration at e[CO2]. Therefore, the aim of this work was to determine the response of sweet pepper plants (Capsicum annuum L.) receiving an additional supply of NH4(+) (90/10 NO3(-)/NH4(+)) to salinity stress (60mM NaCl) under a[CO2] (400μmolmol(-1)) or e[CO2] (800μmolmol(-1)). Salt-stressed plants grown at e[CO2] showed DW accumulation similar to that of the non-stressed plants at a[CO2]. The supply of NH4(+) reduced growth at e[CO2] when salinity was imposed. Moreover, NH4(+) differentially affected the stomatal conductance and water use efficiency and the leaf Cl(-), K(+), and Na(+) concentrations, but the extent of the effects was influenced by the [CO2]. An antioxidant-related response was prompted by salinity, the total phenolics and proline concentrations being reduced by NH4(+) at e[CO2]. Our results show that the effect of NH4(+) on plant salinity tolerance should be globally re-evaluated as e[CO2] can significantly alter the response, when compared with previous studies at a[CO2]. PMID:27317970

  19. Target atmospheric CO2: Where should humanity aim?

    CERN Document Server

    Hansen, J; Kharecha, P; Beerling, D; Masson-Delmotte, V; Pagani, M; Raymo, M; Royer, D L; Zachos, J C

    2008-01-01

    Paleoclimate data show that climate sensitivity is ~3 deg-C for doubled CO2, including only fast feedback processes. Equilibrium sensitivity, including slower surface albedo feedbacks, is ~6 deg-C for doubled CO2 for the range of climate states between glacial conditions and ice-free Antarctica. Decreasing CO2 was the main cause of a cooling trend that began 50 million years ago, large scale glaciation occurring when CO2 fell to 425 +/- 75 ppm, a level that will be exceeded within decades, barring prompt policy changes. If humanity wishes to preserve a planet similar to that on which civilization developed and to which life on Earth is adapted, paleoclimate evidence and ongoing climate change suggest that CO2 will need to be reduced from its current 385 ppm to at most 350 ppm. The largest uncertainty in the target arises from possible changes of non-CO2 forcings. An initial 350 ppm CO2 target may be achievable by phasing out coal use except where CO2 is captured and adopting agricultural and forestry practice...

  20. Atmospheric CO2 level affects plants' carbon use efficiency: insights from a 13C labeling experiment on sunflower stands

    Science.gov (United States)

    Gong, Xiaoying; Schäufele, Rudi; Schnyder, Hans

    2015-04-01

    The increase of atmospheric CO2 concentration has been shown to stimulate plant photosynthesis and (to a lesser extent) growth, thereby acting as a possible sink for the additional atmospheric CO2. However, this effect is dependent on the efficiency with which plants convert atmospheric carbon into biomass carbon, since a considerable proportion of assimilated carbon is returned to the atmosphere via plant respiration. As a core parameter for carbon cycling, carbon use efficiency of plants (CUE, the ratio of net primary production to gross primary production) quantifies the proportion of assimilated carbon that is incorporated into plant biomass. CUE has rarely been assessed based on measurements of complete carbon balance, due to methodological difficulties in measuring respiration rate of plants in light. Moreover, foliar respiration is known to be inhibited in light, thus foliar respiration rate is generally lower in light than in dark. However, this phenomenon, termed as inhibition of respiration in light (IRL), has rarely been assessed at the stand-scale and been incorporated into the calculation of CUE. Therefore, how CUE responses to atmospheric CO2 levels is still not clear. We studied CUE of sunflower stands grown at sub-ambient CO2 level (200 μmol mol-1) and elevated CO2 level (1000 μmol mol-1) using mesocosm-scale gas exchange facilities which enabled continuous measurements of 13CO2/12CO2 exchange. Appling steady-state 13C labeling, fluxes of respiration and photosynthesis in light were separated, and tracer kinetic in respiration was analyzed. This study provides the first data on CUE at a mesocosm-level including respiration in light in different CO2 environments. We found that CUE of sunflower was lower at an elevated CO2 level than at a sub-ambient CO2 level; and the ignorance of IRL lead to erroneous estimations of CUE. Variation in CUE at atmospheric CO2 levels was attributed to several mechanisms. In this study, CO2 enrichment i) affected the

  1. Atmospheric CO2 Enrichment of Water Hyacinths: Effects on Transpiration and Water Use Efficiency

    Science.gov (United States)

    Idso, Sherwood B.; Kimball, Bruce A.; Anderson, Michael G.

    1985-11-01

    Open-top clear plastic wall chambers enclosing pairs of sunken metal stock tanks, one of each pair of which contained a full cover of water hyacinths, were maintained out-of-doors at Phoenix, Arizona for several weeks during the summer of 1984. One of these chambers represented ambient conditions, while the other three were continuously enriched with carbon dioxide to approximate target concentrations of 500, 650, and 900 ppm. During a 4-week period when plant growth was at its maximum, water hyacinth biomass production increased by 36% for a 300-600 ppm doubling of the atmospheric CO2 content, while water use efficiency, or the biomass produced per unit of water transpired, actually doubled. These results are similar to what has been observed in several terrestrial plants and they indicate the general trend which may be expected to occur as atmospheric CO2 continues to rise in the years ahead.

  2. Potentialities of the atmospheric CO2 remote sensing thanks to static Fourier transform spectrometry

    International Nuclear Information System (INIS)

    A global measurement of atmospheric CO2 concentration is required to improve the prediction of the range of global warming. A satellite mission could provide such a measurement. CNES developed a new generation instrument dedicated to atmospheric sounding. It is a static Fourier transform spectrometer whose mass and size are smaller than those of classical spectrometers. The application of the concept for CO2 sounding is studied thanks to an on ground experimental bread board representative of a satellite borne spectrometer. The CO2 concentration is deduced from atmospheric spectra at 1.6 μm thanks to differential spectroscopy technique. The instrumental concept is presented. Then the conception of the spectrometer and the working procedure are described. A study of information content is done. Retrieval simulations show that an error of ±0.6 ppm can be expected, lower than the ±1 ppm goal. Finally the results of a measurement campaign are given. The retrieval precision is compatible with the objectives. Yet the instrument is also sensitive to disruptive parameters. For example deformations of the instrument could engender significant measurement errors. Instrument improvements are proposed to increase the retrieval precision. (author)

  3. Phosphorus feedbacks constraining tropical ecosystem responses to changes in atmospheric CO2 and climate

    Science.gov (United States)

    Yang, Xiaojuan; Thornton, Peter E.; Ricciuto, Daniel M.; Hoffman, Forrest M.

    2016-07-01

    The effects of phosphorus (P) availability on carbon (C) cycling in the Amazon region are investigated using CLM-CNP. We demonstrate that the coupling of P dynamics reduces the simulated historical terrestrial C sink due to increasing atmospheric CO2 concentrations ([CO2]) by about 26%. Our exploratory simulations show that the response of tropical forest C cycling to increasing [CO2] depends on how elevated CO2 affects phosphatase enzyme production. The effects of warming are more complex, depending on the interactions between humidity, C, and nutrient dynamics. While a simulation with low humidity generally shows the reduction of net primary productivity (NPP), a second simulation with higher humidity suggests overall increases in NPP due to the dominant effects of reduced water stress and more nutrient availability. Our simulations point to the need for (1) new observations on how elevated [CO2] affects phosphatase enzyme production and (2) more tropical leaf-scale measurements under different temperature/humidity conditions with different soil P availability.

  4. Stomatal response of Pinus sylvestriformis to elevated CO2 concentrations during the four years of exposure

    Institute of Scientific and Technical Information of China (English)

    ZHOU Yu-mei; HAN Shi-jie; LIU Ying; JIA Xia

    2005-01-01

    Four-year-old Pinus sylvestriformis were exposed for four growing seasons in open top chambers to ambient CO2 concentration (approx. 350 μmol·mol-1) and high CO2 concentrations (500 and 700 μmol·mol-1) at Research Station of Changbai Mountain Forest Ecosystems, Chinese Academy of Sciences at Antu Town, Jilin Province, China (42oN, 128oE). Stomatal response to elevated CO2 concentrations was examined by stomatal conductance (gs), ratio of intercellular to ambient CO2 concentration (ci/ca) and stomatal number. Reciprocal transfer experiments of stomatal conductance showed that stomatal conductance in high-[CO2]-grown plants increased in comparison with ambient-[CO2]-grown plants when measured at their respective growth CO2 concentration and at the same measurement CO2 concentration (except a reduction in 700 μmol·mol-1 CO2 grown plants compared with plants on unchambered field when measured at growth CO2 concentration and 350 μmol·mol-1CO2). High-[CO2]-grown plants exhibited lower ci/ca ratios than ambient-[CO2]-grown plants when measured at their respective growth CO2 concentration. However, ci/ca ratios increased for plants grown in high CO2 concentrations compared with control plants when measured at the same CO2 concentration. There was no significant difference in stomatal number per unit long needle between elevated and ambient CO2. However, elevated CO2 concentrations reduced the total stomatal number of whole needle by the decline of stomatal line and changed the allocation pattern of stomata between upper and lower surface of needle.

  5. The Gulf of Alaska coastal ocean as an atmospheric CO2 sink

    Science.gov (United States)

    Evans, Wiley; Mathis, Jeremy T.

    2013-08-01

    A new data set of directly measured surface seawater carbon dioxide partial pressures (pCO2) was compiled for the Gulf of Alaska (GOA) coastal ocean. Using this information, along with reconstructed atmospheric pCO2 data, we calculate sea-air CO2 fluxes over two interconnected domains: the coastal ocean defined by the Surface Ocean CO2 Atlas (SOCAT) Continental Margin Mask, and the continental margin shoreward of the 1500 m isobath. The continental margin in this region lies within the coastal ocean. Climatological sea-air CO2 fluxes were calculated by constructing monthly climatologies of sea-air pCO2 difference (ΔpCO2), sea surface temperature, salinity, and CO2 solubility, coupled with the monthly second moment of wind speeds from the Scatterometer Climatology of Ocean Winds (SCOW; http://cioss.coas.oregonstate.edu/scow). Climatological sea-air CO2 fluxes showed instances of atmospheric CO2 uptake and outgassing in both domains for nearly all months; however, uptake dominated from April through November, with distinct spring and autumn peaks that coincided with periods of strong winds and undersaturated surface seawater pCO2 with respect to atmospheric levels. Atmospheric CO2 uptake during the spring and autumn peaks was stronger on the continental margin compared with the coastal ocean. Annual mean area-weighted fluxes for the coastal ocean and continental margin were -2.5 and -4 mmol CO2 m-2 d-1, respectively. Scaling these annual means by the respective surface areas of each domain resulted in estimates of substantial atmospheric CO2 uptake between 34 and 14 Tg C yr-1. This region is a large sink for atmospheric CO2, which impacts the current view of weak net CO2 emission from coastal waters surrounding North America.

  6. Spectral parameters and signal-to-noise ratio requirement for TANSAT hyper spectral remote sensor of atmospheric CO2

    Science.gov (United States)

    Wang, Qian; Yang, Zhong-Dong; Bi, Yan-Meng

    2014-11-01

    With the stable increase of carbon dioxide (CO2) concentrations, space based measurements of CO2 concentration in lower atmosphere by reflected sunlight in near infrared band has become a hot research topic at present. Recently, the instruments sensitive to total CO2 column data in near-surface have become available through the SCIAMACHY instrument on ENVISAT and TANSO-FTS on GOSAT. The developing hyper spectral CO2 detector in China carried by TANSAT will be launched in late 2015. Hyper spectral CO2 detector is designed to provide global measurements of CO2 in lower troposphere. It employs high resolution spectra of reflected sunlight taken simultaneously in near-infrared CO2 (1.61μm and 2.06μm) and O2 (0.76μm) bands. Associating climate change with the observation requirements of carbon sources and sinks, the feasibility of making CO2 column concentration measurements with high-resolution and high-precision is studied by high resolution atmosphere radiation transfer model. The effects of key specifications of the hyper spectral CO2 detector such as spectral resolution, sampling ratio and sign-to-noise ratio (SNR) on CO2 detection are analyzed combining the scientific requirements of CO2 measurements of China. The typical characteristics of hyper spectral CO2 detector on TANSAT are grating spectrometer and array-based detector. To achieve the column averaged atmospheric CO2 dry air mole fraction (XCO2) precision requirements of 1×10-6-4×10-6, hyper spectral CO2 detector should provide high resolution at first to resolve CO2 absorption lines from continuous spectra of reflected sunlight. Compared to a variety of simulated spectral resolutions, the spectral resolution of hyper spectral CO2 detector on TANSAT can resolve CO2 spectral features and maintain the moderate radiance sensitivity. Since small size array detector-based instruments may suffer from undersampling of the spectra, the influences of spectral undersampling to CO2 absorption spectra are studied

  7. Elevated atmospheric CO2 triggers compensatory feeding by root herbivores on a C3 but not a C4 grass.

    Directory of Open Access Journals (Sweden)

    Scott N Johnson

    Full Text Available Predicted increases in atmospheric carbon dioxide (CO2 concentrations often reduce nutritional quality for herbivores by increasing the C:N ratio of plant tissue. This frequently triggers compensatory feeding by aboveground herbivores, whereby they consume more shoot material in an attempt to meet their nutritional needs. Little, however, is known about how root herbivores respond to such changes. Grasslands are particularly vulnerable to root herbivores, which can collectively exceed the mass of mammals grazing aboveground. Here we provide novel evidence for compensatory feeding by a grass root herbivore, Sericesthis nigrolineata, under elevated atmospheric CO2 (600 µmol mol(-1 on a C3 (Microlaena stipoides but not a C4 (Cymbopogon refractus grass species. At ambient CO2 (400 µmol mol(-1 M. stipoides roots were 44% higher in nitrogen (N and 7% lower in carbon (C concentrations than C. refractus, with insects performing better on M. stipoides. Elevated CO2 decreased N and increased C:N in M. stipoides roots, but had no impact on C. refractus roots. Root-feeders displayed compensatory feeding on M. stipoides at elevated CO2, consuming 118% more tissue than at ambient atmospheric CO2. Despite this, root feeder biomass remained depressed by 24%. These results suggest that compensatory feeding under elevated atmospheric CO2 may make some grass species particularly vulnerable to attack, potentially leading to future shifts in the community composition of grasslands.

  8. Comparison of CO2 and O2 concentrations in soil air: A lesson learned about CO2 diffusivity in soils

    Science.gov (United States)

    Angert, A.; Davidson, E. A.; Savage, K.; Yakir, D.; Luz, B.

    2002-12-01

    Soil respiration is a major component of the global carbon and oxygen cycles and accounts for about one quarter of global respiration. Since respiration consumes O2 and emits CO2, a simple relationship may be expected between the concentration of these gases in soil-air. However, because the [O2] signal in well-drained soils is small, deriving this relationship from field observations is not trivial. In this study, we present high accuracy measurements of O2 concentrations in soil air, that for the first time, enable precise comparison of these concentrations with CO2 concentrations. Soil air was sampled in two sites: an orchard in Israel, and a temperate forest (Harvard forest). The expected ratio of the decrease in [O2] in soil air to the increase in [CO2] can be calculated from the ratio of O2 consumption to CO2 emission in respiration, and the ratio between the diffusivities of these two gases in air as 0.79-0.07. The measured ratio of the decrease in [O2] to the increase in [CO2] in soil air was 0.56-2.48 in the orchard site and 1.06-1.20 in Harvard Forest. These ratios deviate strongly from the expected relationship. In the orchard site, these deviations were probably caused by reactions in the carbonate system due to the calcareous soil of this site. At Harvard Forest, such reactions cannot be quantitatively important because of the low pH of the soil. In this site, we propose that the relationship between CO2 and O2 in the soil air indicates that the ratio of diffusivity of O2 and CO2 in soils is higher than the diffusivity ratio in air. Our results demonstrate that a combination of high accuracy measurements of the O2 and CO2 in soil air is important for better understanding of the soil CO2 dynamics. Such observations will improve estimates of soil respiration that are based only on CO2 concentration and diffusivity.

  9. Comparing surface and mid-troposphere CO2 concentration and fluxes from central U.S. grasslands

    Science.gov (United States)

    Cochran, F. V.; Brunsell, N. A.; Quick, A. T.

    2010-12-01

    Terrestrial ecosystem dynamics influence the Earth’s climate system, which is affected by variations in atmospheric carbon dioxide (CO2). Assessments of CO2 concentration and net fluxes at regional scales are needed to diminish uncertainties related to the effects of land-use change on ecosystem processes, to identify land management practices that have the potential to mitigate CO2 emissions, and to discern sources and sinks within geopolitical boundaries for reasons of carbon accountability. Understanding how surface CO2 concentration and flux dynamics within heterogeneous landscapes scale to mid-troposphere concentrations is the focus of this study. CO2 flux data from three eddy covariance (EC) towers in northeastern Kansas are compared to mid-tropospheric data collected by the Atmospheric Infrared Sounder (AIRS). EC tower data from two watershed sites on the Konza Prairie Biological Station (KPBS) for the period 2006-2010 and one study site at the Nelson Environmental Study Area (NESA) for the period 2007-2010 are examined. KPBS site 1D is primarily C4 grasses, burned annually; KPBS site 4B is a mix of C3 forbs and C4 grasses, burned every four years; and the NESA site is a mix of C3/C4 grasses, burned approximately every five years, and experiencing woody encroachment. Results show higher concentration of CO2 in the mid-troposphere. Furthermore, mid-troposphere CO2 exhibited daily and seasonal lags and decreased amplitude in flux dynamics compared to surface CO2. Long-term, combined observations of surface and atmospheric CO2 offer the potential for a better understanding of the natural processes and anthropogenic activities related to CO2 source-sink dynamics, seasonal and interannual variability, and climate forcings, including temperature and precipitation changes.

  10. What would dense atmospheric observation networks bring to the quantification of city CO2 emissions?

    Science.gov (United States)

    Wu, Lin; Broquet, Grégoire; Ciais, Philippe; Bellassen, Valentin; Vogel, Felix; Chevallier, Frédéric; Xueref-Remy, Irène; Wang, Yilong

    2016-06-01

    Cities currently covering only a very small portion ( market- or policy-based mitigation actions. Here we analyze the potential of a monitoring tool that could support the development of such procedures at the city scale. It is based on an atmospheric inversion method that exploits inventory data and continuous atmospheric CO2 concentration measurements from a network of stations within and around cities to estimate city CO2 emissions. This monitoring tool is configured for the quantification of the total and sectoral CO2 emissions in the Paris metropolitan area (˜ 12 million inhabitants and 11.4 TgC emitted in 2010) during the month of January 2011. Its performances are evaluated in terms of uncertainty reduction based on observing system simulation experiments (OSSEs). They are analyzed as a function of the number of sampling sites (measuring at 25 m a.g.l.) and as a function of the network design. The instruments presently used to measure CO2 concentrations at research stations are expensive (typically ˜ EUR 50 k per sensor), which has limited the few current pilot city networks to around 10 sites. Larger theoretical networks are studied here to assess the potential benefit of hypothetical operational lower-cost sensors. The setup of our inversion system is based on a number of diagnostics and assumptions from previous city-scale inversion experiences with real data. We find that, given our assumptions underlying the configuration of the OSSEs, with 10 stations only the uncertainty for the total city CO2 emission during 1 month is significantly reduced by the inversion by ˜ 42 %. It can be further reduced by extending the network, e.g., from 10 to 70 stations, which is promising for MRV applications in the Paris metropolitan area. With 70 stations, the uncertainties in the inverted emissions are reduced significantly over those obtained using 10 stations: by 32 % for commercial and residential buildings, by 33 % for road transport, by 18 % for the production

  11. Seven Years of Observations of Mid-Tropospheric CO2 from the Atmospheric Infrared Sounder

    Science.gov (United States)

    Pagano, Thomas S.; Chahine, Moustafa T.; Olsen, Edward T.

    2010-01-01

    The Atmospheric Infrared Sounder (AIRS) on the EOS Aqua Spacecraft was launched on May 4, 2002. AIRS acquires hyperspectral infrared radiances in the 3.7-15.4 um spectral region with spectral resolution of better than 1200. The AIRS was designed to measure temperature and water vapor profiles and cloud properties for improvement in weather forecast and improved parameterization of climate processes. Currently the AIRS Level 1B Radiance Products are assimilated by NWP centers and have shown considerable forecast improvement. Scientists have also demonstrated accurate retrievals of minor gases from AIRS including Carbon Monoxide, Methane, and Ozone. The excellent sensitivity and stability of the AIRS instrument has recently allowed the AIRS team to successfully retrieve Carbon Dioxide (CO2) concentrations in the mid-troposphere (8-10 km) with a horizontal resolution of 100 km and accuracy of 1-2 ppm. The AIRS retrieves over 15,000 measurements per day and can achieve full global coverage in 30 days. The AIRS CO2 accuracy has been validated against a variety of aircraft measurements in the mid-troposphere and upward looking interferometers. Findings from the AIRS data include higher than expected variability in the mid-troposphere, the presence of a belt of CO2 in the southern hemisphere, and numerous observations of atmospheric circulation including the effects of El Nino/La Nina on the CO2 concentrations in the mid-troposphere. The full mid-tropospheric AIRS CO2 data set is now available at the NASA GES/DISC for almost eight years since AIRS has been operational.

  12. Atmosphere-biosphere exchange of CH4, CO2, and O3

    International Nuclear Information System (INIS)

    The atmosphere-biosphere exchange was measured for CO2 and O3 in a tropical rain forest in the wet season of 1987, and for CO2, CH4, and O3 in a subarctic tundra in summer 1988. Photosynthesis and respiration were found to be in approximate balance in the rain forest. Net ecosystem uptake of CO2 in the forest increased with intensity of light in the range of measurements. It is suggested that photosynthesis of a well-watered forest is primarily controlled by photosynthetically active radiation. Changes in the distribution of cloud cover, associated for example with El Nino, might induce globally significant changes in primary productivity and carbon storage. Soil moisture controls in tundra the distribution and association of vegetation types and the atmosphere-biosphere exchange Of CO2, although light intensity also influences the daily and seasonal net exchange of CO2. Methane fluxes from the subarctic tundra averaged 25 ± 1 (SE) mgCH4/M2/d, representing 6 percent the net uptake of carbon for the 30 days of measurement. Ozone deposition fluxes averaged ∼1.0 x 1011 molecules cm-2s-1 in the tropical forest and in the arctic tundra, similar in magnitude to the estimated mean stratospheric input. Ozone deposition fluxes were proportional to O3 concentrations in the surface layer and regulated by turbulent transport and stomatal activity. Day-time ozone concentrations and deposition velocities measured at ∼10 m above canopy averaged ∼5 ppb and 1.8 cm s-1 over the tropical forest and ∼25 ppb and 0.25 cm s-1 over the subarctic tundra, respectively. These results imply that widespread deforestation in the tropics may impact on the ozone budget and the photochemistry of the troposphere in the region

  13. Regulation of CO2 Concentrating Mechanism in Cyanobacteria

    Directory of Open Access Journals (Sweden)

    Robert L. Burnap

    2015-01-01

    Full Text Available In this chapter, we mainly focus on the acclimation of cyanobacteria to the changing ambient CO2 and discuss mechanisms of inorganic carbon (Ci uptake, photorespiration, and the regulation among the metabolic fluxes involved in photoautotrophic, photomixotrophic and heterotrophic growth. The structural components for several of the transport and uptake mechanisms are described and the progress towards elucidating their regulation is discussed in the context of studies, which have documented metabolomic changes in response to changes in Ci availability. Genes for several of the transport and uptake mechanisms are regulated by transcriptional regulators that are in the LysR-transcriptional regulator family and are known to act in concert with small molecule effectors, which appear to be well-known metabolites. Signals that trigger changes in gene expression and enzyme activity correspond to specific “regulatory metabolites” whose concentrations depend on the ambient Ci availability. Finally, emerging evidence for an additional layer of regulatory complexity involving small non-coding RNAs is discussed.

  14. Atmospheric CO2 retrieved from ground-based solar spectra

    Science.gov (United States)

    Yang, Z.; Toon, G. C.; Margolis, J. S.; Wennberg, P. O.

    2002-01-01

    The column-averaged volume mixing ration of CO2 over Kitt Peak, Arizona, has been retrieved from high-resolution solar absorption spectra obtained with the fourier transform spectrometer on the McMath telescope.

  15. Airborne Measurements of CO2 Column Concentration and Range Using a Pulsed Direct-Detection IPDA Lidar

    Science.gov (United States)

    Abshire, James B.; Ramanathan, Anand; Riris, Haris; Mao, Jianping; Allan, Graham R.; Hasselbrack, William E.; Weaver, Clark J.; Browell, Edward V.

    2013-01-01

    We have previously demonstrated a pulsed direct detection IPDA lidar to measure range and the column concentration of atmospheric CO2. The lidar measures the atmospheric backscatter profiles and samples the shape of the 1,572.33 nm CO2 absorption line. We participated in the ASCENDS science flights on the NASA DC-8 aircraft during August 2011 and report here lidar measurements made on four flights over a variety of surface and cloud conditions near the US. These included over a stratus cloud deck over the Pacific Ocean, to a dry lake bed surrounded by mountains in Nevada, to a desert area with a coal-fired power plant, and from the Rocky Mountains to Iowa, with segments with both cumulus and cirrus clouds. Most flights were to altitudes >12 km and had 5-6 altitude steps. Analyses show the retrievals of lidar range, CO2 column absorption, and CO2 mixing ratio worked well when measuring over topography with rapidly changing height and reflectivity, through thin clouds, between cumulus clouds, and to stratus cloud tops. The retrievals shows the decrease in column CO2 due to growing vegetation when flying over Iowa cropland as well as a sudden increase in CO2 concentration near a coal-fired power plant. For regions where the CO2 concentration was relatively constant, the measured CO2 absorption lineshape (averaged for 50 s) matched the predicted shapes to better than 1% RMS error. For 10 s averaging, the scatter in the retrievals was typically 2-3 ppm and was limited by the received signal photon count. Retrievals were made using atmospheric parameters from both an atmospheric model and from in situ temperature and pressure from the aircraft. The retrievals had no free parameters and did not use empirical adjustments, and >70% of the measurements passed screening and were used in analysis. The differences between the lidar-measured retrievals and in situ measured average CO2 column concentrations were 6 km.

  16. CO2 Spectroscopy Evaluation Using Atmospheric Solar Absorption Spectra

    OpenAIRE

    Sen, Bhaswar; Brown, Linda R.; Miller, Charles E.; Toon, Geoffrey C.; Toth, Robert A.; Washenfelder, Rebecca A.; Wennberg, Paul O

    2006-01-01

    We evaluated the improvements in successive versions (1996 - 2004) of HITRAN (1) and other molecular line parameter data set (2) to correctly simulate infrared (IR) and near-infrared (NIR) CO 2 transmittance spectra. Understanding the global sources and sinks of CO 2 requires highly accurate measurements (ó 0.3%) and makes extreme de- mands on the spectroscopy. We evaluated the line parameter data sets by fitting solar absorption spectra measured by the JPL MkIV FTIR spectrometer (3) and the ...

  17. Nitrogen and Carbon Cycling in a Grassland Community Ecosystem as Affected by Elevated Atmospheric CO2

    Directory of Open Access Journals (Sweden)

    H. A. Torbert

    2012-01-01

    Full Text Available Increasing global atmospheric carbon dioxide (CO2 concentration has led to concerns regarding its potential effects on terrestrial ecosystems and the long-term storage of carbon (C and nitrogen (N in soil. This study examined responses to elevated CO2 in a grass ecosystem invaded with a leguminous shrub Acacia farnesiana (L. Willd (Huisache. Seedlings of Acacia along with grass species were grown for 13 months at CO2 concentrations of 385 (ambient, 690, and 980 μmol mol−1. Elevated CO2 increased both C and N inputs from plant growth which would result in higher soil C from litter fall, root turnover, and excretions. Results from the incubation indicated an initial (20 days decrease in N mineralization which resulted in no change in C mineralization. However, after 40 and 60 days, an increase in both C and N mineralization was observed. These increases would indicate that increases in soil C storage may not occur in grass ecosystems that are invaded with Acacia over the long term.

  18. Response of ocean acidification to a gradual increase and decrease of atmospheric CO2

    International Nuclear Information System (INIS)

    We perform coupled climate–carbon cycle model simulations to examine changes in ocean acidity in response to idealized change of atmospheric CO2. Atmospheric CO2 increases at a rate of 1% per year to four times its pre-industrial level of 280 ppm and then decreases at the same rate to the pre-industrial level. Our simulations show that changes in surface ocean chemistry largely follow changes in atmospheric CO2. However, changes in deep ocean chemistry in general lag behind the change in atmospheric CO2 because of the long time scale associated with the penetration of excess CO2 into the deep ocean. In our simulations with the effect of climate change, when atmospheric CO2 reaches four times its pre-industrial level, global mean aragonite saturation horizon (ASH) shoals from the pre-industrial value of 1288 to 143 m. When atmospheric CO2 returns from the peak value of 1120 ppm to pre-industrial level, ASH is 630 m, which is approximately the value of ASH when atmospheric CO2 first increases to 719 ppm. At pre-industrial CO2 9% deep-sea cold-water corals are surrounded by seawater that is undersaturated with aragonite. When atmospheric CO2 reaches 1120 ppm, 73% cold-water coral locations are surrounded by seawater with aragonite undersaturation, and when atmospheric CO2 returns to the pre-industrial level, 18% cold-water coral locations are surrounded by seawater with aragonite undersaturation. Our analysis indicates the difficulty for some marine ecosystems to recover to their natural chemical habitats even if atmospheric CO2 content can be lowered in the future. (paper)

  19. Two micron Heterodyne Doppler DIAL Lidar remote sensing of atmospheric CO2

    International Nuclear Information System (INIS)

    This work deals with the development of a differential absorption lidar (DIAL) instrument and its use for absolute CO2 measurements with a 1-2% precision. The first chapter describes the scientific framework of the thesis: atmospheric branch of the carbon cycle, climatic change and Kyoto protocol, present day monitoring network and main space missions. The modeling, experimental and theoretical aspects of the study are presented in the more general framework of the recovery of surface fluxes and atmospheric CO2 measurements. Chapter 2 treats of the evolution of atmospheric CO2 at the meso-scale. The time, horizontal and vertical representativeness of a CO2 measurement is evaluated. The processes at the origin of the variability of a mixing ratio in the different parts of the atmosphere is presented in order to develop an efficient measurement method. Chapter 3 discusses the DIAL measurement and its optimization for a maximum preciseness of the concentration measurement. A particular attention is given to the spectroscopy and to the optimization of parameters like the optical thickness of the air column, the energy of laser pulses in the atmosphere, and the analysis of statistical and systematic errors. Chapter 4 describes the experimental setup 'LIDIA', the existing Lidar used, its transformations and added parts. A particular attention is given to the signal processing. Then follows the presentation and discussion of the measurements performed night and day during the end of 2004 and during 2005: integrated measurements at the ground level and validation using in-situ measurements, vertical measurements inside the atmospheric boundary layer (ABL), use of cloudy targets, measurements inside the free troposphere and resolved measurements inside the ABL. The contribution of simultaneous wind and vertical velocity measurements with concentration measurements is used to explain the natural and anthropic processes at the origin of the variations with time of the CO2

  20. The Influence of CO2 Admixtures on the Product Composition in a Nitrogen-Methane Atmospheric Glow Discharge Used as a Prebiotic Atmosphere Mimic

    Science.gov (United States)

    Mazankova, V.; Torokova, L.; Krcma, F.; Mason, N. J.; Matejcik, S.

    2016-04-01

    This work extends our previous experimental studies of the chemistry of Titan's atmosphere by atmospheric glow discharge. The Titan's atmosphere seems to be similarly to early Earth atmospheric composition. The exploration of Titan atmosphere was initiated by the exciting results of the Cassini-Huygens mission and obtained results increased the interest about prebiotic atmospheres. Present work is devoted to the role of CO2 in the prebiotic atmosphere chemistry. Most of the laboratory studies of such atmosphere were focused on the chemistry of N2 + CH4 mixtures. The present work is devoted to the study of the oxygenated volatile species in prebiotic atmosphere, specifically CO2 reactivity. CO2 was introduced to the standard N2 + CH4 mixture at different mixing ratio up to 5 % CH4 and 3 % CO2. The reaction products were characterized by FTIR spectroscopy. This work shows that CO2 modifies the composition of the gas phase with the detection of oxygenated compounds: CO and others oxides. There is a strong influence of CO2 on increasing concentration other products as cyanide (HCN) and ammonia (NH3).

  1. Membrane-Associated Polypeptides Induced in Chlamydomonas by Limiting CO(2) Concentrations.

    Science.gov (United States)

    Spalding, M H; Jeffrey, M

    1989-01-01

    Chlamydomonas reinhardtii and other unicellular green algae have a high apparent affinity for CO(2), little O(2) inhibition of photosynthesis, and reduced photorespiration. These characteristics result from operation of a CO(2)-concentrating system. The CO(2)-concentrating system involves active inorganic carbon transport and is under environmental control. Cells grown at limiting CO(2) concentrations have inorganic carbon transport activity, but cells grown at 5% CO(2) do not. Four membrane-associated polypeptides (M(r) 19, 21, 35, and 36 kilodaltons) have been identified which either appear or increase in abundance during adaptation to limiting CO(2) concentrations. The appearance of two of the polypeptides occurs over roughly the same time course as the appearance of the CO(2)-concentrating system activity in response to CO(2) limitation. PMID:16666503

  2. Pollutants transport and atmospheric variability of CO2 over Siberia: contribution of airborne measurements

    International Nuclear Information System (INIS)

    The work presented here intends to characterize the variations of atmospheric concentrations of CO2, CO, O3 and ultrafine particles, over a large scale aircraft transect above Siberia, during three intensive YAK-AEROSIB campaigns in April 2006, September 2006 and August 2007, respectively. Pollutant and greenhouse gases distribution in this poorly studied region is needed to model atmospheric long range transport. I show here that CO concentrations at the time of the campaigns is broadly affected by (1) advection of Chinese pollutants through baro-clinic perturbations, (2) advection (diffuse or not) of European pollutants at various altitudes, (3) and of biomass burning from Central Asia. This set of factors is analyzed through a novel statistical technique based on clustering of backward transport simulated by the FLEXPART Lagrangian model. Large observed CO2 gradients in summer are matched against vertical mixing in GCM simulated CO2. At last I present ultrafine particle measurements, and a possible nucleation summer maximum in the clean, continental mid-troposphere. (author)

  3. Los Angeles megacity: a high-resolution land-atmosphere modelling system for urban CO2 emissions

    Science.gov (United States)

    Feng, Sha; Lauvaux, Thomas; Newman, Sally; Rao, Preeti; Ahmadov, Ravan; Deng, Aijun; Díaz-Isaac, Liza I.; Duren, Riley M.; Fischer, Marc L.; Gerbig, Christoph; Gurney, Kevin R.; Huang, Jianhua; Jeong, Seongeun; Li, Zhijin; Miller, Charles E.; O'Keeffe, Darragh; Patarasuk, Risa; Sander, Stanley P.; Song, Yang; Wong, Kam W.; Yung, Yuk L.

    2016-07-01

    Megacities are major sources of anthropogenic fossil fuel CO2 (FFCO2) emissions. The spatial extents of these large urban systems cover areas of 10 000 km2 or more with complex topography and changing landscapes. We present a high-resolution land-atmosphere modelling system for urban CO2 emissions over the Los Angeles (LA) megacity area. The Weather Research and Forecasting (WRF)-Chem model was coupled to a very high-resolution FFCO2 emission product, Hestia-LA, to simulate atmospheric CO2 concentrations across the LA megacity at spatial resolutions as fine as ˜ 1 km. We evaluated multiple WRF configurations, selecting one that minimized errors in wind speed, wind direction, and boundary layer height as evaluated by its performance against meteorological data collected during the CalNex-LA campaign (May-June 2010). Our results show no significant difference between moderate-resolution (4 km) and high-resolution (1.3 km) simulations when evaluated against surface meteorological data, but the high-resolution configurations better resolved planetary boundary layer heights and vertical gradients in the horizontal mean winds. We coupled our WRF configuration with the Vulcan 2.2 (10 km resolution) and Hestia-LA (1.3 km resolution) fossil fuel CO2 emission products to evaluate the impact of the spatial resolution of the CO2 emission products and the meteorological transport model on the representation of spatiotemporal variability in simulated atmospheric CO2 concentrations. We find that high spatial resolution in the fossil fuel CO2 emissions is more important than in the atmospheric model to capture CO2 concentration variability across the LA megacity. Finally, we present a novel approach that employs simultaneous correlations of the simulated atmospheric CO2 fields to qualitatively evaluate the greenhouse gas measurement network over the LA megacity. Spatial correlations in the atmospheric CO2 fields reflect the coverage of individual measurement sites when a

  4. Sensitivity of the air-sea CO2 exchange in the Baltic Sea and Danish inner waters to atmospheric short term variability

    Science.gov (United States)

    Lansø, A. S.; Bendtsen, J.; Christensen, J. H.; Sørensen, L. L.; Chen, H.; Meijer, H. A. J.; Geels, C.

    2014-12-01

    Minimising the uncertainties in estimates of air-sea CO2 exchange is an important step toward increasing the confidence in assessments of the CO2 cycle. Using an atmospheric transport model makes it possible to investigate the direct impact of atmospheric parameters on the air-sea CO2 flux along with its sensitivity to e.g. short-term temporal variability in wind speed, atmospheric mixing height and the atmospheric CO2 concentration. With this study the importance of high spatiotemporal resolution of atmospheric parameters for the air-sea CO2 flux is assessed for six sub-basins within the Baltic Sea and Danish inner waters. A new climatology of surface water partial pressure of CO2 (pCO2) has been developed for this coastal area based on available data from monitoring stations and underway pCO2 measuring systems. Parameterisations depending on wind speed were applied for the transfer velocity to calculate the air-sea CO2 flux. Two model simulations were conducted - one including short term variability in atmospheric CO2 (VAT), and one where it was not included (CAT). A seasonal cycle in the air-sea CO2 flux was found for both simulations for all sub-basins with uptake of CO2 in summer and release of CO2 to the atmosphere in winter. During the simulated period 2005-2010 the average annual net uptake of atmospheric CO2 for the Baltic Sea, Danish Straits and Kattegat was 287 and 471 Gg C yr-1 for the VAT and CAT simulations, respectively. The obtained difference of 184 Gg C yr-1 was found to be significant, and thus ignoring short term variability in atmospheric CO2 does have a sizeable effect on the air-sea CO2 exchange. The combination of the atmospheric model and the new pCO2 fields has also made it possible to make an estimate of the marine part of the Danish CO2 budget for the first time. A net annual uptake of 2613 Gg C yr-1 was found for the Danish waters. A large uncertainty is connected to the air-sea CO2 flux in particular caused by the transfer velocity

  5. Sensitivity of the air–sea CO2 exchange in the Baltic Sea and Danish inner waters to atmospheric short term variability

    Directory of Open Access Journals (Sweden)

    A. S. Lansø

    2014-12-01

    Full Text Available Minimising the uncertainties in estimates of air–sea CO2 exchange is an important step toward increasing the confidence in assessments of the CO2 cycle. Using an atmospheric transport model makes it possible to investigate the direct impact of atmospheric parameters on the air–sea CO2 flux along with its sensitivity to e.g. short-term temporal variability in wind speed, atmospheric mixing height and the atmospheric CO2 concentration. With this study the importance of high spatiotemporal resolution of atmospheric parameters for the air–sea CO2 flux is assessed for six sub-basins within the Baltic Sea and Danish inner waters. A new climatology of surface water partial pressure of CO2 (pCO2 has been developed for this coastal area based on available data from monitoring stations and underway pCO2 measuring systems. Parameterisations depending on wind speed were applied for the transfer velocity to calculate the air–sea CO2 flux. Two model simulations were conducted – one including short term variability in atmospheric CO2 (VAT, and one where it was not included (CAT. A seasonal cycle in the air–sea CO2 flux was found for both simulations for all sub-basins with uptake of CO2 in summer and release of CO2 to the atmosphere in winter. During the simulated period 2005–2010 the average annual net uptake of atmospheric CO2 for the Baltic Sea, Danish Straits and Kattegat was 287 and 471 Gg C yr-1 for the VAT and CAT simulations, respectively. The obtained difference of 184 Gg C yr-1 was found to be significant, and thus ignoring short term variability in atmospheric CO2 does have a sizeable effect on the air–sea CO2 exchange. The combination of the atmospheric model and the new pCO2 fields has also made it possible to make an estimate of the marine part of the Danish CO2 budget for the first time. A net annual uptake of 2613 Gg C yr-1 was found for the Danish waters. A large uncertainty is connected to the air–sea CO2 flux in particular

  6. The O+ + CO2 reaction: New results and atmospheric implications

    International Nuclear Information System (INIS)

    The vibrational distribution of the O2+ product ion in the reaction of O+ with CO2 has been measured in a selected ion flow tube using the monitor ion technique. At 300 K the measured vibrational distribution is 45% of the ions in v = 1, 32% in v ≥ 2 and 23% in v = 0. However, it is possible that vibrational quenching by the monitor gas may affect the distribution, and the nascent population may be entirely in v > O. The branching ratio between the O2+ + CO and the CO2+ + O product channels has been measured as a function of ion drift velocity. The implications of these experiments for terrestrial releases of CO2 into the ionosphere and for the ionospheres of Mars and Venus are considered

  7. Mesozooplankton community development at elevated CO2 concentrations: results from a mesocosm experiment in an Arctic fjord

    Directory of Open Access Journals (Sweden)

    J. Czerny

    2012-08-01

    Full Text Available The increasing CO2 concentration in the atmosphere caused by burning fossil fuels leads to increasing pCO2 and decreasing pH in the world oceans. These changes may have severe consequences for marine biota, especially in cold-water ecosystems due to higher solubility of CO2. However, studies on the response of mesozooplankton communities to elevated pCO2 are yet lacking. In order to test whether abundance and taxonomic composition change with pCO2, we have sampled nine mesocosms, which were deployed in Kongsfjorden, an Arctic fjord at Svalbard, and were adjusted to eight CO2 concentrations, initially ranging from 185 μatm to 1420 μatm. Samples were taken weekly over a six-week period with an Apstein net (55 μm mesh size in all mesocosms and the surrounding fjord. In addition, sediment trap samples, taken every second day in the mesocosms, were analyzed to account for losses due to vertical migration and mortality. The taxonomic analysis revealed that meroplanktonic larvae (cirripeds, polychaetes, bivalves, gastropod, and decapods dominated in the mesocosms while copepods (Calanus spp., Oithona similis, Acartia longiremis and Microsetella norvegica were found in lower abundances. In the fjord copepods prevailed for most of our study. With time, abundance and taxonomic composition developed similarly in all mesocosms; the pCO2 had no significant effect on the overall community structure. However, single taxa responded to elevated CO2 concentrations. The ratio of cirripedia nauplii to cypris larvae, the next developmental stage, in the sediment traps averaged over the entire experiment increased with pCO2 and this suggests that increased pCO2 may have delayed their development. Also, the number of bivalves, averaged over the experimental period, decreased significantly with increasing pCO2. The nature of the CO2 effect, either direct or indirect, remains open and needs to be addressed in future.

  8. Weak Northern and Strong Tropical Land Carbon Uptake from Vertical Profiles of Atmospheric CO2

    NARCIS (Netherlands)

    Stephens, Britton B.; Gurney, Kevin R.; Tans, Pieter P.; Sweeney, Colm; Peters, Wouter; Bruhwiler, Lori; Ciais, Philippe; Ramonet, Michel; Bousquet, Philippe; Nakazawa, Takakiyo; Aoki, Shuji; Machida, Toshinobu; Inoue, Gen; Vinnichenko, Nikolay; Lloyd, Jon; Jordan, Armin; Heimann, Martin; Shibistova, Olga; Langenfelds, Ray L.; Steele, L. Paul; Francey, Roger J.; Denning, A. Scott

    2007-01-01

    Measurements of midday vertical atmospheric CO2 distributions reveal annual-mean vertical CO2 gradients that are inconsistent with atmospheric models that estimate a large transfer of terrestrial carbon from tropical to northern latitudes. The three models that most closely reproduce the observed an

  9. Weak northern and strong tropical land carbon uptake from vertical profiles of atmospheric CO2

    NARCIS (Netherlands)

    Stephens, B.B.; Gurney, K.R.; Tans, P.P.; Sweeney, C.; Peters, W.

    2007-01-01

    Measurements of midday vertical atmospheric CO2 distributions reveal annual-mean vertical CO2 gradients that are inconsistent with atmospheric models that estimate a large transfer of terrestrial carbon from tropical to northern latitudes. The three models that most closely reproduce the observed an

  10. Cosmic rays as a factor for the sink of atmospheric CO2

    International Nuclear Information System (INIS)

    The paper deals with the problem of atmospheric CO2 sink in the process of the interaction of cosmic rays with the earth atmosphere. It is shown that maximums of nucleon and hard meson components of cosmic rays coincide with CO2 decrease maximum in terms of height. 15 refs., 2 figs

  11. Pulsed Lidar Measurements of Atmospheric CO2 Column Absorption in the ASCENDS 2011 Airborne Campaign

    Science.gov (United States)

    Abshire, James B.; Riris, Haris; Allan, Graham R.; Ramanathan, Anand; Hasselbrack, William E.; Mao, Jianping; Weaver, Clark; Browell, Edward V.

    2012-01-01

    We have previously demonstrated an efficient pulsed, wavelength-resolved IPDA lidar technique for measuring the tropospheric CO2 concentrations as a candidate for NASA's ASCENDS mission. Our team participated in the 2010 ASCENDS airborne campaigns we flew airborne version of the CO2 and O2 lidar on the NASA DC-8. The CO2 lidar measures the atmospheric backscatter profiles and shape of the 1572.33 nm absorption line using 250 mW average laser power, 30 wavelength samples per scan and 300 scans per second. Most flights had 5-6 altitude steps to greater than 12 km, and clear CO2 line shapes were observed at all altitudes. Our post-flight analysis estimated the Iidar range and pulse energies at each wavelength every second. We then solved for the best-fit CO2 absorption line shape, and calculated the Differential Optical Depth (DOD) at the line peak. We compared these to CO2 DODs calculated from spectroscopy based on HITRAN 2008 and the conditions from airborne in-situ readings. Analysis of the 2010 measurements over the Pacific Ocean and Lamont OK shows the expected -linear change of the peak DOD with altitude. For measurements at altitudes greater than 6 km the random errors were approximately 0.3 ppm for 80 sec averaging times. After the 2010 flights we improved the airborne lidar's scan uniformity, calibration and receiver sensitivity. Our team participated in the seven ASCENDS science flights during late July and August 2011. These flights were made over a wide variety of surface and cloud conditions near the US, including over the central valley of California, over several mountain ranges, over both broken and solid stratus cloud deck over the Pacific Ocean, snow patches on mountain tops, over thin and broken clouds above the US Southwest and Iowa, and over forests near the WLEF tower in Wisconsin. Analyses show the retrievals of lidar range and CO2 column absorption, as wen as estimates of CO2 mixing ratio worked well when measuring over topography with rapidly

  12. Isoprene leaf emission under CO2 free atmosphere: why and how?

    Science.gov (United States)

    Garcia, S.

    2015-12-01

    Isoprene (C5H8) is a reactive hydrocarbon gas emitted at high rates by tropical vegetation, which affects atmospheric chemistry and climate and, in the leaf level, is a very important agent against environmental stress. Under optimal conditions for photosynthesis, the majority of carbon used for isoprene biosynthesis is a direct product from recently assimilated atmospheric CO2. However, the contribution of 'alternate' carbon sources, that increase with leaf temperature, have been demonstrated and emissions of isoprene from 'alternate' carbon sources under ambient CO2 below the compensation point for photosynthesis have been observed. In this study, we investigated the response of leaf isoprene emissions under 450 ppm CO2 and CO2 free atmosphere as a function of light and leaf temperature. At constant leaf temperature (30 °C) and CO2 free atmospheres, leaves of the tropical species Inga edulis showed net emissions of CO2 and light-dependent isoprene emissions which stagnated at low light levels (75 µmol m-2 s-1 PAR) and account for 25% of that observed with 450 ppm CO2. Under constant light (1000 µmol m-2 s-1 PAR) and CO2 free atmospheres, a increase of leaf temperatures from 25 to 40 °C resulted in net emissions of CO2 and temperature-dependent isoprene emissions which reached values up to 17% of those under 450 ppm CO2. Our observations suggest that, under environmental stress, as high light/temperature and drought (when the stomata close and the amount of internal CO2 decreases), the 'alternate' carbon can maintain photosynthesis rates resulting in the production of isoprene, independent of atmospheric CO2, through the re-assimilation of internal released CO2 as an 'alternate' carbon sources for isoprene.

  13. Limited carbon storage in soil and litter of experimental forest plots under increased atmospheric CO2

    International Nuclear Information System (INIS)

    The current rise in atmospheric CO2 concentration is thought to be mitigated in part by carbon sequestration within forest ecosystems, where carbon can be stored in vegetation or soils. The storage of carbon in soils is determined by the fraction that is sequestered in persistent organic materials, such as humus. In experimental forest plots of loblolly pine (Pinus taeda) exposed to high CO2 concentrations, nearly half of the carbon uptake is allocated to short-lived tissues, largely foliage. These tissues fall to the ground and decompose, normally contributing only a small portion of their carbon content to refractory soil humic materials. Such findings call into question the role of soils as long-term carbon sinks, and show the need for a better understanding of carbon cycling in forest soils. Here we report a significant accumulation of carbon in the litter layer of experimental forest plots after three years of growth at increased CO2 concentrations (565 μ l1). But fast turnover times of organic carbon in the litter layer (of about three years) appear to constrain the potential size of this carbon sink. Given the observation that carbon accumulation in the deeper mineral soil layers was absent, we suggest that significant, long-term net carbon sequestration in forest soils is unlikely. (author)

  14. Exploring the Sensitivity of Terrestrial Ecosystems and Atmospheric Exchange of CO2 to Global Environmental Factors

    Science.gov (United States)

    Jain, A. K.; Meiyappan, P.; Song, Y.; Barman, R.

    2011-12-01

    This presentation explores the sensitivity of terrestrial ecosystems and atmospheric exchange of carbon to global environmental factors to advance our understanding of uncertainty in CO2 projections. We use a land surface model, the Integrated Science Assessment Model (ISAM) recently coupled into the NCAR Community Earth System Model (CESM1) framework to evaluate ecosystem variability due to climatic and anthropogenic factors. The factors considered here include climate change, increasing ambient CO2 concentrations, anthropogenic nitrogen deposition, and land use change (LUC) activities such as clearing of land for agriculture, pasture, and wood harvest. Each factor has a potential to influence the net ecosystem exchange (NEE) of CO2. Using the ISAM-CESM modeling framework, we evaluate the individual and concurrent effects of all these environmental factors on the terrestrial NEE over the 20th century and the 21st century. The ISAM biogeochemical cycles consist of fully prognostic carbon and nitrogen dynamics associated with changes in land cover, litter decomposition, and soil organic matter. The ISAM biophysical model accounts for water and energy processes in the vegetation and soil column, integrated over a time step of 30 minutes. The newly available CRU-NCEP climate forcing data (1850-2010, 0.5ox0.5o spatial resolution) will be used for the historical period simulations. The 21st century simulations will be carried out using the Representative Concentration Pathway (RCP) storylines. This study will help quantify the importance of various environmental factors towards modeling land-atmosphere carbon exchange and better understand model related differences in CO2 estimates.

  15. Thermogravimetric analyses of combustion of lignocellulosic materials in N2/O2 and CO2/O2 atmospheres.

    Science.gov (United States)

    Lai, ZhiYi; Ma, XiaoQian; Tang, YuTing; Lin, Hai; Chen, Yong

    2012-03-01

    The combustion of paper, fruit waste and plant residue mixtures representing the lignocellulosic materials of municipal solid waste (MSW) in different atmospheres (80N(2)/20O(2), 70N(2)/30O(2), 60N(2)/40O(2), 50N(2)/50O(2), 80CO(2)/20O(2), 70CO(2)/30O(2), 60CO(2)/40O(2), 50CO(2)/50O(2)) was analyzed thermogravimetrically. Replacement of 80% N(2) by 80% CO(2) resulted in a slightly later ignition, a lower maximum weight loss rate and a change in reactions occurring above 600°C; however, as the oxygen concentration increased from 20% to 50% in CO(2)/O(2) atmosphere, the ignition temperature decreased from 318.5 to 310.8°C and the maximum weight loss rate increased from 20.82% to 23.57%/min. An oxygen content of 30% in the CO(2)/O(2) atmosphere achieved a similar combustion performance as a 80N(2)/20O(2). The fruit waste mixture had the least residual weight (about 5%) and the earliest ignition (about 220°C). This work contributes to the comprehensive understanding of lignocellulosic materials combustion and development of MSW oxy-fuel combustion. PMID:22209440

  16. Estimation of 14CO2 flux at soil-atmosphere interface and distribution of 14C in forest ecosystem

    International Nuclear Information System (INIS)

    To realize the dynamical behavior of 14C among exchangeable carbon reservoirs in terrestrial environment, a method for in situ determination of 14CO2 flux at soil-atmosphere interface and a high flow rate CO2 sampler were developed. This method allowed us to collect integrated quantity of CO2 for determining 14C activity over an extended time period under environmental conditions with minimal site disturbance. The 14CO2 flux from ground surface was estimated to be 1.59x10-5 Bq m-2 s-1 in a forest floor with the method. The specific activities of 14C in environmental materials such as some biological and air samples were also determined in the vicinity of the place, where the flux measurement was made, to discuss the behavior of 14C in the forest ecosystem. The results indicated that fresh pine needles had a similar 14C specific activity to the atmospheric CO2 at the same height due to its fairly rapid equilibrium, 14C specific activity in the atmospheric CO2 has a concentration gradient near the ground surface and, at least in this site, CO2 with high 14C specific activity was generated by decomposition of soil organic matter which may be accumulated in soil as a result of former nuclear weapons tests

  17. A permafrost glacial hypothesis to explain atmospheric CO2 and the ice ages during the Pleistocene

    Directory of Open Access Journals (Sweden)

    R. Tarozo

    2010-10-01

    Full Text Available Over the past several 100 ka glacial-interglacial cycles, the concentration of atmospheric CO2 was closely coupled to global temperature, which indicates the importance of CO2 as a greenhouse gas. The reasons for changes in atmospheric CO2 have mainly been sought in the ocean, yet proxy evidence does not support the notion of increased oceanic carbon storage during glacials. Here we present results from the first permafrost loess sequence in Siberia spanning two glacial cycles (~240 ka, which reveal that permafrost soils repeatedly sequestered huge amounts of terrestrial carbon during glacial periods. This can be explained with permafrost favouring more intensive waterlogging conditions and better preservation of soil organic matter. Terrestrial carbon stored in permafrost soils was released upon warming and provided a powerful feedback mechanism for the glacial terminations. We outline a "permafrost glacial hypothesis" building on integrated annual insolation forcing, which readily explains the observed succession of the ice ages during the Pleistocene, including the mid-Pleistocene transition.

  18. Attribution of atmospheric CO2 and temperature increases to regions: importance of preindustrial land use change

    International Nuclear Information System (INIS)

    The historical contribution of each country to today’s observed atmospheric CO2 excess and higher temperatures has become a basis for discussions around burden-sharing of greenhouse gas reduction commitments in political negotiations. However, the accounting methods have considered greenhouse gas emissions only during the industrial era, neglecting the fact that land use changes (LUC) have caused emissions long before the Industrial Revolution. Here, we hypothesize that considering preindustrial LUC affects the attribution because the geographic pattern of preindustrial LUC emissions differs significantly from that of industrial-era emissions and because preindustrial emissions have legacy effects on today’s atmospheric CO2 concentrations and temperatures. We test this hypothesis by estimating CO2 and temperature increases based on carbon cycle simulations of the last millennium. We find that accounting for preindustrial LUC emissions results in a shift of attribution of global temperature increase from the industrialized countries to less industrialized countries, in particular South Asia and China, by up to 2–3%, a level that may be relevant for political discussions. While further studies are needed to span the range of plausible quantifications, our study demonstrates the importance of including preindustrial emissions for the most scientifically defensible attribution. (letter)

  19. Using atmospheric CO2 data to assess a simplified carbon-climate simulation for the 20th century

    International Nuclear Information System (INIS)

    The CSIRO biosphere model has been coupled to an atmosphere model and a simulation has been performed for the 20th century. Both biosphere and atmosphere are forced with global CO2 concentration and the atmosphere is also forced with prescribed sea surface temperatures. The simulation follows the C4MIP Phase 1 protocol. We assess the model simulation using atmospheric CO2 data. Mauna Loa growth rate is well simulated from 1980 but overestimated before that time. The interannual variations in growth rate are reasonably reproduced. Seasonal cycles are underestimated in northern mid-latitudes and are out of phase in the southern hemisphere. The north-south gradient of annual mean CO2 is substantially overestimated due to a northern hemisphere net biosphere source and a southern tropical sink. Diurnal cycles at three northern hemisphere locations are larger than observed in many months, most likely due to larger respiration than observed

  20. Laser Sounder for Global Measurement of CO2 Concentrations in the Troposphere from Space

    Science.gov (United States)

    Abshire, James B.; Riris, Haris; Kawa, S. Randy; Sun, Xiaoli; Chen, Jeffrey; Stephen, Mark A.; Collatz, G. James; Mao, Jianping; Allan, Graham

    2007-01-01

    Measurements of tropospheric CO2 abundance with global-coverage, a few hundred km spatial and monthly temporal resolution are needed to quantify processes that regulate CO2 storage by the land and oceans. The Orbiting Carbon Observatory (OCO) is the first space mission focused on atmospheric CO2 for measuring total column CO, and O2 by detecting the spectral absorption in reflected sunlight. The OCO mission is an essential step, and will yield important new information about atmospheric CO2 distributions. However there are unavoidable limitations imposed by its measurement approach. These include best accuracy only during daytime at moderate to high sun angles, interference by cloud and aerosol scattering, and limited signal from CO2 variability in the lower tropospheric CO2 column. We have been developing a new laser-based technique for the remote measurement of the tropospheric CO2 concentrations from orbit. Our initial goal is to demonstrate a lidar technique and instrument technology that will permit measurements of the CO2 column abundance in the lower troposphere from aircraft. Our final goal is to develop a space instrument and mission approach for active measurements of the CO2 mixing ratio at the 1-2 ppmv level. Our technique is much less sensitive to cloud and atmospheric scattering conditions and would allow continuous measurements of CO2 mixing ratio in the lower troposphere from orbit over land and ocean surfaces during day and night. Our approach is to use the 1570nm CO2 band and a 3-channel laser absorption spectrometer (i.e. lidar used an altimeter mode), which continuously measures at nadir from a near polar circular orbit. The approach directs the narrow co-aligned laser beams from the instrument's lasers toward nadir, and measures the energy of the laser echoes reflected from land and water surfaces. It uses several tunable fiber laser transmitters which allowing measurement of the extinction from a single selected CO2 absorption line in the 1570

  1. CO2-dominated Atmosphere in Equilibrium with NH3-H2O Ocean: Application to Early Titan and Ocean Planets

    Science.gov (United States)

    Marounina, N.; Grasset, O.; Tobie, G.; Carpy, S.

    2015-12-01

    During the accretion of Titan, impact heating may have been sufficient to allow the global melting of water ice (Monteux et al. 2014) and the release of volatile compounds, with CO2 and NH3 as main constituents (Tobie et al. 2012). Thus, on primitive Titan, it is thought that a massive atmosphere was in contact with a global water ocean. Similar configurations may occur on temperate water-rich planets called ocean planets (Léger et al. 2004, Kitzmann et al. 2015).Due to its rather low solubility in liquid water, carbon dioxide is expected to be one of the major components in the atmosphere. The atmospheric amount of CO2 is a key parameter for assessing the thermal evolution of the planetary surface because of its strong greenhouse effect. However, ammonia significantly affects the solubility of CO2 in water and hence the atmosphere-ocean thermo-chemical equilibrium. For primitive Titan, estimating the mass, temperature and composition of the primitive atmosphere is important to determine mechanisms that led to the present-day N2-CH4 dominated atmosphere. Similarly, for ocean planets, the influence of ammonia on the atmospheric abundance in CO2 has consequences for the definition of the habitable zone.To investigate the atmospheric composition of the water-rich worlds for a wide range of initial compositions, we have developed a vapor-liquid equilibrium model of the NH3-CO2-H2O system, where we account for the non-ideal comportment of both vapor and liquid phases and the ion speciation of volatiles dissolved in the aqueous phase. We show that adding NH3 to the CO2-H2O binary system induces an efficient absorption of the CO2 in the liquid phase and thus a lower CO2 partial pressure in the vapor phase. Indeed, the CO2 partial pressure remains low for the CO2/NH3 ratio of liquid concentrations lower than 0.5.Assuming various initial compositions of Titan's global water ocean, we explore the thermal and compositional evolution of a massive primitive atmosphere using

  2. Regional scale modeling of atmospheric CO2 over East Asia and comparison with satellite observations

    Science.gov (United States)

    Shim, C.

    2012-12-01

    East Asia is now the most important regions in terms of CO2 emissions and the analyzing accurate CO2 budget is critical issue for low-carbon policy. He we show the simulated regional scale CO2 distribution. The regional scale chemical transport model (WRF-Chem) was used with 50km x 50km resolution. The lateral boundary conditions were from GEOS-Chem CO2 simulations (with 2x2.5 degree resolution) where the chemical CO2 production and 3-D emissions from aviation were included. It is clear that the seasonal changes in north-south gradient of CO2 concentration over East Asia is shown by the model. In spring, the westerly transport of CO2 from north-east China is dominant, which increases the higher CO2 concentration in northern part of East Asia in the lower troposphere (global low carbon policy for responding to recent climate change.

  3. Study of satellite retrieved CO2 and CH4 concentration over India

    Science.gov (United States)

    Prasad, Prabhunath; Rastogi, Shantanu; Singh, R. P.

    2014-11-01

    This paper reports a study of spatial and temporal variations of columnar averaged concentration of CO2 and CH4 over India using SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) and Greenhouse gas Observing SATellite (GOSAT) data. Comparison of these data with the global view National Oceanic and Atmospheric Administration (NOAA) land data and also location specific flask data is made. The temporal variation in column averaged global CO2 is similar to that over India and it is also similar to the NOAA surface flask data and global view. The variation in NOAA surface CH4 is location dependent and its global view appears to vary seasonally in opposite phase with the column averaged CH4 values from satellites, reflecting the limited comparability of surface and column averaged data. Over India the CO2 maximum is in May and minimum in August/September while for CH4 the maximum is in September and minimum in February/March. The seasonal variation of CH4 over India is correlated with the eastern coastal rice cultivation.

  4. Effect of CO2 concentrations on the activity of photosynthetic CO2 fixation and extracelluar carbonic anhydrase in the marine diatom Skeletonema costatum

    Institute of Scientific and Technical Information of China (English)

    CHEN Xiongwen; GAO Kunshan

    2003-01-01

    The growth and activity of photosynthetic CO2 uptake and extracellular carbonic anhydrase (Caext) of the marine diatom Skeletonema costatum were investigated while cultured at different levels of CO2 in order to see its physiological response to different CO2 concentrations under either a low (30 μmol·m-2·s-1) or high (210 μmol·m-2·s-1) irradiance. The changes in CO2 concentrations (4-31 μmol/L) affected the growth and net photosynthesis to a greater extent under the low than under the high light regime. Caext was detected in the cells grown at 4 μmol/L CO2 but not at 31 and 12 μmol/L CO2, with its activity being about 2.5-fold higher at the high than at the low irradiance. Photo- synthetic CO2 affinity (1/ K1/2(CO2)) of the cells decreased with increased CO2 concentrations in culture. The cells cultured under the high-light show significantly higher photosynthetic CO2 affinity than those grown at the low-light level. It is concluded that the regulations of Caext activity and photosynthetic CO2 affinity are dependent not only on CO2 concentration but also on light availability, and that the development of higher Caext activity and CO2 affinity under higher light level could sufficiently support the photosynthetic demand for CO2 even at low level of CO2.

  5. Pressure sensing of the atmosphere by solar occultation using broadband CO2 absorption

    Science.gov (United States)

    Park, J. H.; Russell, J. M., III; Drayson, S. R.

    1979-01-01

    A technique for obtaining pressure at the tangent point in an IR solar occulation experiment is described. By measuring IR absorption in bands of atmospheric CO2 (e.g., 2.0, 2.7, or 4.3 microns), mean pressure values for each tangent point layer (vertical thickness 2 km or less) of the atmosphere can be obtained with rms errors of less than 3%. The simultaneous retrieval of pressure and gas concentration in a remote-sensing experiment will increase the accuracy of inverted gas concentrations and minimize the dependence of the experiment on pressure or mass path error resulting from use of climatological pressure data, satellite ephemeris, and instrument pointing accuracy.

  6. A Ground-based validation of GOSAT-observed atmospheric CO2 in Inner-Mongolian grasslands

    International Nuclear Information System (INIS)

    Atmospheric carbon dioxide (CO2) is a long-lived greenhouse gas that significantly contributes to global warming. Long-term and continuous measurements of atmospheric CO2 to investigate its global distribution and concentration variations are important for accurately understanding its potential climatic effects. Satellite measurements from space can offer atmospheric CO2 data for climate change research. For that, ground-based measurements are required for validation and improving the precision of satellite-measured CO2. We implemented observation experiment of CO2 column densities in the Xilinguole grasslands in Inner Mongolia, China, using a ground-based measurement system, which mainly consists of an optical spectrum analyzer (OSA), a sun tracker and a notebook controller. Measurements from our ground-based system were analyzed and compared with those from the Greenhouse gas Observation SATellite (GOSAT). The ground-based measurements had an average value of 389.46 ppm, which was 2.4 ppm larger than from GOSAT, with a standard deviation of 3.4 ppm. This result is slightly larger than the difference between GOSAT and the Total Carbon Column Observing Network (TCCON). This study highlights the usefulness of the ground-based OSA measurement system for analyzing atmospheric CO2 column densities, which is expected to supplement the current TCCON network

  7. Seven years of observational atmospheric CO2 at a maritime site in northernmost Japan and its implications.

    Science.gov (United States)

    Zhu, Chunmao; Yoshikawa-Inoue, Hisayuki

    2015-08-15

    Surface atmospheric CO2 mixing ratio reflects both natural fluctuation of the carbon cycle and the effect of anthropogenic activities. Long-term observation of atmospheric CO2 forms the basis for model simulations of the carbon cycle both in the straightforward and the inversion ways. Atmospheric CO2 has been measured on Rishiri Island (45.1°N, 141.2°E) in the western North Pacific since May 2006. We report the first 7-year temporal CO2 variations from diurnal to inter-annual scales and the implications on the vegetation phenology. Diurnally, an obvious cycle appeared as a minimum in the afternoon and maximum at midnight in the summer months, caused by local vegetation. Seasonally, the maximum CO2 concentration appeared around the beginning of April, while the minimum appeared around the middle of August. This seasonal variation implied the natural cycle of terrestrial biological activities of the boreal forest, mostly in the east Eurasia. A mean growing season length of ~126 days was estimated. In the period from 2007 to 2012, the peak-to-peak amplitude increased until 2009 and decreased thereafter, with a mean value of 19.7 ppm. Inter-annually, atmospheric CO2 is increasing by a mean growth rate of 2.1 ppm year(-1). The study provides invaluable dataset and useful information to better understand the carbon cycle and its interaction with climate change. PMID:25911544

  8. Transcriptional and metabolic insights into the differential physiological responses of arabidopsis to optimal and supraoptimal atmospheric CO2.

    Directory of Open Access Journals (Sweden)

    Fatma Kaplan

    Full Text Available BACKGROUND: In tightly closed human habitats such as space stations, locations near volcano vents and closed culture vessels, atmospheric CO(2 concentration may be 10 to 20 times greater than Earth's current ambient levels. It is known that super-elevated (SE CO(2 (>1,200 µmol mol(-1 induces physiological responses different from that of moderately elevated CO(2 (up to 1,200 µmol mol(-1, but little is known about the molecular responses of plants to supra-optimal [CO(2]. METHODOLOGY/PRINCIPAL FINDINGS: To understand the underlying molecular causes for differential physiological responses, metabolite and transcript profiles were analyzed in aerial tissue of Arabidopsis plants, which were grown under ambient atmospheric CO(2 (400 µmol mol(-1, elevated CO(2 (1,200 µmol mol(-1 and SE CO(2 (4,000 µmol mol(-1, at two developmental stages early and late vegetative stage. Transcript and metabolite profiling revealed very different responses to elevated versus SE [CO(2]. The transcript profiles of SE CO(2 treated plants were closer to that of the control. Development stage had a clear effect on plant molecular response to elevated and SE [CO(2]. Photosynthetic acclimation in terms of down-regulation of photosynthetic gene expression was observed in response to elevated [CO(2], but not that of SE [CO(2] providing the first molecular evidence that there appears to be a fundamental disparity in the way plants respond to elevated and SE [CO(2]. Although starch accumulation was induced by both elevated and SE [CO(2], the increase was less at the late vegetative stage and accompanied by higher soluble sugar content suggesting an increased starch breakdown to meet sink strength resulting from the rapid growth demand. Furthermore, many of the elevated and SE CO(2-responsive genes found in the present study are also regulated by plant hormone and stress. CONCLUSIONS/SIGNIFICANCE: This study provides new insights into plant acclimation to elevated and SE [CO

  9. Arctic sea ice and atmospheric circulation under the abrupt4xCO2 scenario

    Institute of Scientific and Technical Information of China (English)

    YU Xiaoyong; Annette Rinke; JI Duoying; CUI Xuefeng; John C Moore

    2014-01-01

    We analyze sea ice changes from eight different earth system models that have conducted experiment abrupt4xCO2 of the Coupled Model Intercomparison Project Phase 5 (CMIP5). In response to abrupt quadrupling of CO2 from preindustrial levels, Arctic temperatures dramatically rise by about 10°C—16°C in winter and the seasonal sea ice cycle and sea ice concentration are signiifcantly changed compared with the pre-industrial control simulations (piControl). Changes of Arctic sea ice concentration are spatially correlated with temperature patterns in all seasons and highest in autumn. Changes in sea ice are associated with changes in atmospheric circulation patterns at heights up to the jet stream. While the pattern of sea level pressure changes is generally similar to the surface air temperature change pattern, the wintertime 500 hPa circulation displays a positive Paciifc North America (PNA) anomaly under abrupt4xCO2-piControl. This large scale teleconnection may contribute to, or feedback on, the simulated sea ice cover change and is associated with an intensiifcation of the jet stream over East Asia and the north Paciifc in winter.

  10. Laser Sounder for Global Measurement of CO2 Concentrations in the Troposphere from Space: Update

    Science.gov (United States)

    Abshire, J. B.; Riris, H.; Kawa, S. R.; Sun, X.; Krainak, M. A.; Mao, J.; Jian, P.; Collatz, G. J.; Stephen, M.

    2006-12-01

    We report progress in developing a laser technique for the remote measurement of the tropospheric CO2 concentrations from orbit. Our initial goal is to demonstrate a lidar technique and instrument technology that will permit measurements of the CO2 column abundance in the lower troposphere from aircraft. Our final goal is to develop a practical space instrument and mission approach for active CO2 measurements at the 1 ppmv level. This would allow continuous measurements of CO2 mixing ratio, both day and night, over land and ocean surfaces, under realistic atmospheric scattering conditions. Measuring the CO2 mixing ratio in the troposphere from space is quite challenging. High signal-to-noise ratios and measurement stabilities are needed for accurate mixing ratio estimates. Our laser sounder approach has some fundamental advantages over passive sensors which use sunlight. It always uses a common nadir/zenith measurement path and the narrow laser divergence angles produce small laser footprints. The laser source allows it to measure in sunlight and darkness over different surfaces giving full global coverage. It can measure continuously over the ocean, to cloud tops and through broken clouds. The lasers are pulsed and potential measurement errors from aerosol scattering can be greatly reduced by using time gating in the receiver. Our approach uses a dual channel laser altimeter/spectrometer, which continuously measures at nadir from a near polar circular orbit. It uses several tunable fiber lasers for simultaneous measurement of the absorption from CO2 and O2, and aerosol backscatter in the same path. It directs the narrow co-aligned laser beams from the instrument's lasers toward nadir, and measures the energy of the laser echoes reflected from land and water surfaces During the measurement its lasers are tuned on- and off- a selected CO2 line near 1572 nm and a selected O2 line near 768 nm in the Oxygen A band at kHz rates. The receiver uses a 1-m diameter

  11. Regulation of CO2 Concentrating Mechanism in Cyanobacteria

    OpenAIRE

    Burnap, Robert L.; Martin Hagemann; Aaron Kaplan

    2015-01-01

    In this chapter, we mainly focus on the acclimation of cyanobacteria to the changing ambient CO2 and discuss mechanisms of inorganic carbon (Ci) uptake, photorespiration, and the regulation among the metabolic fluxes involved in photoautotrophic, photomixotrophic and heterotrophic growth. The structural components for several of the transport and uptake mechanisms are described and the progress towards elucidating their regulation is discussed in the context of studies, which have documented ...

  12. What caused the glacial/interglacial atmospheric pCO2 cycles?

    Science.gov (United States)

    Archer, David; Winguth, Arne; Lea, David; Mahowald, Natalie

    2000-05-01

    Fifteen years after the discovery of major glacial/interglacial cycles in the CO2 concentration of the atmosphere, it seems that all of the simple mechanisms for lowering pCO2 have been eliminated. We use a model of ocean and sediment geochemistry, which includes new developments of iron limitation of biological production at the sea surface and anoxic diagenesis and its effect on CaCO3 preservation in the sediments, to evaluate the current proposals for explaining the glacial/interglacial pCO2 cycles within the context of the ocean carbon cycle. After equilibration with CaCO3 the model is unable to generate glacial pCO2 by increasing ocean NO3- but predicts that a doubling of ocean H4SiO4 might suffice. However, the model is unable to generate a doubling of ocean H4SiO4 by any reasonable changes in SiO2 weathering or production. Our conclusions force us to challenge one or more of the assumptions at the foundations of chemical oceanography. We can abandon the stability of the "Redfield ratio" of nitrogen to phosphorus in living marine phytoplankton and the ultimate limitation of marine photosynthesis by phosphorus. We can challenge the idea that the pH of the deep ocean is held relatively invariant by equilibrium with CaCO3. A third possibility, which challenges physical oceanographers, is that diapycnal mixing in ocean circulation models exceeds the rate of mixing in the real ocean, diminishing the model pCO2 sensitivity to biological carbon uptake.

  13. Effect of photosynthesis on the abundance of 18O13C16O in atmospheric CO2

    Science.gov (United States)

    Hofmann, Magdalena E. G.; Pons, Thijs L.; Ziegler, Martin; Lourens, Lucas J.; Röckmann, Thomas

    2016-04-01

    The abundance of the isotopologue 18O13C16O (Δ47) in atmospheric air is a promising new tracer for the atmospheric carbon cycle (Eiler and Schauble, 2004; Affek and Eiler, 2006; Affek et al., 2007). The large gross fluxes in CO2 between the atmosphere and biosphere are supposed to play a major role in controlling its abundance. Eiler and Schauble (2004) set up a box model describing the effect of air-leaf interaction on the abundance of 18O13C16O in atmospheric air. The main assumption is that the exchange between CO2 and water within the mesophyll cells will imprint a Δ47 value on the back-diffusing CO2 that reflects the leaf temperature. Additionally, kinetic effects due to CO2 diffusion into and out of the stomata are thought to play a role. We investigated the effect of photosynthesis on the residual CO2 under controlled conditions using a leaf chamber set-up to quantitatively test the model assumptions suggested by Eiler and Schauble (2004). We studied the effect of photosynthesis on the residual CO2 using two C3 and one C4 plant species: (i) sunflower (Helianthus annuus), a C3 species with a high leaf conductance for CO2 diffusion, (ii) ivy (Hedera hibernica), a C3 species with a low conductance, and (iii), maize (Zea mays), a species with the C4 photosynthetic pathway. We also investigated the effect of different light intensities (photosynthetic photon flux density of 200, 700 and 1800 μmol m2s‑1), and thus, photosynthetic rate in sunflower and maize. A leaf was mounted in a cuvette with a transparent window and an adjustable light source. The air inside was thoroughly mixed, making the composition of the outgoing air equal to the air inside. A gas-mixing unit was attached at the entrance of the cuvette that mixed air with a high concentration of scrambled CO2 with a Δ47 value of 0 to 0.1‰ with CO2 free air to set the CO2 concentration of ingoing air at 500 ppm. The flow rate through the cuvette was adjusted to the photosynthetic activity of the

  14. Effects of elevated CO2 concentration on growth and water usage of tomato seedlings under different ammonium/nitrate ratios

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Increasing atmospheric CO2 concentration is generally expected to enhance photosynthesis and growth of agricultural C3 vegetable crops,and therefore results in an increase in crop yield.However,little is known about the combined effect of elevated CO2 and N species on plant growth and development.Two growth-chamber experiments were conducted to determine the effects of NH4+/NO3- ratio and elevated CO2 concentration on the physiological development and water use of tomato seedlings.Tomato was grown for 45 d in containers with nutrient solutions varying in NH4+/NO3- ratios and CO2 concentrations in growth chambers.Results showed that plant height,stem thickness,total dry weight,dry weight of the leaves,stems and roots,G value (total plant dry weight/seedling days),chlorophyll content,photosynthetic rate,leaf-level and whole plant-level water use efficiency and cumulative water consumption of tomato seedlings were increased with increasing proportion of NO3- in nutrient solutions in the elevated CO2 treatment.Plant biomass,plant height,stem thickness and photosynthetic rate were 67%,22%,24% and 55% higher at elevated CO2 concentration than at ambient CO2 concentration,depending on the values of NH4+/NO3- ratio.These results indicated that elevating CO2 concentration did not mitigate the adverse effects of 100% NH4+-N (in nutrient solution) on the tomato seedlings.At both CO2 levels,NH4+/NO3- ratios of nutrient solutions strongly influenced almost every measure of plant performance,and nitrate-fed plants attained a greater biomass production,as compared to ammonium-fed plants.These phenomena seem to be related to the coordinated regulation of photosynthetic rate and cumulative water consumption of tomato seedlings.

  15. Laser Sounder for Global Measurement of CO2 Concentrations in the Troposphere from Space: Progress

    Science.gov (United States)

    Abshire, J. B.; Krainak, M.; Riris, H. J.; Sun, X.; Riris, H.; Andrews, A. E.; Collatz, J.

    2004-01-01

    We describe progress toward developing a laser-based technique for the remote measurement of the tropospheric CO2 concentrations from orbit. Our goal is to demonstrate a lidar technique and instrument technology that will permit measurements of the CO2 column abundance in the lower troposphere from aircraft at the few ppm level, with a capability of scaling to permit global CO2 measurements from orbit. Accurate measurements of the tropospheric CO2 mixing ratio from space are challenging due to the many potential error sources. These include possible interference from other trace gas species, the effects of temperature, clouds, aerosols & turbulence in the path, changes in surface reflectivity, and variability in dry air density caused by changes in atmospheric pressure, water vapor and topographic height. Some potential instrumental errors include frequency drifts in the transmitter, small transmission and sensitivity drifts in the instrument. High signal-to-noise ratios and measurement stability are needed for mixing ratio estimates at the few ppm level. We have been developing a laser sounder approach as a candidate for a future space mission. It utilizes multiple different laser transmitters to permit simultaneous measurement of CO2 and O2 extinction, and aerosol backscatter in the same measurement path. It directs the narrow co-aligned laser beams from the instrument's fiber lasers toward nadir, and measures the energy of the strong laser echoes reflected from the Earth's land and water surfaces. During the measurement its narrow linewidth lasers are rapidly tuned on- and off- selected CO2 line near 1572 nm and an O2 absorption line near 770 nm. The receiver measures the energies of the laser echoes from the surface and any clouds and aerosols in the path with photon counting detectors. Ratioing the on- to off-line echo pulse energies for each gas permits the column extinction and column densities of CO2 and O2 to be estimated simultaneously via the

  16. Responses of plant rhizosphere to atmospheric CO2 enrichment

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Plant root growth is generally stimulated under elevated CO2. This will bring more carbon to the below-ground through root death and exudate. This potential increase in below-ground carbon sink may lead to changes in long-term soil sequestration and relationship between host plants and symbions. On the other hand, changes in litter components due to the changes in plant chemical composition may also affect soil processes, such as litter decomposition, soil organic matter sequestration and hetero-nutritional bacteria activities. These issues are discussed.

  17. Interactive Effects of Drought Stresses and Elevated CO2 Concentration on Photochemistry Efficiency of Cucumber Seedlings

    Institute of Scientific and Technical Information of China (English)

    Qing-Ming Li; Bin-Bin Liu; Yang Wu; Zhi-Rong Zou

    2008-01-01

    To reveal and quantify the interactive effects of drought stresses and elevated CO2 concentration [CO2] on photochemistry efficiency of cucumber seedlings, the portable chlorophyll meter was used to measure the chlorophyll content, and the Imaging-PAM was used to image the chlorophyll fluorescence parameters and rapid light response curves (RLC) of leaves in two adjacent greenhouses. The results showed that chlorophyll content of leaves was reduced significantly with drought stress aggravated. Minimal fluorescence (Fo) was increased while maximal quantum yield of PSII (Fv/Fm) decreased significantly by severe drought stress. The significant decrease of effective quantum yield of PSll (Y(Ⅱ)) accompanied by the significant increase of quantum yield of regulated energy dissipation (Y(NPQ)) was observed under severe drought stress condition, but there was no change of quantum yield of nonregulated energy dissipation (Y(NO)). We detected that the coefficient of photochemical quenching (Qp) decreased, and non-photochemical quenching (NPQ) increased significantly under severe drought stress. Furthermore, we found that maximum apparent electron transport rate (ETRmax) and saturating photosynthetically active radiation (PPFDsat) decreased significantly with drought stress aggravated. However, elevated [CO2] significantly increased FvlFm, Qp and PPFDsat, and decreased NPQ under all water conditions, although there were no significant effects on chlorophyll content, Fo, Y(Ⅱ), Y(NPQ), Y(NO) and ETRmax. Therefore, it is concluded that CO2-fertilized greenhouses or elevated atmospheric [CO2] in the future could be favorable for cucumber growth and development, and beneficial to alleviate the negative effects of drought stresses to a certain extent.

  18. Effects of elevated CO2 concentrations on soil microbial respiration and root/rhizosphere respiration in-forest soils

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The two main components of soil respiration,i.e.,root/rhizosphere and microbial respiration,respond differently to elevated atmospheric CO2 concentrations both in mechanism and sensitivity because they have different substrates derived from plant and soil organic matter,respectively.To model the carbon cycle and predict the carbon source/sink of forest ecosystems,we must first understand the relative contributions of root/rhizosphere and microbial respiration to total soil respiration under elevated CO2 concentrations.Root/rhizosphere and soil microbial respiration have been shown to increase,decrease and remain unchanged under elevated CO2 concentrations.A significantly positive relationship between root biomass and root/rhizosphere respiration has been found.Fine roots respond more strongly to elevated CO2 concentrations than coarse roots.Evidence suggests that soil microbial respiration is highly variable and uncertain under elevated CO2 concentrations.Microbial biomass and activity are related or unrelated to rates of microbial respiration.Because substrate availability drives microbial metabolism in soils,it is likely that much of the variability in microbial respiration results from differences in the response of root growth to elevated CO2 concentrations and subsequent changes in substrate production.Biotic and abiotic factors affecting soil respiration were found to affect both root/rhizosphere and microbial respiration.

  19. Physiological Significance of Low Atmospheric CO 2 for Plant-Climate Interactions

    Science.gov (United States)

    Cowling, Sharon A.; Sykes, Martin T.

    1999-09-01

    Methods of palaeoclimate reconstruction from pollen are built upon the assumption that plant-climate interactions remain the same through time or that these interactions are independent of changes in atmospheric CO2. The latter may be problematic because air trapped in polar ice caps indicates that atmospheric CO2 has fluctuated significantly over at least the past 400,000 yr, and likely the last 1.6 million yr. Three other points indicate potential biases for vegetation-based climate proxies. First, C3-plant physiological research shows that the processes that determine growth optima in plants (photosynthesis, mitochondrial respiration, photorespiration) are all highly CO2-dependent, and thus were likely affected by the lower CO2 levels of the last glacial maximum. Second, the ratio of carbon assimilation per unit transpiration (called water-use efficiency) is sensitive to changes in atmospheric CO2 through effects on stomatal conductance and may have altered C3-plant responses to drought. Third, leaf gas-exchange experiments indicate that the response of plants to carbon-depleting environmental stresses are strengthened under low CO2 relative to today. This paper reviews the scope of research addressing the consequences of low atmospheric CO2 for plant and ecosystem processes and highlights why consideration of the physiological effects of low atmospheric CO2 on plant function is recommended for any future refinements to pollen-based palaeoclimatic reconstructions.

  20. Impact of oceanic circulation changes on atmospheric δ13CO2

    Science.gov (United States)

    Menviel, L.; Mouchet, A.; Meissner, K. J.; Joos, F.; England, M. H.

    2015-11-01

    δ13CO2 measured in Antarctic ice cores provides constraints on oceanic and terrestrial carbon cycle processes linked with millennial-scale changes in atmospheric CO2. However, the interpretation of δ13CO2 is not straightforward. Using carbon isotope-enabled versions of the LOVECLIM and Bern3D models, we perform a set of sensitivity experiments in which the formation rates of North Atlantic Deep Water (NADW), North Pacific Deep Water (NPDW), Antarctic Bottom Water (AABW), and Antarctic Intermediate Water (AAIW) are varied. We study the impact of these circulation changes on atmospheric δ13CO2 as well as on the oceanic δ13C distribution. In general, we find that the formation rates of AABW, NADW, NPDW, and AAIW are negatively correlated with changes in δ13CO2: namely, strong oceanic ventilation decreases atmospheric δ13CO2. However, since large-scale oceanic circulation reorganizations also impact nutrient utilization and the Earth's climate, the relationship between atmospheric δ13CO2 levels and ocean ventilation rate is not unequivocal. In both models atmospheric δ13CO2 is very sensitive to changes in AABW formation rates: increased AABW formation enhances the transport of low δ13C waters to the surface and decreases atmospheric δ13CO2. By contrast, the impact of NADW changes on atmospheric δ13CO2 is less robust and might be model dependent. This results from complex interplay between global climate, carbon cycle, and the formation rate of NADW, a water body characterized by relatively high δ13C.

  1. Global and Regional Constraints on Exchanges of CO2 Between the Atmosphere and Terrestrial Biosphere

    Science.gov (United States)

    Piper, S. C.

    2001-12-01

    The vigorous atmospheric circulation rapidly mixes CO2 that is exchanged with the terrestrial biosphere and oceans. Therefore, at time scales greater than 1 year, the approximate interhemispheric exchange time of the atmosphere, an average of CO2 measurements from a network of surface stations can be used to accurately determine the global net change in atmospheric CO2. By subtracting CO2 produced by fossil fuel combustion, which is well characterized by national statistics, the global the sum of terrestrial biospheric and oceanic net fluxes, here termed the "nonfossil" CO2 flux, can also be accurately determined. The nonfossil CO2 flux averaged -2.1+/-0.3 PgC/yr and -3.2+/-0.4 PgC/yr in the 1980s and 1990s respectively (negative denotes out of the atmosphere), and varied in annual average from about 0 to -4 PgC/yr over these two decades. Two primary methods have been used to further partition the nonfossil CO2 flux between land and oceans: the O2 and 13C/12C methods, which rely, respectively, on measurements of atmospheric O2 (actually O2/N2 for technical reasons) and of the 13C/12C ratio of CO2. Burning of fossil fuel consumes atmospheric O2 and releases CO2 with a 13C/12C ratio lower than that of atmospheric CO2 whereas uptake of CO2 by terrestrial plants releases O2, and increases the atmospheric 13C/12C ratio owing to the preferential assimilation of 12CO2 relative to 13CO2. In contrast, the uptake of CO2 by the oceans has little effect on either the atmospheric O2 or 13C/12C ratio. Therefore, the net CO2 uptake or release from the terrestrial biosphere can be calculated in either method by subtracting the change owing to fossil fuel emissions from the measured change in the atmosphere, utilizing known stoichiometric ratios of O2 and CO2 in the O2 method, and isotopic fractionation factors in the 13C/12C method. Currently, the O2 method gives a net global terrestrial biospheric CO2 flux of -0.2+/-0.7 PgC/yr and -1.4+/-0.7 PgC/yr for the 1980s and the 1990s

  2. Simulated effect of calcification feedback on atmospheric CO2 and ocean acidification

    OpenAIRE

    Han Zhang; Long Cao

    2016-01-01

    Ocean uptake of anthropogenic CO2 reduces pH and saturation state of calcium carbonate materials of seawater, which could reduce the calcification rate of some marine organisms, triggering a negative feedback on the growth of atmospheric CO2. We quantify the effect of this CO2-calcification feedback by conducting a series of Earth system model simulations that incorporate different parameterization schemes describing the dependence of calcification rate on saturation state of CaCO3. In a scen...

  3. Isotopic composition of atmospheric CO2 inferred from carbon in C4 plant cellulose

    International Nuclear Information System (INIS)

    The isotopic composition of atmospheric carbon dioxide provides an important constraint for models of the global carbon cycle. It is shown that carbon in C4 plants preserves an isotopic record of the CO2 used in photosynthesis. Data for the maize plant Zea mays yield results for the isotopic composition of atmospheric CO2 consistent with measurements of modern air and air trapped in polar ice. Data from C4 plants may thus be used to extend the isotopic record of atmospheric CO2 into the past, complementing data from other sources. (author)

  4. Rapid, Long-term Monitoring of CO2 Concentration and δ13CO2 at CCUS Sites Allows Discrimination of Leakage Patterns from Natural Background Values

    Science.gov (United States)

    Galfond, B.; Riemer, D. D.; Swart, P. K.

    2014-12-01

    In order for Carbon Capture Utilization and Storage (CCUS) to gain wide acceptance as a method for mitigating atmospheric CO2 concentrations, schemes must be devised to ensure that potential leakage is detected. New regulations from the US Environmental Protection Agency require monitoring and accounting for Class VI injection wells, which will remain a barrier to wide scale CCUS deployment until effective and efficient monitoring techniques have been developed and proven. Monitoring near-surface CO2 at injection sites to ensure safety and operational success requires high temporal resolution CO2 concentration and carbon isotopic (δ13C) measurements. The only technologies currently capable of this rapid measurement of δ13C are optical techniques such as Cavity Ringdown Spectroscopy (CRDS). We have developed a comprehensive remote monitoring approach using CRDS and a custom manifold system to obtain accurate rapid measurements from a large sample area over an extended study period. Our modified Picarro G1101-i CRDS allows for automated rapid and continuous field measurement of δ13CO2 and concentrations of relevant gas species. At our field site, where preparations have been underway for Enhanced Oil Recovery (EOR) operations, we have been able to measure biogenic effects on a diurnal scale, as well as variation due to precipitation and seasonality. Taking these background trends into account, our statistical treatment of real data has been used to improve signal-to-noise ratios by an order of magnitude over published models. Our system has proven field readiness for the monitoring of sites with even modest CO2 fluxes.

  5. The role of artificial atmospheric CO2 removal in stabilizing Earth's climate

    Science.gov (United States)

    Zickfeld, K.; Tokarska, K.

    2014-12-01

    The current CO2 emission trend entails a risk that the 2°C target will be missed, potentially causing "dangerous" changes in Earth's climate system. This research explores the role of artificial atmospheric CO2 removal (also referred to as "negative emissions") in stabilizing Earth's climate after overshoot. We designed a range of plausible CO2 emission scenarios, which follow a gradual transition from a fossil fuel driven economy to a zero-emission energy system, followed by a period of negative emissions. The scenarios differ in peak emissions rate and, accordingly, the amount of negative emissions, to reach the same cumulative emissions compatible with the 2°C temperature stabilization target. The climate system components' responses are computed using the University of Victoria Earth System Climate Model of intermediate complexity. Results suggest that negative emissions are effective in reversing the global mean temperature and stabilizing it at a desired level (2°C above pre-industrial) after overshoot. Also, changes in the meridional overturning circulation and sea ice are reversible with the artificial removal of CO2 from the atmosphere. However, sea level continues to rise and is not reversible for several centuries, even under assumption of large amounts of negative emissions. For sea level to decline, atmospheric CO2 needs to be reduced to pre-industrial levels in our simulations. During the negative emission phase, outgassing of CO2 from terrestrial and marine carbon sinks offsets the artificial removal of atmospheric CO2, thereby reducing its effectiveness. On land, the largest CO2 outgassing occurs in the Tropics and is partially compensated by CO2 uptake at northern high latitudes. In the ocean, outgassing occurs mostly in the Southern Ocean, North Atlantic and tropical Pacific. The strongest outgassing occurs for pathways entailing greatest amounts of negative emissions, such that the efficiency of CO2 removal - here defined as the change in

  6. Response of atmospheric CO2 to the abrupt cooling event 8200 years ago

    Science.gov (United States)

    Ahn, Jinho; Brook, Edward J.; Buizert, Christo

    2014-01-01

    Atmospheric CO2 records for the centennial scale cooling event 8200 years ago (8.2 ka event) may help us understand climate-carbon cycle feedbacks under interglacial conditions, which are important for understanding future climate, but existing records do not provide enough detail. Here we present a new CO2 record from the Siple Dome ice core, Antarctica, that covers 7.4-9.0 ka with 8 to 16 year resolution. We observe a small, about 1-2 ppm, increase of atmospheric CO2 during the 8.2 ka event. The increase is not significant when compared to other centennial variations in the Holocene that are not linked to large temperature changes. Our results do not agree with leaf stomata records that suggest a CO2 decrease of up to ~25 ppm and imply that the sensitivity of atmospheric CO2 to the primarily Northern Hemisphere cooling of the 8.2 ka event was limited.

  7. Radiocarbon isotopic evidence for assimilation of atmospheric CO2 by the seagrass Zostera marina

    Directory of Open Access Journals (Sweden)

    K. Watanabe

    2015-05-01

    Full Text Available Submerged aquatic vegetation assimilates dissolved inorganic carbon (DIC in the water column as a carbon source across its thin cuticle layer. However, it is expected that marine macrophytes also use atmospheric CO2 when exposed to the air during low tide, although assimilation of atmospheric CO2 has never been quantitatively evaluated. Using the radiocarbon isotopic signatures (Δ14C of the seagrass Zostera marina and DIC, we show quantitatively that Z. marina takes up and assimilates atmospheric modern CO2 in a shallow coastal ecosystem. The Δ14C values of the seagrass (−36 to −8‰ were significantly higher than those of aquatic DIC (−45 to −18‰, indicating that the seagrass uses a 14C-rich carbon source (atmospheric CO2, +17‰. A carbon-source mixing model indicated that the seagrass assimilated ~ 46% (mean: 22% of its inorganic carbon as atmospheric CO2. CO2 exchange between the air and the seagrass may be enhanced by the presence of a very thin water film over the air-exposed leaves during low tide. Our radiocarbon isotope analysis, showing assimilation of atmospheric modern CO2 as an inorganic carbon source, offers better understanding of the role of seagrass meadows in coastal carbon dynamics.

  8. Radiocarbon isotopic evidence for assimilation of atmospheric CO2 by the seagrass Zostera marina

    Science.gov (United States)

    Watanabe, K.; Kuwae, T.

    2015-10-01

    Submerged aquatic vegetation takes up water-column dissolved inorganic carbon (DIC) as a carbon source across its thin cuticle layer. It is expected that marine macrophytes also use atmospheric CO2 when exposed to air during low tide, although assimilation of atmospheric CO2 has never been quantitatively evaluated. Using the radiocarbon isotopic signatures (Δ14C) of the seagrass Zostera marina, DIC and particulate organic carbon (POC), we show quantitatively that Z. marina takes up and assimilates atmospheric modern CO2 in a shallow coastal ecosystem. The Δ14C values of the seagrass (-40 to -10 ‰) were significantly higher than those of aquatic DIC (-46 to -18 ‰), indicating that the seagrass uses a 14C-rich carbon source (atmospheric CO2, +17 ‰). A carbon-source mixing model indicated that the seagrass assimilated 0-40 % (mean, 17 %) of its inorganic carbon as atmospheric CO2. CO2 exchange between the air and the seagrass might be enhanced by the presence of a very thin film of water over the air-exposed leaves during low tide. Our radiocarbon isotope analysis, showing assimilation of atmospheric modern CO2 as an inorganic carbon source, improves our understanding of the role of seagrass meadows in coastal carbon dynamics.

  9. Impacts of elevated atmospheric CO2 on forest trees and forest ecosystems: knowledge gaps

    International Nuclear Information System (INIS)

    Atmospheric CO2 is rising rapidly, and options for slowing the CO2 rise are politically charged as they largely require reductions in industrial CO2 emissions for most developed countries. As forests cover some 43% of the Earth's surface, account for some 70% of terrestrial net primary production (NPP), and are being bartered for carbon mitigation, it is critically important that we continue to reduce the uncertainties about the impacts of elevated atmospheric CO2 on forest tree growth, productivity, and forest ecosystem function. In this paper, 1 review knowledge gaps and research needs on the effects of elevated atmospheric CO2 on forest above- and below-ground growth and productivity, carbon sequestration, nutrient cycling, water relations, wood quality, phonology, community dynamics and biodiversity, antioxidants and stress tolerance, interactions with air pollutants, heterotrophic interactions, and ecosystem functioning. Finally, 1 discuss research needs regarding modelling of the impacts of elevated atmospheric CO2 on forests. Even though there has been a tremendous amount of research done with elevated CO2 and forest trees, it remains difficult to predict future forest growth and productivity under elevated atmospheric CO2. Likewise, it is not easy to predict how forest ecosystem processes will respond to enriched CO2. The more we study the impacts of increasing CO2, the more we realize that tree and forest responses are yet largely uncertain due to differences in responsiveness by species, genotype, and functional group, and the complex interactions of elevated atmospheric CO2 with soil fertility, drought, pests, and co-occurring atmospheric pollutants such as nitrogen deposition and O3. Furthermore, it is impossible to predict ecosystem-level responses based on short-term studies of young trees grown without interacting stresses and in small spaces without the element of competition. Long-term studies using free-air CO2 enrichment (FACE) technologies or

  10. Climate change goes underground: effects of elevated atmospheric CO2 on microbial community structure and activities in the rhizosphere

    NARCIS (Netherlands)

    Drigo, B.; Kowalchuk, G.A.; Van Veen, J.A.

    2008-01-01

    General concern about climate change has led to growing interest in the responses of terrestrial ecosystems to elevated concentrations of CO2 in the atmosphere. Experimentation during the last two to three decades using a large variety of approaches has provided sufficient information to conclude th

  11. Effects of increasing UV-B radiation and atmospheric CO2 on photosynthesis and growth: implications for terrestrial ecosystems

    International Nuclear Information System (INIS)

    Increases in UV-B radiation reaching the earth as a result of stratospheric ozone depletion will most likely accompany increases in atmospheric CO2 concentrations. Many studies have examined the effects of each factor independently, but few have evaluated the combined effects of both UV-B radiation and elevated CO2. In general the results of such studies have shown independent effects on growth or seed yield. Although interspecific variation is large, high levels of UV-B radiation tends to reduce plant growth in sensitive species, while CO2 enrichment tends to promote growth in most C3 species. However, most previous studies have not looked at temporal effects or at the relationship between photosynthetic acclimation to CO2 and possible photosynthetic limitations imposed by UV-B radiation. Elevated CO2 may provide some protection against UV-B for some species. In contrast, UV-B radiation may limit the ability to exploit elevated CO2 in other species. Interactions between the effects of CO2 enrichment and UV-B radiation exposure have also been shown for biomass allocation. Effects on both biomass allocation and photosynthetic acclimation may be important to ecosystem structure in terms of seedling establishment, competition and reproductive output. Few studies have evaluated ecosystem processes such as decomposition or nutrient cycling. Interactive effects may be subtle and species specific but should not be ignored in the assessment of the potential impacts of increases in CO2 and UV-B radiation on plants. (author)

  12. Radon-222 in urban atmosphere: assessing the local fluxes of CO2 and CH4

    International Nuclear Information System (INIS)

    under substantial influence of a large coal mining and industrial centre (Upper Silesia) located approximately 60 km west of the city with its substantial sources of anthropogenic sources of CO2 and CH4. Radon-222 has been monitored in Krakow since June 2004 using filter method. The air intake is located ca. 30 meter above the ground, on the roof of the Faculty building. In the same location, quasi-continuous measurements of CO2 and CH4 mixing ratios in the local atmosphere are performed. Rn-222 exhibits substantial seasonal and diurnal fluctuations. The maximum of mean monthly 222Rn concentration occurs usually in October (ca. 10 Bqm-3), while minimum is recorded in March or April (ca. 2.5 Bqm-3). Daily mean values fluctuate between ca. 1 Bqm-3 and 18 Bqm-3. Radon-222 can be used as a proxy for assessing surface emissions of other gases which have their sources distributed roughly uniformly on the surface. This is the case of CO2 and CH4 in an urban environment where CO2 and CH4emissions are controlled by multitude of small sources (car traffic, local heating systems, leakages from gas network, etc.). If the flux of 222Rn into the atmosphere on the given area is known or can be reasonably assessed, the surface fluxes of other gases, such as CO2 and/or CH4, can be calculated for the periods of time when concentrations of 222Rn and those gases in the lower atmosphere are controlled mainly by intensity of sources. This typically happens during periods of atmospheric inversion. The record of 222Rn specific activity, available for the period June 2004 - June 2007, was analyzed in combination with CO2and CH4 mixing ratios data with the aim to obtain quantitative assessment of monthly mean fluxes of carbon dioxide and methane into the urban atmosphere of Krakow. (author)

  13. Electrochemical CO2 reduction

    OpenAIRE

    Kriescher, Stefanie M. A.

    2015-01-01

    The atmospheric concentration of CO2 has increased significantly during the last two centuries. Since CO2 is considered to be one of the largest contributors to the greenhouse effect and is postulated to cause global warming, it is important to stabilize and/or reduce its concentration. Apart from regulations for the amount of CO2 that may be emmitted, carbon dioxide capture and storage (CCS), biological and chemical conversions are potential ways to stabilize and/or reduce the atmospheric co...

  14. An assessment procedure for chemical utilisation schemes intended to reduce CO2 emissions to atmosphere

    NARCIS (Netherlands)

    Audus, H.; Oonk, H.

    1997-01-01

    The concept of reducing emissions of CO2 to the atmosphere by producing chemicals has been suggested by many people as a potential greenhouse gas mitigation option. The goal of such schemes is either: (i) fixation of CO2 in a chemical compound for a significant time, or, (ii) reduction of emissions

  15. How does atmospheric elevated CO2 affect crop pests and their natural enemies? Case histories from China

    Institute of Scientific and Technical Information of China (English)

    Yu-Cheng Sun; Jin Yin; Fa-Jun Chen; Gang Wu; Feng Ge

    2011-01-01

    Global atmospheric CO2 concentrations have risen rapidly since the Industrial Revolution and are considered as a primary factor in climate change.The effects of elevated CO2 on herbivore insects were found to be primarily through the CO2-induced changes occurring in their host plants,which then possibly affect the intensity and frequency of pest outbreaks on crops.This paper reviews several ongoing research models using primary pests of crops (cotton bollworm,whitefly,aphids) and their natural enemies (ladybeetles,parasitoids) in China to examine insect responses to elevated CO2.It is generally indicated that elevated CO2 prolonged the development of cotton bollworm,Helicoverpa armigera,a chewing insect,by decreasing the foliar nitrogen of host plants.In contrast,the phloemsucking aphid and whitefly insects had species-specific responses to elevated CO2 because of complex interactions that occur in the phloem sieve elements of plants.Some aphid species,such as cotton aphid,Aphis gossypii and wheat aphid,Sitobion avenae,were considered to represent the only feeding guild to respond positively to elevated CO2 conditions.Although whitefly,Bemisia tabaci,a major vector of Tomato yellow leaf curl virus,had neutral response to elevated CO2,the plants became less vulnerable to the virus infection under elevated CO2.The predator and parasitoid response to elevated CO2 were frequently idiosyncratic.These documents from Chinese scientists suggested that elevated CO2 initially affects the crop plant and then cascades to a higher trophic level through the food chain to encompass herbivores (pests),their natural enemies,pathogens and underground nematodes,which disrupt the natural balance observed previously in agricultural ecosystems.

  16. Concentration and stable carbon isotopic composition of CO2 in cave air of Postojnska jama, Slovenia

    Directory of Open Access Journals (Sweden)

    Magda Mandic

    2013-09-01

    Full Text Available Partial pressure of CO2 (pCO2 and its isotopic composition (δ13CairCO2 were measured in Postojnska jama, Slovenia, at 10 locations inside the cave and outside the cave during a one-year period. At all interior locations the pCO2 was higher and δ13CairCO2 lower than in the outside atmosphere. Strong seasonal fluctuations in both parameters were observed at locations deeper in the cave, which are isolated from the cave air circulation. By using a binary mixing model of two sources of CO2, one of them being the atmospheric CO2, we show that the excess of CO2 in the cave air has a δ13C value of -23.3 ± 0.7 ‰, in reasonable agreement with the previously measured soil-CO2 δ13C values. The stable isotope data suggest that soil CO2 is brought to the cave by drip water.

  17. Root Herbivores Drive Changes to Plant Primary Chemistry, but Root Loss Is Mitigated under Elevated Atmospheric CO2.

    Science.gov (United States)

    McKenzie, Scott W; Johnson, Scott N; Jones, T Hefin; Ostle, Nick J; Hails, Rosemary S; Vanbergen, Adam J

    2016-01-01

    Above- and belowground herbivory represents a major challenge to crop productivity and sustainable agriculture worldwide. How this threat from multiple herbivore pests will change under anthropogenic climate change, via altered trophic interactions and plant response traits, is key to understanding future crop resistance to herbivory. In this study, we hypothesized that atmospheric carbon enrichment would increase the amount (biomass) and quality (C:N ratio) of crop plant resources for above- and belowground herbivore species. In a controlled environment facility, we conducted a microcosm experiment using the large raspberry aphid (Amphorophora idaei), the root feeding larvae of the vine weevil (Otiorhynchus sulcatus), and the raspberry (Rubus idaeus) host-plant. There were four herbivore treatments (control, aphid only, weevil only and a combination of both herbivores) and an ambient (aCO2) or elevated (eCO2) CO2 treatment (390 versus 650 ± 50 μmol/mol) assigned to two raspberry cultivars (cv Glen Ample or Glen Clova) varying in resistance to aphid herbivory. Contrary to our predictions, eCO2 did not increase crop biomass or the C:N ratio of the plant tissues, nor affect herbivore abundance either directly or via the host-plant. Root herbivory reduced belowground crop biomass under aCO2 but not eCO2, suggesting that crops could tolerate attack in a CO2 enriched environment. Root herbivory also increased the C:N ratio in leaf tissue at eCO2, potentially due to decreased N uptake indicated by lower N concentrations found in the roots. Root herbivory greatly increased root C concentrations under both CO2 treatments. Our findings confirm that responses of crop biomass and biochemistry to climate change need examining within the context of herbivory, as biotic interactions appear as important as direct effects of eCO2 on crop productivity. PMID:27379129

  18. Root Herbivores Drive Changes to Plant Primary Chemistry, but Root Loss Is Mitigated under Elevated Atmospheric CO2

    Science.gov (United States)

    McKenzie, Scott W.; Johnson, Scott N.; Jones, T. Hefin; Ostle, Nick J.; Hails, Rosemary S.; Vanbergen, Adam J.

    2016-01-01

    Above- and belowground herbivory represents a major challenge to crop productivity and sustainable agriculture worldwide. How this threat from multiple herbivore pests will change under anthropogenic climate change, via altered trophic interactions and plant response traits, is key to understanding future crop resistance to herbivory. In this study, we hypothesized that atmospheric carbon enrichment would increase the amount (biomass) and quality (C:N ratio) of crop plant resources for above- and belowground herbivore species. In a controlled environment facility, we conducted a microcosm experiment using the large raspberry aphid (Amphorophora idaei), the root feeding larvae of the vine weevil (Otiorhynchus sulcatus), and the raspberry (Rubus idaeus) host-plant. There were four herbivore treatments (control, aphid only, weevil only and a combination of both herbivores) and an ambient (aCO2) or elevated (eCO2) CO2 treatment (390 versus 650 ± 50 μmol/mol) assigned to two raspberry cultivars (cv Glen Ample or Glen Clova) varying in resistance to aphid herbivory. Contrary to our predictions, eCO2 did not increase crop biomass or the C:N ratio of the plant tissues, nor affect herbivore abundance either directly or via the host-plant. Root herbivory reduced belowground crop biomass under aCO2 but not eCO2, suggesting that crops could tolerate attack in a CO2 enriched environment. Root herbivory also increased the C:N ratio in leaf tissue at eCO2, potentially due to decreased N uptake indicated by lower N concentrations found in the roots. Root herbivory greatly increased root C concentrations under both CO2 treatments. Our findings confirm that responses of crop biomass and biochemistry to climate change need examining within the context of herbivory, as biotic interactions appear as important as direct effects of eCO2 on crop productivity. PMID:27379129

  19. Controle de Rhyzopertha dominica pela atmosfera controlada com CO2, em trigo Control of Rhyzopertha dominica using a controlled atmosphere with CO2, in wheat

    Directory of Open Access Journals (Sweden)

    Rogério Amaro Gonçalves

    2000-01-01

    Full Text Available A utilização de gases inertes como fumigantes no controle de pragas é uma alternativa ao uso de fosfina. O objetivo deste trabalho foi avaliar a eficiência de uma atmosfera com CO2 no controle de Rhyzoperta dominica (Fabr. (Coleoptera: Bostrichidae em grãos de trigo armazenado. O trabalho constou de cinco concentrações de CO2 (0, 30 , 40, 50 e 60%, completadas com N2, três períodos de exposição (5, 10, 15 dias, três populações de R. dominica (Fabr. (Coleoptera: Bostrichidae (Campo Mourão, PR, Sete Lagoas, MG e Santa Rosa, RS e sete fases de desenvolvimento do inseto (ovo, larva de 1º, 2º, 3º e 4º ínstar, pupa e adulto com três repetições. As diferentes fases da R. dominica foram acondicionadas em tecido organza e levadas para câmaras de expurgo de 200 litros com 75% deste volume repletos de grãos. As câmaras foram vedadas com borracha de silicone para garantir a hermeticidade. Após a vedação das câmaras injetavam-se os gases contendo diferentes teores de CO2. Os resultados mostraram que todos os teores de CO2 causaram 100% de mortalidade de adultos das três populações nos três períodos de exposição utilizados. Em pupas a mortalidade atingiu 100% no teor de 60% de CO2 para as três populações no período de 15 dias de exposição; porém, todos os teores de CO2 utilizados no período de 15 dias de exposição causaram 100% de mortalidade das pupas da população de Santa Rosa. Para o adequado controle de larvas de diferentes ínstares são necessários teores de CO2 iguais ou acima de 50%. Nos períodos de 10 e 15 dias de exposição, todos os teores de CO2 causaram 100% de mortalidade dos ovos das três populações avaliadas.Controlled atmosphere with inert gases offers an alternative to phosphine use to control stored grain pests. The objective of this research was to test a controlled atmosphere with CO2 to control Rhyzoperta dominica, (Fabr. (Coleoptera: Bostrichidae, an important pest of stored wheat

  20. Phenol-Formaldehyde Resin-Based Carbons for CO2 Separation at Sub-Atmospheric Pressures

    Directory of Open Access Journals (Sweden)

    Noelia Álvarez-Gutiérrez

    2016-03-01

    Full Text Available The challenge of developing effective separation and purification technologies that leave much smaller energy footprints is greater for carbon dioxide (CO2 than for other gases. In addition to its involvement in climate change, CO2 is present as an impurity in biogas and bio-hydrogen (biological production by dark fermentation, in post-combustion processes (flue gas, CO2-N2 and many other gas streams. Selected phenol-formaldehyde resin-based activated carbons prepared in our laboratory have been evaluated under static conditions (adsorption isotherms as potential adsorbents for CO2 separation at sub-atmospheric pressures, i.e., in post-combustion processes or from biogas and bio-hydrogen streams. CO2, H2, N2, and CH4 adsorption isotherms at 25 °C and up to 100 kPa were obtained using a volumetric equipment and were correlated by applying the Sips model. Adsorption equilibrium was then predicted for multicomponent gas mixtures by extending the multicomponent Sips model and the Ideal Adsorbed Solution Theory (IAST in conjunction with the Sips model. The CO2 uptakes of the resin-derived carbons from CO2-CH4, CO2-H2, and CO2-N2 at atmospheric pressure were greater than those of the reference commercial carbon (Calgon BPL. The performance of the resin-derived carbons in terms of equilibrium of adsorption seems therefore relevant to CO2 separation in post-combustion (flue gas, CO2-N2 and in hydrogen fermentation (CO2-H2, CO2-CH4.

  1. Experimental study of concentration of tomato juice by CO2 hydrate formation

    OpenAIRE

    Li Shifeng; Shen Yanming; Liu Dongbing; Fan Lihui; Tan Zhe; Zhang Zhigang; Li Wenxiu; Li Wenpeng

    2015-01-01

    A new tomato juice concentration technology was presented by CO2 hydrate formation. The CO2 hydrate equilibrium conditions were measured by isochoric pressure search method and tomato juice concentration experiments were carried out in a high-pressure stirred reactor. Moreover, dehydration ratio was defined and CO2 hydrate formation rate constants were calculated with different feed pressure. The effects of feed pressure, temperature, and juice volume on de...

  2. Elevated atmospheric CO2 levels affect community structure of rice root-associated bacteria

    OpenAIRE

    Okubo, Takashi; Liu, Dongyan; Tsurumaru, Hirohito; Ikeda, Seishi; Asakawa, Susumu; Tokida, Takeshi; Tago, Kanako; Hayatsu, Masahito; Aoki, Naohiro; Ishimaru, Ken; Ujiie, Kazuhiro; Usui, Yasuhiro; Nakamura, Hirofumi; Sakai, Hidemitsu; Hayashi, Kentaro

    2015-01-01

    A number of studies have shown that elevated atmospheric CO2 ([CO2]) affects rice yields and grain quality. However, the responses of root-associated bacteria to [CO2] elevation have not been characterized in a large-scale field study. We conducted a free-air CO2 enrichment (FACE) experiment (ambient + 200 μmol.mol−1) using three rice cultivars (Akita 63, Takanari, and Koshihikari) and two experimental lines of Koshihikari [chromosome segment substitution and near-isogenic lines (NILs)] to de...

  3. Elevated atmospheric CO2 levels affect community structure of rice root-associated bacteria

    OpenAIRE

    Kiwamu eMinamisawa; Takashi eOkubo; Dongyan eLiu; Hirohito eTsurumaru; Seishi eIkeda; Susumu eAsakawa; Takeshi eTokida; Kanako eTago; Masahito eHayatsu; Naohiro eAoki; Ken eIshimaru; Kazuhiro eUjiie; Yasuhiro eUsui; Hirofumi eNakamura; Hidemitsu eSakai

    2015-01-01

    A number of studies have shown that elevated atmospheric CO2 ([CO2]) affects rice yields and grain quality. However, the responses of root-associated bacteria to [CO2] elevation have not been characterized in a large-scale field study. We conducted a free-air CO2 enrichment (FACE) experiment (ambient + 200 μmol⋅mol−1) using three rice cultivars (Akita 63, Takanari, and Koshihikari) and two experimental lines of Koshihikari (chromosome segment substitution and near-isogenic lines) to determine...

  4. Sensitivity of Pliocene Arctic climate to orbital forcing, atmospheric CO2 and sea ice albedo parameterisation

    Science.gov (United States)

    Howell, Fergus W.; Haywood, Alan M.; Dowsett, Harry J.; Pickering, Steven J.

    2016-05-01

    General circulation model (GCM) simulations of the mid-Pliocene Warm Period (mPWP, 3.264 to 3.025 Myr ago) do not reproduce the magnitude of Northern Hemisphere high latitude surface air and sea surface temperature (SAT and SST) warming that proxy data indicate. There is also large uncertainty regarding the state of sea ice cover in the mPWP. Evidence for both perennial and seasonal mPWP Arctic sea ice is found through analyses of marine sediments, whilst in a multi-model ensemble of mPWP climate simulations, half of the ensemble simulated ice-free summer Arctic conditions. Given the strong influence that sea ice exerts on high latitude temperatures, an understanding of the nature of mPWP Arctic sea ice would be highly beneficial. Using the HadCM3 GCM, this paper explores the impact of various combinations of potential mPWP orbital forcing, atmospheric CO2 concentrations and minimum sea ice albedo on sea ice extent and high latitude warming. The focus is on the Northern Hemisphere, due to availability of proxy data, and the large data-model discrepancies in this region. Changes in orbital forcings are demonstrated to be sufficient to alter the Arctic sea ice simulated by HadCM3 from perennial to seasonal. However, this occurs only when atmospheric CO2 concentrations exceed 300 ppm. Reduction of the minimum sea ice albedo from 0.5 to 0.2 is also sufficient to simulate seasonal sea ice, with any of the combinations of atmospheric CO2 and orbital forcing. Compared to a mPWP control simulation, monthly mean increases north of 60°N of up to 4.2 °C (SST) and 9.8 °C (SAT) are simulated. With varying CO2, orbit and sea ice albedo values we are able to reproduce proxy temperature records that lean towards modest levels of high latitude warming, but other proxy data showing greater warming remain beyond the reach of our model. This highlights the importance of additional proxy records at high latitudes and ongoing efforts to compare proxy signals between sites.

  5. Simulation of atmospheric CO2 over Europe and western Siberia using the regional scale model REMO

    OpenAIRE

    Chevillard, Anne; Karstens, Ute; Ciais, Philippe; Lafont, Sébastien; Heimann, Martin

    2002-01-01

    The spatial distribution and the temporal variability of atmospheric CO2 over Europe and western Siberia are investigated using the regional atmospheric model, REMO. The model, of typical horizontal resolution 50 km, is part of a nested modelling framework that has been established as a concerted action during the EUROSIBERIAN CARBONFLUX project. In REMO, the transport of CO2 is simulated together with climate variables, which offers the possibility of calculating at each time step the land a...

  6. A Test of Sensitivity to Convective Transport in a Global Atmospheric CO2 Simulation

    Science.gov (United States)

    Bian, H.; Kawa, S. R.; Chin, M.; Pawson, S.; Zhu, Z.; Rasch, P.; Wu, S.

    2006-01-01

    Two approximations to convective transport have been implemented in an offline chemistry transport model (CTM) to explore the impact on calculated atmospheric CO2 distributions. GlobalCO2 in the year 2000 is simulated using theCTM driven by assimilated meteorological fields from the NASA s Goddard Earth Observation System Data Assimilation System, Version 4 (GEOS-4). The model simulates atmospheric CO2 by adopting the same CO2 emission inventory and dynamical modules as described in Kawa et al. (convective transport scheme denoted as Conv1). Conv1 approximates the convective transport by using the bulk convective mass fluxes to redistribute trace gases. The alternate approximation, Conv2, partitions fluxes into updraft and downdraft, as well as into entrainment and detrainment, and has potential to yield a more realistic simulation of vertical redistribution through deep convection. Replacing Conv1 by Conv2 results in an overestimate of CO2 over biospheric sink regions. The largest discrepancies result in a CO2 difference of about 7.8 ppm in the July NH boreal forest, which is about 30% of the CO2 seasonality for that area. These differences are compared to those produced by emission scenario variations constrained by the framework of Intergovernmental Panel on Climate Change (IPCC) to account for possible land use change and residual terrestrial CO2 sink. It is shown that the overestimated CO2 driven by Conv2 can be offset by introducing these supplemental emissions.

  7. 2-micron Pulsed Direct Detection IPDA Lidar for Atmospheric CO2 Measurements

    Science.gov (United States)

    Yu, J.; Singh, U.; Petros, M.

    2012-12-01

    A 2-micron high energy, pulsed Integrated Path Differential Absorption (IPDA) lidar is being developed for atmospheric CO2 measurements. Development of this lidar heavily leverages the 2-micron laser technologies developed in LaRC over the last decade. The high pulse energy, direct detection lidar operating at CO2 2-micron absorption band provides an alternate approach to measure CO2 concentrations with significant advantages. It is expected to provide high-precision measurement capability by unambiguously eliminating contamination from aerosols and clouds that can bias the IPDA measurement. Our objective is to integrate an existing high energy double-pulsed 2-micron laser transmitter with a direct detection receiver and telescope to enable an airborne capability to perform a first proof of principle demonstration of airborne direct detection CO2 measurements. The 2-micron transmitter provides 100mJ at 10Hz with double pulse format specifically designed for DIAL/IPDA instrument. The compact, rugged, highly reliable transceiver is based on unique Ho:Tm:YLF high-energy 2-micron pulsed laser technology. All the optical mounts are custom designed and have space heritage. A 16-inch diameter telescope has been designed and being manufactured for the direct detection lidar. The detector is an InGaAs Positive-Intrinsic-Negative (PIN) photodiode manufactured by Hamamatsu Corporation. The performance of the detector is characterized at various operating temperatures and bias voltages for spectral response, NEP, response time, dynamic range, and linearity. A collinear lidar structure is designed to be integrated to NASA UC12 or B200 research aircrafts. This paper will describe the design of the airborne 2-micron pulsed IPDA lidar system; the lidar operation parameters; the wavelength pair selection; laser transmitter energy, pulse rate, beam divergence, double pulse generation and accurate frequency control; detector characterization; telescope design; lidar structure design

  8. Elevated atmospheric [CO2 ] can dramatically increase wheat yields in semi-arid environments and buffer against heat waves.

    Science.gov (United States)

    Fitzgerald, Glenn J; Tausz, Michael; O'Leary, Garry; Mollah, Mahabubur R; Tausz-Posch, Sabine; Seneweera, Saman; Mock, Ivan; Löw, Markus; Partington, Debra L; McNeil, David; Norton, Robert M

    2016-06-01

    Wheat production will be impacted by increasing concentration of atmospheric CO2 [CO2 ], which is expected to rise from about 400 μmol mol(-1) in 2015 to 550 μmol mol(-1) by 2050. Changes to plant physiology and crop responses from elevated [CO2 ] (e[CO2 ]) are well documented for some environments, but field-level responses in dryland Mediterranean environments with terminal drought and heat waves are scarce. The Australian Grains Free Air CO2 Enrichment facility was established to compare wheat (Triticum aestivum) growth and yield under ambient (~370 μmol(-1) in 2007) and e[CO2 ] (550 μmol(-1) ) in semi-arid environments. Experiments were undertaken at two dryland sites (Horsham and Walpeup) across three years with two cultivars, two sowing times and two irrigation treatments. Mean yield stimulation due to e[CO2 ] was 24% at Horsham and 53% at Walpeup, with some treatment responses greater than 70%, depending on environment. Under supplemental irrigation, e[CO2 ] stimulated yields at Horsham by 37% compared to 13% under rainfed conditions, showing that water limited growth and yield response to e[CO2 ]. Heat wave effects were ameliorated under e[CO2 ] as shown by reductions of 31% and 54% in screenings and 10% and 12% larger kernels (Horsham and Walpeup). Greatest yield stimulations occurred in the e[CO2 ] late sowing and heat stressed treatments, when supplied with more water. There were no clear differences in cultivar response due to e[CO2 ]. Multiple regression showed that yield response to e[CO2 ] depended on temperatures and water availability before and after anthesis. Thus, timing of temperature and water and the crop's ability to translocate carbohydrates to the grain postanthesis were all important in determining the e[CO2 ] response. The large responses to e[CO2 ] under dryland conditions have not been previously reported and underscore the need for field level research to provide mechanistic understanding for adapting crops to a changing

  9. Carbon and Oxygen Stable Isotope Measurements of Martian Atmospheric CO2 by the Phoenix Lander

    Science.gov (United States)

    Niles, Paul B.; Boynton, W. V.; Hoffman, J. H.; Ming, D. W.; Hamara, D.

    2010-01-01

    Precise stable isotope measurements of the CO2 in the martian atmosphere have the potential to provide important constraints for our understanding of the history of volatiles, the carbon cycle, current atmospheric processes, and the degree of water/rock interaction on Mars [1]. The isotopic composition of the martian atmosphere has been measured using a number of different methods (Table 1), however a precise value (carbonates in martian meteorites [2-4] it has been proposed that the martian atmosphere was enriched in 13C [8]. This was supported by measurements of trapped CO2 gas in EETA 79001[2] which showed elevated Delta(sup 13)C values (Table 1). More recently, Earth-based spectroscopic measurements of the martian atmosphere have measured the martian CO2 to be depleted in C-13 relative to CO2 in the terrestrial atmosphere[ 7, 9-11]. The Thermal and Evolved Gas Analyzer (TEGA) instrument on the Mars Phoenix Lander [12] included a magnetic-sector mass spectrometer (EGA) [13] which had the goal of measuring the isotopic composition of martian atmospheric CO2 to within 0.5%. The mass spectrometer is a miniature instrument intended to measure both the martian atmosphere as well as gases evolved from heating martian soils.

  10. Anthropogenic and biophysical contributions to increasing atmospheric CO2 growth rate and airborne fraction

    Directory of Open Access Journals (Sweden)

    C. Le Quéré

    2008-11-01

    Full Text Available We quantify the relative roles of natural and anthropogenic influences on the growth rate of atmospheric CO2 and the CO2 airborne fraction, considering both interdecadal trends and interannual variability. A combined ENSO-Volcanic Index (EVI relates most (~75% of the interannual variability in CO2 growth rate to the El-Niño-Southern-Oscillation (ENSO climate mode and volcanic activity. Analysis of several CO2 data sets with removal of the EVI-correlated component confirms a previous finding of a detectable increasing trend in CO2 airborne fraction (defined using total anthropogenic emissions including fossil fuels and land use change over the period 1959–2006, at a proportional growth rate 0.24% y−1 with probability ~0.9 of a positive trend. This implies that the atmospheric CO2 growth rate increased slightly faster than total anthropogenic CO2 emissions. To assess the combined roles of the biophysical and anthropogenic drivers of atmospheric CO2 growth, the increase in the CO2 growth rate (1.9% y−1 over 1959–2006 is expressed as the sum of the growth rates of four global driving factors: population (contributing +1.7% y−1; per capita income (+1.8% y−1; the total carbon intensity of the global economy (−1.7% y−1; and airborne fraction (averaging +0.2% y−1 with strong interannual variability. The first three of these factors, the anthropogenic drivers, have therefore dominated the last, biophysical driver as contributors to accelerating CO2 growth. Together, the recent (post-2000 increase in growth of per capita income and decline in the negative growth (improvement in the carbon intensity of the economy will drive a significant further acceleration in the CO2 growth rate over coming decades, unless these recent trends reverse.

  11. The declining uptake rate of atmospheric CO2 by land and ocean sinks

    Directory of Open Access Journals (Sweden)

    M. R. Raupach

    2014-07-01

    Full Text Available Through 1959–2012, an airborne fraction (AF of 0.44 of total anthropogenic CO2 emissions remained in the atmosphere, with the rest being taken up by land and ocean CO2 sinks. Understanding of this uptake is critical because it greatly alleviates the emissions reductions required for climate mitigation, and also reduces the risks and damages that adaptation has to embrace. An observable quantity that reflects sink properties more directly than the AF is the CO2 sink rate (kS, the combined land–ocean CO2 sink flux per unit excess atmospheric CO2 above preindustrial levels. Here we show from observations that kS declined over 1959–2012 by a factor of about 1 / 3, implying that CO2 sinks increased more slowly than excess CO2. Using a carbon–climate model, we attribute the decline in kS to four mechanisms: slower-than-exponential CO2 emissions growth (~ 35% of the trend, volcanic eruptions (~ 25%, sink responses to climate change (~ 20%, and nonlinear responses to increasing CO2, mainly oceanic (~ 20%. The first of these mechanisms is associated purely with the trajectory of extrinsic forcing, and the last two with intrinsic, feedback responses of sink processes to changes in climate and atmospheric CO2. Our results suggest that the effects of these intrinsic, nonlinear responses are already detectable in the global carbon cycle. Although continuing future decreases in kS will occur under all plausible CO2 emission scenarios, the rate of decline varies between scenarios in non-intuitive ways because extrinsic and intrinsic mechanisms respond in opposite ways to changes in emissions: extrinsic mechanisms cause kS to decline more strongly with increasing mitigation, while intrinsic mechanisms cause kS to decline more strongly under high-emission, low-mitigation scenarios as the carbon–climate system is perturbed further from a near-linear regime.

  12. Acetylene fuel from atmospheric CO2 on Mars

    Science.gov (United States)

    Landis, Geoffrey A.; Linne, Diane L.

    1992-01-01

    The Mars mission scenario proposed by Baker and Zubrin (1990) intended for an unmanned preliminary mission is extended to maximize the total impulse of fuel produced with a minimum mass of hydrogen from Earth. The hydrogen along with atmospheric carbon dioxide is processed into methane and oxygen by the exothermic reaction in an atmospheric processing module. Use of simple chemical reactions to produce acetylene/oxygen rocket fuel on Mars from hydrogen makes it possible to produce an amount of fuel that is nearly 100 times the mass of hydrogen brought from earth. If such a process produces the return propellant for a manned Mars mission, the required mission mass in LEO is significantly reduced over a system using all earth-derived propellants.

  13. Impact of elevated CO2 concentration under three soil water levels on growth of Cinnamomum camphora

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Forest plays very important roles in global system with about 35% land area producing about 70% of total land net production. It is important to consider both elevated CO2 concentrations and different soil moisture when the possible effects of elevated CO2 concentration on trees are assessed. In this study, we grew Cinnamomum camphora seedlings under two CO2 concentrations (350 μmol/mol and 500 μmol/mol) and three soil moisture levels [80%, 60% and 40% FWC (field water capacity)] to focus on the effects of exposure of trees to elevated CO2 on underground and aboveground plant growth, and its dependence on soil moisture. The results indicated that high CO2 concentration has no significant effects on shoot height but significantly impacts shoot weight and ratio of shoot weight to height under three soil moisture levels. The response of root growth to CO2 enrichment is just reversed, there are obvious effects on root length growth, but no effects on root weight growth and ratio of root weight to length. The CO2 enrichment decreased 20.42%, 32.78%, 20.59% of weight ratio of root to shoot under 40%, 60% and 80% FWC soil water conditions, respectively. And elevated CO2 concentration significantly increased the water content in aboveground and underground parts. Then we concluded that high CO2 concentration favours more tree aboveground biomass growth than underground biomass growth under favorable soil water conditions. And CO2 enrichment enhanced lateral growth of shoot and vertical growth of root. The responses of plants to elevated CO2 depend on soil water availability, and plants may benefit more from CO2 enrichment with sufficient water supply.

  14. Factors limiting the reduction of atmospheric CO2 by iron fertilization

    International Nuclear Information System (INIS)

    A limit on the reduction in atmospheric CO2 partial pressure (pCO2) in the next century resulting from purposeful Fe fertilization of the Antarctic Ocean is estimated with an advection-diffusion model calibrated with transient tracer distributions. To evaluate the possible increase in atmospheric CO2 with and without fertilization, the authors adopt a business-as-usual scenario of anthropogenic CO2 emission. Such increase is computed from the atmospheric pCO2 in the ocean-atmosphere total C system as it responds to this emission scenario. Assuming completely successful Fe fertilization, the authors calculate an 8% atmospheric CO2 reduction for a case with a 3 cm2 s-1 vertical diffusivity and 17.4 Sv upwelling flux, as derived from distribution of bomb-14c in the ocean. Hence, if atmospheric pCO2 reaches 800 μatm in the next century, the maximum possible reduction is ∼64 μatm. Doubling of upwelling flux to 34.8 Sv results in a reduction of 96 μatm. If they assume the surface area of the Antarctic Ocean is 16% of the total ocean area instead of 10% as used in the standard case, the reduction is ∼71 μatm. As they hold the surface water PO4 content at a near-zero value, it makes no difference at what depth the organic material is oxidized. Changes in the gas exchange rate over the Antarctic Ocean also do not have a significant effect on the magnitude of atmospheric CO2 drawdown. Doubling the gas exchange rate in the Antarctic region after fertilization results in a reduction of 68 μatm. Doubling of vertical diffusivity to 6 cm2 s-1 in Antarctic deep water yields a reduction of 75 μatm. The key parameters are the rate of upwelling in the Antarctic and the fate of this upwelled water

  15. Atmosphere-soil-vegetation model including CO2 exchange processes; SOLVEG2

    OpenAIRE

    永井 晴康

    2004-01-01

    A new atmosphere-soil-vegetation model named SOLVEG2 (SOLVEG version 2) was developed to study the heat, water, and CO2 exchanges between the atmosphere and land-surface. The model consists of one-dimensional multilayer sub-models for the atmosphere, soil, and vegetation. It also includes sophisticated processes for solar and long-wave radiation transmission in vegetation canopy and CO2 exchanges among the atmosphere, soil, and vegetation. The model can be also used by coupling with a three-d...

  16. Seasonally varying contributions to urban CO2 in the Chicago, Illinois, USA region: Insights from a high-resolution CO2 concentration and δ13C record

    OpenAIRE

    Joel Moore; Jacobson, Andrew D.

    2015-01-01

    Abstract Understanding urban carbon cycling is essential given that cities sustain 54% of the global population and contribute 70% of anthropogenic CO2 emissions. When combined with CO2 concentration measurements ([CO2]), stable carbon isotope analyses (δ13C) can differentiate sources of CO2, including ecosystem respiration and combustion of fossil fuels, such as petroleum and natural gas. In this study, we used a wavelength scanned-cavity ringdown spectrometer to collect ∼2x106 paired measur...

  17. QCL - Optical-Feedback Cavity Enhanced Absorption Spectroscopy For The Analysis Of Atmospheric 13CO2/12CO2 In Ice-Core Gas Bubbles

    Science.gov (United States)

    Gorrotxategi Carbajo, Paula; Romanini, Daniele; Maisons, Gregory; Carras, Mathieu; Chappellaz, Jerome; Kerstel, Erik

    2013-04-01

    In the context of a globally warming climate it is crucial to study the climate variability in the past and to understand the underlying mechanisms. The composition of gas stored in bubbles in polar ice presents a paleo-climate archive that provides a powerful means to study the exact mechanisms involved in the ~40% increase in the atmospheric CO2 concentration between glacial and interglacial climates. It is particularly important to understand such natural coupling between climate and the carbon cycle, as it will partly determine what natural feedback can be expected on the atmospheric CO2 concentration in a future warmer world. The source of the CO2 released into the atmosphere during previous deglaciations can be constrained from isotopic measurements by the fact that the different CO2 reservoirs (terrestrial biosphere, oceans) and associated mechanisms (biological or physical) have different isotopic signatures. Unfortunately, such isotope studies have been seriously hampered by the experimental difficulty of extracting the CO2 without contamination or fractionation, and measuring the isotope signal off-line on an isotope ratio mass spectrometer (IRMS). Here we present an alternative method that leverages the extreme sensitivity afforded by Optical Feedback Cavity Enhanced Absorption Spectroscopy (OF-CEAS) in the Mid-Infrared [1]. This region of the spectrum is accessed by a custom-developed Quantum Cascade Laser operating near 4.35 µm. The feedback to the laser of light that has been spectrally filtered by a high-finesse, V-shaped enhancement cavity has the effect of spectrally narrowing the laser emission and to auto-lock the laser frequency to one of the cavity's longitudinal modes, with clear advantages in terms of acquisition time and signal-to-noise ratio of the measurement. The line strengths in this region are about 5 orders of magnitude higher than in the more easily accessible NIR region near 1.6 µm and about 1000 times higher than at 2 µm. The

  18. Characteristics of the atmospheric CO2 signal as observed over the conterminous United States during INTEX-NA

    Science.gov (United States)

    Choi, Yonghoon; Vay, Stephanie A.; Vadrevu, Krishna P.; Soja, Amber J.; Woo, Jung-Hun; Nolf, Scott R.; Sachse, Glen W.; Diskin, Glenn S.; Blake, Donald R.; Blake, Nicola J.; Singh, Hanwant B.; Avery, Melody A.; Fried, Alan; Pfister, Leonhard; Fuelberg, Henry E.

    2008-04-01

    High resolution in situ measurements of atmospheric CO2 were made from the NASA DC-8 aircraft during the Intercontinental Chemical Transport Experiment-North America (INTEX-NA) campaign, part of the wider International Consortium for Atmospheric Research on Transport and Transformation (ICARTT). During the summer of 2004, eighteen flights comprising 160 h of measurements were conducted within a region bounded by 27 to 53°N and 36 to 139°W over an altitude range of 0.15 to 12 km. These large-scale surveys provided the opportunity to examine the characteristics of the atmospheric CO2 signal over sparsely sampled areas of North America and adjacent ocean basins. The observations showed a high degree of variability (≤18%) due to the myriad source and sink processes influencing the air masses intercepted over the INTEX-NA sampling domain. Surface fluxes had strong effects on continental scale concentration gradients. Clear signatures of CO2 uptake were seen east of the Mississippi River, notably a persistent CO2 deficit in the lowest 2-3 km. When combining the airborne CO2 measurements with LANDSAT and MODIS data products, the lowest CO2 mixing ratios observed during the campaign (337 ppm) were tied to mid-continental agricultural fields planted in corn and soybeans. We used simultaneous measurements of CO, O3, C2Cl4, C2H6, C2H2 and other unique chemical tracers to differentiate air mass types. Coupling these distinct air mass chemical signatures with transport history permitted identification of convection, stratosphere-troposphere exchange, long-range transport from Eastern Asia, boreal wildfires, and continental outflow as competing processes at multiple scales influencing the observed concentrations. Our results suggest these are important factors contributing to the large-scale distribution in CO2 mixing ratios thus these observations offer new constraints in the computation of the North American carbon budget.

  19. Microtopographic hydrologic variability change resulting from vegetation acclimation response to elevated atmospheric CO2

    Science.gov (United States)

    Le, P. V.; Kumar, P.

    2015-12-01

    The elevated concentration of atmospheric CO2 increases the ratio of carbon fixation to water loss from plants or water use efficiency, which reduces transpiration. However, the magnitude of the effects of this vegetation acclimation on hydrologic dynamics, such as soil moisture content and surface runoff controlled by microtopographic variability on the land surface, remains unclear. Here we integrate a multi-layer canopy-root-soil model (MLCan) with a coupled surface-subsurface flow model (GCSFlow) to capture the acclimation responses of vegetation to climate change and predict how these changes affect hydrologic dynamics on landscapes at fine scales. The model is implemented on a hybrid CPU-GPU parallel computing environment to overcome challenges associated with the high density of computational grid and nonlinear solvers. The model is capable of simulating large-scale heterogeneities due to both microtopography and soils and lateral water fluxes at emerging lidar-scale resolutions (~1m). We demonstrate that hybrid computing is feasible for detailed, large-scale ecohydrologic modeling, which has been previously assumed to be an intractable computational problem. Simulations are performed for corn crop in the Goose Creek watershed in central Illinois, USA at present and projected higher concentrations of atmospheric CO2, 400 ppm and 550 ppm, respectively. The results show a net decrease of 11% for the average annual evapotranspiration of corn, which increases water content in the soil and at the land surface. These results highlight the critical role of a warming climate on atmospheric-soil-vegetation interactions and the need to understand other dynamics near the soil surface associated with water and vegetation.

  20. Specific radioactivity of glycolate and photorespiration during 14CO2 assimilation at four different CO2 concentrations by sunflower and bean leaves

    International Nuclear Information System (INIS)

    Using an open gas-exchange system, the rates of apparent CO2 uptake (APS), true CO2 uptake (TIPS), CO2 evolution in light (PR), and the relative specific radioactivity of photorespiration (RSA) by sunflower and bean leaves were measured at four different CO2 concentrations. At the end of the 14CO2 assimilation period the leaves were killed and extract for the analysis of glycolic acid. The rate of PR was CO2 independent at low and normal CO2 concentrations but inreased at CO2 concentrations above normal. The ratio of PR/TPS which declined with an increase in CO2 was compatible with the ratio of vo/2vo of the RuBP-Carboxylase/Oxygenase reaction. At low and normal concentrations of CO2 the concentration as well as the specific radioactivity of glycolic acid increased with an increase in CO2 and the relative specific activity (RSA) of glycolic acid resembled the RSA of photorespiration. It was concluded that these results support the concept of RuBP-carboxylase/oxygenase regulating the fluxes of carbon via the photosynthetic carbon reduction and the glycolate pathway. (orig.)

  1. Coal devolatilization and char conversion under suspension fired conditions in O2/N2 and O2/CO2 atmospheres

    DEFF Research Database (Denmark)

    Jensen, Anker Degn; Brix, Jacob; Jensen, Peter Arendt

    2010-01-01

    indicates that a shift from air to oxy-fuel combustion does not influence the devolatilization process significantly. Char combustion experiments yielded similar char conversion profiles when N2 was replaced with CO2 under conditions where combustion was primarily controlled by chemical kinetics. When char......The aim of the present investigation is to examine differences between O2/N2 and O2/CO2 atmospheres during devolatilization and char conversion of a bituminous coal at conditions covering temperatures between 1173 K and 1673 K and inlet oxygen concentrations between 5 and 28 vol.%. The experiments...... have been carried out in an electrically heated entrained flow reactor that is designed to simulate the conditions in a suspension fired boiler. Coal devolatilized in N2 and CO2 atmospheres provided similar results regarding char morphology, char N2-BET surface area and volatile yield. This strongly...

  2. Airborne Measurements of CO2 Column Concentration and Range Using a Pulsed Direct-Detection IPDA Lidar

    Directory of Open Access Journals (Sweden)

    James B. Abshire

    2013-12-01

    Full Text Available We have previously demonstrated a pulsed direct detection IPDA lidar to measure range and the column concentration of atmospheric CO2. The lidar measures the atmospheric backscatter profiles and samples the shape of the 1,572.33 nm CO2 absorption line. We participated in the ASCENDS science flights on the NASA DC-8 aircraft during August 2011 and report here lidar measurements made on four flights over a variety of surface and cloud conditions near the US. These included over a stratus cloud deck over the Pacific Ocean, to a dry lake bed surrounded by mountains in Nevada, to a desert area with a coal-fired power plant, and from the Rocky Mountains to Iowa, with segments with both cumulus and cirrus clouds. Most flights were to altitudes >12 km and had 5–6 altitude steps. Analyses show the retrievals of lidar range, CO2 column absorption, and CO2 mixing ratio worked well when measuring over topography with rapidly changing height and reflectivity, through thin clouds, between cumulus clouds, and to stratus cloud tops. The retrievals shows the decrease in column CO2 due to growing vegetation when flying over Iowa cropland as well as a sudden increase in CO2 concentration near a coal-fired power plant. For regions where the CO2 concentration was relatively constant, the measured CO2 absorption lineshape (averaged for 50 s matched the predicted shapes to better than 1% RMS error. For 10 s averaging, the scatter in the retrievals was typically 2–3 ppm and was limited by the received signal photon count. Retrievals were made using atmospheric parameters from both an atmospheric model and from in situ temperature and pressure from the aircraft. The retrievals had no free parameters and did not use empirical adjustments, and >70% of the measurements passed screening and were used in analysis. The differences between the lidar-measured retrievals and in situ measured average CO2 column concentrations were <1.4 ppm for flight measurement altitudes >6

  3. The impact of Southern Ocean residual upwelling on atmospheric CO2 on centennial and millennial timescales

    Science.gov (United States)

    Lauderdale, Jonathan M.; Williams, Richard G.; Munday, David R.; Marshall, David P.

    2016-05-01

    The Southern Ocean plays a pivotal role in climate change by exchanging heat and carbon, and provides the primary window for the global deep ocean to communicate with the atmosphere. There has been a widespread focus on explaining atmospheric CO2 changes in terms of changes in wind forcing in the Southern Ocean. Here, we develop a dynamically-motivated metric, the residual upwelling, that measures the primary effect of Southern Ocean dynamics on atmospheric CO2 on centennial to millennial timescales by determining the communication with the deep ocean. The metric encapsulates the combined, net effect of winds and air-sea buoyancy forcing on both the upper and lower overturning cells, which have been invoked as explaining atmospheric CO2 changes for the present day and glacial-interglacial changes. The skill of the metric is assessed by employing suites of idealized ocean model experiments, including parameterized and explicitly simulated eddies, with online biogeochemistry and integrated for 10,000 years to equilibrium. Increased residual upwelling drives elevated atmospheric CO2 at a rate of typically 1-1.5 parts per million/106 m3 s-1 by enhancing the communication between the atmosphere and deep ocean. This metric can be used to interpret the long-term effect of Southern Ocean dynamics on the natural carbon cycle and atmospheric CO2, alongside other metrics, such as involving the proportion of preformed nutrients and the extent of sea ice cover.

  4. Evolution and challenges of dynamic global vegetation models for some aspects of plant physiology and elevated atmospheric CO2

    Science.gov (United States)

    Rezende, L. F. C.; Arenque, B. C.; Aidar, S. T.; Moura, M. S. B.; Von Randow, C.; Tourigny, E.; Menezes, R. S. C.; Ometto, J. P. H. B.

    2016-07-01

    Dynamic global vegetation models (DGVMs) simulate surface processes such as the transfer of energy, water, CO2, and momentum between the terrestrial surface and the atmosphere, biogeochemical cycles, carbon assimilation by vegetation, phenology, and land use change in scenarios of varying atmospheric CO2 concentrations. DGVMs increase the complexity and the Earth system representation when they are coupled with atmospheric global circulation models (AGCMs) or climate models. However, plant physiological processes are still a major source of uncertainty in DGVMs. The maximum velocity of carboxylation (Vcmax), for example, has a direct impact over productivity in the models. This parameter is often underestimated or imprecisely defined for the various plant functional types (PFTs) and ecosystems. Vcmax is directly related to photosynthesis acclimation (loss of response to elevated CO2), a widely known phenomenon that usually occurs when plants are subjected to elevated atmospheric CO2 and might affect productivity estimation in DGVMs. Despite this, current models have improved substantially, compared to earlier models which had a rudimentary and very simple representation of vegetation-atmosphere interactions. In this paper, we describe this evolution through generations of models and the main events that contributed to their improvements until the current state-of-the-art class of models. Also, we describe some main challenges for further improvements to DGVMs.

  5. Evolution and challenges of dynamic global vegetation models for some aspects of plant physiology and elevated atmospheric CO2

    Science.gov (United States)

    Rezende, L. F. C.; Arenque, B. C.; Aidar, S. T.; Moura, M. S. B.; Von Randow, C.; Tourigny, E.; Menezes, R. S. C.; Ometto, J. P. H. B.

    2015-10-01

    Dynamic global vegetation models (DGVMs) simulate surface processes such as the transfer of energy, water, CO2, and momentum between the terrestrial surface and the atmosphere, biogeochemical cycles, carbon assimilation by vegetation, phenology, and land use change in scenarios of varying atmospheric CO2 concentrations. DGVMs increase the complexity and the Earth system representation when they are coupled with atmospheric global circulation models (AGCMs) or climate models. However, plant physiological processes are still a major source of uncertainty in DGVMs. The maximum velocity of carboxylation (Vcmax), for example, has a direct impact over productivity in the models. This parameter is often underestimated or imprecisely defined for the various plant functional types (PFTs) and ecosystems. Vcmax is directly related to photosynthesis acclimation (loss of response to elevated CO2), a widely known phenomenon that usually occurs when plants are subjected to elevated atmospheric CO2 and might affect productivity estimation in DGVMs. Despite this, current models have improved substantially, compared to earlier models which had a rudimentary and very simple representation of vegetation-atmosphere interactions. In this paper, we describe this evolution through generations of models and the main events that contributed to their improvements until the current state-of-the-art class of models. Also, we describe some main challenges for further improvements to DGVMs.

  6. Fossil fuel CO2 estimation by atmospheric 14C measurement and CO2 mixing ratios in the city of Debrecen, Hungary

    International Nuclear Information System (INIS)

    A field unit was installed in the city of Debrecen (East Hungary) during the summer of 2008 to monitor urban atmospheric fossil fuel CO2. To establish a reference level simultaneous CO2 sampling has been carried out at a rural site (Hegyhatsal) in Western Hungary. Using the Hungarian background 14CO2 observations from the rural site atmospheric fossil fuel CO2 component for the city of Debrecen was reported in a regional 'Hungarian' scale. A well visible fossil fuel CO2 peak (10-15 ppm) with a maximum in the middle of winter 2008 (January) was observed in Debrecen air. Significant local maximum (∼20 ppm) in fossil fuel CO2 during Octobers of 2008 and 2009 was also detected. Stable isotope results are in agreement with the 14C based fossil fuel CO2 observations as the winter of 2008 and 2009 was different in atmospheric δ13C variations too. The more negative δ13C of atmospheric CO2 in the winter of 2008 means more fossil carbon in the atmosphere than during the winter of 2009. (author)

  7. Mesozooplankton community development at elevated CO2 concentrations: results from a mesocosm experiment in an Arctic fjord

    Directory of Open Access Journals (Sweden)

    B. Niehoff

    2013-03-01

    Full Text Available The increasing CO2 concentration in the atmosphere caused by burning fossil fuels leads to increasing pCO2 and decreasing pH in the world ocean. These changes may have severe consequences for marine biota, especially in cold-water ecosystems due to higher solubility of CO2. However, studies on the response of mesozooplankton communities to elevated CO2 are still lacking. In order to test whether abundance and taxonomic composition change with pCO2, we have sampled nine mesocosms, which were deployed in Kongsfjorden, an Arctic fjord at Svalbard, and were adjusted to eight CO2 concentrations, initially ranging from 185 μatm to 1420 μatm. Vertical net hauls were taken weekly over about one month with an Apstein net (55 μm mesh size in all mesocosms and the surrounding fjord. In addition, sediment trap samples, taken every second day in the mesocosms, were analysed to account for losses due to vertical migration and mortality. The taxonomic analysis revealed that meroplanktonic larvae (Cirripedia, Polychaeta, Bivalvia, Gastropoda, and Decapoda dominated in the mesocosms while copepods (Calanus spp., Oithona similis, Acartia longiremis and Microsetella norvegica were found in lower abundances. In the fjord copepods prevailed for most of our study. With time, abundance and taxonomic composition developed similarly in all mesocosms and the pCO2 had no significant effect on the overall community structure. Also, we did not find significant relationships between the pCO2 level and the abundance of single taxa. Changes in heterogeneous communities are, however, difficult to detect, and the exposure to elevated pCO2 was relatively short. We therefore suggest that future mesocosm experiments should be run for longer periods.

  8. Direct impact of atmospheric CO2 enrichment on regional transpiration.

    NARCIS (Netherlands)

    Jacobs, C.M.J.

    1994-01-01

    Plant physiological research has revealed that stomatal aperture of many plant species is reduced by CO 2 . Therefore, the question has been raised as to how transpiration will be affected if the ambient C0 2 concentration increases. This study focuses on the prediction of chan

  9. Temporal variability and spatial dynamics of CO2 and CH4 concentrations and fluxes in the Zambezi River system

    Science.gov (United States)

    Teodoru, Cristian; Borges, Alberto; Bouillon, Steven; Nyoni, Frank; Nyambe, Imasiku

    2014-05-01

    Spanning over 2900 km in length and with a catchment of approximately 1.4 million km2, the Zambezi River is the fourth largest river in Africa and the largest flowing into the Indian Ocean from the African continent. Yet, there is surprisingly little or no information on carbon (C) cycling in this large river system. As part of a broader study on the riverine biogeochemistry in the Zambezi River basin, we present here mainstream dissolved CO2 and CH4 data collected during 2012 and 2013 over two climatic seasons (dry and wet) to constrain the interannual variability, seasonality and spatial heterogeneity of partial pressure of CO2 (pCO2) and CH4 concentrations and fluxes along the aquatic continuum, in relation to physico-chemical parameters (temperature, conductivity, oxygen, and pH) and various carbon pools (dissolved and particulate, organic and inorganic carbon, total alkalinity, primary production, respiration and net aquatic metabolism). Both pCO2 and CH4 variability was high, ranging from minimal values of 150 ppm and 7 nM, respectively, mainly in the two large reservoirs (the Kariba and the Cabora Bassa characterized by high pH and oxygen and low DOC), up to maximum values of 12,500 ppm and 12,130 nM, CO2 and CH4, respectively, mostly below floodplains/wetlands (low pH and oxygen levels, high DOC and POC concentrations). The interannual variability was relatively large for both CO2 and CH4 (mean pCO2: 2350 ppm in 2013 vs. 3180 ppm in 2013; mean CH4: 600 nM in 2012 vs. 1000 nM in 2013) and significantly higher (up to two fold) during wet season compared to dry season closely linked to distinct seasonal hydrological characteristics. Overall, no clear pattern was observed along the longitudinal gradient as river CO2 and CH4 concentrations are largely influenced by the presence of floodplains/wetlands, anthropogenic reservoirs or natural barriers (waterfalls/ rapids). Following closely the concentration patterns, river CO2 and CH4 mean fluxes of 3440 mg C-CO2 m

  10. Characteristics of atmospheric CO2 and CH4 at the Shangdianzi regional background station in China

    Science.gov (United States)

    Fang, Shuang-xi; Tans, Pieter P.; Dong, Fan; Zhou, Huaigang; Luan, Tian

    2016-04-01

    Atmospheric CO2 and CH4 have been continuously measured at the Shangdianzi regional background station (SDZ) in China from 2009 to 2013. Based on the influences of local surface wind and long-distance transport, the observed records were flagged into locally influenced, Beijing-Tianjin-Hebei (BTH) influenced, and Russia, Mongolia, and Inner Mongolia autonomous region influenced (RMI). ∼ 81.4% of CO2 and ∼75.6% of CH4 mole fractions were flagged as locally representative, indicating that the atmospheric CO2 and CH4 at SDZ were strongly influenced by local sources and sinks. Cluster analysis of back trajectories proved that the atmospheric CO2 and CH4 were influenced by air masses from northwest (RMI) or from south and southeast (BTH). The CO2 and CH4 mole fractions in BTH are always higher than in RMI, with the largest difference of 11.5 ± 0.3 ppm for CO2 and 102 ± 1 ppb for CH4 in July. The annual growth rates of CO2 and CH4 in BTH are 3.8 ± 0.01 ppm yr-1 and 10 ± 0.1 ppb yr-1, respectively, which are apparently higher than those of the RMI and the global means. The long-term trends of CO2 and CH4 in BTH are deviating from those in RMI, with ratios of ∼1.0 ppm yr-1 for CO2 and ∼2 ppb yr-1 for CH4, indicating the strengths of CO2 and CH4 emission in Beijing-Tianjin-Hebei plain increased more than 20% every year.

  11. Atmospheric Fossil Fuel CO2 Traced by Δ(14)C in Beijing and Xiamen, China: Temporal Variations, Inland/Coastal Differences and Influencing Factors.

    Science.gov (United States)

    Niu, Zhenchuan; Zhou, Weijian; Wu, Shugang; Cheng, Peng; Lu, Xuefeng; Xiong, Xiaohu; Du, Hua; Fu, Yunchong; Wang, Gehui

    2016-06-01

    One year of atmospheric Δ(14)CO2 were observed in 2014 in the inland city of Beijing and coastal city of Xiamen, China, to trace temporal CO2ff variations and to determine the factors influencing them. The average CO2ff concentrations at the sampling sites in Beijing and Xiamen were 39.7 ± 36.1 ppm and 13.6 ± 12.3 ppm, respectively. These contributed 75.2 ± 14.6% and 59.1 ± 26.8% to their respective annual ΔCO2 offsets over background CO2 concentrations. Significantly (p < 0.05) high CO2ff values were observed in winter in Beijing. We did not find any significant differences in CO2ff values between weekdays and weekends. Diurnal CO2ff variations were plainly evident, with high values between midnight and 4:00, and during morning and afternoon rush hours. The sampling site in the inland city of Beijing displayed much higher CO2ff inputs and overall temporal variations than the site in the coastal city of Xiamen. The variations of CO2ff at both sites were controlled by a combination of emission sources, topography, and atmospheric dispersion. In particular, diurnal observations at the urban site in Beijing showed that CO2ff was easily accumulated under the southeast wind conditions. PMID:27171980

  12. Developing Model Constraints on Northern Extra-Tropical Carbon Cycling Based on measurements of the Abundance and Isotopic Composition of Atmospheric CO2

    Energy Technology Data Exchange (ETDEWEB)

    Keeling, Ralph [UCSD-SIO

    2014-12-12

    The objective of this project was to perform CO2 data syntheses and modeling activities to address two central questions: 1) how much has the seasonal cycle in atmospheric CO2 at northern high latitudes changed since the 1960s, and 2) how well do prognostic biospheric models represent these changes. This project also supported the continuation of the Scripps time series of CO2 isotopes and concentration at ten baseline stations distributed globally.

  13. Elevated temperature and CO2 concentration effects on xylem anatomy of Scots pine

    International Nuclear Information System (INIS)

    The effects of carbon dioxide (CO2) concentrations and elevated temperatures on the xylem anatomy of 20-year old Scots pine trees were investigated. The experiment was conducted in 16 chambers containing 4 trees each with a factorial combination of both ambient and elevated CO2 concentrations and 2 different temperature regimes. CO2 concentrations were doubled with a corresponding increase of between 2 and 6 degrees C according to each season over a period of 6 years. The study showed that elevated CO2 concentrations increased the ring width in 4 of the 6 analyzed treatment years. Earlywood width increased during the first 2 years of the experiment, while latewood width increased during the third year of the study. The study also showed that the tracheid walls in both the latewood and earlywood samples were thicker when either temperature levels or CO2 levels were increased. It was noted that combined CO2 and temperature elevations resulted in thinner tracheid walls. However, latewood tracheid lumen diameters were larger in all CO2 and temperature treatments than trees grown in ambient conditions. It was concluded that xylem anatomy was impacted more by increases in temperature than by elevated CO2 concentrations. 48 refs., 2 tabs., 6 figs

  14. Chemical Effects of CO2 Concentration on Soot Formation in Jet-stirred/Plug-flow Reactor

    Institute of Scientific and Technical Information of China (English)

    张引弟; 娄春; 刘德华; 李勇; 阮龙飞

    2013-01-01

    Soot formation was investigated numerically with CO2 addition in a jet-stirred/plug-flow reactor (JSR/PFR) C2H4/O2/N2 reactor (C/O ratio of 2.2) at atmospheric pressure. An updated Kazakov mechanism empha-sizes the effect of the O2/CO2 atmosphere instead of an O2/N2 one in the premixed flame. The soot formation was taken into account in the JSR/PFR for C2H4/O2/N2. The effects of CO2 addition on soot formation in different C2H4/O2/CO2/N2 atmospheres were studied, with special emphasis on the chemical effect. The simulation shows that the endothermic reaction CO2+H CO+OH is responsible of the reduction of hydrocarbon intermediates in the CO2 added combustion through the supplementary formation of hydroxyl radicals. The competition of CO2 for H radical through the above forward reaction with the single most important chain branching reaction H+O2 O+OH reduces significantly the fuel burning rate. The chemical effects of CO2 cause a significant increase in residence time and mole fractions of CO and OH, significant decreases in some intermediates (H, C2H2), polycyclic aromatic hydrocarbons (PAHs, C6H6 and C16H10, etc.) and soot volume fraction. The CO2 addition will leads to a decrease by only about 5%to 20%of the maximum mole fractions of some C3 to C10 hydrocarbon intermediates. The sensitivity analysis and reaction-path analysis results show that C2H4 reaction path and products are altered due to the CO2 addition.

  15. CORRELATION BETWEEN CORAL CALCIFICATION TREND AND RISE IN ATMOSPHERIC CO2 CONCENTRATION AND GLOBAL WARMING IN LAST SEVERAL DECADES IN THE SOUTHERN SOUTH CHINA SEA%南海南部最近几十年珊瑚钙化趋势与大气CO2浓度升高和全球变暖的联系

    Institute of Scientific and Technical Information of China (English)

    苏瑞侠; 隋丹丹; 张叶春; 孙东怀; 郭峰; 徐玉芬; 张月宝; 李再军

    2012-01-01

    with lowest rainfall and cloud cover in April. Natural geographical conditions are suitable for reef coral living. Extension rate represents coral upward linear extension growth per year ( cm/a) , density represents coral skeletal quality per cm (g/cm) reflecting comprehensive environment quality; Calcification rate represents quality of calcium carbonate per cm and year ( g/cm2· a) excreted by coral, and calculated from the product of extension rate and density. In this study,the 3 growth parameters of the 11 Porites colonies were obtained along their main growth axes using digital X-radiography image of which the reative density is transferred to density with measured true density. The results show that their average extension rate is 0. 96±0. 05cm/a, increasing 10. 77% in the last 16 years with a rate of 0. 67%/a; The average density is 1. 17±0. 03g/cm3, decreasing 6. 92% with a rate of -0. 43%/a; The average calcification rate is 1. 13±0. 05g/cm2·a,,increasing 2. 69% with a rate of 0. 17%/a. Two coral species of P. lutea and P. lobata show slightly different variations in their 3 growth parameters. Standard diviation analysis indicate that density is less variable than extension and calcification rate for Porites, which reveal that increase in calcification rate is mainly induced by increase in extension rate. Our analysis summarize three vriational forms for the three growth parameters in 11 Porites colonies:1 ) A lot of corals assume increase in extension and calcification rate and decrease in density; 2) A few of corals assume increase in all of the 3 growth parameters; 3)A few of P. lobata colonies show decrease in all of the 3 growth parameters. Linear regression analysis indicates that increase or decrease in the 3 growth parameters correlates significantly with increase in both CO2 concentration and temperature. However, positive responses of extension and calcification rate and negative response of density are much stronger than their opposite

  16. Atmosphere-soil-vegetation model including CO2 exchange processes: SOLVEG2

    International Nuclear Information System (INIS)

    A new atmosphere-soil-vegetation model named SOLVEG2 (SOLVEG version 2) was developed to study the heat, water, and CO2 exchanges between the atmosphere and land-surface. The model consists of one-dimensional multilayer sub-models for the atmosphere, soil, and vegetation. It also includes sophisticated processes for solar and long-wave radiation transmission in vegetation canopy and CO2 exchanges among the atmosphere, soil, and vegetation. Although the model usually simulates only vertical variation of variables in the surface-layer atmosphere, soil, and vegetation canopy by using meteorological data as top boundary conditions, it can be used by coupling with a three-dimensional atmosphere model. In this paper, details of SOLVEG2, which includes the function of coupling with atmosphere model MM5, are described. (author)

  17. Salt concentrations during water production resulting from CO2 storage

    DEFF Research Database (Denmark)

    Walter, Lena; Class, Holger; Binning, Philip John

    2014-01-01

    present in the saline aquifer. The brine can be displaced over large areas and can reach shallower groundwater resources. High salt concentrations could lead to a degradation of groundwater quality. For water suppliers the most important information is whether and how much salt is produced at a water...... production well. In this approach the salt concentrations at water production wells depending on different parameters are determined for the assumption of a 2D model domain accounting for groundwater flow. Recognized ignorance resulting from grid resolution is qualitatively studied and statistical...... very demanding because many simulations runs are needed to get an appropriate statistical accuracy. A possible way to handle the complexity and uncertainties with acceptable computational costs is by running MC simulations with a reduced model using a model reduction technique called arbitrary...

  18. Plant species, atmospheric CO2 and soil N interactively or additively control C allocation within plant-soil systems

    Institute of Scientific and Technical Information of China (English)

    FU Shenglei; Howard Ferris

    2006-01-01

    Two plant species, Medicago truncatula (legume) and Avena sativa (non-legume), were grown in low- or high-N soils under two CO2 concentrations to test the hypothesis whether C allocation within plant-soil system is interactively or additively controlled by soil N and atmospheric CO2 is dependent upon plant species. The results showed the interaction between plant species and soil N had a significant impact on microbial activity and plant growth. The interaction between CO2 and soil N had a significant impact on soil soluble C and soil microbial biomass C under Madicago but not under Avena. Although both CO2 and soil N affected plant growth significantly, there was no interaction between CO2 and soil N on plant growth. In other words, the effects of CO2 and soil N on plant growth were additive. We considered that the interaction between N2 fixation trait of legume plant and elevated CO2 might have obscured the interaction between soil N and elevated CO2 on the growth of legume plant. In low-N soil, the shoot-to-root ratio of Avena dropped from 2.63±0.20 in the early growth stage to 1.47±0.03 in the late growth stage, indicating that Avena plant allocated more energy to roots to optimize nutrient uptake (i.e. N) when soil N was limiting. In high-N soil, the shoot-to-root ratio of Medicago increased significantly over time (from 2.45±0.30 to 5.43±0.10), suggesting that Medicago plants allocated more energy to shoots to optimize photosynthesis when N was not limiting.The shoot-to-root ratios were not significantly different between two CO2 levels.

  19. Changes in the activities of starch metabolism enzymes in rice grains in response to elevated CO2 concentration

    Science.gov (United States)

    Xie, Li-Yong; Lin, Er-Da; Zhao, Hong-Liang; Feng, Yong-Xiang

    2016-05-01

    The global atmospheric CO2 concentration is currently (2012) 393.1 μmol mol-1, an increase of approximately 42 % over pre-industrial levels. In order to understand the responses of metabolic enzymes to elevated CO2 concentrations, an experiment was conducted using the Free Air CO2 Enrichment (FACE )system. Two conventional japonica rice varieties ( Oryza sativa L. ssp. japonica) grown in North China, Songjing 9 and Daohuaxiang 2, were used in this study. The activities of ADPG pyrophosphorylase, soluble and granule-bound starch synthases, and soluble and granule-bound starch branching enzymes were measured in rice grains, and the effects of elevated CO2 on the amylose and protein contents of the grains were analyzed. The results showed that elevated CO2 levels significantly increased the activity of ADPG pyrophosphorylase at day 8, 24, and 40 after flower, with maximum increases of 56.67 % for Songjing 9 and 21.31 % for Daohuaxiang 2. Similarly, the activities of starch synthesis enzymes increased significantly from the day 24 after flower to the day 40 after flower, with maximum increases of 36.81 % for Songjing 9 and 66.67 % for Daohuaxiang 2 in soluble starch synthase (SSS), and 25.00 % for Songjing 9 and 36.44 % for Daohuaxiang 2 in granule-bound starch synthase (GBSS), respectively. The elevated CO2 concentration significantly increased the activity of soluble starch branching enzyme (SSBE) at day 16, 32, and 40 after flower, and also significantly increased the activity of granule-bound starch branching enzyme (GBSBE) at day 8, 32, and 40 after flower. The elevated CO2 concentration increased the peak values of enzyme activity, and the timing of the activity peaks for SSS and GBSBE were earlier in Songjing 9 than in Daohuaxiang 2. There were obvious differences in developmental stages between the two varieties of rice, which indicated that the elevated CO2 concentration increased enzyme activity expression and starch synthesis, affecting the final contents

  20. Developing a passive trap for diffusive atmospheric 14CO2 sampling

    Science.gov (United States)

    Walker, Jennifer C.; Xu, Xiaomei; Fahrni, Simon M.; Lupascu, Massimo; Czimczik, Claudia I.

    2015-10-01

    14C-CO2 measurement is an unique tool to quantify source-based emissions of CO2 for both the urban and natural environments. Acquiring a sample that temporally integrates the atmospheric 14C-CO2 signature that allows for precise 14C analysis is often necessary, but can require complex sampling devices, which can be difficult to deploy and maintain, especially for multiple locations. Here we describe our progress in developing a diffusive atmospheric CO2 molecular sieve trap, which requires no power to operate. We present results from various cleaning procedures, and rigorously tested for blank and memory effects. Traps were tested in the environment along-side conventional sampling flasks for accuracy. Results show that blank and memory effects can be minimized with thorough cleaning and by avoiding overheating, and that diffusively collected air samples agree well with traditionally canister-sampled air.

  1. Quantifying Diurnal and Spatial Variations in CO2 Concentrations and Partial Columns using High-Resolution Global Model Simulations

    Science.gov (United States)

    Pawson, S.; Nielsen, J.; Ott, L. E.; Darmenov, A.; Putman, W.

    2015-12-01

    Model-data fusion approaches, such as global inverse modeling for surface flux estimation, have traditionally been performed at spatial resolutions of several tens to a few hundreds of kilometers. Use of such coarse scales presents a fundamental limitation in reconciling the modeled field with both the atmospheric observations and the distribution of surface emissions and uptake. Emissions typically occur on small scales, including point sources (e.g. power plants, forest fires) or with inhomegeneous structure. Biological uptake can have spatial variations related to complex, diverse vegetation, etc. Atmospheric observations of CO2 are either surface based, providing information at a single point, or space based with a finite-sized footprint. For instance, GOSAT and OCO-2 have footprint sizes of around 10km and proposed active sensors (such as ASCENDS) will likely have even finer footprints. One important aspect of reconciling models to measurements is the representativeness of the observation for the model field, and this depends on the generally unknown spatio-temporal variations of the CO2 field around the measurement location and time. This work presents an assessment of the global spatio-temporal variations of the CO2 field using the "7km GEOS-5 Nature Run" (7km-G5NR), which includes CO2 emissions and uptake mapped to the finest possible resolution. Results are shown for surface CO2 concentrations, total-column CO2, and separate upper and lower tropospheric columns. Spatial variability is shown to be largest in regions with strong point sources and at night in regions with complex terrain, especially where biological processes dominate the local CO2 fluxes, where the day-night differences are also most marked. The spatio-temporal variations are strongest for surface concentrations and for lower tropospheric CO2. While these results are largely anticipated, these high resolution simulations provide quantitative estimates of the global nature of spatio

  2. ENSO, Volcanic Activities and Interannual Variations of Atmospheric CO2%ENSO,火山活动与大气CO2的年际变化

    Institute of Scientific and Technical Information of China (English)

    陈中笑; 程军

    2011-01-01

    利用大气CO2及其δ13C的观测数据分析了不同区域大气CO2的季节和年际变化特征,并结合δ13C的变化趋势判断大气CO2变化的主要影响因素是来自陆地还是海洋.结果表明:大气CO2的年际变化主要受ENSO引起的陆地植被初级生产量而不是海洋吸收变化的影响,且La Ni(n)a对大气CO2的影响大于El Ni(n)o.火山活动后大气CO2的增加幅度减小,甚至掩盖了ENSO的影响,喷发后δ13C的增幅同步减小说明大气CO2增幅减小缘自温度持续降低引起的海洋吸收的增加或陆地呼吸作用的减弱.%Based on the observations of atmospheric CO2 and its δ13C, the characters of seasonal and interannual variations of atmospheric CO2 were analyzed in different regions.The trends of atmospheric δ13C were used to distinguish whether the dominative influential factor for the variations of atmospheric CO2 is from the terrestrial or the ocean.The results show that the interannual variations of atmospheric CO2 are mainly influenced by ENSOrelated change of terrestrial vegetation primary production, not by oceanic sink.And the intensity of La Ni(n)a has more effect on atmospheric CO2 than that of El Ni(n)o.The atmospheric CO2 increase would decrease after volcano events, which even conceal ENSO effects.The synchronized decrease in atmospheric δ13C increase after volcano eruptions indicates that it is likely due to the increase of oceanic uptake or the weakening of terrestrial respiration resulted from persistent decrease of surface temperature.

  3. Photorespiration and carbon concentrating mechanisms: two adaptations to high O2, low CO2 conditions.

    Science.gov (United States)

    Moroney, James V; Jungnick, Nadine; Dimario, Robert J; Longstreth, David J

    2013-11-01

    This review presents an overview of the two ways that cyanobacteria, algae, and plants have adapted to high O2 and low CO2 concentrations in the environment. First, the process of photorespiration enables photosynthetic organisms to recycle phosphoglycolate formed by the oxygenase reaction catalyzed by ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco). Second, there are a number of carbon concentrating mechanisms that increase the CO2 concentration around Rubisco which increases the carboxylase reaction enhancing CO2 fixation. This review also presents possibilities for the beneficial modification of these processes with the goal of improving future crop yields. PMID:23771683

  4. Inter-annual variability in the interhemispheric atmospheric CO2 gradient: contributions from transport and the seasonal rectifier

    International Nuclear Information System (INIS)

    The observed interhemispheric gradient in atmospheric carbon dioxide (CO2) indicates the distribution of CO2 sources and sinks, and for recent decades is evidence of a Northern mid-latitudes sink, a tropical source and southern hemisphere sink. As such, the variability in the gradient also reflects how these fluxes vary with time. However, the variability in the gradient is sensitive to the network of stations used to calculate the gradient. Also, an important consideration when dealing with variability in atmospheric measurements is the contribution due to the variability in the atmospheric transport. Most previous studies have ignored transport variability. Using an atmospheric tracer transport model driven with analysed circulation products, we demonstrate here that the interannual variability in the interhemispheric gradient due to transport alone is significant when compared with the observations. Model experiments show that interannually varying transport combined with both cyclostationary terrestrial biosphere fluxes and time-constant fossil CO2 fluxes generates significant interannual variability, but that the component due to the interannually varying transport and the ocean CO2 fluxes is small. The key contributor to the transport generated interannual variability is due to the variability in the seasonal rectifier (the covariance between the seasonality in the terrestrial biosphere fluxes and atmospheric transport, which results in non-zero surface CO2 concentrations despite the fluxes balancing at each grid-point). This study shows that the rectifier variability is complex, with different regions displaying different modes of variability. We also investigate the role of the Pearman Pump (gradient due to the seasonal covariance in the fluxes and cross-hemispheric transport) and show that while it appears to be a process occurring in the atmosphere, it is of second-order importance in forcing the interhemispheric gradient

  5. O2/CO2气氛下CO2和H2O气化反应对煤及煤焦燃烧特性的影响%Effect of CO2 and H2O gasification on the combustion characteristics of coal and char under O2/CO2 atmosphere

    Institute of Scientific and Technical Information of China (English)

    雷鸣; 黄星智; 王春波

    2015-01-01

    The burning behaviors of Datong coal and char under O2/N2 , O2/CO2 and O2/H2 O/CO2 atmosphere were comparatively investigated by thermogravimetric analyzer. The influence of CO2 and H2 O gasification on the oxy-fuel combustion characteristics of coal and char were mainly studied. The results indicate that at 5%oxygen concentration the burning rate of pulverized coal in each atmosphere decreases in the order of O2/N2 , O2/CO2 and O2/H2 O/CO2 . When the oxygen concentration reduces to 2%, owing to the CO2 and H2 O gasification, the overall reaction rate of pulverized coal increases in the same order at high temperatures. The burning rate of char is slower in O2/CO2 than that in O2/N2 at 5% oxygen concentration, but as the burning process is delayed, the overall reaction rate of char in O2/H2 O/CO2 rises significantly due to the action of gasification. At 2% oxygen concentration, the overall reaction rate of char in O2/CO2 is higher than the burning rate of char in O2/N2 with the rise in temperature. The overall reaction rate of char in O2/H2 O/CO2 further increases because the H2 O gasification plays a major role in CO2 and H2 O co-gasification. The kinetic analysis shows that at 5% oxygen concentration the apparent activation energy in the atmosphere increases in the order of O2/N2 , O2/CO2 and O2/H2 O/CO2 . However, the apparent activation energy of different atmospheres declines with the decrease of oxygen concentration.%利用热天平对比研究了大同煤及煤焦在O2/N2、O2/CO2 和O2/H2O/CO2 中的燃烧行为,探讨CO2 和H2O气化反应对其富氧燃烧特性的影响. 结果表明,在5%氧气浓度下,煤粉在O2/N2、O2/CO2 和O2/H2 O/CO2 中的燃烧速率按顺序依次降低. 氧气浓度降低到2%,由于CO2 和H2 O气化反应的作用,煤粉在高温区的整体反应速率按顺序依次增大. 当氧气浓度为5%时,煤焦在O2/CO2 中的燃烧速率要低于 O2/N2 中的燃烧速率,但燃烧反应推迟后气化反

  6. CO2 Dissociation using the Versatile Atmospheric Dielectric Barrier Discharge Experiment (VADER)

    Science.gov (United States)

    Lindon, Michael Allen

    As of 2013, the Carbon Dioxide Information Analysis Center (CDIAC) estimates that the world emits approximately 36 trillion metric tons of Carbon Dioxide (CO2) into the atmosphere every year. These large emissions have been correlated to global warming trends that have many consequences across the globe, including glacial retraction, ocean acidification and increased severity of weather events. With green technologies still in the infancy stage, it can be expected that CO2 emissions will stay this way for along time to come. Approximately 41% of the emissions are due to electricity production, which pump out condensed forms of CO2. This danger to our world is why research towards new and innovative ways of controlling CO2 emissions from these large sources is necessary. As of now, research is focused on two primary methods of CO2 reduction from condensed CO2 emission sources (like fossil fuel power plants): Carbon Capture and Sequestration (CCS) and Carbon Capture and Utilization (CCU). CCS is the process of collecting CO2 using absorbers or chemicals, extracting the gas from those absorbers and finally pumping the gas into reservoirs. CCU on the other hand, is the process of reacting CO2 to form value added chemicals, which can then be recycled or stored chemically. A Dielectric Barrier discharge (DBD) is a pulsed, low temperature, non-thermal, atmospheric pressure plasma which creates high energy electrons suitable for dissociating CO2 into its components (CO and O) as one step in the CCU process. Here I discuss the viability of using a DBD for CO2 dissociation on an industrial scale as well as the fundamental physics and chemistry of a DBD for CO2 dissociation. This work involved modeling the DBD discharge and chemistry, which showed that there are specific chemical pathways and plasma parameters that can be adjusted to improve the CO2 reaction efficiencies and rates. Experimental studies using the Versatile Atmospheric dielectric barrier Discharge Expe

  7. An Assessment of Biases in Satellite CO2 Measurements Using Atmospheric Inversion

    Science.gov (United States)

    Baker, D. F.; O'Dell, C.

    2014-12-01

    Column-integrated CO2 mixing ratio measurements from satellite should provide a new view of the global carbon cycle, thanks to their ability to measure with great coverage in places that are poorly sampled by the in situ network (e.g. the tropics) using a new approach (full-column averages rather than point measurements). For this new insight to be useful, however, systematic errors in these data must first be identified and removed. Here we use atmospheric transport modeling to perform a global comparison of satellite CO2 measurements to higher-quality reference data (in situ data from flasks and aircraft, column CO2 data from the upward-looking spectrometers of the TCCON network) to assess systematic errors in the satellite data. This broad comparison is meant to complement the more direct validation done at specific TCCON sites. A suite of 3-D CO2 mixing ratio histories are generated across 2009-2014 using combinations of several different a priori fossil fuel, land biospheric, and oceanic CO2 fluxes run through the PCTM off-line atmospheric transport model driven by MERRA 1°x1.25° winds and vertical mixing parameters. Each member of the suite is forced to agree with in situ CO2 measurements (flask, tall tower, and routine light aircraft profiles) through use of a variational carbon data assimilation (4Dvar) system. The optimized 3-D CO2 fields are then compared to ACOS column CO2 retrievals of GOSAT data, with the differences being fit to different independent variables (aerosol optical depth, atmospheric path length, surface albedo, etc.) to derive a GOSAT bias correction. ACOS-GOSAT CO2 retrievals, corrected by this scheme, as well as with the "official" ACOS bias correction, will then be assimilated using the same 4Dvar approach. The benefit of the GOSAT data with and without the bias corrections will then be assessed by comparing the optimized CO2 fields to independent data (TCCON column data, as well as aircraft data left out of the in situ inversions

  8. The seasonal cycle of ocean-atmosphere CO2 Flux in Ryder Bay, West Antarctic Peninsula.

    OpenAIRE

    Legge, Oliver J.; Bakker, Dorothee C. E.; Johnson, Martin T.; Meredith, Michael P.; Venables, Hugh J.; Brown, Peter J.; Lee, Gareth A.

    2015-01-01

    Approximately 15 million km2 of the Southern Ocean is seasonally ice covered, yet the processes affecting carbon cycling and gas exchange in this climatically important region remain inadequately understood. Here, 3 years of dissolved inorganic carbon (DIC) measurements and carbon dioxide (CO2) fluxes from Ryder Bay on the west Antarctic Peninsula (WAP) are presented. During spring and summer, primary production in the surface ocean promotes atmospheric CO2 uptake. In winter, higher DIC, caus...

  9. LA Megacity: An Integrated Land-Atmosphere System for Urban CO2 Emissions

    Science.gov (United States)

    Feng, S.; Lauvaux, T.; Newman, S.; Rao, P.; Patarasuk, R.; o'Keefe, D.; Huang, J.; Ahmadov, R.; Wong, C.; Song, Y.; Gurney, K. R.; Diaz Isaac, L. I.; Jeong, S.; Fischer, M. L.; Miller, C. E.; Duren, R. M.; Li, Z.; Yung, Y. L.; Sander, S. P.

    2015-12-01

    About 10% of the global population lives in the word's 20 megacities (cities with urban populations greater than 10 million people). Megacities account for approximately 20% of the global anthropogenic fossil fuel CO2 (FFCO2) emissions, and their proportion of emissions increases monotonically with the world population and urbanization. Megacities range in spatial extent from ~1000 - 10,000 km2 with complex topography and variable landscapes. We present here the first attempt at building an integrated land-atmosphere modeling system for megacity environments, developed and evaluated for urban CO2 emissions over the Los Angeles (LA) Megacity area. The Weather Research and Forecasting (WRF) - Chem model was coupled to a ~1.3-km FFCO2 emission product, "Hestia-LA", to simulate the transport of CO2 across the LA magacity. We define the optimal model resolution to represent both the spatial variability of the atmospheric dynamics and the spatial patterns from the CO2 emission distribution. In parallel, we evaluate multiple configurations of WRF with various physical schemes, using meteorological observations from the CalNex-LA campaign of May-June 2010. Our results suggest that there is no remarkable difference between the medium- (4-km) and high- (1.3-km) resolution simulations in terms of atmospheric model performance. However, the high-resolution modeled CO2 mixing ratios clearly outperform the results at medium resolution for capturing both the spatial distribution and the temporal variability of the urban CO2 signals. We compare the impact of physical representation errors and emission aggregation errors on the modeled CO2 mixing ratios across the LA megacity. Finally, we present a novel approach to evaluate the design of the current surface network over the LA megacity using the modeled spatial correlations. These results reinforce the importance of using high-resolution emission products over megacities to represent correctly the large spatial gradients in

  10. Modern soil system constraints on reconstructing deep-time atmospheric CO2

    Science.gov (United States)

    Montañez, Isabel P.

    2013-01-01

    Paleosol carbonate-based estimates of paleo-atmospheric CO2 play a prominent role in constraining radiative-forcing and climate sensitivity in the deep-time. Large uncertainty in paleo-CO2 estimates made using the paleosol-carbonate CO2-barometer, however, arises primarily from their sensitivity to soil-respired CO2 (S(z)). This parameter is poorly constrained due to a paucity of soil CO2 measurements during carbonate formation in modern soils and a lack of widely applicable proxies of paleo-soil CO2. Here the δ13C values of carbonate and soil organic matter (SOM) pairs from 130 Holocene soils are applied to a two-component CO2-mixing equation to define soil order-specific ranges of soil CO2 applicable for constraining S(z) in their corresponding paleosol analogs. Equilibrium carbonate-SOM pairs, characterized by Δ13Ccarb-SOM values of 12.2-15.8‰, define a mean effective fractionation of 14.1‰ and overall inferred total soil CO2 contents during calcite formation of Calcisols and Argillisols), a best estimate of S(z) during calcite formation is 1500-2000 ppmv (range of 500-2500 ppmv). Overall higher values (2000-5000 ppmv) are indicated by the subset of these soils characterized by higher moisture content and productivity. Near atmospheric levels (400 ± 200 ppmv) of estimated S(z) are indicated by immature soils, recording their low soil productivity. Vertisols define the largest range in total soil CO2 (25,000 ppmv) reflecting their seasonally driven dynamic hydrochemistry. A S(z) range of 1000-10,000 ppmv is suggested for paleo-Vertisols for which calcite precipitation can be constrained to have occurred in an open system with two-component CO2 mixing, with a best estimate of 2000 ppmv ± 1000 ppmv appropriate for paleo-Vertisols for which evidence of protracted water saturation is lacking. Mollisol pairs define a best estimate of S(z) of 2500 ppmv (range of 600-4000 ppmv) for late Cretaceous and Cenozoic analogs. Non-equilibrium pairs with Δ13C values >16

  11. Absorption and Decomposition of CO2 by Active Ferrites Prepared by Atmospheric Plasma Spraying

    Science.gov (United States)

    Li, Shaowei; He, Zhida; Zheng, Yanjun; Chen, Changfeng

    2015-12-01

    Active ferrites, which play an important role in the catalytic decomposition of CO2, have been fabricated by atmospheric plasma spraying to incorporate FeO and anoxic iron oxide [Fe3O4-δ (0 powder a greater ability to decompose CO2 when compared to hydrogen-reduced Fe3O4 or Fe2O3 particles. Spraying distance is found to play an important role in modulating the decomposition ability of the powders, while elevated temperatures can also enhance the catalytic decomposition of CO2.

  12. Atmospheric fossil fuel CO2 record in Debrecen city during the winter of 2008

    International Nuclear Information System (INIS)

    Complete text of publication follows. Fossil fuel CO2 content in the air of a major Hungarian city (Debrecen) was determined using together measurement of CO2 mixing ratio and radiocarbon (14C) content of air. In this project we developed a high precision atmospheric CO2 monitoring station in Debrecen. An integrating sampling system (developed by ATOMKI) was applied for radiocarbon measurements. One sampler was installed in Debrecen station and two independent 14CO2 sampling line were installed 300 km far from Debrecen at Hegyhatsal station as independent background references, where high precision atmospheric CO2 mixing ratio measurement is also running since 1997. During the winter of 2008/09 we measured the mixing ratio and radiocarbon content of atmospheric CO2 at Debrecen and the reference station simultaneously. It was concluded that trends in CO2 mixing ratio variations in time are very similar at the three different sampling points (3 m above ground in Debrecen, 10 m and 115 m above ground in Hegyhatsal). Air quality in Debrecen during September of 2008 seemed to be relatively clear from the point of view of its CO2 content at least When winter came closer in October, with lover outside temperature and less sunshine hours the CO2 content of air was increased in general at all the three sampling points, but this effect was more intensive closer to the ground level. According our radiocarbon observations it was clearly indicated that there was not significant amount of fossil fuel CO2 in the air of Debrecen during September in 2008. But during the winter of 2008/09 the Δ14C value of atmospheric CO2 of Debrecen decreased with more than 40 per mill relative to September's results, and according our calculations it was caused by about 20 ppm fossil fuel CO2 which appeared as a surplus amount in the air above the September level (Figure 1.). Acknowledgements This research project was supported by Hungarian NSF (Ref No. OTKA-F69029) and Isotoptech Zrt.

  13. Weathering by tree root-associating fungi diminishes under simulated Cenozoic atmospheric CO2 decline

    Directory of Open Access Journals (Sweden)

    J. Quirk

    2013-10-01

    Full Text Available Trees dominate terrestrial biotic weathering of silicate minerals by converting solar energy into chemical energy that fuels roots and their ubiquitous nutrient-mobilising fungal symbionts. These biological activities regulate atmospheric CO2 ([CO2]a over geologic timescales by driving calcium and magnesium fluvial ion export and marine carbonate formation, but the important stabilising feedbacks between [CO2]a and biotic weathering anticipated by geochemical carbon cycle models remain untested. We report experimental evidence for a negative feedback across a declining Cenozoic [CO2]a range from 1500 ppm to 200 ppm, whereby low [CO2]a curtails mineral surface alteration via trenching and etch pitting by arbuscular mycorrhizal (AM and ectomycorrhizal (EM fungal partners of tree roots. Optical profile imaging using vertical scanning interferometry reveals changes in nanoscale surface topography consistent with a dual mode of attack involving delamination and trenching by AM and EM fungal hyphae on phyllosilicate mineral flakes. This is consistent with field observations of micropores in feldspar, hornblende and basalt, purportedly caused by EM fungi, but with little confirmatory evidence. Integrating these findings into a process-based biotic weathering model revealed that low [CO2]a effectively acts as a "carbon starvation" brake, causing a three-fold drop in tree-driven fungal weathering fluxes of calcium and magnesium from silicate rock grains as [CO2]a falls from 1500 ppm to 200 ppm. The feedback is regulated through the action of low [CO2]a on host tree productivity and provides empirical evidence for the role of [CO2]a starvation in diminishing the contribution of trees and mycorrhizal fungi to rates of biological weathering. More broadly, diminished tree-driven weathering under declining [CO2]a may provide an important contributory mechanism stabilising Earth's [CO2]a minimum over the past 24 million years.

  14. Soil fertility limits carbon sequestration by forest ecosystems in a CO2-enriched atmosphere

    International Nuclear Information System (INIS)

    Northern mid-latitude forests are a larger terrestrial carbon sink. Ignoring nutrient limitations, large increases in carbon sequestration from carbon dioxide (CO2) fertilization are expected in these forests. Yet, forests are usually relegated to sites of moderate to poor fertility, where tree growth is often limited by nutrient supply, in particular nitrogen. Here we present evidence that estimates of increases in carbon sequestration of forests, which is expected to partially compensate for increasing CO2 in the atmosphere, are unduly optimistic. In two forest experiments on maturing pines exposed to elevated atmospheric CO2, the CO2-induced biomass carbon increment without added nutrients was undetectable at a nutritionally poor site, and the stimulation at a nutritionally moderate site was transient, stabilizing at a marginal gain after three years. However, a large synergistic gain from higher CO2 and nutrients was detected with nutrients added. This gain was even larger at the poor site (threefold higher than the expected additive effect) than at the moderate site (twofold higher). Thus, fertility can restrain the response of wood carbon sequestration to increased atmospheric CO2. Assessment of future carbon sequestration should consider the limitations imposed by soil fertility, as well as interactions with nitrogen deposition. (author)

  15. Why are Nitrogen Concentrations in Plant Tissues Lower under Elevated CO2? A Critical Examination of the Hypotheses

    Institute of Scientific and Technical Information of China (English)

    Daniel R. Taub; Xianzhong Wang

    2008-01-01

    Plants grown under elevated atmospheric [CO2] typically have decreased tissue concentrations of N compared with plants grown under current ambient [CO2]. The physiological mechanisms responsible for this phenomenon have not been definitely established, although a considerable number of hypotheses have been advanced to account for it. In this review we discuss and critically evaluate these hypotheses. One contributing factor to the decreases in tissue N concentrations clearly is dilution of N by increased photosynthetic assimilation of C. In addition, studies on intact plants show strong evidence for a general decrease in the specific uptake rates (uptake per unit mass or length of root) of N by roots under elevated CO2. This decreased root uptake appears likely to be the result both of decreased N demand by shoots and of decreased ability of the soil-root system to supply N. The best-supported mechanism for decreased N supply is a decrease in transpiration-driven mass flow of N in soils due to decreased stomatal conductance at elevated CO2, although some evidence suggests that altered root system architecture may also play a role. There is also limited evidence suggesting that under elevated CO2, plants may exhibit increased rates of N loss through volatilization and/or root exudation, further contributing to lowering tissue N concentrations.

  16. 大气14CO2观测:2010~2011年广州城市大气中化石源CO2浓度变化特征%Fossil fuel-derived CO2 contribution to the urban atmosphere in Guangzhou, South China by 14CO2 observation, 2010-2011

    Institute of Scientific and Technical Information of China (English)

    丁平; 沈承德; 易惟熙; 王宁; 丁杏芳; 付东坡; 刘克新

    2013-01-01

    中国科学院广州地球化学研究所(GIGCAS)大气CO2观测点的数据显示:2010年10月至2011年11月,该站点大气CO2浓度变化范围为460~550 mL/m3,月平均浓度介于470~530 mL/m3之间,呈现夏、秋季浓度低,春、冬季浓度较高的特点。大气CO2的δ13C值变化介于–9.00‰~–13.10‰之间,月平均值介于–9.60‰~–11.80‰之间,与大气 CO2浓度之间关系不显著,反映了人类活动对城市大气 CO2的影响。GIGCAS 站点大气CO2的Δ14C值波动剧烈,介于29.1‰~–85.2‰之间,月平均值波动范围为4.9‰~–41.7‰,年平均大气CO2的Δ14C值为–16.4‰。较高的Δ14C值出现在夏、秋两季(7~9月),均值约为–5.2‰,较低的Δ14C值出现在冬、春两季(12月至次年4月)、均值约为–27.1‰,据此计算得出的化石源CO2浓度变化范围为1~58 mL/m3,年平均值约24 mL/m3,较低的大气化石源CO2浓度出现在夏、秋两季(7~9月),均值为17 mL/m3,较高大气化石源CO2量出现在冬、春两季(12月至次年4月),均值约为29 mL/m3。气象条件和人类活动对城市大气化石源CO2浓度影响巨大,调整人类活动是减少大气化石源CO2污染的途径之一。%During October 2010 to November 2011, the urban atmospheric CO2 concentration observed in Guangzhou Institute of Geochemistry, Chinese Academy of Sciences in Guangzhou ranges from 550 mL/m3 to 460 mL/m3, with the monthly mean concentration fluctuating between 530 mL/m3 and 470 mL/m3. It shows lower concentrations in summer and autumn, and higher concentrations in spring and winter. The CO2δ13C values vary between –9.00‰ and –13.10‰, with the monthly mean values fluctuating between –9.60‰ and –11.80‰. The relationship between CO2 concentration and δ13C values is not significant, reflecting the influence from human activities on the urban atmospheric CO2. The Δ14C values of urban atmospheric CO2 in Guangzhou fluctuate dramatically from 29.1‰to–85.2‰, with

  17. Continental-scale enrichment of atmospheric 14CO2 from the nuclear power industry: potential impact on the estimation of fossil fuel-derived CO2

    OpenAIRE

    Graven, H. D.; Gruber, N.

    2011-01-01

    The 14C-free fossil carbon added to atmospheric CO2 by combustion dilutes the atmospheric 14C/C ratio (Δ14C), potentially providing a means to verify fossil CO2 emissions calculated using economic inventories. However, sources of 14C from nuclear power generation and spent fuel reprocessing can counteract this dilution and may bias 14C/C-based estimates of fossil fuel-derived CO2 if these nuclear influences are not correctly accounted for. Previous studies have examined nuclear influenc...

  18. O2/CO2气氛下火焰传播速度影响因素分析%Analysis of Influence Factors on Flame Speed Under O2/CO2 Atmosphere

    Institute of Scientific and Technical Information of China (English)

    钟孝蛟; 刘豪; 赵然; 王子剑; 胡翰; 闫志强; 邱建荣

    2011-01-01

    The flame propagation characteristic of hydrocarbons has a significant relationship with high CO2 concentrarion in an Oe/CO2 atmosphere. Laminar flame speed of C1-C7 n-alkanes were studied by detailed chemical kinetic models for O2/CO2 atmosphere, O2/N2 atmosphere and O2/ CO2/AR atmosphere respectively. The equivalence ratios were varied from 0.6 to 1.4 for initial pressure p=105 Pa, initial temperature T=298 K. The effects of equivalence ratio, O2 concentration, CO2 concentration and atmospheres on flame speed were explored. Results show that flame speed increases with equivalence ratio in fuel lean region, then decreases in the fuel rich region, and the maximum flame speed ap, pears at equivalence ratio 1.0 or 1.1. For the same O2 concentration, flame speed in an O2/CO2 atmosphere is markedly lower than that in O2/N2, which reveals that CO2 has a negative effect on flame propagation. Under O2/CO2/AR atmophere, flame speed decreases with increasing CO2 concentration, when O2 concentration remains unchanged. Besides, improving the O2 concentration in O2/CO2 atmosphere can increase flame speed, having a positive effect on n-alkanes combution process.%摘要:O2/CO2气 氛下高浓度CO2的存在对碳氢化合物的火焰传播特性有重要影响。基于化学动力学分析软件CHEMKIN对初始压力为10^5Pa,初始温度为298K,当量比为0.6~1.4的C1~C7直链烷烃在O2/CO2、O2/hi2、O2/CO2/AR气氛下的层流火焰传播速度进行模拟计算,探讨气氛、当量比、O2浓度、CO2浓度对火焰传播速度的影响规律。结果表明,火焰传播速度随当量比的增大而先增大后减小,火焰传播速度的最大值出现在当量比1.0或1.1处;在相同O2浓度下,O2/CO2气氛下火焰传播速度要比

  19. Assessing the near surface sensitivity of SCIAMACHY atmospheric CO2 retrieved using (FSI WFM-DOAS

    Directory of Open Access Journals (Sweden)

    N. Vinnichenko

    2007-07-01

    Full Text Available Satellite observations of atmospheric CO2 offer the potential to identify regional carbon surface sources and sinks and to investigate carbon cycle processes. The extent to which satellite measurements are useful however, depends on the near surface sensitivity of the chosen sensor. In this paper, the capability of the SCIAMACHY instrument on board ENVISAT, to observe lower tropospheric and surface CO2 variability is examined. To achieve this, atmospheric CO2 retrieved from SCIAMACHY near infrared (NIR spectral measurements, using the Full Spectral Initiation (FSI WFM-DOAS algorithm, is compared to in-situ aircraft observations over Siberia and additionally to tower and surface CO2 data over Mongolia, Europe and North America. Preliminary validation of daily averaged SCIAMACHY/FSI CO2 against ground based Fourier Transform Spectrometer (FTS column measurements made at Park Falls, reveal a negative bias of about −2.0% for collocated measurements within ±1.0° of the site. However, at this spatial threshold SCIAMACHY can only capture the variability of the FTS observations at monthly timescales. To observe day to day variability of the FTS observations, the collocation limits must be increased. Furthermore, comparisons to in-situ CO2 observations demonstrate that SCIAMACHY is capable of observing a seasonal signal that is representative of lower tropospheric variability on (at least monthly timescales. Out of seventeen time series comparisons, eleven have correlation coefficients of 0.7 or more, and have similar seasonal cycle amplitudes. Additional evidence of the near surface sensitivity of SCIAMACHY, is provided through the significant correlation of FSI derived CO2 with MODIS vegetation indices at over twenty selected locations in the United States. The SCIAMACHY/MODIS comparison reveals that at many of the sites, the amount of CO2 variability is coincident with the amount of vegetation activity. The presented analysis suggests that

  20. Assessing the near surface sensitivity of SCIAMACHY atmospheric CO2 retrieved using (FSI WFM-DOAS

    Directory of Open Access Journals (Sweden)

    N. Vinnichenko

    2007-02-01

    Full Text Available Satellite observations of atmospheric CO2 offer the potential to identify regional carbon surface sources and sinks and to investigate carbon cycle processes. The extent to which satellite measurements are useful however, depends on the near surface sensitivity of the chosen sensor. In this paper, the capability of the SCIAMACHY instrument on board ENVISAT, to observe lower tropospheric and surface CO2 variability is examined. To achieve this, atmospheric CO2 retrieved from SCIAMACHY near infrared (NIR spectral measurements, using the Full Spectral Initiation (FSI WFM-DOAS algorithm, is compared to in situ aircraft observations over Siberia and additionally to tower and surface CO2 data over Mongolia, Europe and North America. Preliminary validation of daily averaged SCIAMACHY/FSI CO2 against ground based Fourier Transform Spectrometer (FTS column measurements made at Park Falls, reveal a negative bias of about −2.0% for collocated measurements within ±1.0degree of the site. However, at this spatial threshold SCIAMACHY can only capture the variability of the FTS observations at monthly timescales. To observe day to day variability of the FTS observations, the collocation limits must be increased. Furthermore, comparisons to in-situ CO2 observations demonstrate that SCIAMACHY is capable of observing lower tropospheric variability on (at least monthly timescales. Out of seventeen time series comparisons, eleven have correlation coefficients of 0.7 or more, and have similar seasonal cycle amplitudes. Additional evidence of the near surface sensitivity of SCIAMACHY, is provided through the significant correlation of FSI derived CO2 with MODIS vegetation indices at over twenty selected locations in the United States. The SCIAMACHY/MODIS comparison reveals that at many of the sites, the amount of CO2 variability is coincident with the amount of vegetation activity. It is evident, from this analysis, that SCIAMACHY therefore has the potential to

  1. The impact on atmospheric CO2 of iron fertilization induced changes in the ocean's biological pump

    Directory of Open Access Journals (Sweden)

    J. C. McWilliams

    2007-10-01

    Full Text Available Using numerical simulations, we quantify the impact of changes in the ocean's biological pump on the air-sea balance of CO2 by fertilizing a small surface patch in the high-nutrient, low-chlorophyll region of the eastern tropical Pacific with iron. Decade-long fertilization experiments are conducted in a basin-scale, eddy-permitting coupled physical biogeochemical ecological model. In contrast to previous studies, we find that most of the dissolved inorganic carbon (DIC removed from the euphotic zone by the enhanced biological export is replaced by uptake of CO2 from the atmosphere. Atmospheric uptake efficiencies, the ratio of the perturbation in air-sea CO2 flux to the perturbation in export flux across 100 m, are 0.75 to 0.93 in our patch size-scale experiments. The atmospheric uptake efficiency is insensitive to the duration of the experiment. The primary factor controlling the atmospheric uptake efficiency is the vertical distribution of the enhanced biological production. Iron fertilization at the surface tends to induce production anomalies primarily near the surface, leading to high efficiencies. In contrast, mechanisms that induce deep production anomalies (e.g. altered light availability tend to have a low uptake efficiency, since most of the removed DIC is replaced by lateral and vertical transport and mixing. Despite high atmospheric uptake efficiencies, patch-scale iron fertilization of the ocean's biological pump tends to remove little CO2 from the atmosphere over the decadal timescale considered here.

  2. VUV-absorption cross section of CO2 at high temperatures and impact on exoplanet atmospheres

    Directory of Open Access Journals (Sweden)

    Venot Olivia

    2014-02-01

    Full Text Available Ultraviolet (UV absorption cross sections are an essential ingredient of photochemical atmosphere models. Exoplanet searches have unveiled a large population of short-period objects with hot atmospheres, very different from what we find in our solar system. Transiting exoplanets whose atmospheres can now be studied by transit spectroscopy receive extremely strong UV fluxes and have typical temperatures ranging from 400 to 2500 K. At these temperatures, UV photolysis cross section data are severely lacking. Our goal is to provide high-temperature absorption cross sections and their temperature dependency for important atmospheric compounds. This study is dedicated to CO2, which is observed and photodissociated in exoplanet atmospheres. We performed these measurements for the 115 - 200 nm range at 300, 410, 480, and 550 K. In the 195 - 230 nm range, we worked at seven temperatures between 465 and 800 K. We found that the absorption cross section of CO2 is very sensitive to temperature, especially above 160 nm. Within the studied range of temperature, the CO2 cross section can vary by more than two orders of magnitude. This, in particular, makes the absorption of CO2 significant up to wavelengths as high as 230 nm, while it is negligible above 200 nm at 300 K. To investigate the influence of these new data on the photochemistry of exoplanets, we implemented the measured cross section into a 1D photochemical model. The model predicts that accounting for this temperature dependency of CO2 cross section can affect the computed abundances of NH3, CO2, and CO by one order of magnitude in the atmospheres of hot Jupiter and hot Neptune.

  3. [Variation of CO2 concentration in solar greenhouse in Northern China].

    Science.gov (United States)

    Wei, Min; Xing, Yuxian; Wang, Xiufeng; Ma, Hong

    2003-03-01

    The variation of CO2 concentration in winter-spring cultivated solar greenhouse in northern China was studied. The diurnal change of CO2 concentration showed an irregular 'U' shape in most case, the maximum value appeared prior to unveiling straw mat in the morning, and the minimum between 12:00 and 14:00 PM. Sometimes, an irregular 'W' shape curve with two valleys was also observed, with the first one appeared prior to the ventilation at noon, and the second occurred between 15:00-16:30 PM. During the period of winter-spring cultivation, the daily maximum concentration of CO2 in solar greenhouse decreased gradually, while the daily minimum concentration and daytime average concentration dropped first, then went up. At the same time, the time of CO2 depletion lasted longer and longer. In December, CO2 depletion happened 2.1-3.1 hours after morning unveiling. In the next March, however, it moved up to 0.6-1.1 hours after unveiling in the morning. At daytime, both during and after ventilation, solar greenhouse often showed CO2 depletion. The period of CO2 depletion extended from 4-5.8 hours per day in December to 8-8.5 hours per day in March of next year. The spacial distribution of CO2 concentrations within the greenhouse showed that in the morning and in the evening, the order was the front > the middle > the back, and the ground > the canopy > the upper, and at midday, the order was the front the upper > the canopy. Photon flux density was the most important environmental factor affecting CO2 concentration in greenhouse. Ventilation did not avoided CO2 depletion. Canopy photosynthetic rate and soil respiratory rate were measured at different growth stages of tomato. At seedling stage, CO2 concentration in greenhouse was higher than that outside, due to the vigorous soil respiration and lower canopy photosynthetic rate. But at fruiting stage, severe CO2 depletion occurred because of stronger canopy photosynthesis and weak soil respiration. PMID:12836540

  4. 14C concentration of liberated CO2 in the free fermentation process of Japanese SAKE brewing

    International Nuclear Information System (INIS)

    The daily variation of 14C concentrations of liberated CO2 in the free fermentation process of Japanese SAKE brewing was studied. Each of the concentrations measured in the initial and final stages of the fermentation process correlated with levels of koji rice and steamed rice, obtained from different areas and used for SAKE production. This shows that analysis of fermenting CO2 of SAKE could be used to estimate the 14C level in a local environment. (author) 4 refs.; 1 tab

  5. Regulation of hormonal responses of sweet pepper as affected by salinity and elevated CO2 concentration.

    Science.gov (United States)

    Piñero, María Carmen; Houdusse, Fabrice; Garcia-Mina, Jose M; Garnica, María; Del Amor, Francisco M

    2014-08-01

    This study examines the extent to which the predicted CO2 -protective effects on the inhibition of growth, impairment of photosynthesis and nutrient imbalance caused by saline stress are mediated by an effective adaptation of the endogenous plant hormonal balance. Therefore, sweet pepper plants (Capsicum annuum, cv. Ciclón) were grown at ambient or elevated [CO2] (400 or 800 µmol mol(-1)) with a nutrient solution containing 0 or 80 mM NaCl. The results show that, under saline conditions, elevated [CO2] increased plant dry weight, leaf area, leaf relative water content and net photosynthesis compared with ambient [CO2], whilst the maximum potential quantum efficiency of photosystem II was not modified. In salt-stressed plants, elevated [CO2 ] increased leaf NO3(-) concentration and reduced Cl(-) concentration. Salinity stress induced ABA accumulation in the leaves but it was reduced in the roots at high [CO2], being correlated with the stomatal response. Under non-stressed conditions, IAA was dramatically reduced in the roots when high [CO2] was applied, which resulted in greater root DW and root respiration. Additionally, the observed high CK concentration in the roots (especially tZR) could prevent downregulation of photosynthesis at high [CO2], as the N level in the leaves was increased compared with the ambient [CO2], under salt-stress conditions. These results demonstrate that the hormonal balance was altered by the [CO2], which resulted in significant changes at the growth, gas exchange and nutritional levels. PMID:24152078

  6. 低浓度 CO2捕集的吸收率测算%Absorption rate measurement and calculation of low-concentration CO2 capture technical

    Institute of Scientific and Technical Information of China (English)

    马超援

    2016-01-01

    The paper introduces low-concentration CO2 absorbinf methods,describes the measurement and calculation methods of low-concentra-tion CO2 capture technical and explores the elements of determininf absorbinf afent,which has certain meaninf for control indoor CO2 concentration.%介绍了常用的低浓度 CO2气体吸收方法,就低浓度 CO2捕集吸收率的测算方法进行了阐述,并探讨了确定吸收剂的要素,对室内 CO2浓度的控制有一定的意义。

  7. Response of Sphagnum mosses to increased CO2 concentration and nitrogen deposition

    International Nuclear Information System (INIS)

    The main objective of this work was to study the effects of different CO2 concentration and N deposition rates on Sphagna adapted to grow along a nutrient availability gradient (i.e. ombrotrophy-mesotrophy-eutrophy). The study investigated: (i) the effects of various longterm CO2 concentrations on the rate of net photosynthesis in Sphagna, (ii) the effects of the CO2 and N treatments on the moss density, shoot dry masses, length increment and dry mass production in Sphagna, (iii) the concentrations of the major nutrients in Sphagna after prolonged exposure to the CO2 and N treatments, and (iv) species dependent differences in potential NH4+ and NO3- uptake rates. The internal nutrient concentration of the capitulum and the production of biomass were effected less by the elevated CO2 concentrations because the availability of N was a controlling factor. In addition responses to the N treatments were related to ecological differences between the Sphagna species. Species with a high tolerance of N availability were able to acclimatise to the increased N deposition rates. The data suggests a high nutrient status is less significant than the adaptation of the Sphagna to their ecological niche (e.g. low tolerance of meso-eutrophic S. warnstorfii to high N deposition rate). At the highest N deposition rate the ombrotrophic S. fuscum had the highest increase in tissue N concentration among the Sphagna studied. S. fuscum almost died at the highest N deposition rate because of the damaging effects of N to the plant's metabolism. Ombrotrophic hummock species such as S. fuscum, were also found to have the highest potential N uptake rate (on density of dry mass basis) compared to lawn species. The rate of net photosynthesis was initially increased with elevated CO2 concentrations, but photosynthesis was down regulated with prolonged exposure to CO2. The water use efficiency in Sphagna appeared not to be coupled with exposure to the long-term CO2 concentration. The effects of CO

  8. VUV-absorption cross section of CO2 at high temperatures and impact on exoplanet atmospheres

    CERN Document Server

    Venot, Olivia; Bénilan, Yves; Gazeau, Marie-Claire; Hébrard, Eric; Larcher, Gwenaelle; Schwell, Martin; Dobrijevic, Michel; Selsis, Franck

    2015-01-01

    Ultraviolet (UV) absorption cross sections are an essential ingredient of photochemical atmosphere models. Exoplanet searches have unveiled a large population of short-period objects with hot atmospheres, very different from what we find in our solar system. Transiting exoplanets whose atmospheres can now be studied by transit spectroscopy receive extremely strong UV fluxes and have typical temperatures ranging from 400 to 2500 K. At these temperatures, UV photolysis cross section data are severely lacking. Our goal is to provide high-temperature absorption cross sections and their temperature dependency for important atmospheric compounds. This study is dedicated to CO2, which is observed and photodissociated in exoplanet atmospheres. We performed these measurements for the 115 - 200 nm range at 300, 410, 480, and 550 K. In the 195 - 230 nm range, we worked at seven temperatures between 465 and 800 K. We found that the absorption cross section of CO2 is very sensitive to temperature, especially above 160 nm....

  9. Effects of simulated spring thaw of permafrost from mineral cryosol on CO2 emissions and atmospheric CH4 uptake

    Science.gov (United States)

    Stackhouse, Brandon T.; Vishnivetskaya, Tatiana A.; Layton, Alice; Chauhan, Archana; Pfiffner, Susan; Mykytczuk, Nadia C.; Sanders, Rebecca; Whyte, Lyle G.; Hedin, Lars; Saad, Nabil; Myneni, Satish; Onstott, Tullis C.

    2015-09-01

    Previous studies investigating organic-rich tundra have reported that increasing biodegradation of Arctic tundra soil organic carbon (SOC) under warming climate regimes will cause increasing CO2 and CH4 emissions. Organic-poor, mineral cryosols, which comprise 87% of Arctic tundra, are not as well characterized. This study examined biogeochemical processes of 1 m long intact mineral cryosol cores (1-6% SOC) collected in the Canadian high Arctic. Vertical profiles of gaseous and aqueous chemistry and microbial composition were related to surface CO2 and CH4 fluxes during a simulated spring/summer thaw under light versus dark and in situ versus water saturated treatments. CO2 fluxes attained 0.8 ± 0.4 mmol CO2 m-2 h-1 for in situ treatments, of which 85 ± 11% was produced by aerobic SOC oxidation, consistent with field observations and metagenomic analyses indicating aerobic heterotrophs were the dominant phylotypes. The Q10 values of CO2 emissions ranged from 2 to 4 over the course of thawing. CH4 degassing occurred during initial thaw; however, all cores were CH4 sinks at atmospheric concentration CH4. Atmospheric CH4 uptake rates ranged from -126 ± 77 to -207 ± 7 nmol CH4 m-2 h-1 with CH4 consumed between 0 and 35 cm depth. Metagenomic and gas chemistry analyses revealed that high-affinity Type II methanotrophic sequence abundance and activity were highest between 0 and 35 cm depth. Microbial sulfate reduction dominated the anaerobic processes, outcompeting methanogenesis for H2 and acetate. Fluxes, microbial community composition, and biogeochemical rates indicate that mineral cryosols of Axel Heiberg Island act as net CO2 sources and atmospheric CH4 sinks during summertime thaw under both in situ and water saturated states.

  10. Effect of urban parks on CO2 concentrations in Toluca, Mexico

    Science.gov (United States)

    Vieyra Gómez, J. A.; González Sosa, E.; Mastachi-Loza, C. A.; Cervantes, M.; Martínez Valdéz, H.

    2013-05-01

    Despite green areas are used for amusement, they have several benefits such as: microclimate regulation, groundwater recharge, noise abatement, oxygen production and CO2 capture. The last one has a notable importance, as CO2 is considered to be one of the most pollutant gases of the greenhouse effect. The city of Toluca, has a considerable urban growth. However, there are few studies aimed to assess the importance of the green areas in urban locations. About this, it is estimated than only 4m2/hab of vegetal coverage is found in big cities, which means a 50% deficit according to the international standards.The aim of this study was to assess the urban parks impact in Toluca, as regulators of CO2 means through measurements in autumn-winter seasonal period, 2012-2013.It was performed 20 measurements in 4 local parks (Urawa, Alameda, Municipal and Metropolitano), in order to evaluate the possible effect of urban parks on CO2 concentrations. Transects were made inside and outside the parks and the CO2 concentrations were registered by a portable quantifier (GMP343).The data analysis allowed the separation of the parks based on CO2 concentrations; however, it was perceived a decreasing of CO2 inside the parks (370ppm), between 10 and 40 ppm less than those areas with traffic and pedestrians (399 ppm).

  11. Climate-vegetation modelling and fossil plant data suggest low atmospheric CO2 in the late Miocene

    Science.gov (United States)

    Forrest, M.; Eronen, J. T.; Utescher, T.; Knorr, G.; Stepanek, C.; Lohmann, G.; Hickler, T.

    2015-12-01

    There is an increasing need to understand the pre-Quaternary warm climates, how climate-vegetation interactions functioned in the past, and how we can use this information to understand the present. Here we report vegetation modelling results for the Late Miocene (11-7 Ma) to study the mechanisms of vegetation dynamics and the role of different forcing factors that influence the spatial patterns of vegetation coverage. One of the key uncertainties is the atmospheric concentration of CO2 during past climates. Estimates for the last 20 million years range from 280 to 500 ppm. We simulated Late Miocene vegetation using two plausible CO2 concentrations, 280 ppm CO2 and 450 ppm CO2, with a dynamic global vegetation model (LPJ-GUESS) driven by climate input from a coupled AOGCM (Atmosphere-Ocean General Circulation Model). The simulated vegetation was compared to existing plant fossil data for the whole Northern Hemisphere. For the comparison we developed a novel approach that uses information of the relative dominance of different plant functional types (PFTs) in the palaeobotanical data to provide a quantitative estimate of the agreement between the simulated and reconstructed vegetation. Based on this quantitative assessment we find that pre-industrial CO2 levels are largely consistent with the presence of seasonal temperate forests in Europe (suggested by fossil data) and open vegetation in North America (suggested by multiple lines of evidence). This suggests that during the Late Miocene the CO2 levels have been relatively low, or that other factors that are not included in the models maintained the seasonal temperate forests and open vegetation.

  12. Drought × CO2 interactions in trees: a test of the low-intercellular CO2 concentration (Ci ) mechanism.

    Science.gov (United States)

    Kelly, Jeff W G; Duursma, Remko A; Atwell, Brian J; Tissue, David T; Medlyn, Belinda E

    2016-03-01

    Models of tree responses to climate typically project that elevated atmospheric CO2 concentration (eCa ) will reduce drought impacts on forests. We tested one of the mechanisms underlying this interaction, the 'low Ci effect', in which stomatal closure in drought conditions reduces the intercellular CO2 concentration (Ci ), resulting in a larger relative enhancement of photosynthesis with eCa , and, consequently, a larger relative biomass response. We grew two Eucalyptus species of contrasting drought tolerance at ambient and elevated Ca for 6-9 months in large pots maintained at 50% (drought) and 100% field capacity. Droughted plants did not have significantly lower Ci than well-watered plants, which we attributed to long-term changes in leaf area. Hence, there should not have been an interaction between eCa and water availability on biomass, and we did not detect one. The xeric species did have higher Ci than the mesic species, indicating lower water-use efficiency, but both species exhibited similar responses of photosynthesis and biomass to eCa , owing to compensatory differences in the photosynthetic response to Ci . Our results demonstrate that long-term acclimation to drought, and coordination among species traits may be important for predicting plant responses to eCa under low water availability. PMID:26526873

  13. Daily European CO2 fluxes inferred by inversion of atmospheric transport

    Science.gov (United States)

    Bousquet, P.; Peylin, P.; Rayner, P.; Carouge, C.; Rivier, L.; Ciais, P.; Heinrich, P.; Hourdin, F.

    2002-12-01

    Continuous measurements of atmospheric CO2 over continental areas offer the potential to better understand the carbon fluxes between the terrestrial biosphere and the atmosphere. Up to now, most atmospheric inversions have provided monthly fluxes averaged over large sub continental regions. Refining space and time resolution of European fluxes calculated by inversion of atmospheric transport requires i) continuous CO2 measurements over Europe, ii) a high resolution transport model that can reproduce the variability of CO2 over continents and provide continuous response functions at model resolution, and iii) an updated inverse procedure that can use the increased associated information. We use here continuous CO2 measurements obtained through AEROCARB EU project (part of CARBOEUROPE cluster) for year 1998 at 10 continental stations to retrieve daily fluxes over Europe at model resolution with LMDZ transport model. LMDZ model is a global transport model with zoom and back-transport capabilities. A zoom was defined over Europe, with 0.4° maximum resolution. Back transport is based on self-adjoint property of atmospheric transport that makes it possible to get model daily response functions at model resolution and at low computing cost. In this talk, we present the new features of the inverse procedure and we detail the LMDZ back transport. First results obtained for daily European fluxes of the two last months of 1998 are presented and analysed. The question of retrieving fossil emissions from continuous measurements is also developed.

  14. Global carbon - nitrogen - phosphorus cycle interactions: A key to solving the atmospheric CO2 balance problem?

    Science.gov (United States)

    Peterson, B. J.; Mellillo, J. M.

    1984-01-01

    If all biotic sinks of atmospheric CO2 reported were added a value of about 0.4 Gt C/yr would be found. For each category, a very high (non-conservative) estimate was used. This still does not provide a sufficient basis for achieving a balance between the sources and sinks of atmospheric CO2. The bulk of the discrepancy lies in a combination of errors in the major terms, the greatest being in a combination of errors in the major terms, the greatest being in the net biotic release and ocean uptake segments, but smaller errors or biases may exist in calculations of the rate of atmospheric CO2 increase and total fossil fuel use as well. The reason why biotic sinks are not capable of balancing the CO2 increase via nutrient-matching in the short-term is apparent from a comparison of the stoichiometry of the sources and sinks. The burning of fossil fuels and forest biomass releases much more CO2-carbon than is sequestered as organic carbon.

  15. Evaluating Satellite Observed CO2 Column by a 3-D Atmospheric Transport Model

    International Nuclear Information System (INIS)

    Satellite remote sensing is the latest method of measuring atmospheric CO2, which covers a wide range and makes periodic observation. But due to lack of ground-based observation sites, global satellite observed CO2 column is not evaluated efficiently. This paper assess the applicability of using GEOS-Chem model to forward simulate atmospheric CO2 for verifying Greenhouse Gas Observation SATellite (GOSAT) observed CO2 column. It is shown that GEOS-Chem performs well in modelling atmospheric CO2 and there are generally no significant differences between ground-based observation and model results. According to the comparsion, the spatial and temporal distribution of XCO2 agrees well between GOSAT and GEOS-Chem. GOSAT XCO2 is turned out to be 2.6 ppm lower than the model results. The mean difference observed between GOSAT and GEOS-Chem varies from −1.8 to −3.1 ppm seasonally, with the standard deviation ranging from 1.4 to 2.1 ppm. And in general, the difference is larger in summer than that in winter, in land area than in sea area. It might have been caused by the different land-sea distribution and eco-system's changing with seasons

  16. Effects of Atmospheric CO2 Enrichment, Applied Nitrogen and Soil Moisture on Dry Matter Accumulation and Nitrogen Uptake in Spring Wheat

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Spring wheat (Triticum aestivum L. cv. Dingxi No. 8654) was treated with two concentrations of atmospheric COz (350 and 700 μmol mol-1), two levels of soil moisture (well-watered and drought) and five rates of nitrogen fertilizer (0, 50, 100, 150, and 200 mg kg-1 soil) to study the atmospheric CO2 concentration effect on dry matter accumulation and N uptake of spring wheat. The effects of CO2 enrichment on the shoot and total mass depended largely on soil nitrogen level, and the shoot and total mass increased significantly in the moderate to high N treatments but did not increase significantly in the low N treatment. Enriched CO2concentration did not increase more shoot and total mass in the drought treatment than in the well-watered treatment. Thus, elevated CO2 did not ameliorate the depressive effects of drought and nitrogen stress. In addition, root mass decreased slightly and root/shoot ratio decreased significantly due to CO2 enrichment in no N treatment under well-watered condition. Enriched CO2 decreased shoot N content and shoot and total N uptake; but it reduced root N content and uptake slightly. Shoot critical N concentration was lower for spring wheat grown at 700 μmol mol-1 CO2 than at 350 μmol mol-1 CO2 in both well-watered and drought treatments. The critical N concentrations were 16 and 19 g kg-1 for the well-watered treatment and drought treatment at elevated CO2 and 21 and 26 g kg-1 at ambient CO2, respectively. The reductions in the movement of nutrients to the plant roots through mass flow due to the enhancement in WUE (water use efficiency) and the increase in N use efficiency at elevated CO2 could elucidate the reduction of shoot and root N concentrations.

  17. Dynamics of dimethylsulphoniopropionate and dimethylsulphide under different CO2 concentrations during a mesocosm experiment

    Directory of Open Access Journals (Sweden)

    C. LeQuéré

    2008-03-01

    Full Text Available The potential impact of seawater acidification on the concentrations of dimethylsulfide (DMS and dimethylsulfoniopropionate (DMSP, and the activity of the enzyme DMSP-lyase was investigated during a pelagic ecosystem CO2 enrichment experiment (PeECE III in spring 2005. Natural phytoplankton blooms were studied for 24 days under present, double and triple partial pressures of CO2 (pCO2; pH=8.3, 8.0, 7.8 in triplicate 25 m3 enclosures. The results indicate similar DMSP concentrations and DMSP-lyase activity (DLA patterns for all treatments. Hence, DMSP and DLA do not seem to have been affected by the CO2 treatment. In contrast, DMS concentrations showed small but statistically significant differences in the temporal development of the low versus the high CO2 treatments. The low pCO2 enclosures had higher DMS concentrations during the first 10 days, after which the levels decreased earlier and more rapidly than in the other treatments. Integrated over the whole study period, DMS concentrations were not significantly different from those of the double and triple pCO2 treatments. Pigment and flow-cytometric data indicate that phytoplanktonic populations were generally similar between the treatments, suggesting a certain resilience of the marine ecosystem under study to the induced pH changes, which is reflected in DMSP and DLA. However, there were significant differences in bacterial community structure and the abundance of one group of viruses infecting nanoeukaryotic algae. The amount of DMS accumulated per total DMSP or chlorophyll-a differed significantly between the present and future scenarios, suggesting that the pathways for DMS production or bacterial DMS consumption were affected by seawater pH. A comparison with previous work (PeECE II suggests that DMS concentrations do not respond consistently to pelagic ecosystem CO2 enrichment experiments.

  18. Reconstructing CO2 concentrations in basaltic melt inclusions using Raman analysis of vapor bubbles

    Science.gov (United States)

    Aster, Ellen M.; Wallace, Paul J.; Moore, Lowell R.; Watkins, James; Gazel, Esteban; Bodnar, Robert J.

    2016-09-01

    Melt inclusions record valuable information about pre-eruptive volatile concentrations of melts. However, a vapor bubble commonly forms in inclusions after trapping, and this decreases the dissolved CO2 concentration in the melt (glass) phase in the inclusion. To quantify CO2 loss to vapor bubbles, Raman spectroscopic analysis was used to determine the density of CO2 in bubbles in melt inclusions from two Cascade cinder cones near Mt. Lassen and two Mexican cinder cones (Jorullo, Parícutin). Using analyses of dissolved CO2 and H2O in the glass in the inclusions, the measured CO2 vapor densities were used to reconstruct the original dissolved CO2 contents of the melt inclusions at the time of trapping. Our results show that 30-90% of the CO2 in a melt inclusion is contained in the vapor bubble, values similar to those found in other recent studies. We developed a model for vapor bubble growth to show how post-entrapment bubbles form in melt inclusions as a result of cooling, crystallization, and eruptive quenching. The model allows us to predict the bubble volume fraction as a function of ΔT (the difference between the trapping temperature and eruptive temperature) and the amount of CO2 lost to a bubble. Comparison of the Raman and modeling methods shows highly variable agreement. For 10 of 17 inclusions, the two methods are within ± 550 ppm CO2 (avg. difference 290 ppm), equivalent to ±~300 bars uncertainty in estimated trapping pressure for restored inclusions. Discrepancies between the two methods occur for inclusions that have been strongly affected by post-entrapment diffusive H+ loss, because this process enhances bubble formation. For our dataset, restoring the CO2 lost to vapor bubbles increases inferred trapping pressures of the inclusions by 600 to as much as 4000 bars, highlighting the importance of accounting for vapor bubble formation in melt inclusion studies.

  19. Declining Atmospheric pCO2 During the Late Miocene and Early Pliocene: New Insights from Paired Alkenone and Coccolith Stable Isotope Barometry

    Science.gov (United States)

    Phelps, S. R.; Polissar, P. J.; deMenocal, P. B.; Swann, J. P.; Guo, M. Y.; Stoll, H. M.

    2015-12-01

    The relationship between atmospheric CO2 concentrations and climate is broadly understood for the Cenozoic era: warmer periods are associated with higher atmospheric carbon dioxide. This understanding is supported by atmospheric samples of the past 800,000 years from ice cores, which suggest CO2 levels play a key role in regulating global climate on glacial interglacial timescales as well. In this context, the late Miocene poses a challenge: sea-surface temperatures indicate substantial global warmth, though existing data suggest atmospheric CO2 concentrations were lower than pre-industrial values. Recent work using the stable carbon and oxygen isotopic composition of coccolith calcite has demonstrated these organisms began actively diverting inorganic carbon away from calcification and to the site of photosynthesis during the late Miocene. This process occurs in culture experiments in response to low aqueous CO2 concentrations, and suggests decreasing atmospheric pCO2 values during the late Miocene. Here we present new data from ODP Site 806 in the western equatorial Pacific Ocean that supports declining atmospheric CO2 across the late Miocene. Carbon isotope values of coccolith calcite from Site 806 demonstrate carbon limitation and re-allocation of inorganic carbon to photosynthesis starting between ~8 and 6 Ma. The timing of this limitation at Site 806 precedes shifts at other ODP sites, reflecting the higher mixed layer temperature and resultant lower CO2 solubility at Site 806. New measurements of carbon isotope values from alkenones at Site 806 show an increase in photosynthetic carbon fractionation (ɛp) accompanied the carbon limitation evident from coccolith calcite stable isotope data. While higher ɛp is typically interpreted as higher CO2 concentrations, at Site 806, our data suggest it reflects enhancement of chloroplast CO2 from active carbon transport by the coccolithophore algae in response to lower CO2 concentrations. Our new data from ODP Site

  20. The concentration and efflux of tree stem CO2 and the role of xylem sap flow

    Institute of Scientific and Technical Information of China (English)

    Ping ZHAO; Dirk H(O)LSCHER

    2009-01-01

    The accurate assessment of actual tree stem respiration and its relation with temperature plays a considerable role in investigating the forest carbon cycle.An increasing number of research reports have indicated that tree stem respiration determined with the commonlyapplied chamber gas exchange measuring system does not follow expectations regarding temperature relationships.theory that the respired CO2 in a tree stem would all diffuse outward into the atmosphere,However,it neglects partial CO2 that is dissolved in the xylem sap and is carried away by the transpirational stream.Scientists have started to realize that the respired CO2 measured with the chamber gas exchange method is only a portion of the total stem respiration (CO2 efflux),while the other portion,which is sometimes very substantial in quantity (thought to occupy maybe 15%-75% of the total stem respiration),is transported to the upper part of the stem and to the canopy by sap flow.This suggests that the CO2 produced by respiration is re-allocated within the stem.Accordingly,the change in CO2 efflux could be reflected in the rates of sap flow in addition to its dependence on temperature.Proper methods and instruments are required to quantify the internal and external CO2 fluxes in the trunk and their interaction with related environmental factors.

  1. NO emission characteristics of superfine pulverized coal combustion in the O2/CO2 atmosphere

    International Nuclear Information System (INIS)

    Highlights: • Superfine pulverized coal combustion in O2/CO2 atmosphere is a new promising technology. • NO emissions of superfine pulverized coal combustion in O2/CO2 mixture were focused. • Coal particle sizes have significant effects on NO emissions in O2/CO2 combustion. - Abstract: The combination of O2/CO2 combustion and superfine pulverized coal combustion technology can make full use of their respective merits, and solve certain inherent disadvantages of each technology. The technology of superfine pulverized coal combustion in the O2/CO2 atmosphere is easy and feasible to be retrofitted with few reconstructions on the existing devices. It will become a useful and promising method in the future. In this paper, a one-dimensional drop-tube furnace system was adopted to study the NO emission characteristics of superfine pulverized coal combustion in the O2/CO2 atmosphere. The effects of coal particle size, coal quality, furnace temperature, stoichiometric ratio, etc. were analyzed. It is important to note that coal particle sizes have significant influence on NO emissions in the O2/CO2 combustion. For the homogeneous NO reduction, smaller coal particles can inhibit the homogeneous NO formations under fuel-rich combustion conditions, while it becomes disadvantageous for fuel-lean combustion. However, under any conditions, heterogeneous reduction is always more significant for smaller coal particle sizes, which have smoother pore surfaces and simpler pore structures. The results from this fundamental research will provide technical support for better understanding and developing this new combustion process

  2. Biomass Energy for Transport and Electricity: Large scale utilization under low CO2 concentration scenarios

    Energy Technology Data Exchange (ETDEWEB)

    Luckow, Patrick; Wise, Marshall A.; Dooley, James J.; Kim, Son H.

    2010-01-25

    This paper examines the potential role of large scale, dedicated commercial biomass energy systems under global climate policies designed to stabilize atmospheric concentrations of CO2 at 400ppm and 450ppm. We use an integrated assessment model of energy and agriculture systems to show that, given a climate policy in which terrestrial carbon is appropriately valued equally with carbon emitted from the energy system, biomass energy has the potential to be a major component of achieving these low concentration targets. The costs of processing and transporting biomass energy at much larger scales than current experience are also incorporated into the modeling. From the scenario results, 120-160 EJ/year of biomass energy is produced by midcentury and 200-250 EJ/year by the end of this century. In the first half of the century, much of this biomass is from agricultural and forest residues, but after 2050 dedicated cellulosic biomass crops become the dominant source. A key finding of this paper is the role that carbon dioxide capture and storage (CCS) technologies coupled with commercial biomass energy can play in meeting stringent emissions targets. Despite the higher technology costs of CCS, the resulting negative emissions used in combination with biomass are a very important tool in controlling the cost of meeting a target, offsetting the venting of CO2 from sectors of the energy system that may be more expensive to mitigate, such as oil use in transportation. The paper also discusses the role of cellulosic ethanol and Fischer-Tropsch biomass derived transportation fuels and shows that both technologies are important contributors to liquid fuels production, with unique costs and emissions characteristics. Through application of the GCAM integrated assessment model, it becomes clear that, given CCS availability, bioenergy will be used both in electricity and transportation.

  3. Capability of Raman lidar for monitoring the variation of atmospheric CO2 profile

    Institute of Scientific and Technical Information of China (English)

    Zhao Pei-Tao; Zhang Yin-Chao; Wang Lian; Hu Shun-Xing; Su Jia; Cao Kai-Fa; Zhao Yue-Feng; Hu Huan-Ling

    2008-01-01

    Lidar (Light detection and ranging) has special capabilities for remote sensing of many different behaviours of the atmosphere.One of the techniques which show a great deal of promise for several applications is Raman scattering.The detecting capability,including maximum operation range and minimum detectable gas concentration is one of the most significant parameters for lidar remote sensing of pollutants.In this paper,based on the new method for evaluating the capabilities of a Raman lidar system,we present an evaluation of detecting capability of Raman lidar for monitoring atmospheric CO2 in Hefei.Numerical simulations about the influence of atmospheric conditions on lidar detecting capability were carried out,and a conclusion can be drawn that the maximum difference of the operation ranges caused by the weather conditions alone can reach about 0.4 to 0.5kin with a measuring precision within 30ppmv.The range of minimum detectable concentration caused by the weather conditions alone can reach about 20 to 35 ppmv in vertical direction for 20000 shots at a distance of 1 km on the assumption that other parameters are kept constant.The other corresponding parameters under different conditions are also given.The capability of Raman lidar operated in vertical direction was found to be superior to that operated in horizontal direction.During practical measurement with the Raman lidar whose hardware components were fixed,aerosol scattering extinction effect would be a significant factor that influenced the capability of Raman lidar.This work may be a valuable reference for lidar system designing,measurement accuracy improving and data processing.

  4. Capability of Raman lidar for monitoring the variation of atmospheric CO2 profile

    International Nuclear Information System (INIS)

    Lidar (Light detection and ranging) has special capabilities for remote sensing of many different behaviours of the atmosphere. One of the techniques which show a great deal of promise for several applications is Raman scattering. The detecting capability, including maximum operation range and minimum detectable gas concentration is one of the most significant parameters for lidar remote sensing of pollutants. In this paper, based on the new method for evaluating the capabilities of a Raman lidar system, we present an evaluation of detecting capability of Raman lidar for monitoring atmospheric CO2 in Hefei. Numerical simulations about the influence of atmospheric conditions on lidar detecting capability were carried out, and a conclusion can be drawn that the maximum difference of the operation ranges caused by the weather conditions alone can reach about 0.4 to 0.5km with a measuring precision within 30ppmv. The range of minimum detectable concentration caused by the weather conditions alone can reach about 20 to 35 ppmv in vertical direction for 20000 shots at a distance of 1 km on the assumption that other parameters are kept constant. The other corresponding parameters under different conditions are also given. The capability of Raman lidar operated in vertical direction was found to be superior to that operated in horizontal direction. During practical measurement with the Raman lidar whose hardware components were fixed, aerosol scattering extinction effect would be a significant factor that influenced the capability of Raman lidar. This work may be a valuable reference for lidar system designing, measurement accuracy improving and data processing

  5. Atmosphere-based estimates of non-CO2 greenhouse gas emissions for the U.S. derived from 14CO2 during 2009-2012.

    Science.gov (United States)

    Montzka, S. A.; Miller, J. B.; Lehman, S.; Miller, B.; Hu, L.; Andrews, A. E.; Sweeney, C.; Dlugokencky, E. J.; Southon, J. R.; Wolak, C.; Elkins, J. W.; Tans, P. P.; Turnbull, J. C.; LaFranchi, B. W.; Guilderson, T. P.; Fischer, M. L.

    2014-12-01

    Atmospheric measurements of trace gases with 'known' emissions provide a means to derive emission magnitudes of other simultaneously measured trace gases, provided sources are co-located and co-varying. Here we consider atmospheric mixing ratio covariations in the fossil fuel derived component of observed CO2 (Cff; derived from high-precision measurements of the radiocarbon fraction of atmospheric CO2) relative to more than 20 other anthropogenic trace gases including CO, CH4, N2O, SF6, and halo- and hydro-carbons over large industrialized land areas. Pairing Cff with boundary-layer concentration enhancements of these gases allows us to determine apparent emission ratios for each gas with respect to Cff. When combined with sample-specific model-derived spatial footprints and the relatively accurate U.S. inventory of fossil fuel emissions (i.e., estimated uncertainty of ±10%), absolute emission rates for the correlate gases are derived. Here we will present U.S. annual emission magnitudes for select gases based on year-round measurements from tall towers and aircraft profiling sites in California, Texas, the mid-west, south-east and north-east for the 2009-2012 period. Statistically significant and coherent spatial and seasonal patterns in emission ratios and absolute emissions are determined for many gases based on these measurements. For HFC-134a and HCFC-22, results derived with this approach generally agree very well with an independent Bayesian-inversion based analysis of the larger number of samples collected and analyzed in our network, but that are not paired with Cff measurements. We believe this approach provides reliable 'top down', observationally-based emission estimates for these gases, many of which influence climate, air quality and stratospheric ozone.

  6. Feeding a Gas Turbine with Aluminum Plant Exhaust for Increased CO2 Concentration in Capture Plant

    OpenAIRE

    Jordal, Kristin; Anantharaman, Rahul; Genrup, Magnus; Aarhaug, Thor Anders; Bakken, Jørn; Lilliestråle, Astrid; Mejdell, Thor; Holt, Nancy J.

    2015-01-01

    Aluminum production contributes to global CO2 emissions both due to the production process itself and due to the generation of electric power required for aluminum production. A concept is presented for increasing the CO2 concentration in the aluminum exhaust from ∼1% to ∼5% through the feeding of aluminum plant exhaust gas to a natural gas combined cycle (NGCC). The specific energy demand for CO2 capture is therewith reduced for both the aluminum plant and the NGCC. An evaluation was made of...

  7. Impact of optimized mixing heights on simulated regional atmospheric transport of CO2

    Directory of Open Access Journals (Sweden)

    R. Kretschmer

    2014-02-01

    Full Text Available The mixing height (MH is a crucial parameter in commonly used transport models that proportionally affects air concentrations of trace gases with sources/sinks near the ground and on diurnal scales. Past synthetic data experiments indicated the possibility to improve tracer transport by minimizing errors of simulated MHs. In this paper we evaluate a method to constrain the Langrangian particle dispersion model STILT (Stochastic Time-Inverted Lagrangian Transport with MH diagnosed from radiosonde profiles using a bulk Richardson method. The same method was used to obtain hourly MHs for the period September/October 2009 from the Weather Research and Forecasting (WRF model, which covers the European continent at 10 km horizontal resolution. Kriging with External Drift (KED was applied to estimate optimized MHs from observed and modelled MHs, which were used as input for STILT to assess the impact on CO2 transport. Special care has been taken to account for uncertainty in MH retrieval in this estimation process. MHs and CO2 concentrations were compared to vertical profiles from aircraft in-situ data. We put an emphasis on testing the consistency of estimated MHs to observed vertical mixing of CO2. Modelled CO2 was also compared with continuous measurements made at Cabauw and Heidelberg stations. WRF MHs were significantly biased by ~10–20% during day and ~40–60% during night. Optimized MHs reduced this bias to ~5% with additional slight improvements in random errors. The KED MHs were generally more consistent with observed CO2 mixing. The use of optimized MHs had in general a favourable impact on CO2 transport, with bias reductions of 5–45% (day and 60–90% (night. This indicates that a large part of the found CO2 model-data mismatch was indeed due to MH errors. Other causes for CO2 mismatch are discussed. Applicability of our method is discussed in the context of CO2 inversions at regional scales.

  8. Impact of optimized mixing heights on simulated regional atmospheric transport of CO2

    Directory of Open Access Journals (Sweden)

    R. Kretschmer

    2014-07-01

    Full Text Available The mixing height (MH is a crucial parameter in commonly used transport models that proportionally affects air concentrations of trace gases with sources/sinks near the ground and on diurnal scales. Past synthetic data experiments indicated the possibility to improve tracer transport by minimizing errors of simulated MHs. In this paper we evaluate a method to constrain the Lagrangian particle dispersion model STILT (Stochastic Time-Inverted Lagrangian Transport with MH diagnosed from radiosonde profiles using a bulk Richardson method. The same method was used to obtain hourly MHs for the period September/October 2009 from the Weather Research and Forecasting (WRF model, which covers the European continent at 10 km horizontal resolution. Kriging with external drift (KED was applied to estimate optimized MHs from observed and modelled MHs, which were used as input for STILT to assess the impact on CO2 transport. Special care has been taken to account for uncertainty in MH retrieval in this estimation process. MHs and CO2 concentrations were compared to vertical profiles from aircraft in situ data. We put an emphasis on testing the consistency of estimated MHs to observed vertical mixing of CO2. Modelled CO2 was also compared with continuous measurements made at Cabauw and Heidelberg stations. WRF MHs were significantly biased by ~10–20% during day and ~40–60% during night. Optimized MHs reduced this bias to ~5% with additional slight improvements in random errors. The KED MHs were generally more consistent with observed CO2 mixing. The use of optimized MHs had in general a favourable impact on CO2 transport, with bias reductions of 5–45% (day and 60–90% (night. This indicates that a large part of the found CO2 model–data mismatch was indeed due to MH errors. Other causes for CO2 mismatch are discussed. Applicability of our method is discussed in the context of CO2 inversions at regional scales.

  9. Effects of elevated atmospheric CO2, prolonged summer drought and temperature increase on N2O and CH4 fluxes in a temperate heathland

    DEFF Research Database (Denmark)

    Carter, Mette Sustmann; Ambus, Per; Albert, Kristian Rost;

    2011-01-01

    change manipulations were initiated. The soil was generally a net sink for atmospheric CH4. Elevated temperature (T) increased the CH4 uptake by on average 10 μg C m−2 h−1, corresponding to a rise in the uptake rate of about 20%. However, during winter elevated CO2 (CO2) reduced the CH4 uptake, which......In temperate regions, climate change is predicted to increase annual mean temperature and intensify the duration and frequency of summer droughts, which together with elevated atmospheric carbon dioxide (CO2) concentrations, may affect the exchange of nitrous oxide (N2O) and methane (CH4) between...

  10. Stabilization of CO2 Atmospheres on Exoplanets around M Dwarf Stars

    CERN Document Server

    Gao, Peter; Robinson, Tyler D; Li, Cheng; Yung, Yuk L

    2015-01-01

    We investigate the chemical stability of CO2-dominated atmospheres of M dwarf terrestrial exoplanets using a 1-dimensional photochemical model. On planets orbiting Sun-like stars, the photolysis of CO2 by Far-UV (FUV) radiation is balanced by the reaction between CO and OH, the rate of which depends on H2O abundance. By comparison, planets orbiting M dwarf stars experience higher FUV radiation compared to planets orbiting Sun-like stars, and they are also likely to have low H2O abundance due to M dwarfs having a prolonged, high-luminosity pre-main sequence (Luger & Barnes 2015). We show that, for H2O-depleted planets around M dwarfs, a CO2-dominated atmosphere is stable to conversion to CO and O2 by relying on a catalytic cycle involving H2O2 photolysis. However, this cycle breaks down for planets with atmospheric hydrogen mixing ratios below ~1 ppm, resulting in ~40% of the atmospheric CO2 being converted to CO and O2 on a time scale of 1 Myr. The increased abundance of O2 also results in high O3 concent...

  11. Prebiotic synthesis in atmospheres containing CH4, CO, and CO2. I - Amino acids

    Science.gov (United States)

    Schlesinger, G.; Miller, S. L.

    1983-01-01

    The prebiotic synthesis of amino acids, HCN, H2CO, and NH3 using a spark discharge on various simulated primitive earth atmospheres at 25 C is investigated. Various mixtures of CH4, CO, CO2, N2, NH3, H2O, and H2 were utilized in different experiments. The yields of amino acids (1.2-4.7 percent based on the carbon) are found to be approximately independent of the H2/CH4 ratio and the presence of NH3, and a wide variety of amino acids are obtained. Glycine is found to be almost the only amino acid produced from CO and CO2 model atmospheres, with the maximum yield being about the same for the three carbon sources at high H2/carbon ratios,whereas CH4 is superior at low H2/carbon ratios. In addition, it is found that the directly synthesized NH3 together with the NH3 obtained from the hydrolysis of HCN, nitriles, and urea could have been a major source of ammonia in the atmosphere and oceans of the primitive earth. It is determined that prebiotic syntheses from HCN and H2CO to give products such as purines and sugars and some amino acids could have occurred in primitive atmospheres containing CO and CO2 provided the H2/CO and H2/CO2 ratios were greater than about 1.0.

  12. Liquid water on Mars - An energy balance climate model for CO2/H2O atmospheres

    Science.gov (United States)

    Hoffert, M. I.; Callegari, A. J.; Hsieh, C. T.; Ziegler, W.

    1981-01-01

    A simple climatic model is developed for a Mars atmosphere containing CO2 and sufficient liquid water to account for the observed hydrologic surface features by the existence of a CO2/H2O greenhouse effect. A latitude-resolved climate model originally devised for terrestrial climate studies is applied to Martian conditions, with the difference between absorbed solar flux and emitted long-wave flux to space per unit area attributed to the divergence of the meridional heat flux and the poleward heat flux assumed to equal the atmospheric eddy heat flux. The global mean energy balance is calculated as a function of atmospheric pressure to assess the CO2/H2O greenhouse liquid water hypothesis, and some latitude-resolved cases are examined in detail in order to clarify the role of atmospheric transport and temperature-albedo feedback. It is shown that the combined CO2/H2O greenhouse at plausible early surface pressures may account for climates hot enough to support a hydrological cycle and running water at present-day insolation and visible albedo levels.