Science.gov

Sample records for atmospheric co2 variations

  1. Seasonal and interannual variations of atmospheric CO2 and climate

    USGS Publications Warehouse

    Dettinger, M.D.; Ghil, M.

    1998-01-01

    Interannual variations of atmospheric CO2 concentrations at Mauna Loa are almost masked by the seasonal cycle and a strong trend; at the South Pole, the seasonal cycle is small and is almost lost in the trend and interannual variations. Singular-spectrum analysis (SSA) issued here to isolate and reconstruct interannual signals at both sites and to visualize recent decadal changes in the amplitude and phase of the seasonal cycle. Analysis of the Mauna Loa CO2 series illustrates a hastening of the CO2 seasonal cycle, a close temporal relation between Northern Hemisphere (NH) mean temperature trends and the amplitude of the seasonal CO2 cycle, and tentative ties between the latter and seasonality changes in temperature over the NH continents. Variations of the seasonal CO2 cycle at the South Pole differ from those at Mauna Loa: it is phase changes of the seasonal cycle at the South Pole, rather than amplitude changes, that parallel hemispheric and global temperature trends. The seasonal CO2 cycles exhibit earlier occurrences of the seasons by 7 days at Mauna Loa and 18 days at the South Pole. Interannual CO2 variations are shared at the two locations, appear to respond to tropical processes, and can be decomposed mostly into two periodicities, around (3 years)-1 and (4 years)-1, respectively. Joint SSA analyses of CO2 concentrations and tropical climate indices isolate a shared mode with a quasi-triennial (QT) period in which the CO2 and sea-surface temperature (SST) participation are in phase opposition. The other shared mode has a quasi-quadrennial (QQ) period and CO2 variations are in phase with the corresponding tropical SST variations throughout the tropics. Together these interannual modes exhibit a mean lag between tropical SSTs and CO2 variations of about 6-8 months, with SST leading. Analysis of the QT and QQ signals in global gridded SSTs, joint SSA of CO2 and ??13C isotopic ratios, and SSA of CO2 and NH-land temperatures indicate that the QT variations in

  2. Influence of Atmospheric CO2 Variation on Strom Track Behavior

    NASA Astrophysics Data System (ADS)

    Martynova, Yuliya; Krupchatnikov, Vladimir

    2015-04-01

    The storm tracks are the regions of strong baroclinicity where surface cyclones occur. The effect of increase with following decrease of anthropogenic load on storm tracks activity in the Northern Hemisphere was studied. The global climate system model of intermediate complexity ('Planet Simulator', Fraedrich K. et al., 2005) was used in this study. Anthropogenic forcing was set according to climatic scenario RCP8.5 continued till 4000 AD with fixed CO2 concentration till 3000 AD and linear decrease of anthropogenic load to preindustrial value at two different rates: for 100 and 1000 years. Modeling data analysis showed meridional shift of storm tracks due to atmospheric CO2 concentration variation. When CO2 concentration increases storm tracks demonstrate poleward shifting. When CO2 concentration decreases to preindustrial value storm tracks demonstrate a tendency to equator-ward shifting. Storm tracks, however, don't recover their original activity and location to the full. This manifests itself particularly for 'fast' CO2 concentration decrease. Heat and moisture fluxes demonstrate the same behavior. In addition, analysis of eddy length scale (Kidston J. Et al., 2011) showed their increase at mid-latitudes and decrease at tropic latitudes due to intensive CO2 concentration increase. This might cause poleward shift of mid-latitude jets. Acknowledgements. This work is partially supported by SB RAS project VIII.80.2.1, RFBR grant 13-05-12034, 13-05-00480, 14-05-00502 and grant of the President of the Russian Federation. Fraedrich K., Jansen H., Kirk E., Luksch U., and Lunkeit F. The Planet Simulator: Towards a user friendly model // Meteorol. Zeitschrift. 2005, 14, 299-304. Kidston J., Vallis G.K., Dean S.M., Renwick J.A. Can the increase in the eddy length scale ander global warming cause the poleward shift of the jet streams? // J. Climate. 2011, V.24. P. 3764-3780.

  3. Biodynamic mechanism of variations of the atmospheric CO2 concentration

    NASA Astrophysics Data System (ADS)

    Lapenis, A. G.

    1988-06-01

    Using Lapenis's (1986) five-zone model of the world ocean, it is shown that changes in the production of lime plankton caused by changes in the oceanic water circulation during ice ages could significantly affect the oceanic calcium and carbon balances. Changes in Ca and C occurring in surface waters due to glaciation would in turn cause significant declines in atmospheric CO2. A decrease in the atmospheric CO2 would cause additional cooling of the earth surface during ice ages.

  4. Genotypic variation in physiological and growth responses of Populus tremuloides to elevated atmospheric CO2 concentration.

    PubMed

    Wang, X; Curtis, P S; Pregitzer, K S; Zak, D R

    2000-09-01

    Physiological and biomass responses of six genotypes of Populus tremuloides Michx., grown in ambient t (357 micromol mol(-1)) or twice ambient (707 micromol mol(-1)) CO2 concentration ([CO2]) and in low-N or high-N soils, were studied in 1995 and 1996 in northern Lower Michigan, USA. There was a significant CO2 x genotype interaction in photosynthetic responses. Net CO2 assimilation (A) was significantly enhanced by elevated [CO2] for five genotypes in high-N soil and for four genotypes in low-N soil. Enhancement of A by elevated [CO2] ranged from 14 to 68%. Genotypes also differed in their biomass responses to elevated [CO2], but biomass responses were poorly correlated with A responses. There was a correlation between magnitude of A enhancement by elevated [CO2] and stomatal sensitivity to CO2. Genotypes with low stomatal sensitivity to CO2 had a significantly higher A at elevated [CO2] than at ambient [CO2], but elevated [CO2] did not affect the ratio of intercellular [CO2] to leaf surface [CO2]. Stomatal conductance and A of different genotypes responded differentially to recovery from drought stress. Photosynthetic quantum yield and light compensation point were unaffected by elevated [CO2]. We conclude that P. tremuloides genotypes will respond differentially to rising atmospheric [CO2], with the degree of response dependent on other abiotic factors, such as soil N and water availability. The observed genotypic variation in growth could result in altered genotypic representation within natural populations and could affect the composition and structure of plant communities in a higher [CO2] environment in the future.

  5. Effect on atmospheric CO2 from seasonal variations in the high latitude ocean

    NASA Technical Reports Server (NTRS)

    Volk, Tyler

    1989-01-01

    Data from the North Pacific gyre, Bering Sea, and North Atlantic show large seasonal fluctuations in the pCO2 of surface waters. The seasonal variation in these latitudes apparently has a generic pattern: higher surface water pCO2 in winter and lower in summer. Satellite data will eventually help decipher the relative effects of temperature and biological production in the seasonal carbon cycle, but as yet little work has been done on what possible role the seasonality of pCO2 in the high latitudes might have on the average value of atmospheric pCO2. A model is developed that shows the average value for atmospheric pCO2 depends upon the ratio of the rates at which the ocean/atmosphere system moves toward equilibrium values during the summer and winter conditions of the high latitude ocean.

  6. Effect on atmospheric CO2 from seasonal variations in the high latitude ocean

    NASA Technical Reports Server (NTRS)

    Volk, Tyler

    1989-01-01

    Data from the North Pacific gyre, Bering Sea, and North Atlantic show large seasonal fluctuations in the pCO2 of surface waters. The seasonal variation in these latitudes apparently has a generic pattern: higher surface water pCO2 in winter and lower in summer. Satellite data will eventually help decipher the relative effects of temperature and biological production in the seasonal carbon cycle, but as yet little work has been done on what possible role the seasonality of pCO2 in the high latitudes might have on the average value of atmospheric pCO2. A model is developed that shows the average value for atmospheric pCO2 depends upon the ratio of the rates at which the ocean/atmosphere system moves toward equilibrium values during the summer and winter conditions of the high latitude ocean.

  7. [Diurnal and seasonal variations of surface atmospheric CO2 concentration in the river estuarine marsh].

    PubMed

    Zhang, Lin-Hai; Tong, Chuan; Zeng, Cong-Sheng

    2014-03-01

    Characteristics of diurnal and seasonal variations of surface atmospheric CO2 concentration were analyzed in the Minjiang River estuarine marsh from December 2011 to November 2012. The results revealed that both the diurnal and seasonal variation of surface atmospheric CO2 concentration showed single-peak patterns, with the valley in the daytime and the peak value at night for the diurnal variations, and the maxima in winter and minima in summer for the seasonal variation. Diurnal amplitude of CO2 concentration varied from 16.96 micromol x mol(-1) to 38.30 micromol x mol(-1). The seasonal averages of CO2 concentration in spring, summer, autumn and winter were (353.74 +/- 18.35), (327.28 +/- 8.58), (354.78 +/- 14.76) and (392.82 +/- 9.71) micromol x mol(-1), respectively, and the annual mean CO2 concentration was (357.16 +/- 26.89) micromol x mol(-1). The diurnal CO2 concentration of surface atmospheric was strongly negatively correlated with temperature, wind speed, photosynthetically active radiation and total solar radiation (P < 0.05). The diurnal concentration of CO2 was negatively related with tidal level in January, but significantly positively related in July.

  8. Changes in the High-latitude Ocean as Possible Causes of Atmospheric CO2 Variations

    NASA Technical Reports Server (NTRS)

    Siegenthaler, U.

    1984-01-01

    Measurements on air enclosed in old polar ice have indicated that the atmospheric CO2 concentration was ca. 50 to 70 ppm lower in late glacial times than during the Holocene. Similar measurements performed on samples from a Greenland ice core, dating ca. 30,000 to 40,000 B.P., and have yielded evidence of several CO2 oscillations with an amplitude of ca. 50 ppm. Each change lasted on the order of a few centuries. A mechanism by which circulation changes in the high-latitude ocean could lead to rapid variations in atmospheric CO2 is proposed. In the Antarctic Ocean a slowing down of the vertical mixing would imply a smaller upward flux of sigma CO2 and nutrients. Assuming constant productivity, sigma CO2 and nutrients would be more completely used which would imply lower CO2 in these high-latitude surface waters. In areas with a warm surface, a slowing down of the circulation would not have a direct impact on CO2 because productivity would automatically decrease by the same factor as the upwelling rate of nutrients. Studies with a simple box model of the ocean-atmosphere system suggest that a suddent decrease by a factor of 2 of the water exchange between the surface and deep sea in high latitudes could lead to a CO2 decrease of ca. 40 to 50 ppm with a time constant of ca. 200 years. Deep-sea sediment studies indicate rapid changes in the high-latitude surface conditions of the North Atlantic and the Antarctic Oceans at the end of the last glaciation. Studies of carbon isotope ratios should help ascertain whether this proposed mechanism was indeed responsible for the CO2 variation.

  9. Changes in the High-latitude Ocean as Possible Causes of Atmospheric CO2 Variations

    NASA Technical Reports Server (NTRS)

    Siegenthaler, U.

    1984-01-01

    Measurements on air enclosed in old polar ice have indicated that the atmospheric CO2 concentration was ca. 50 to 70 ppm lower in late glacial times than during the Holocene. Similar measurements performed on samples from a Greenland ice core, dating ca. 30,000 to 40,000 B.P., and have yielded evidence of several CO2 oscillations with an amplitude of ca. 50 ppm. Each change lasted on the order of a few centuries. A mechanism by which circulation changes in the high-latitude ocean could lead to rapid variations in atmospheric CO2 is proposed. In the Antarctic Ocean a slowing down of the vertical mixing would imply a smaller upward flux of sigma CO2 and nutrients. Assuming constant productivity, sigma CO2 and nutrients would be more completely used which would imply lower CO2 in these high-latitude surface waters. In areas with a warm surface, a slowing down of the circulation would not have a direct impact on CO2 because productivity would automatically decrease by the same factor as the upwelling rate of nutrients. Studies with a simple box model of the ocean-atmosphere system suggest that a suddent decrease by a factor of 2 of the water exchange between the surface and deep sea in high latitudes could lead to a CO2 decrease of ca. 40 to 50 ppm with a time constant of ca. 200 years. Deep-sea sediment studies indicate rapid changes in the high-latitude surface conditions of the North Atlantic and the Antarctic Oceans at the end of the last glaciation. Studies of carbon isotope ratios should help ascertain whether this proposed mechanism was indeed responsible for the CO2 variation.

  10. Interannual variations in δ18O of Atmospheric CO2 and its correlation to hydrological changes

    NASA Astrophysics Data System (ADS)

    Buenning, N. H.; Noone, D. C.; Still, C. J.; Riley, W. J.

    2009-12-01

    Measurements of the δ18O value of CO2 at the NOAA/ESRL baseline observatories showed a gradual downward trend for most of the 1990s and a slight increase after 2000. The exact cause of these variations is not well understood, although this could be due to a change in the isotopic composition of the terrestrial water pools with which CO2 interacts during photosynthesis and respiration, particularly within the tropics, where the largest isotope C18OO forcing occurs. There are a number of factors that affect the isotopic composition of soil and leaf water; however, studies have indicated that relative humidity has a strong impact on the isotopic composition of water pools. While increases in humidity would increase stomatal conductance and in turn increase biospheric productivity, it also will cause leaves to take in more of the isotopically light water vapor, causing the leaf water to become less enriched in 18O. This study correlates the observed δ18O values of atmospheric CO2 from Mauna Loa with observed station relative humidity from WMO’s Global Summaries of the Day. Six regions were identified as having a robust negative correlation between relative humidity and the δ18O value of atmospheric CO2, supporting the hypothesis that near surface relative humidity is a strong control. Two of these regions are within the tropics: Southeast Asia and the tropical Americas. The correlations are largely a result of an increase in relative humidity during the 1990s, followed by a decrease after 2000. The magnitude of the relative humidity variations ranges between 5-20%, which would cause a change in the isotopic composition of leaf water (and subsequently the δ18O value of leaf CO2 fluxes) by about 1.8-7.4‰ assuming the Craig-Gordon relationship. This change is large considering the observed variation in δ18O-CO2 values at Mauna Loa is about 0.8‰. However, leaf CO2 fluxes in these regions only make up a fraction of the world’s total CO2 flux, and the resulting

  11. [Near surface atmospheric CO2 variations in autumn at suburban Xiamen, China].

    PubMed

    Li, Yan-li; Mu, Chao; Deng, Jun-jun; Zhao, Shu-hui; Du, Ke

    2013-05-01

    Near surface concentrations of carbon dioxide (CO2) were measured at the super station of atmospheric monitoring located at the suburban area of Xiamen in the fall of 2011. The results were analyzed together with the meteorological data and concentrations of other gaseous pollutants to study the diurnal variations of near-surface atmospheric CO2 concentration and the relationships of CO, with wind speed and gaseous pollutants. The diurnal variation of CO2 concentrations showed a single-peak pattern with the highest value (408.54 micromol x mol(-1)) observed in dawn when the atmosphere was stable and the lowest value (379.14 micromol x mol(-1)) was recorded in late afternoon following several hours of relatively unstable condition. The average CO, concentration at night (400.87 +/- 4.05) micromol.mol(-1) was higher than that of daytime (388.8 +/- 9.40) micromol c mol(-1). Overall, the COz concentrations ranged from 375.74 micromol.mol(-1) to 418.18 micromol x mol(-1). CO2 and wind speed showed opposite trends. At night the CO2 concentration (400.72 +/- 2.12) micromol x mol(-1) was stable with wind speed of 1.0-1.5 m x s(-1). During daytime, the CO2 concentrations 379.14-394.83 micromol x mol(-1) were more variable with wind speed of 2.0-2.5 m x s(-1). The background CO2 concentration of this site was estimated to be 386.84 micromol x mol(-1) using an exponential function model. Northeast wind was dominant at this site. The correlation coefficient between the wind speed and the CO2 concentrations (r = -0.67, P < 0.01) was higher for wind direction of NE than other directions (r = -0.41, P < 0.01). The source contributions were different for different wind directions. Moreover, the CO2 concentration had a significant negative correlation with temperature and irradiation, and had a significant positive correlation with humidity. CO2 had a higher correlation with primary air pollutants CO and NO (r = 0.469/0.436, P < 0.01) than SO2 (r = 0.126, P < 0.01), indicating that

  12. [Temporal variation of background atmospheric CO2 and CH4 at Mount Waliguan, China].

    PubMed

    Liu, Peng; Zhang, Guo-qing; Wang, Jian-qiong; Wu, Hao; Li, Bao-xin; Wang, Ning-zhang

    2014-09-01

    In this paper, the continuous (2009-2010) measurement of atmospheric CO2 and CH4 from the Mount Waliguan Baseline Observatory of Western China are presented. The results show that about 17% of CO2 observations are classified as polluted due to more frequently influence of regional emission on local measurement in summer time. The mean concentration of CO2 measured at the period of 2009 to 2010 was 390.72 x 10(-6) which was 17.4 x 10(-6) higher than that measured from 1995 to 2008, and the median concentration of CH4 was 1851.11 x 10(-9) which was 16 x 10(-9) higher than that from 2002 to 2006, which implied that the regional emission of CO2 and CH4 was continuously increased. The unavailable data were filled by back propagation neural network (BPNN) and optimized by genetic algorithm (GA) , which were analyzed by the Fourier analysis of time series of air temperature, wind speed, concentration of CO2 and CH4. At the daily time scale, strong spectrum peak occurred and concentration recorded at periods of 12 and 24 hours,due to the daily sun activity changes. At the monthly time scale, the spectrum gap occurred in CO2 concentration at periods of 30 day suggesting that the effect of meteorological and phenological factors on the variation of CO2 concentration was insignificant.

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

    NASA Astrophysics Data System (ADS)

    Morimoto, Shinji; Nakazawa, Takakiyo; Aoki, Shuji; Hashida, Gen; Yamanouchi, Takashi

    2003-04-01

    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-1. 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.

  14. Atmospheric CO2 variations on millennial-scale during MIS 6

    NASA Astrophysics Data System (ADS)

    Shin, Jinhwa; Grilli, Roberto; Chappellaz, Jérôme; Teste, Grégory; Nehrbass-Ahles, Christoph; Schmidely, Loïc; Schmitt, Jochen; Stocker, Thomas; Fischer, Hubertus

    2017-04-01

    Understanding natural carbon cycle / climate feedbacks on various time scales is highly important for predicting future climate changes. Paleoclimate records of Antarctic temperatures, relative sea level and foraminiferal isotope and pollen records in sediment cores from the Portuguese margin have shown climate variations on millennial time scale over the Marine Isotope Stage 6 (MIS 6; from approximately 135 to 190 kyr BP). These proxy data suggested iceberg calving in the North Atlantic result in cooling in the Northern hemisphere and warming in Antarctica by changes in the Atlantic Meridional Overturning Circulation, which is explained by a bipolar see-saw trend in the ocean (Margari et al., 2010). Atmospheric CO2 reconstruction from Antarctic ice cores can provide key information on how atmospheric CO2 concentrations are linked to millennial-scale climate changes. However, existing CO2 records cannot be used to address this relationship because of the lack of suitable temporal resolution. In this work, we will present a new CO2 record with an improved time resolution, obtained from the Dome C ice core (75˚ 06'S, 123˚ 24'E) spanning the MIS 6 period, using dry extraction methods. We will examine millennial-scale features in atmospheric CO2, and their possible links with other proxies covering MIS 6. Margari, V., Skinner, L. C., Tzedakis, P. C., Ganopolski, A., Vautravers, M., and Shackleton, N. J.: The nature of millennial scale climate variability during the past two glacial periods, Nat.Geosci., 3, 127-131, 2010.

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

    NASA Astrophysics Data System (ADS)

    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

  16. Variations in atmospheric CO2 growth rates coupled with tropical temperature

    PubMed Central

    Wang, Weile; Ciais, Philippe; Nemani, Ramakrishna R.; Canadell, Josep G.; Piao, Shilong; Sitch, Stephen; White, Michael A.; Hashimoto, Hirofumi; Milesi, Cristina; Myneni, Ranga B.

    2013-01-01

    Previous studies have highlighted the occurrence and intensity of El Niño–Southern Oscillation as important drivers of the interannual variability of the atmospheric CO2 growth rate, but the underlying biogeophysical mechanisms governing such connections remain unclear. Here we show a strong and persistent coupling (r2 ≈ 0.50) between interannual variations of the CO2 growth rate and tropical land–surface air temperature during 1959 to 2011, with a 1 °C tropical temperature anomaly leading to a 3.5 ± 0.6 Petagrams of carbon per year (PgC/y) CO2 growth-rate anomaly on average. Analysis of simulation results from Dynamic Global Vegetation Models suggests that this temperature–CO2 coupling is contributed mainly by the additive responses of heterotrophic respiration (Rh) and net primary production (NPP) to temperature variations in tropical ecosystems. However, we find a weaker and less consistent (r2 ≈ 0.25) interannual coupling between CO2 growth rate and tropical land precipitation than diagnosed from the Dynamic Global Vegetation Models, likely resulting from the subtractive responses of tropical Rh and NPP to precipitation anomalies that partly offset each other in the net ecosystem exchange (i.e., net ecosystem exchange ≈ Rh − NPP). Variations in other climate variables (e.g., large-scale cloudiness) and natural disturbances (e.g., volcanic eruptions) may induce transient reductions in the temperature–CO2 coupling, but the relationship is robust during the past 50 y and shows full recovery within a few years after any such major variability event. Therefore, it provides an important diagnostic tool for improved understanding of the contemporary and future global carbon cycle. PMID:23884654

  17. The 1994 to 2008 concentration variations of atmospheric CO2 observed at Jubany Station (Antarctica)

    NASA Astrophysics Data System (ADS)

    Gallo, Veronica; de Simone, Sara; Ciattaglia, Luigi; Rafanelli, Claudio; Diego, Piero

    2010-05-01

    Since 1994 the Italian PNRA (National Research Program in Antarctica) and the Argentina DNA (Direction National de Antartico) have been collecting continuous atmospheric carbon dioxide measurements at Jubany. The Antarctic station at Jubany (62° 14'S, 58° 40'W) is located in King George Island, in the South Shetland archipelago, north of the Antarctic Peninsula. The laboratory is situated at an elevation of 15 m.s.l. on the SE slope of Potter Bay. The measurements are taken by using a Siemens U5 analyzer based on NDIR (Non Dispersive InfraRed) absorption method. Details are given on the station environment, meteorological conditions, instrumentation, and data selection strategy. The paper presents the first 14 years (1994-2008) of continuous atmospheric CO2 measurements; the interannual and seasonal variations of CO2 data are described

  18. Marginal Lands Gross Primary Production Dominate Atmospheric CO2 Interannual Variations

    NASA Astrophysics Data System (ADS)

    Ahlström, A.; Raupach, M. R.; Schurgers, G.; Arneth, A.; Jung, M.; Reichstein, M.; Smith, B.

    2014-12-01

    Since the 1960s terrestrial ecosystems have acted as a substantial sink for atmospheric CO2, sequestering about one quarter of anthropogenic emissions in an average year. Variations in this land carbon sink are also responsible for most of the large interannual variability in atmospheric CO2 concentrations. While most evidence places the majority of the sink in highly productive forests and at high latitudes experiencing warmer and longer growing seasons, the location and the processes governing the interannual variations are still not well characterised. Here we evaluate the hypothesis that the long-term trend and the variability in the land CO2 sink are respectively dominated by geographically distinct regions: the sink by highly productive lands, mainly forests, and the variability by semi-arid or "marginal" lands where vegetation activity is strongly limited by water and therefore responds strongly to climate variability. Using novel analysis methods and data from both upscaled flux-tower measurements and a dynamic global vegetation model, we show that (1) the interannual variability in the terrestrial CO2 sink arises mainly from variability in terrestrial gross primary production (GPP); (2) most of the interannual variability in GPP arises in tropical and subtropical marginal lands, where negative anomalies are driven mainly by warm, dry conditions and positive anomalies by cool, wet conditions; (3) the variability in the GPP of high-latitude marginal lands (tundra and shrublands) is instead controlled by temperature and light, with warm bright conditions resulting in positive anomalies. The influence of ENSO (El Niño-Southern Oscillation) on the growth rate of atmospheric CO2 concentrations is mediated primarily through climatic effects on GPP in marginal lands, with opposite signs in subtropical and higher-latitude regions. Our results show that the land sink of CO2 (dominated by forests) and its interannual variability (dominated by marginal lands) are

  19. What Drives Regional Variation in Global Ocean-Atmosphere CO2 Fluxes?

    NASA Astrophysics Data System (ADS)

    Lauderdale, J. M.; Dutkiewicz, S.; Williams, R. G.; Follows, M. J.

    2016-02-01

    Oceanic and atmospheric carbon reservoirs are tightly linked by air-sea exchange of carbon dioxide. Regional and seasonal variations in the CO2 flux reflect the balance of drivers such as surface heat (solubility) forcing, freshwater fluxes, biological sources and sinks associated with photosynthesis and respiration, and upwelling of biologically regenerated dissolved inorganic carbon. Here, we present a comprehensive, mechanistic diagnostic framework that quantifies the relative contributions of these processes to the total air-sea CO2 flux. We test the framework using simulations with a global circulation-biogeochemistry model (MITgcm) where the "true" CO2 fluxes are known. Generally, the leading order balance is between the CO2 fluxes driven by regional surface heat fluxes and opposed by a combination of biologically-driven carbon uptake and disequilibrium-driven carbon outgassing, with the disequilibrium dominating at mid- to high latitudes and biological uptake dominating at low latitudes. Only minor modifications are due to the net effect of freshwater fluxes on surface salinity, alkalinity and carbon concentrations. We then apply the diagnostic suite to climatological observations and map the relative contributions of the physical and biological drivers in setting the regional patterns of air-sea CO2 fluxes.

  20. Causes of atmospheric CO2 variations over the last glacial-interglacial cycle

    NASA Astrophysics Data System (ADS)

    Kemppinen, K. M.; Holden, P.; Edwards, N.; Ridgwell, A. J.; Friend, A. D.; Wolff, E.

    2013-12-01

    During glacial-interglacial cycles, atmospheric CO2 increases by about 100 ppmv during brief interglacials. Despite years of research, the causes of this change are still not entirely understood. Here we attempt to explain the change in CO2 using, for the first time, an ensemble of coupled climate-carbon cycle simulations designed to consider the processes that are thought to contribute to variability of atmospheric CO2 on glacial/interglacial timescales. We begin by running the ensemble to equilibrium with Last Glacial Maximum (LGM; 21 kyr BP) forcings. By comparing the simulations with ice core data, we find that a small subset of the ensemble produces plausible atmospheric CO2 concentrations and climate. We build emulators of the full model with respect to atmospheric CO2, and perform sensitivity analyses on them to quantify the contributions of atmospheric, sea ice, ocean, and vegetation processes to variability in atmospheric CO2 under glacial forcings. We find that the variability is dominated by a few key parameters. We also use singular vector decomposition to investigate the parameter interactions required for achieving plausible CO2 at the LGM. This work is ongoing, and if plausible states are found, a transient ensemble will be run over the last glacial-interglacial cycle (126 kyr) using the associated parameter sets. This experiment will be the first of its kind as it allows simulated atmospheric CO2 to feedback to the physical climate model in an unconstrained manner.

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

    NASA Astrophysics Data System (ADS)

    Smallman, T. L.; Williams, M.; Moncrieff, J. B.

    2014-02-01

    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-SPA simulated atmospheric CO2 concentrations were compared with two coarse global inversion models, CarbonTrackerEurope and the National Oceanic and Atmospheric Administration's CarbonTracker (CTE-CT). WRF-SPA realistically modelled both seasonal (except post harvest) and daily cycles seen in observed atmospheric CO2 at the tall tower (R2 = 0.67, rmse = 3.5 ppm, bias = 0.58 ppm). Atmospheric CO2 concentrations from the tall tower were well simulated by CTE-CT, but the inverse model showed a poorer representation of diurnal variation and simulated a larger bias from observations (up to 1.9 ppm) at seasonal timescales, compared to the forward modelling of WRF-SPA. However, we have highlighted a consistent post-harvest increase in the seasonal bias between WRF-SPA and observations. Ecosystem-specific tracers of CO2 exchange indicate that the increased bias is potentially due to the representation of agricultural processes within SPA and/or biases in land cover maps. The ecosystem-specific tracers also indicate that the majority of seasonal variation in CO2 uptake for Scotland's dominant ecosystems (forests, cropland and managed grassland) is detectable in observations within the footprint of the tall tower; however, the amount of variation explained varies between years. The between years variation in detectability of Scotland's ecosystems is potentially due to seasonal and interannual variation in the simulated prevailing wind direction. This result highlights the importance of

  2. [Characteristics of atmospheric CO2 concentration and variation of carbon source & sink at Lin'an regional background station].

    PubMed

    Pu, Jing-Jiao; Xu, Hong-Hui; Kang, Li-Li; Ma, Qian-Li

    2011-08-01

    Characteristics of Atmospheric CO2 concentration obtained by Flask measurements were analyzed at Lin'an regional background station from August 2006 to July 2009. According to the simulation results of carbon tracking model, the impact of carbon sources and sinks on CO2 concentration was evaluated in Yangtze River Delta. The results revealed that atmospheric CO2 concentrations at Lin'an regional background station were between 368.3 x 10(-6) and 414.8 x 10(-6). The CO2 concentration varied as seasons change, with maximum in winter and minimum in summer; the annual difference was about 20.5 x 10(-6). The long-term trend of CO2 concentration showed rapid growth year by year; the average growth rate was about 3.2 x 10(-6)/a. CO2 flux of Yangtze River Delta was mainly contributed by fossil fuel burning, terrestrial biosphere exchange and ocean exchange, while the contribution of fire emission was small. CO2 flux from fossil fuel burning played an important role in carbon source; terrestrial biosphere and ocean were important carbon sinks in this area. Seasonal variations of CO2 concentration at Lin'an regional background station were consistent with CO2 fluxes from fossil fuel burning and terrestrial biosphere exchange.

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

    PubMed

    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

    2016-03-29

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  5. Antarctic Ice Sheet Sensitivity to Atmospheric CO2 Variations During the Early to Mid-Miocene

    NASA Astrophysics Data System (ADS)

    Levy, R. H.; Harwood, D. M.; Florindo, F.; Sangiorgi, F.; Eagle, R.; von Eynatten, H.; Gasson, E.; Kuhn, G.; Tripati, A.; Deconto, R. M.; Fielding, C. R.; Field, B.; Golledge, N. R.; Mckay, R. M.; Naish, T.; Olney, M.; Pollard, D.; Schouten, S.; Talarico, F. M.; Warny, S.; Willmott, V.

    2015-12-01

    The Early to mid-Miocene (23 to 14 million years ago) is a compelling interval to study Antarctic ice sheet sensitivity to changes in atmospheric CO2 as oceanic and atmospheric circulation patterns in the southern hemisphere were broadly similar to present and reconstructed atmospheric CO2 concentrations were analogous to those projected for the next several decades. This time interval includes the Miocene Climatic Optimum (MCO), a period of global warmth during which average surface temperatures were 3 to 4°C higher than today. Miocene sediments in the AND-2A drill core from the Western Ross Sea, Antarctica provide direct information regarding ice sheet variability through this key time interval and offer insight into the potential Antarctic contribution to future sea level rise. A multi-proxy dataset derived from AND-2A 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 marine-based ice across the Ross Sea. They all correlate with major positive shifts in benthic oxygen isotope records and episodes of sea-level fall, and generally coincide with intervals when atmospheric CO2 concentrations were below current levels (~400 ppm). Five intervals reflect ice sheet minima and air temperatures warm enough for significant ice mass loss during episodes of high (>400 ppm) atmospheric CO2. These results suggest that polar climate and the Antarctic Ice Sheet (AIS) were highly sensitive to relatively small changes in CO2 during the early to mid-Miocene, which is supported by numerical ice sheet and climate modelling.

  6. Carbon allocation changes: an adaptive response to variations in atmospheric CO2

    NASA Astrophysics Data System (ADS)

    Harrison, Sandy; Li, Guangqi; Prentice, Iain Colin

    2016-04-01

    Given the ubiquity of nutrient constraints on primary production, an optimal carbon allocation strategy is expected to increase total below-ground allocation (fine root production and turnover, allocation to mycorrhizae and carbon exudation to the rhizophere) as atmospheric CO2 concentration increases. Conversely, below-ground allocation should be reduced when atmospheric CO2 concentrations were low, as occurred during glacial times. Using a coupled generic primary production and tree-growth model, we quantify the changes in carbon allocation that are required to explain the apparent homoeostasis of tree radial growth during recent decades and between glacial and interglacial conditions. These results suggest a resolution of the apparent paradox of continuing terrestrial CO2 uptake (a consequence of CO2 fertilization) and the widespread lack of observed enhancement of stem growth in trees. Adaptive shifts in carbon allocation are thus a key feature that should to be accounted for in models to predict tree growth and future timber harvests, as well as in large-scale ecosystem and carbon cycle models.

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

    PubMed Central

    Levy, Richard; Harwood, David; Florindo, Fabio; Sangiorgi, Francesca; Tripati, Robert; von Eynatten, Hilmar; 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

    2016-01-01

    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. PMID:26903644

  8. Forecasting global atmospheric CO2

    NASA Astrophysics Data System (ADS)

    Agustí-Panareda, A.; Massart, S.; Chevallier, F.; Boussetta, S.; Balsamo, G.; Beljaars, A.; Ciais, P.; Deutscher, N. M.; Engelen, R.; Jones, L.; Kivi, R.; Paris, J.-D.; Peuch, V.-H.; Sherlock, V.; Vermeulen, A. T.; Wennberg, P. O.; Wunch, D.

    2014-11-01

    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 products retrieved from satellite measurements and

  9. Forecasting global atmospheric CO2

    NASA Astrophysics Data System (ADS)

    Agustí-Panareda, A.; Massart, S.; Chevallier, F.; Boussetta, S.; Balsamo, G.; Beljaars, A.; Ciais, P.; Deutscher, N. M.; Engelen, R.; Jones, L.; Kivi, R.; Paris, J.-D.; Peuch, V.-H.; Sherlock, V.; Vermeulen, A. T.; Wennberg, P. O.; Wunch, D.

    2014-05-01

    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 become available in

  10. On the ability of a global atmospheric inversion to constrain variations of CO2 fluxes over Amazonia

    NASA Astrophysics Data System (ADS)

    Molina, L.; Broquet, G.; Imbach, P.; Chevallier, F.; Poulter, B.; Bonal, D.; Burban, B.; Ramonet, M.; Gatti, L. V.; Wofsy, S. C.; Munger, J. W.; Dlugokencky, E.; Ciais, P.

    2015-01-01

    The exchanges of carbon, water, and energy between the atmosphere and the Amazon Basin have global implications for current and future climate. Here, the global atmospheric inversion system of the Monitoring of Atmospheric Composition and Climate service (MACC) was used to further study the seasonal and interannual variations of biogenic CO2 fluxes in Amazonia. The system assimilated surface measurements of atmospheric CO2 mole fractions made over more than 100 sites over the globe into an atmospheric transport model. This study added four surface stations located in tropical South America, a region poorly covered by CO2 observations. The estimates of net ecosystem exchange (NEE) optimized by the inversion were compared to independent estimates of NEE upscaled from eddy-covariance flux measurements in Amazonia, and against reports on the seasonal and interannual variations of the land sink in South America from the scientific literature. We focused on the impact of the interannual variation of the strong droughts in 2005 and 2010 (due to severe and longer-than-usual dry seasons), and of the extreme rainfall conditions registered in 2009. The spatial variations of the seasonal and interannual variability of optimized NEE were also investigated. While the inversion supported the assumption of strong spatial heterogeneity of these variations, the results revealed critical limitations that prevent global inversion frameworks from capturing the data-driven seasonal patterns of fluxes across Amazonia. In particular, it highlighted issues due to the configuration of the observation network in South America and the lack of continuity of the measurements. However, some robust patterns from the inversion seemed consistent with the abnormal moisture conditions in 2009.

  11. On the ability of a global atmospheric inversion to constrain variations of CO2 fluxes over Amazonia

    NASA Astrophysics Data System (ADS)

    Molina, L.; Broquet, G.; Imbach, P.; Chevallier, F.; Poulter, B.; Bonal, D.; Burban, B.; Ramonet, M.; Gatti, L. V.; Wofsy, S. C.; Munger, J. W.; Dlugokencky, E.; Ciais, P.

    2015-07-01

    The exchanges of carbon, water and energy between the atmosphere and the Amazon basin have global implications for the current and future climate. Here, the global atmospheric inversion system of the Monitoring of Atmospheric Composition and Climate (MACC) service is used to study the seasonal and interannual variations of biogenic CO2 fluxes in Amazonia during the period 2002-2010. The system assimilated surface measurements of atmospheric CO2 mole fractions made at more than 100 sites over the globe into an atmospheric transport model. The present study adds measurements from four surface stations located in tropical South America, a region poorly covered by CO2 observations. The estimates of net ecosystem exchange (NEE) optimized by the inversion are compared to an independent estimate of NEE upscaled from eddy-covariance flux measurements in Amazonia. They are also qualitatively evaluated against reports on the seasonal and interannual variations of the land sink in South America from the scientific literature. We attempt at assessing the impact on NEE of the strong droughts in 2005 and 2010 (due to severe and longer-than-usual dry seasons) and the extreme rainfall conditions registered in 2009. The spatial variations of the seasonal and interannual variability of optimized NEE are also investigated. While the inversion supports the assumption of strong spatial heterogeneity of these variations, the results reveal critical limitations of the coarse-resolution transport model, the surface observation network in South America during the recent years and the present knowledge of modelling uncertainties in South America that prevent our inversion from capturing the seasonal patterns of fluxes across Amazonia. However, some patterns from the inversion seem consistent with the anomaly of moisture conditions in 2009.

  12. [Remote sensing of seasonal variation in column concentration of atmospheric CO2 and CH4 in Hefei].

    PubMed

    Cheng, Si-Yang; Gao, Min-Guang; Xu, Liang; Jin, Ling; Li, Sheng; Tong, Jing-Jing; Wei, Xiu-Li; Liu, Jian-Guo; Liu, Wen-Qing

    2014-03-01

    In order to observe two kinds of greenhouse gases, CO2 and CH4, making the biggest contribution to global warming, a ground-based Fourier transform near-infrared spectral remote sensing system was developed to record the perpendicular incidence sun spectra from February 2012 to April 2013 in Hefei continuously. The measured total transmittances in the atmosphere were obtained from perpendicular incidence sun spectra. Methods of line-by-line and low-order polynomial approximation were used to model the total atmospheric transmittances in forward model. The measured transmittance spectra were fitted iteratively using the modeled transmittance spectra in the regions of CO2 6,150-6,270 and CH4 5,970-6,170 cm(-1) in order to obtain their column concentrations. The column-average dry-air mole fractions of CO2 and CH4 were obtained with the internal standard function of O2 column concentrations. CO2 and CH4 daily average values of column-average dry-air mole fractions changed with a larger fluctuation and obvious seasonal periodicity. Their monthly average values were consistent as a whole, although there were different characteristics. Compared with the results reported by Japanese greenhouse-gas satellite in the area of Waliguan, there was a time lag corresponding to peak and trough of CO2 content and the change from peak to trough costed a longtime. CHR content showed variation tendency of unique peak and trough, higher in summer and lower in winter, compared with average values of nationwide CH4 column concentrations based on SCIAMACHY data. The variation characteristics were related to complex factors such as the balance of source and sink, meteorological and climate conditions, and required long-term observation and further study.

  13. Sensitivity of Venus surface emissivity retrieval to model variations of CO2 opacity, cloud features, and deep atmosphere temperature field

    NASA Astrophysics Data System (ADS)

    Kappel, David; Arnold, Gabriele; Haus, Rainer

    2012-07-01

    The Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) aboard ESA's Venus Express space probe has acquired a wealth of nightside emission spectra from Venus and provides the first global database for systematic atmospheric and surface studies in the IR. The infrared mapping channel (VIRTIS-M-IR) sounds the atmosphere and surface at high spatial and temporal resolution and coverage. Quantitative analyses of data call for a sophisticated radiative transfer simulation model of Venus' atmosphere to be used in atmospheric and surface parameter retrieval procedures that fit simulated spectra to the measured data. The surface emissivity can be retrieved from VIRTIS-M-IR measurements in the transparency windows around 1 μm, but it is not easy to derive, since atmospheric influences strongly interfere with surface information. There are mainly three atmospheric model parameters that may affect quantitative results of surface emissivity retrievals: CO_2 opacity, cloud features, and deep atmosphere temperature field. The CO_2 opacity with respect to allowed transitions is usually computed by utilizing a suitable line data base and certain line shape models that consider collisional line mixing. Both line data bases and shape models are not well established from measurements under the environmental conditions in the deep atmosphere of Venus. Pressure-induced additional continuum absorption introduces further opacity uncertainties. The clouds of Venus are usually modeled by a four-modal distribution of spherical droplets of about 75% sulfuric acid, where each mode is characterized by a different mean and standard deviation of droplet size distribution and a different initial altitude abundance profile. The influence of possible cloud mode variations on surface emissivity retrieval results is investigated in the paper. Future retrieval procedures will aim at a separation of cloud mode and surface emissivity variations using different atmospheric windows sounded by

  14. Atmospheric Fossil Fuel CO2 Traced by Δ(14)C in Beijing and Xiamen, China: Temporal Variations, Inland/Coastal Differences and Influencing Factors.

    PubMed

    Niu, Zhenchuan; Zhou, Weijian; Wu, Shugang; Cheng, Peng; Lu, Xuefeng; Xiong, Xiaohu; Du, Hua; Fu, Yunchong; Wang, Gehui

    2016-06-07

    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.

  15. Carbon allocation changes: an adaptive response to variations in atmospheric CO2

    NASA Astrophysics Data System (ADS)

    Harrison, S. P.; Li, G.; Prentice, I. C. C.

    2015-12-01

    Given the ubiquity of nutrient constraints on primary production, an optimal carbon allocation strategy is expected to increase total below-ground allocation (fine root production and turnover, allocation to mycorrhizae and carbon exudation to the rhizophere) as CO2 concentration increases. Conversely, below-ground allocation should be reduced under low CO2 concentrations, as occurred during glacial times. Using a coupled generic primary production and tree-growth model, we quantify the changes in carbon allocation that are required to explain the apparent homoeostasis of tree radial growth during recent decades and between glacial and interglacial conditions. These results suggest a resolution of the apparent paradox of continuing terrestrial CO2 uptake (a consequence of CO2 fertilization) and the widespread lack of observed radial growth enhancement in trees. Adaptive shifts in carbon allocation are thus a key feature that needs to be accounted for in models to predict, for example, future timber yields as well as in large-scale ecosystem and carbon cycle models.

  16. Characteristics of variations of climate change and atmospheric CO2 concentration at different time scales over the past 500 Ma

    NASA Astrophysics Data System (ADS)

    LIU, Z.; Huang, S. S. X. E. C.; Tang, X.

    2015-12-01

    It is generally believed that current global warming is due to the persistent rise of atmospheric greenhouse gas CO2. The consensus is based mostly on the observational data of past decades and the polar ice core records. To understand the relationship between climate change and atmospheric CO2, their behaviors over a longer interval at different time scales need to be appreciated. Here, we collect and analyze past 500 Ma records of atmospheric CO2 and temperature in six time periods, namely Phanerozoic, Cenozoic, middle Pleistocene, last deglaciation, past millennium, and recent decades. According to the carriers and time spans, we divide these records into three categories: 1.The millionaire and longer records from model calculation and paleosols/paleobotany proxies. Although the trends of both variables are generally consistent on this time scale, it is difficult to establish a clear causal relationship because of great uncertainties and low resolutions of both sets of data. 2.The orbital scale mainly from the polar ice core. High precise CO2 and temperature reconstructions allow for an examination of the possible role of atmospheric CO2 in the glacial-interglacial transformation. 3.The records at centennial and shorter time scales over the past millennium from ice, snow, and instrumental data. The past millennium records are most abundant and accurate, especially CO2 has been measured directly in recent decades. However, due to the difficulties in distinguishing the effect of CO2 from other factors, there are great uncertainties in the interpretation of climate change versus CO2. Overall, we come to the following conclusions:1.Paleoclimatic reconstructions show that both temperature and atmospheric CO2 have generally decreased over the past 500 Ma. However, there are no consistent sequential orders in the changes between these two variables. 2.The Earth's atmospheric CO2 has a drastic oscillation history. There were many high CO2 periods when the values were

  17. Sensitivity of a coupled atmosphere-dynamic upper ocean GCM to variations of CO2, solar constant, and orbital forcing

    NASA Astrophysics Data System (ADS)

    Syktus, Jozef; Gordon, Hal; Chappell, John

    1994-07-01

    Sensitivity of a coupled atmosphere-dynamic upper ocean general circulation model (GCM) to varying CO2, solar constant, and orbital forcing was examined. Response to atmospheric CO2 concentrations ranging from 100-3500 ppm is logarithmic at all latitudes and seasons, with highest sensitivity at high latitudes, during the winter season. Solar constant response is approximately linear over the range of values +2%, but the sensitivity at high latitudes is less than for equivalent CO2 forcing. Sensitivity to 'cold northern summer' orbital forcing, which occurred at the start of the last glacial cycle, is strongly affected by CO2. For CO2 at or below the present level, perennial snow cover in the northern hemisphere expands dramatically with 'cold summer' orbital forcing, but this effect becomes very small for CO2 levels in the range 410-460 ppm. This result suggests that the Quaternary 'ice age' mode of climatic behavior may have been initiated by an atmospheric CO2 decrease below a critical value, probably around 350-450 ppm.

  18. Global variations in optical thickness of the atmosphere of Venus. III. Analysis of behavior of equivalent widths of CO2 lines for an inhomogeneous model atmosphere.

    NASA Astrophysics Data System (ADS)

    Fomin, N. N.; Yanovitskij, E. G.

    A two-layer model of Venus atmosphere is considered. The upper layer is a gas-and-aerosol medium with a fixed lower boundary height (h = 50 km) above the planet's surface. The lower layer is a pure CO2 gas. The pressure and temperature in the layers are assumed to satisfy the polytrope equation. The observed variations in the equivalent widths of R(0) lines in the CO2 absorption bands λλ788.3 and 868.9 nm are studied within the context of this model. The observed scatter in the equivalent widths is shown to be explicable in the framework of the model of globally asymmetrical cloud layer on Venus proposed earlier by the authors. The optical thickness of the cloud layer is found in such a case to be τx = 34.4 for one hemisphere, while it is τn = 24.4 for the other hemisphere. The heights of the cloud layer upper boundary in this case are 68.4 and 75.8 km, respectively. The value τx/τn = 1.4 is in complete agreement with independent estimate obtained earlier from measurements of the integral brightness of the planet. Observed variations in the equivalent widths of R(0) lines of the CO2 absorption bands λλ782.0 and 1062.7 nm verify this estimate. Finally, variations in the height of the cloud layer upper boundary are in complete accord with observed scatter in the amount of polarization over the disk of Venus in the UV region. Further feasible observational tests of this effect are discussed.

  19. Evaluation of variations in CO2 gas exchange in the atmosphere of the BTLSS with plants grown in a conveyor mode on the soil-like substrate

    NASA Astrophysics Data System (ADS)

    Velichko, Vladimir; Tikhomirov, Alexander A.; Tikhomirova, Natalia; Ushakova, Sofya

    2016-07-01

    The soil-like substrate (SLS) included in the bioregenerative life support system (BLSS) exerts a substantial effect on its gas exchange. This effect is determined by the non-uniform rate of organic matter degradation in the SLS, on the one hand, and by the variable intensity of photosynthesis of the plants grown on it, on the other. The purpose of this study was to compare CO2 variations in the atmosphere of the higher plants - SLS system at different intervals in uneven-aged higher plant conveyers. The study showed that CO2 concentration could reach and exceed the levels of atmospheric carbon dioxide acceptable for humans (over 1%) even when the conveyer interval was rather short. CO2 variations in the atmosphere of the higher plants - SLS system were determined not only by the frequency of adding plant waste to the SLS and the mass of the waste but also by the amount of the harvested actively photosynthesizing plant biomass. At the same time, no significant differences were found in the mineral and production components between the plants in different experiments. Results of the study can be used to optimize the conveyor interval and the associated effectiveness of mineralization of the plant waste added to the SLS and to stabilize the CO2 gas exchange. This study was carried out in the IBP SB RAS and supported by the grant of the Russian Science Foundation (Project No. 14-14-00599).

  20. Earth's Atmospheric CO2 Saturated IR Absorption

    NASA Astrophysics Data System (ADS)

    Wall, Ernst

    2008-10-01

    Using the on-line SpectraCalc IR absorption simulator, the amount of IR absorption by the 15 μ line of the current atmospheric CO2 was obtained and compared with that of twice the amount of CO2. The simulation required a fixed density equivalent for the atmospheric path length. This was obtained by numerically integrating the NOAA Standard Atmospheric model. While the current line is saturated, doubling the CO2 will cause a slight width increase. Using this and the blackbody radiation curve plus considering the effects of water vapor, the temperature rise of the Earth will be less than 2.5 deg. C. Integrating a NASA Martian atmospheric model, we find that the Martian atmosphere has 45 times more CO2 to penetrate than Earth, and yet, the Martian diurnal temperature swings exceed those of the Sahara desert. I.e., large amounts of CO2 alone do not necessarily cause planetary warming. As the oceans warm from any cause, more CO2 is boiled out, but if they cool, they will absorb more CO2 just as a carbonated drink does, so that temperature and CO2 density will correlate. It is to be noted that the Earth's known petroleum reserves contain only enough CO2 to increase the atmospheric CO2 by some 15%.

  1. [Responses of tissue carbon and delta 13C in epilithic mosses to the variations of anthropogenic CO2 and atmospheric nitrogen deposition in city area].

    PubMed

    Liu, Xue-yan; Xiao, Hua-yun; Liu, Cong-qiang; Li, You-yi; Xiao, Hong-wei

    2009-01-01

    We investigated the carbon (C) and nitrogen (N) concentrations and isotopic signatures (delta 13C and delta15 N) in epilithic mosses collected from urban sites to rural sites along four directions at Guiyang area. Mosses C (34.47%-52.76%) decreased significantly with distance from urban to rural area and strongly correlated with tissue N (0.85%-2.97%), showing atmospheric N deposition has positive effect on C assimilation of epilithic mosses, higher atmospheric N/NHx deposition at urban area has improved the photosynthesis and C fixation of mosses near urban, which also caused greater 13C discrimination for urban mosses. Mosses delta 13C signatures (-30.69% per hundred - -26.96% per hundred) got less negative with distance from urban to rural area, which was also related to the anthropogenic CO2 emissions in the city, and these 12C-enriched CO2 sources would lead to more negative mosses delta 13C through enhancing the atmospheric CO2 concentration in urban area. Moreover, according to the characteristics of mosses C and delta 13C variations with distance, it is estimated that the influences of urban anthropogenic CO2 sources on plants was mainly within 20 km from city center. This study mainly focused on the factors regulating tissue C and delta 13C of mosses in city area and the interaction between C and N in mosses, the responses of mosses C and delta 13C to urban CO2 emission and atmospheric N deposition have been revealed, which could provide new geochemical evidences for the control of city atmospheric pollution and the protection of ecosystems around city.

  2. Seasonal and interannual variations in carbon and oxygen isotopes of atmospheric CO2 observed over a C4-dominated tallgrass prairie in central Kansas, USA

    NASA Astrophysics Data System (ADS)

    Lai, C.; Owensby, C.; Ham, J.; Ehleringer, J.

    2004-12-01

    We conducted weekly measurements of carbon (\\delta13C) and oxygen (\\delta18O) isotopes in atmospheric CO2 over a C4-dominated tallgrass prairie in 2002, 2003 and 2004. Air samples above and within canopies were collected using 100-ml flasks for both day- and nighttime periods. A two-source mixing line approach estimated isotope ratios of ecosystem respired CO2 for both carbon (\\delta13CR) and oxygen (\\delta18OR). In general, values of \\delta13CR showed a significant shift from ˜ -20 ‰ in early spring to ˜ -12 ‰ in mid-summer for all 3 years, reflecting the dominance of C4 photosynthesis in the {wet} and warm environment. Precipitation in the spring has a profound impact on the seasonal variations in \\delta13CR values and net ecosystem exchange (NEE) CO2 fluxes. Variations in \\delta13CR corresponded with NEE fluxes on both weekly and interannual time scales; more positive \\delta13CR values (C4 dominance) were observed with greater NEE fluxes under well-watered conditions. When C4 photosynthetic uptake of atmospheric CO2 decreased, values of \\delta13CR reflected an increased impact of C3 forbs and nearby C3 cropland. The coupling between photosynthetic fluxes and respired \\delta13C suggests that a significant portion of recently fixed carbon was returned to the atmosphere through autotrophic respiration within days. Measuring oxygen isotopes of ecosystem CO2 provides a means to further separate total ecosystem respiration into contributions from above- and belowground components. Our measurements showed that values of \\delta18OR ranged from ˜22 to ˜35 ‰ (VSMOW scale) within a season. These variations were a result of respired CO2 equilibrated with two isotopically distinct ecosystem water pools: \\delta18O values in leaf water are more positive relative to soil water owing to the evaporative enrichment during the day. \\delta18O values of leaf and soil water will be modeled to constrain \\delta18OR measurements in order to partition respiratory

  3. Atmospheric CO2 Variability Observed From ASCENDS Flight Campaigns

    NASA Technical Reports Server (NTRS)

    Lin, Bing; Browell, Edward; Campbell, Joel; Choi, Yonghoon; Dobler, Jeremy; Fan, Tai-Fang; Harrison, F. Wallace; Kooi, Susan; Liu, Zhaoyan; Meadows, Byron; hide

    2015-01-01

    Significant atmospheric CO2 variations on various spatiotemporal scales were observed during ASCENDS flight campaigns. For example, around 10-ppm CO2 changes were found within free troposphere in a region of about 200x300 sq km over Iowa during a summer 2014 flight. Even over extended forests, about 2-ppm CO2 column variability was measured within about 500-km distance. For winter times, especially over snow covered ground, relatively less horizontal CO2 variability was observed, likely owing to minimal interactions between the atmosphere and land surface. Inter-annual variations of CO2 drawdown over cornfields in the Mid-West were found to be larger than 5 ppm due to slight differences in the corn growing phase and meteorological conditions even in the same time period of a year. Furthermore, considerable differences in atmospheric CO2 profiles were found during winter and summer campaigns. In the winter CO2 was found to decrease from about 400 ppm in the atmospheric boundary layer (ABL) to about 392 ppm above 10 km, while in the summer CO2 increased from 386 ppm in the ABL to about 396 ppm in free troposphere. These and other CO2 observations are discussed in this presentation.

  4. Impact of atmospheric CO2 levels on continental silicate weathering

    NASA Astrophysics Data System (ADS)

    Beaulieu, E.; GoddéRis, Y.; Labat, D.; Roelandt, C.; Oliva, P.; Guerrero, B.

    2010-07-01

    Anthropogenic sources are widely accepted as the dominant cause for the increase in atmospheric CO2 concentrations since the beginning of the industrial revolution. Here we use the B-WITCH model to quantify the impact of increased CO2 concentrations on CO2 consumption by weathering of continental surfaces. B-WITCH couples a dynamic biogeochemistry model (LPJ) and a process-based numerical model of continental weathering (WITCH). It allows simultaneous calculations of the different components of continental weathering fluxes, terrestrial vegetation dynamics, and carbon and water fluxes. The CO2 consumption rates are estimated at four different atmospheric CO2 concentrations, from 280 up to 1120 ppmv, for 22 sites characterized by silicate lithologies (basalt, granite, or sandstones). The sensitivity to atmospheric CO2 variations is explored, while temperature and rainfall are held constant. First, we show that under 355 ppmv of atmospheric CO2, B-WITCH is able to reproduce the global pattern of weathering rates as a function of annual runoff, mean annual temperature, or latitude for silicate lithologies. When atmospheric CO2 increases, evapotranspiration generally decreases due to progressive stomatal closure, and the soil CO2 pressure increases due to enhanced biospheric productivity. As a result, vertical drainage and soil acidity increase, promoting CO2 consumption by mineral weathering. We calculate an increase of about 3% of the CO2 consumption through silicate weathering (mol ha-1 yr-1) for 100 ppmv rise in CO2. Importantly, the sensitivity of the weathering system to the CO2 rise is not uniform and heavily depends on the climatic, lithologic, pedologic, and biospheric settings.

  5. [Spatial and temporal variations of near surface atmospheric CO2 with mobile measurements in fall and spring in Xiamen, China].

    PubMed

    Li, Yan-Li; Xing, Zhen-Yu; Mu, Chao; Du, Ke

    2014-05-01

    The study on the spatial distribution of near surface air pollutants carbon dioxide (CO2) and particulate matters (PM) is essential for understanding the pollution characteristics with mobile measurements. Near surface concentrations of CO2, PM and meteorological parameters were measured in Xiamen city, China along the route passing through different functional areas using the mobile laboratory during different time periods of the day [09:00- 12: 00, 13 :00- 16 : 00, 22 : 00-01 : 00 (local time) ] in spring (April) and fall (November), 2013. Carbon dioxide, PM and meteorological parameters data were analyzed for the spatial distribution of CO2 in different functional areas and the relationship of CO2, and PM2.5. During the study period, the measurements started at the northern part of the city, across the suburban area and ended at about 60 km in the southern Xiamen. The spatial distribution of CO2 along the road showed a high CO2 level in the central area of the city and low values in the outlying areas. Different CO2 concentrations were observed at different functional areas because of the differences in emissions from traffic and industry, the emission and absorption by vegetation, and meteorological conditions. The concentrations of CO, at different areas fell into the following order: areas with heavy traffic (477.33 micromol.mol-1 +/- 6. 11 micromol.mol-1 ) > commercial residential area (454. 95 micromol.mol-1 +/- 5.45 micromol.mol-1 ) > the naturalscenic spot (441.01 micromol.mol-1 +/- 6.24 micromol.mol-1 ) >cultivated land (436.79 micromol.mol-1 +/- 1.87 micromol.mol-1 ) > mountain woodlands (434.06 micromol.mol-1 +/-0.31 micromol.mol-1 ). The average CO, concentration in spring 2013 was measured to be 452.04 micromol mol -1 +/- 20.24 micro.mol. mol-1 with the maximum value of 533.10 micromol.mol-1 at the heavy traffic area in downtown Jiahe on April 12, 2013 and the minimum value of 413.25 micromol.mol-1 on April 10, 2013 at the mountain woodland, which is

  6. Atmospheric CO2 Removal by Enhancing Weathering

    NASA Astrophysics Data System (ADS)

    Koster van Groos, A. F.; Schuiling, R. D.

    2014-12-01

    The increase of the CO2 content in the atmosphere by the release of anthropogenic CO2 may be addressed by the enhancement of weathering at the surface of the earth. The average emission of mantle-derived CO2 through volcanism is ~0.3 Gt/year (109 ton/year). Considering the ~3.000 Gt of CO2 present in the atmosphere, the residence time of CO2 in the earth's atmosphere is ~10,000 years. Because the vast proportion of carbon in biomass is recycled through the atmosphere, CO2 is continuously removed by a series of weathering reactions of silicate minerals and stored in calcium and magnesium carbonates. The addition of anthropogenic CO2 from fossil fuel and cement production, which currently exceeds 35 Gt/year and dwarfs the natural production 100-fold, cannot be compensated by current rates of weathering, and atmospheric CO2 levels are rising rapidly. To address this increase in CO2 levels, weathering rates would have to be accelerated on a commensurate scale. Olivine ((Mg,Fe)2SiO4) is the most reactive silicate mineral in the weathering process. This mineral is the major constituent in relatively common ultramafic rocks such as dunites (olivine content > 90%). To consume the current total annual anthropogenic release of CO2, using a simplified weathering reaction (Mg2SiO4 + 4CO2 + 4H2O --> 2 Mg2+ + 4HCO3- + H4SiO4) would require ~30 Gt/year or ~8-9 km3/year of dunite. This is a large volume; it is about double the total amount of ore and gravel currently mined (~ 17 Gt/year). To mine and crush these rocks to <100 μm costs ~ 8/ton. The transport and distribution over the earth's surface involves additional costs, that may reach 2-5/ton. Thus, the cost of remediation for the release of anthropogenic CO2 is 300-400 billion/year. This compares to a 2014 global GDP of ~80 trillion. Because weathering reactions require the presence of water and proceed more rapidly at higher temperatures, the preferred environments to enhance weathering are the wet tropics. From a socio

  7. Large-scale variations in the vegetation growing season and annual cycle of atmospheric CO2 at high northern latitudes from 1950 to 2011.

    PubMed

    Barichivich, Jonathan; Briffa, Keith R; Myneni, Ranga B; Osborn, Timothy J; Melvin, Thomas M; Ciais, Philippe; Piao, Shilong; Tucker, Compton

    2013-10-01

    We combine satellite and ground observations during 1950-2011 to study the long-term links between multiple climate (air temperature and cryospheric dynamics) and vegetation (greenness and atmospheric CO(2) concentrations) indicators of the growing season of northern ecosystems (>45°N) and their connection with the carbon cycle. During the last three decades, the thermal potential growing season has lengthened by about 10.5 days (P < 0.01, 1982-2011), which is unprecedented in the context of the past 60 years. The overall lengthening has been stronger and more significant in Eurasia (12.6 days, P < 0.01) than North America (6.2 days, P > 0.05). The photosynthetic growing season has closely tracked the pace of warming and extension of the potential growing season in spring, but not in autumn when factors such as light and moisture limitation may constrain photosynthesis. The autumnal extension of the photosynthetic growing season since 1982 appears to be about half that of the thermal potential growing season, yielding a smaller lengthening of the photosynthetic growing season (6.7 days at the circumpolar scale, P < 0.01). Nevertheless, when integrated over the growing season, photosynthetic activity has closely followed the interannual variations and warming trend in cumulative growing season temperatures. This lengthening and intensification of the photosynthetic growing season, manifested principally over Eurasia rather than North America, is associated with a long-term increase (22.2% since 1972, P < 0.01) in the amplitude of the CO(2) annual cycle at northern latitudes. The springtime extension of the photosynthetic and potential growing seasons has apparently stimulated earlier and stronger net CO(2) uptake by northern ecosystems, while the autumnal extension is associated with an earlier net release of CO(2) to the atmosphere. These contrasting responses may be critical in determining the impact of continued warming on northern terrestrial ecosystems and the

  8. Atmospheric CO2 Variability Observed during ASCENDS Flight Campaigns

    NASA Astrophysics Data System (ADS)

    Lin, B.; Browell, E. V.; Campbell, J. F.; Choi, Y.; Dobler, J. T.; Fan, T. F.; Harrison, F. W.; Kooi, S. A.; Liu, Z.; Meadows, B.; Nehrir, A. R.; Obland, M. D.; Plant, J.; Yang, M. M.

    2015-12-01

    Accurate observations of atmospheric CO2 with a space-based lidar system, such as for the NASA ASCENDS mission, will improve knowledge of global CO2 distribution and variability and increase the confidence in predictions of future climate changes. To prepare for the ASCENDS mission, the NASA Langley Research Center and Exelis Inc. (now part of Harris Corp.) have been collaborating in the development and evaluation of an Intensity-Modulated Continuous-Wave (IM-CW) lidar approach for measuring atmospheric CO2 from space. Two airborne IM-CW lidars operating in the 1.57-mm CO2 absorption band have been developed and flight tested to demonstrate precise atmospheric CO2 column measurements. A total of 14 flight campaigns have been conducted with the two lidar and in-situ CO2 measurement systems. Significant atmospheric CO2 variations on various spatiotemporal scales were observed during these campaigns. For example, around 10-ppm CO2 changes were found within free troposphere in a region of about 200×300 km2 over Iowa during a summer 2014 flight. Even over extended forests, about 2-ppm CO2 column variability was measured within about 500-km distance. For winter times, especially over snow covered ground, relatively less horizontal CO2 variability was observed, likely owing to minimal interactions between the atmosphere and land surface. Inter-annual variations of CO2 drawdown over cornfields in the Mid-West were found to be larger than 5 ppm due to slight differences in the corn growing phase and meteorological conditions even in the same time period of a year. Furthermore, considerable differences in atmospheric CO2 profiles were found during winter and summer campaigns. In the winter CO2 was found to decrease from about 400 ppm in the atmospheric boundary layer (ABL) to about 392 ppm above 10 km, while in the summer CO2 increased from 386 ppm in the ABL to about 396 ppm in free troposphere. These and other CO2 observations are discussed in this presentation.

  9. Atmospheric CO2 stabilization and ocean acidification

    NASA Astrophysics Data System (ADS)

    Cao, Long; Caldeira, Ken

    2008-10-01

    We use a coupled climate/carbon-cycle model to examine the consequences of stabilizing atmospheric CO2 at different levels for ocean chemistry. Our simulations show the potential for major damage to at least some ocean ecosystems at atmospheric CO2 stabilization levels as low as 450 ppm. Before the industrial revolution, more than 98% of corals reefs were surrounded by waters that were >3.5 times saturated with respect to their skeleton materials (aragonite). If atmospheric CO2 is stabilized at 450 ppm only 8% of existing coral reefs will be surrounded by water with this saturation level. Also at this CO2 level 7% of the ocean South of 60°S will become undersaturated with respect to aragonite, and parts of the high latitude ocean will experience a decrease in pH by more than 0.2 units. Results presented here provide an independent and additional basis for choosing targets of atmospheric CO2 stabilization levels.

  10. Atmospheric CO2 from fossil plant cuticles.

    PubMed

    Kerp, Hans

    2002-01-03

    Plants respond to changes in atmospheric carbon dioxide levels by regulating the number of stomata in their leaves. In his reconstruction of a continuous, 300-million-year record of atmospheric CO2, Retallack bases his curve on stomatal counts of fossil plant cuticles taken from published micrographs. However, the preservation of cuticles from Permian times is generally too fragmentary for the stomatal index to be reliably determined, the micrographs used could have biased the results, and there are important errors in the supplementary data - all of which cast doubt on the Permian part of Retallack's record.

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

    PubMed

    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.

  12. He bulge revealed: He and CO2 diurnal and seasonal variations in the upper atmosphere of Mars as detected by MAVEN NGIMS

    NASA Astrophysics Data System (ADS)

    Elrod, M. K.; Bougher, S.; Bell, J.; Mahaffy, P. R.; Benna, M.; Stone, S.; Yelle, R.; Jakosky, B.

    2017-02-01

    Analysis of the Neutral Gas and Ion Mass Spectrometer (NGIMS) on the Mars Atmosphere Volatiles and EvolutioN (MAVEN) spacecraft closed source data from all orbits with good pointing revealed an enhanced Helium [He] density on the nightside orbits and a depressed He density on the dayside by about a factor of 10-20. He was also found to be larger in the polar regions than in the equatorial regions. The northern polar winter nightside He bulge was approximately twice that of the northern polar summer nightside bulge. The first 6 weeks of the MAVEN prime mission had periapsis at high latitudes on the nightside during northern winter, followed by the midlatitudes on the dayside moving to low latitudes on the nightside returning to the high latitudes during northern summer. In this study we examined the NGIMS data not only in the different latitudes but sorted by solar longitude (Ls) in order to separate the diurnal or local solar time (LST) effects from the seasonal effects. The Mars Global Ionosphere-Thermosphere Model (M-GITM) has predicted the formation of a He bulge in the upper atmosphere of Mars on the nightside early morning hours (Ls = 2-5 h) with more He collecting around the poles. Taking a slice at constant altitude across all orbits indicates corresponding variations in He and CO2 with respect to LST and Ls and a diurnal and seasonal dependence.

  13. Temporal Variations of the Atmospheric CO2 Concentration and Its Carbon Isotope Ratio at Ny-Ålesund, Svalbard and Estimation of Global Carbon Budget

    NASA Astrophysics Data System (ADS)

    Goto, D.; Morimoto, S.; Ishidoya, S.; Aoki, S.; Nakazawa, T.

    2016-12-01

    Long-term measurements of the atmospheric CO2 concentration and its carbon isotope ratio (δ13C) are useful for partitioning anthropogenic CO2 into the terrestrial biosphere and the ocean, if the carbon isotopic disequilibrium flux (so-called isoflux), combining terrestrial and oceanic contributions, is quantified. For a better understanding of the global carbon cycle, we have carried out the systematic observation of the atmospheric CO2 concentration and δ13C at Ny-Ålesund, Svalbard (78.93°N, 11.83°E) since 1991. Air samples were collected into stainless-steel flasks at the Japanese observatory in Ny-Ålesund, once a week and sent to NIPR every two months. CO2 concentrations of the air samples were determined by using a NDIR analyzer, and CO2 samples extracted cryogenically from the remaining air in the flasks were analyzed for δ13C using a mass spectrometer. Analytical precisions for CO2 and δ13C were 0.01 ppm and 0.02 ‰, respectively. The CO2 concentration shows a clear seasonal cycle with peak-to-peak amplitude of about 17 ppm, which reaches a maximum in late April to early May and a minimum in late August, superimposed on a secular increase with an average rate of 2.0 ppm/yr for the period of 1996-2013. On the other hand, the δ13C decreases secularly at an average rate of -0.018 ‰/yr, and varies seasonally in opposite phase with the CO2 concentration. By analyzing the CO2 concentration and δ13C using the isoflux calculated with a box-diffusion model, the terrestrial biospheric and oceanic CO2 sinks are estimated to be 1.5 ± 0.3 and 2.4 ± 0.4 GtC/yr, respectively, for the 13-year period (2001-2013). On the other hand, the secular trends of the atmospheric δ(O2/N2) and CO2 concentration at Ny-Ålesund (Ishidoya et al., 2012) yield the respective sink values of 1.7 ± 0.8 and 2.2 ± 0.7 GtC/yr for the same period. The estimates from the two methods are in good agreement with each other.

  14. Atmospheric effects on CO2 laser propagation

    NASA Technical Reports Server (NTRS)

    Murty, S. S. R.; Bilbro, J. W.

    1978-01-01

    An investigation was made of the losses encountered in the propagation of CO2 laser radiation through the atmosphere, particularly as it applies to the NASA/Marshall Space Flight Center Pulsed Laser Doppler System. As such it addresses three major areas associated with signal loss: molecular absorption, refractive index changes in a turbulent environment, and aerosol absorption and scattering. In particular, the molecular absorption coefficients of carbon dioxide, water vapor, and nitrous oxide are calculated for various laser lines in the region of 10.6 mu m as a function of various pressures and temperatures. The current status in the physics of low-energy laser propagation through a turbulent atmosphere is presented together with the analysis and evaluation of the associated heterodyne signal power loss. Finally, aerosol backscatter and extinction coefficients are calculated for various aerosol distributions and the results incorporated into the signal-to-noise ratio equation for the Marshall Space Flight Center system.

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

    PubMed

    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.

  16. A role for atmospheric CO2 in preindustrial climate forcing

    PubMed Central

    van Hoof, Thomas B.; 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 volume, considerably exceeds maximum shifts measured in Antarctic ice. Inferred changes in CO2 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 CO2 as a preindustrial climate-forcing factor. The stomata-based CO2 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 CO2 changes. PMID:18838689

  17. The carbon isotope composition of atmospheric CO 2 in Paris

    NASA Astrophysics Data System (ADS)

    Widory, David; Javoy, Marc

    2003-10-01

    One characteristic of air pollution in the urban environment is high CO 2 concentrations resulting from human activities. Determining the relative contributions of the different CO 2 sources can be addressed simply and elegantly by combining isotope and concentration measurements. Using this approach on atmospheric CO 2 samples collected in Paris, its suburbs and the open country provides fairly accurate conclusions. Our results show that air pollution within the first few metres above ground results basically from binary mixtures among which road traffic is the main contributor and, in particular, vehicles using unleaded gasoline (˜90% of the total). Heating sources, which account for 50% of the CO 2 input below the atmospheric inversion level, and vehicles using diesel contribute very little. Human respiration has a recognisable signature at street level under certain circumstances. The combined isotope and concentration analysis provides a sensitive tracer of local variations, even detecting the occasional prevalence of human respiration and the onset of actions in which natural gas is burnt. It also detects surprising inlets of 'clean air' (CO 2-wise) in the very centre of the city.

  18. Sources and Sinks of Atmospheric CO2

    NASA Astrophysics Data System (ADS)

    Sarmiento, J. L.; Gloor, M.; Gruber, N.; Jacobson, A.; Mikaloff-Fletcher, S.; Pacala, S.; Rodgers, K.

    2008-12-01

    Between 1960 and 2006, the ocean took up ~33% of the cumulative fossil fuel emissions of 251 Pg C and increases in atmospheric CO2 concentration accounted for ~56%. The remaining ~11% of fossil fuel emissions were taken up by the terrestrial biosphere despite emissions from deforestation occurring mostly in the tropics. Around 1990/91, the global carbon cycle appears to have undergone a major shift. The atmospheric growth rate decelerated from an average of 58.4 ' 1.8% of fossil fuel emissions prior to 1990, to 52.1% thereafter. Furthermore, ocean carbon model simulations suggest that the oceanic uptake leveled off after ~1990 instead of increasing as expected. Taken together, this implies an increase in the net uptake by the terrestrial biosphere of ~0.9 Pg C yr-1. While the impact of the 1991 Mt. Pinatubo eruption can account for about one-third of this increase, we cannot explain the remainder. Estimates of the regional distribution of sources and sinks over the oceans have improved greatly in the last decade, but remain a vexing challenge for the land biosphere. The difficulty in accounting for land sources and sinks and the associated uncertainty with regard to mechanisms leads to major uncertainties in the future behavior of the global carbon sinks, with major implications for climate policy.

  19. The carbon cycle and atmospheric CO2: Natural variations archean to present; Proceedings of the Chapman Conference on Natural Variations in Carbon Dioxide and the Carbon Cycle, Tarpon Springs, FL, January 9-13, 1984

    NASA Astrophysics Data System (ADS)

    Sundquist, E. T.; Broecker, W. S.

    The present conference on the history of the relationship between atmospheric CO2 and the carbon cycle treats data obtained concerning the most recent deglaciation, the Pleistocene, the Zenozoic, and the Phanerozoic-Precambrian. Specific attention is given to the geophysical implications of the tropospheric methane cycle, transient response of the marine carbon cycle, factors regulating glacial to interglacial CO2 changes, the high latitude ocean as a control of atmospheric CO2, and the relationships among atmospheric CO2, orbital forcing, and climate. Also discussed are the distribution of major vegetation types during the Tertiary, a 'Strangelove' ocean in the earliest Tertiary, high atmospheric CO2 as a plausible mechanism for warm Cretaceous climates, and potential estimation errors in carbonate rock accumulation over geologic time.

  20. The Abundance of Atmospheric CO2 in Ocean Exoplanets: a Novel CO2 Deposition Mechanism

    NASA Astrophysics Data System (ADS)

    Levi, A.; Sasselov, D.; Podolak, M.

    2017-03-01

    We consider super-Earth sized planets which have a water mass fraction large enough to form an external mantle composed of high-pressure water-ice polymorphs and also lack a substantial H/He atmosphere. We consider such planets in their habitable zone, so that their outermost condensed mantle is a global, deep, liquid ocean. For these ocean planets, we investigate potential internal reservoirs of CO2, the amount of CO2 dissolved in the ocean for the various saturation conditions encountered, and the ocean-atmosphere exchange flux of CO2. We find that, in a steady state, the abundance of CO2 in the atmosphere has two possible states. When wind-driven circulation is the dominant CO2 exchange mechanism, an atmosphere of tens of bars of CO2 results, where the exact value depends on the subtropical ocean surface temperature and the deep ocean temperature. When sea-ice formation, acting on these planets as a CO2 deposition mechanism, is the dominant exchange mechanism, an atmosphere of a few bars of CO2 is established. The exact value depends on the subpolar surface temperature. Our results suggest the possibility of a negative feedback mechanism, unique to water planets, where a reduction in the subpolar temperature drives more CO2 into the atmosphere to increase the greenhouse effect.

  1. Different representations of biological nitrogen fixation cause major variation in projected terrestrial biosphere responses to elevated levels of atmospheric CO2

    NASA Astrophysics Data System (ADS)

    Meyerholt, J.; Zaehle, S.; Smith, M. J.

    2015-12-01

    Including a land nitrogen (N) cycle in current Earth system models has led to substantial attenuation of predicted land-climate feedbacks, but the magnitude of this N effect remains highly uncertain. The current magnitude and global change responses of major land N cycle processes are still not well understood. Biological nitrogen fixation (BNF) is one particularly important process, being the largest natural land input of N. However, global terrestrial BNF rates are highly uncertain and models lack observations on which to base their predictions. The current variety of terrestrial biosphere models use a wide array of differing, largely untested BNF representations. We tested the six most widely used formulations within the O-CN model and examined the resulting differences in model predictions both under current atmospheric [CO2], as well as under future scenarios of elevated atmospheric [CO2]: a prescribed global map of static BNF rates, two simple empirical relationships between BNF and other ecosystem variables (net primary production and evapotranspiration), two process-based formulations based on plant N status, and an approach following a basic form of optimality of plant N acquisition. We found that the predicted global BNF rates for current conditions were fairly comparable, ranging from 93 to 134 Tg N yr-1 (median 118 Tg N yr-1). However, at 587 ppm atmospheric [CO2], model responses in BNF rates ranged from -5 Tg N yr-1 (-4 %) to 113 Tg N yr-1 (+88 %) (median 14 Tg N yr-1 (+15 %)). As a consequence, future projections of global net primary productivity and carbon storage (increases of different magnitudes), as well as N2O emission (negative responses or unchanged) differed significantly across the different model formulations. Our results emphasize the importance of better understanding the nature and magnitude of BNF responses to change induced perturbations; particularly through new empirical perturbation experiments.

  2. The natural latitudinal distribution of atmospheric CO 2

    NASA Astrophysics Data System (ADS)

    Taylor, John A.; Orr, James C.

    2000-12-01

    Although poorly understood, the north-south distribution of the natural component of atmospheric CO 2 offers information essential to improving our understanding of the exchange of CO 2 between the atmosphere, oceans, and biosphere. The natural or unperturbed component is equivalent to that part of the atmospheric CO 2 distribution which is controlled by non-anthropogenic CO 2 fluxes from the ocean and terrestrial biosphere. Models should be able to reproduce the true north-south gradient in CO 2 due to the natural component before they can reliably estimate present-day CO 2 sources and sinks and predict future atmospheric CO 2. We have estimated the natural latitudinal distribution of atmospheric CO 2, relative to the South Pole, using measurements of atmospheric CO 2 during 1959-1991 and corresponding estimates of anthropogenic CO 2 emissions to the atmosphere. Key features of the natural latitudinal distribution include: (1) CO 2 concentrations in the northern hemisphere that are lower than those in the southern hemisphere; (2) CO 2 concentration differences that are higher in the tropics (associated with outgassing of the oceans) than those currently measured; and (3) CO 2 concentrations over the southern ocean that are relatively uniform. This natural latitudinal distribution and its sensitivity to increasing fossil fuel emissions both indicate that near-surface concentrations of atmospheric CO 2 in the northern hemisphere are naturally lower than those in the southern hemisphere. Models that find the contrary will also mismatch present-day CO 2 in the northern hemisphere and incorrectly ascribe that region as a large sink of anthropogenic CO 2.

  3. Seasonal variations in δ13C and δ18O of atmospheric CO2 measured in the urban boundary layer over Vancouver, Canada in relation to fuel emissions.

    NASA Astrophysics Data System (ADS)

    Lee, J.; Christen, A.; Ketler, R.; Nesic, Z.; Schwendenmann, L.; Semmens, C.

    2014-12-01

    Recent advances in techniques to measure carbon dioxide (CO2) in urban plumes show potential for validating and monitoring emission inventories at regional to urban scale. A major challenge remains the attribution of elevated CO2 in urban plumes to different fuel and biogenic sources. Stable isotopes are a promising source of additional information. Here, we report a full year of measurements of CO2 mixing ratios, δ13C and δ18O in CO2 in the urban boundary layer over Vancouver, Canada. The goal of the work is to link seasonally changing isotopic composition to dominant fuel sources and put the urban enhancement into the context of regional background concentrations. Atmospheric composition in the urban atmosphere was measured continuously using a tunable diode laser absorption system (TGA 200, Campbell Scientific, Logan, UT, USA). In addition, end member signatures were determined by means of bag samples from representative fuel emission sources (gasoline, diesel, natural gas). While δ13C depends on the fuel type and origin (for Vancouver in 2013/14: δ13C gasoline 27.2‰; diesel -28.8‰; natural gas -41.6‰), δ18O is fractionated in catalytic converters (d18O gasoline vehicles -12.5‰; diesel -18.6‰; natural gas -22.7‰) and exhibits higher variability between samples. Additional signatures were determined for human, soil and plant respiration. During the study year, monthly mean mixing ratios in the urban atmosphere ranged between 410.5 (Jul) and 425.7 ppm (Dec), which was on average 18 ppm elevated above the regional background. As expected, mean monthly δ13C was lower in winter than summer with seasonally changing intercepts between -33.6‰ (JJF) and -27.7‰ (MJJ). Making the simple assumption that natural gas and gasoline are the only major fuel sources, natural gas would contribute ~45% to emissions in winter and ~3% in early summer, which is lower than the downscaled Local Emissions Inventory (57% in winter and 20% in summer). Mean δ18O showed

  4. Observational constraints on the global atmospheric CO2 budget

    NASA Technical Reports Server (NTRS)

    Tans, Pieter P.; Fung, Inez Y.; Takahashi, Taro

    1990-01-01

    Observed atmospheric concentrations of CO2 and data on the partial pressures of CO2 in surface ocean waters are combined to identify globally significant sources and sinks of CO2. The atmospheric data are compared with boundary layer concentrations calculated with the transport fields generated by a general circulation model (GCM) for specified source-sink distributions. In the model the observed north-south atmospheric concentration gradient can be maintained only if sinks for CO2 are greater in the Northern than in the Southern Hemisphere. The observed differences between the partial pressure of CO2 in the surface waters of the Northern Hemisphere and the atmosphere are too small for the oceans to be the major sink of fossil fuel CO2. Therefore, a large amount of the CO2 is apparently absorbed on the continents by terrestrial ecosystems.

  5. A joint global carbon inversion system using both CO2 and 13CO2 atmospheric concentration data

    NASA Astrophysics Data System (ADS)

    Chen, Jing M.; Mo, Gang; Deng, Feng

    2017-03-01

    Observations of 13CO2 at 73 sites compiled in the GLOBALVIEW database are used for an additional constraint in a global atmospheric inversion of the surface CO2 flux using CO2 observations at 210 sites (62 collocated with 13CO2 sites) for the 2002-2004 period for 39 land regions and 11 ocean regions. This constraint is implemented using prior CO2 fluxes estimated with a terrestrial ecosystem model and an ocean model. These models simulate 13CO2 discrimination rates of terrestrial photosynthesis and ocean-atmosphere diffusion processes. In both models, the 13CO2 disequilibrium between fluxes to and from the atmosphere is considered due to the historical change in atmospheric 13CO2 concentration. This joint inversion system using both13CO2 and CO2 observations is effectively a double deconvolution system with consideration of the spatial variations of isotopic discrimination and disequilibrium. Compared to the CO2-only inversion, this 13CO2 constraint on the inversion considerably reduces the total land carbon sink from 3.40 ± 0.84 to 2.53 ± 0.93 Pg C year-1 but increases the total oceanic carbon sink from 1.48 ± 0.40 to 2.36 ± 0.49 Pg C year-1. This constraint also changes the spatial distribution of the carbon sink. The largest sink increase occurs in the Amazon, while the largest source increases are in southern Africa, and Asia, where CO2 data are sparse. Through a case study, in which the spatial distribution of the annual 13CO2 discrimination rate over land is ignored by treating it as a constant at the global average of -14. 1 ‰, the spatial distribution of the inverted CO2 flux over land was found to be significantly modified (up to 15 % for some regions). The uncertainties in our disequilibrium flux estimation are 8.0 and 12.7 Pg C year-1 ‰ for land and ocean, respectively. These uncertainties induced the unpredictability of 0.47 and 0.54 Pg C year-1 in the inverted CO2 fluxes for land and ocean, respectively. Our joint inversion system is therefore

  6. Will atmospheric CO2 concentration continue to increase if anthropogenic CO2 emissions cease?

    NASA Astrophysics Data System (ADS)

    MacDougall, A. H.; Eby, M.; Weaver, A. J.

    2013-12-01

    If anthropogenic CO2 emissions were to suddenly cease, the evolution of the atmospheric CO2 concentration would depend on the magnitude and sign of natural carbon sources and sinks. Experiments using Earth system models indicate that overall carbon sinks would dominate. However, these models have typically neglected the permafrost carbon pool, which has the potential to introduce an additional terrestrial source of carbon to the atmosphere. Here we use the University of Victoria Earth System Climate Model, which has recently been expanded to include permafrost carbon stocks and exchanges with the atmosphere. In a scenario of zeroed CO2 and sulphate aerosol emissions, we assess whether the warming induced by specified constant concentrations of non-CO2 greenhouse gases could slow the CO2 decline following zero emissions, or even reverse this trend and cause CO2 to increase over time. We find that a radiative forcing from non-CO2 gases of approximately 0.6 W m-2 results in a near balance of CO2 emissions from the terrestrial biosphere and uptake of CO2 by the oceans, resulting in near-constant atmospheric CO2 concentrations for at least a century after emissions are eliminated. At higher values of non-CO2 radiative forcing, CO2 concentrations increase over time, regardless of when emissions cease during the 21st century. Given that the present-day radiative forcing from non-CO2 greenhouse gases is about 0.95 W m-2, our results suggest that if we were to eliminate all CO2 and aerosols emissions without also decreasing non-CO2 greenhouse gas emissions, CO2 levels would increase over time, resulting in a small increase in climate warming. The sudden and total cessation of anthropogenic CO2 emissions is an unlikely future scenario. However, such cessation experiments provide a useful method for evaluating the relative strength of the terrestrial and oceanic carbon cycle feedbacks in the presence of forcing from non-CO2 greenhouse gasses.

  7. Halloysite nanotubes capturing isotope selective atmospheric CO2.

    PubMed

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

    2015-03-04

    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 ((12)C(16)O2, (13)C(16)O2, and (12)C(16)O(18)O) from the ambient air by amine functionalized HNTs has been explored using an optical cavity-enhanced integrated cavity output spectroscopy. CO2 adsorption/desorption cycling measurements demonstrate that the adsorbent can be regenerated at relatively low temperature and thus, recycled repeatedly to capture atmospheric CO2. The amine grafted halloysite shows excellent stability even in oxidative environments and has high efficacy of CO2 capture, introducing a new route to the adsorption of isotope selective atmospheric CO2.

  8. Atmospheric CO2 enrichment and grassland productivity: Scaling CO2 effects through the plant community

    USDA-ARS?s Scientific Manuscript database

    Ecosystem responses to atmospheric CO2 enrichment, as to other climate change drivers, depend on plant community responses to CO2 (community response) and feedbacks from community change on ecosystem processes (community effect). We used data from two multi-year experiments in central Texas, USA to...

  9. Atmospheric measurement of point source fossil fuel CO2 emissions

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

    We use the Kapuni Gas Treatment Plant to examine methodologies for atmospheric monitoring of point source fossil fuel CO2 (CO2ff) emissions. The Kapuni plant, located in rural New Zealand, removes CO2 from locally extracted natural gas and vents that CO2 to the atmosphere, at a rate of ~0.1 Tg carbon per year. The plant is located in a rural dairy farming area, with no other significant CO2ff sources nearby, but large, diurnally varying, biospheric CO2 fluxes from the surrounding highly productive agricultural grassland. We made flask measurements of CO2 and 14CO2 (from which we derive the CO2ff component) and in situ measurements of CO2 downwind of the Kapuni plant, using a Helikite to sample transects across the emission plume from the surface up to 100 m a.g.l. We also determined the surface CO2ff content averaged over several weeks from the 14CO2 content of grass samples collected from the surrounding area. We use the WindTrax plume dispersion model to compare the atmospheric observations with the emissions reported by the Kapuni plant, and to determine how well atmospheric measurements can constrain the emissions. The model has difficulty accurately capturing the fluctuations and short-term variability in the Helikite samples, but does quite well in representing the observed CO2ff in 15 min averaged surface flask samples and in ~1 week integrated CO2ff averages from grass samples. In this pilot study, we found that using grass samples, the modeled and observed CO2ff emissions averaged over one week agreed to within 30%. The results imply that greater verification accuracy may be achieved by including more detailed meteorological observations and refining 14CO2 sampling strategies.

  10. Carboxylation of Phenols with CO2 at Atmospheric Pressure.

    PubMed

    Luo, Junfei; Preciado, Sara; Xie, Pan; Larrosa, Igor

    2016-05-10

    A convenient and efficient method for the ortho-carboxylation of phenols under atmospheric CO2 pressure has been developed. This method provides an alternative to the previously reported Kolbe-Schmitt method, which requires very high pressures of CO2 . The addition of a trisubstituted phenol has proved essential for the successful carboxylation of phenols with CO2 at standard atmospheric pressure, allowing the efficient preparation of a broad variety of salicylic acids.

  11. Comparison of Surface and Column Variations of CO2 Over Urban Areas for Future Active Remote CO2 Sensors

    NASA Technical Reports Server (NTRS)

    Choi, Yonghoon; Yang, Melissa; Kooi, Susan; Browell, Edward

    2015-01-01

    High resolution in-situ CO2 measurements were recorded onboard the NASA P-3B during the DISCOVER-AQ (Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality) Field Campaign, to investigate the ability of space-based observations to accurately assess near surface conditions related to air quality. This campaign includes, Washington DC/Baltimore, MD (July 2011), San Joaquin Valley, CA (January - February 2013), Houston, TX (September 2013), and Denver, CO (July-August 2014). Each of these campaigns consisted of missed approaches and approximately two hundred vertical soundings of CO2 within the lower troposphere (surface to about 5 km). In this study, surface (0 - 1 km) and column-averaged (0 - 3.5 km) CO2 mixing ratio values from the vertical soundings in the four geographically different urban areas are used to investigate the temporal and spatial variability of CO2 within the different urban atmospheric emission environments. Tracers such as CO, CH2O, NOx, and NMHCs are used to identify the source of CO2 variations in the urban sites. Additionally, we apply nominal CO2 column weighting functions for potential future active remote CO2 sensors operating in the 1.57-microns and 2.05-microns measurement regions to convert the in situ CO2 vertical mixing ratio profiles to variations in CO2 column optical depths, which is what the active remote sensors actually measure. Using statistics calculated from the optical depths at each urban site measured during the DISCOVER-AQ field campaign and for each nominal weighting function, we investigate the natural variability of CO2 columns in the lower troposphere; relate the CO2 column variability to the urban surface emissions; and show the measurement requirements for the future ASCENDS (Active Sensing of CO2 Emissions over Nights, Days, and Seasons) in the continental U.S. urban areas.

  12. Three dimensional global modeling of atmospheric CO2

    NASA Technical Reports Server (NTRS)

    Hanse, J.; Fung, I.; Rind, D.

    1984-01-01

    The initial attempts to model the atmospheric CO2 distribution, including couplings to the ocean and biosphere as sources and sinks of atmospheric CO2, encourage the notion that this approach will lead to useful quantitative constraints on CO2 fluxes. Realization of this objective will require: (1) continued improvement in the realism of the global transport modeling; (2) extended timeline of atmospheric CO2 monitoring, which improved precision and improved definition of the uncertainties in the measured CO2 amounts; and (3) given an accurate knowledge of model capabilities and limitations and given a good understanding of CO2 observations and their limitations, there is a need for good ideas concerning what quantitative information on the carbon cycle can be inferred from global modeling.

  13. Three dimensional global modeling of atmospheric CO2

    NASA Technical Reports Server (NTRS)

    Hanse, J.; Fung, I.; Rind, D.

    1984-01-01

    The initial attempts to model the atmospheric CO2 distribution, including couplings to the ocean and biosphere as sources and sinks of atmospheric CO2, encourage the notion that this approach will lead to useful quantitative constraints on CO2 fluxes. Realization of this objective will require: (1) continued improvement in the realism of the global transport modeling; (2) extended timeline of atmospheric CO2 monitoring, which improved precision and improved definition of the uncertainties in the measured CO2 amounts; and (3) given an accurate knowledge of model capabilities and limitations and given a good understanding of CO2 observations and their limitations, there is a need for good ideas concerning what quantitative information on the carbon cycle can be inferred from global modeling.

  14. Atmospheric measurement of point source fossil CO2 emissions

    NASA Astrophysics Data System (ADS)

    Turnbull, J. C.; Keller, E. D.; Baisden, T.; Brailsford, G.; Bromley, T.; Norris, M.; Zondervan, A.

    2014-05-01

    We use the Kapuni Gas Treatment Plant to examine methodologies for atmospheric monitoring of point source fossil fuel CO2 (CO2ff) emissions. The Kapuni plant, located in rural New Zealand, removes CO2 from locally extracted natural gas and vents that CO2 to the atmosphere, at a rate of ~0.1 Tg carbon per year. The plant is located in a rural dairy farming area, with no other significant CO2ff sources nearby, but large, diurnally varying, biospheric CO2 fluxes from the surrounding highly productive agricultural grassland. We made flask measurements of CO2 and 14CO2 (from which we derive the CO2ff component) and in situ measurements of CO2 downwind of the Kapuni plant, using a Helikite to sample transects across the emission plume from the surface up to 100 m above ground level. We also determined the surface CO2ff content averaged over several weeks from the 14C content of grass samples collected from the surrounding area. We use the WindTrax plume dispersion model to compare the atmospheric observations with the emissions reported by the Kapuni plant, and to determine how well atmospheric measurements can constrain the emissions. The model has difficulty accurately capturing the fluctuations and short-term variability in the Helikite samples, but does quite well in representing the observed CO2ff in 15 min averaged surface flask samples and in ~ one week integrated CO2ff averages from grass samples. In this pilot study, we found that using grass samples, the modeled and observed CO2ff emissions averaged over one week agreed to within 30%. The results imply that greater verification accuracy may be achieved by including more detailed meteorological observations and refining 14C sampling strategies.

  15. Lidar Measurements of Atmospheric CO2 From Regional to Global Scales

    NASA Technical Reports Server (NTRS)

    Lin, Bing; Harrison, F. Wallace; Nehrir, Amin; Browell, Edward; Dobler, Jeremy; Campbell, Joel; Meadows, Byron; Obland, Michael; Ismail, Syed; Kooi, Susan; hide

    2015-01-01

    Atmospheric CO2 is a critical forcing for the Earth's climate and the knowledge on its distributions and variations influences predictions of the Earth's future climate. Large uncertainties in the predictions persist due to limited observations. This study uses the airborne Intensity-Modulated Continuous-Wave (IMCW) lidar developed at NASA Langley Research Center to measure regional atmospheric CO2 spatio-temporal variations. Further lidar development and demonstration will provide the capability of global atmospheric CO2 estimations from space, which will significantly advances our knowledge on atmospheric CO2 and reduce the uncertainties in the predictions of future climate. In this presentation, atmospheric CO2 column measurements from airborne flight campaigns and lidar system simulations for space missions will be discussed. A measurement precision of approx.0.3 ppmv for a 10-s average over desert and vegetated surfaces has been achieved. Data analysis also shows that airborne lidar CO2 column measurements over these surfaces agree well with in-situ measurements. Even when thin cirrus clouds present, consistent CO2 column measurements between clear and thin cirrus cloudy skies are obtained. Airborne flight campaigns have demonstrated that precise atmospheric column CO2 values can be measured from current IM-CW lidar systems, which will lead to use this airborne technique in monitoring CO2 sinks and sources in regional and continental scales as proposed by the NASA Atmospheric Carbon and Transport â€" America project. Furthermore, analyses of space CO2 measurements shows that applying the current IM-CW lidar technology and approach to space, the CO2 science goals of space missions will be achieved, and uncertainties in CO2 distributions and variations will be reduced.

  16. Elevated Eocene atmospheric CO2 and its subsequent decline.

    PubMed

    Lowenstein, Tim K; Demicco, Robert V

    2006-09-29

    Quantification of the atmospheric concentration of CO2 ([CO2]atm) during warm periods of Earth's history is important because burning of fossil fuels may produce future [CO2]atm approaching 1000 parts per million by volume (ppm). The early Eocene (~56 to 49 million years ago) had the highest prolonged global temperatures of the past 65 million years. High Eocene [CO2]atm is established from sodium carbonate minerals formed in saline lakes and preserved in the Green River Formation, western United States. Coprecipitation of nahcolite (NaHCO3) and halite (NaCl) from surface waters in contact with the atmosphere indicates [CO2]atm > 1125 ppm (four times preindustrial concentrations), which confirms that high [CO2]atm coincided with Eocene warmth.

  17. Radiocarbon observations in atmospheric CO2: determining fossil fuel CO2 over Europe using Jungfraujoch observations as background.

    PubMed

    Levin, Ingeborg; Hammer, Samuel; Kromer, Bernd; Meinhardt, Frank

    2008-03-01

    Monthly mean 14CO2 observations at two regional stations in Germany (Schauinsland observatory, Black Forest, and Heidelberg, upper Rhine valley) are compared with free tropospheric background measurements at the High Alpine Research Station Jungfraujoch (Swiss Alps) to estimate the regional fossil fuel CO2 surplus at the regional stations. The long-term mean fossil fuel CO2 surplus at Schauinsland is 1.31+/-0.09 ppm while it is 10.96+/-0.20 ppm in Heidelberg. No significant trend is observed at both sites over the last 20 years. Strong seasonal variations of the fossil fuel CO2 offsets indicate a strong seasonality of emissions but also of atmospheric dilution of ground level emissions by vertical mixing.

  18. A Global Perspective of Atmospheric CO2 Concentrations

    NASA Technical Reports Server (NTRS)

    Putman, William M.; Ott, Lesley; Darmenov, Anton; daSilva, Arlindo

    2016-01-01

    Carbon dioxide (CO2) is the most important greenhouse gas affected by human activity. About half of the CO2 emitted from fossil fuel combustion remains in the atmosphere, contributing to rising temperatures, while the other half is absorbed by natural land and ocean carbon reservoirs. Despite the importance of CO2, many questions remain regarding the processes that control these fluxes and how they may change in response to a changing climate. The Orbiting Carbon Observatory-2 (OCO-2), launched on July 2, 2014, is NASA's first satellite mission designed to provide the global view of atmospheric CO2 needed to better understand both human emissions and natural fluxes. This visualization shows how column CO2 mixing ratio, the quantity observed by OCO-2, varies throughout the year. By observing spatial and temporal gradients in CO2 like those shown, OCO-2 data will improve our understanding of carbon flux estimates. But, CO2 observations can't do that alone. This visualization also shows that column CO2 mixing ratios are strongly affected by large-scale weather systems. In order to fully understand carbon flux processes, OCO-2 observations and atmospheric models will work closely together to determine when and where observed CO2 came from. Together, the combination of high-resolution data and models will guide climate models towards more reliable predictions of future conditions.

  19. Effects of atmospheric CO2 enrichment on soil CO2 efflux in a young longleaf pine system

    USDA-ARS?s Scientific Manuscript database

    Elevated atmospheric carbon dioxide (CO2) can affect the quantity and quality of plant tissues which will impact carbon (C) cycling and storage in plant/soil systems and the release of CO2 back to the atmosphere. Research is needed to quantify the effects of elevated CO2 on soil CO2 efflux to predi...

  20. Ecological impacts of atmospheric CO2 enrichment on terrestrial ecosystems.

    PubMed

    Körner, Christian

    2003-09-15

    Global change has many facets, of which land use and the change of atmospheric chemistry are unquestioned primary agents, which induce a suite of secondary effects, including climatic changes. The largest single contribution to the compositional change of the atmosphere, CO(2) enrichment, has (besides its influence on climate) immediate and direct effects on plants. Quantitatively, CO(2) is the plant 'food' number one, and the rate of photosynthetic CO(2) uptake by leaves is not yet CO(2)-saturated. This abrupt change of the biosphere's diet does and will affect all aspects of life, including our food. However, the plant and ecosystem responses are more subtle than had been assumed from the results of responses of isolated, well-fertilized and well-watered plants in greenhouses during the early days of CO(2)-enrichment research. In this article, I discuss potential responses of complex natural grassland and diverse forests, and address three key themes: CO(2) and nutrients; CO(2) and water; CO(2) and plant-animal interactions. Examples from a suite of climatic regions emphasize that the most important ecosystem level responses to elevated CO(2) will be introduced by differential responses of species. Atmospheric CO(2) enrichment is a biodiversity issue. Classical physiological baseline responses of leaves to elevated CO(2) can be overrun by biodiversity effects to such an extent that some of the traditional predictions may even become reversed. For instance, biodiversity effects may cause humid tropical forests (those which avoid destruction) to become more dynamic and store less, rather than more, carbon as CO(2) enrichment continues. The abundance of certain life forms and species and their lifespans exert major controls over the half-life of carbon stored in forest biomass, and there is evidence that elevated CO(2) can affect these controls and most likely does so already. Also, long-term hydrological consequences of atmospheric CO(2) enrichment will be driven

  1. Long-term elevated atmospheric CO2 enhances forest productivity

    NASA Astrophysics Data System (ADS)

    Loecke, T. D.; Groffman, P. M.; Treseder, K. K.; LaDeau, S.

    2011-12-01

    Global atmospheric CO2 concentrations are increasing at historically unprecedented but ecologically gradual rates. The implications of this perturbation for carbon sequestration and feedback on global climate change are difficult to predict due in part to its gradual and largely uniform nature. We used long-term (>40 years) spatial gradients in atmospheric CO2 concentration, produced by spatially heterogeneous fossil fuel combustion along a rural to urban transect, to test the hypotheses that 1) rural to urban CO2 spatial gradients are useful analogs for gradual climate change and 2) higher atmospheric CO2 concentration promotes tree growth and C sequestration. Fossil fuel derived CO2 imparts a distinctive 14C isotopic signature on atmospheric CO2; as this CO2 is fixed into annual tree rings, a proxy for fossil fuel derived CO2 is preserved. Ten four-year tree ring segments were analyzed for α-cellulose 14C content by AMS from trees within 10 closed canopy forested sites in the Baltimore Maryland metropolitan area. Tree growth parameters were assessed by measuring the annual ring width change of 224 trees across the 10 sites. A hierarchical Bayesian model was constructed to determine the influence of CO2 concentration and other site and environmental factors on tree growth. Our proxy for historical CO2 concentrations indicates a detectable but diminishing spatial CO2 gradient across the rural to urban transect that ranged from a 5.6% gradient during the 1970s to a 1.4% gradient in recent years (2000-2008). This observation is consistent with urban deindustrialization and concurrent expansion of suburban development. As an analog for future atmospheric conditions, this spatial gradient is equivalent to a temporal gradient of ca. 15, 7.2, 9.8, 2.6 years of atmospheric CO2 rise during the past four decades. The CO2 spatial gradient had an overall positive effect on tree size adjusted ring width growth. Modeled air surface temperature differences among sites indicate

  2. Laser Sounder Approach for Measuring Atmospheric CO2 from Orbit

    NASA Technical Reports Server (NTRS)

    Krainak, Michael A.; Andrews, Arlyn E.; Allan, Graham R.; Burris, John F.; Collatz, G. James; Riris, Harris; Stephen, Mark A.; Sun, Xiao-Li; Abshire, James B.

    2004-01-01

    We report on an active remote sensing approach using an erbium fiber amplifier based transmitter for atmospheric CO2 measurements in an overtone band near 1.57 microns and initial horizontal path measurements to less than 1% precision.

  3. Biosphere-atmosphere interactions and rising CO2

    NASA Astrophysics Data System (ADS)

    Gentine, Pierre

    2017-04-01

    We will discuss the role of rising CO2 on land-atmosphere interactions and the the impact of land-atmosphere interactions on climate in the context of rising CO2 concertations. We will show that increased leaf level CO2 (physiological effect) concentrations can compete with the effect of rising CO2 concentration on temperature (radiative effect). We will first show that an implications of those feedbacks is a modification of the hydrological cycle, its seasonality and response to extremes. Then we will discuss implications for future droughts. We will then show that the coupling between the carbon and water cycle offers opportunity for observations of those feedbacks. Finally we will question the use of offline simulations to assess the future of ecosystems and further carbon uptake, as land-atmosphere interactions in the future will have such a profound effect on atmospheric aridity that the biosphere cannot be considered in isolation.

  4. Biosequestration of atmospheric CO2 and flue gas-containing CO2 by microalgae.

    PubMed

    Cheah, Wai Yan; Show, Pau Loke; Chang, Jo-Shu; Ling, Tau Chuan; Juan, Joon Ching

    2015-05-01

    The unceasing rise of greenhouse gas emission has led to global warming and climate change. Global concern on this phenomenon has put forward the microalgal-based CO2 sequestration aiming to sequester carbon back to the biosphere, ultimately reducing greenhouse effects. Microalgae have recently gained enormous attention worldwide, to be the valuable feedstock for renewable energy production, due to their high growth rates, high lipid productivities and the ability to sequester carbon. The photosynthetic process of microalgae uses atmospheric CO2 and CO2 from flue gases, to synthesize nutrients for their growth. In this review article, we will primarily discuss the efficiency of CO2 biosequestration by microalgae species, factors influencing microalgal biomass productions, microalgal cultivation systems, the potential and limitations of using flue gas for microalgal cultivation as well as the bio-refinery approach of microalgal biomass.

  5. Monitoring Atmospheric CO2 From Space: Challenge & Approach

    NASA Technical Reports Server (NTRS)

    Lin, Bing; Harrison, F. Wallace; Nehrir, Amin; Browell, Edward; Dobler, Jeremy; Campbell, Joel; Meadows, Byron; Obland, Michael; Kooi, Susan; Fan, Tai-Fang; Ismail, Syed

    2015-01-01

    Atmospheric CO2 is the key radiative forcing for the Earth's climate and may contribute a major part of the Earth's warming during the past 150 years. Advanced knowledge on the CO2 distributions and changes can lead considerable model improvements in predictions of the Earth's future climate. Large uncertainties in the predictions have been found for decades owing to limited CO2 observations. To obtain precise measurements of atmospheric CO2, certain challenges have to be overcome. For an example, global annual means of the CO2 are rather stable, but, have a very small increasing trend that is significant for multi-decadal long-term climate. At short time scales (a second to a few hours), regional and subcontinental gradients in the CO2 concentration are very small and only in an order of a few parts per million (ppm) compared to the mean atmospheric CO2 concentration of about 400 ppm, which requires atmospheric CO2 space monitoring systems with extremely high accuracy and precision (about 0.5 ppm or 0.125%) in spatiotemporal scales around 75 km and 10-s. It also requires a decadal-scale system stability. Furthermore, rapid changes in high latitude environments such as melting ice, snow and frozen soil, persistent thin cirrus clouds in Amazon and other tropical areas, and harsh weather conditions over Southern Ocean all increase difficulties in satellite atmospheric CO2 observations. Space lidar approaches using Integrated Path Differential Absorption (IPDA) technique are considered to be capable of obtaining precise CO2 measurements and, thus, have been proposed by various studies including the 2007 Decadal Survey (DS) of the U.S. National Research Council. This study considers to use the Intensity-Modulated Continuous-Wave (IM-CW) lidar to monitor global atmospheric CO2 distribution and variability from space. Development and demonstration of space lidar for atmospheric CO2 measurements have been made through joint adventure of NASA Langley Research Center and

  6. Sensitivity of simulated CO2 concentration to sub-annual variations in fossil fuel CO2 emissions

    NASA Astrophysics Data System (ADS)

    Zhang, X.; Gurney, K. R.; Rayner, P. J.; Baker, D. F.; Liu, Y.; Asefi-Najafabady, S.

    2014-12-01

    This study presents a sensitivity analysis of the impact of sub-annual fossil fuel CO2 emissions on simulated CO2 concentration using a global tracer transport model. Four sensitivity experiments were conducted to investigate the impact of three cyclic components (diurnal, weekly and monthly) and a complete cyclic component (the combination of the three) by comparing with a temporally "flat" fossil fuel CO2 emissions inventory. A complete exploration of these impacts is quantified at annual, seasonal, weekly and diurnal time scales of the CO2concentration for the surface, vertical profile and column-integral structure. Result shows an annual mean surface concentration difference varying from -1.35 ppm to 0.13 ppm at grid scale for the complete cyclic fossil fuel emissions, which is mainly driven by a large negative diurnal rectification and less positive seasonal rectification. The negative diurnal rectification is up to 1.45 ppm at grid scale and primarily due to the covariation of diurnal fossil fuel CO2 emissions and diurnal variations of vertical mixing. The positive seasonal rectification is up to 0.23 ppm at grid scale which is mainly driven by the monthly fossil fuel CO2emissions coupling with atmospheric transport. Both the diurnal and seasonal rectifier effects are indicated at local-to-regional scales with center at large source regions and extend to neighboring regions in mainly Northern Hemisphere. The diurnal fossil fuel CO2 emissions is found to significantly affect the simulated diurnal CO2 amplitude (up to 9.12 ppm at grid scale), which is primarily contributed by the minima concentration differences around local sunset time. Similarly, large impact on the seasonal CO2 amplitude (up to 6.11 ppm) is found at regional scale for the monthly fossil fuel emissions. An impact of diurnal fossil fuel CO2 emissions on simulated afternoon CO2 concentration is also identified by up to 1.13 ppm at local scales. The study demonstrates a large cyclic fossil fuel

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

    PubMed

    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.

  8. [Quantitative estimation source of urban atmospheric CO2 by carbon isotope composition].

    PubMed

    Liu, Wei; Wei, Nan-Nan; Wang, Guang-Hua; Yao, Jian; Zeng, You-Shi; Fan, Xue-Bo; Geng, Yan-Hong; Li, Yan

    2012-04-01

    To effectively reduce urban carbon emissions and verify the effectiveness of currently project for urban carbon emission reduction, quantitative estimation sources of urban atmospheric CO2 correctly is necessary. Since little fractionation of carbon isotope exists in the transportation from pollution sources to the receptor, the carbon isotope composition can be used for source apportionment. In the present study, a method was established to quantitatively estimate the source of urban atmospheric CO2 by the carbon isotope composition. Both diurnal and height variations of concentrations of CO2 derived from biomass, vehicle exhaust and coal burning were further determined for atmospheric CO2 in Jiading district of Shanghai. Biomass-derived CO2 accounts for the largest portion of atmospheric CO2. The concentrations of CO2 derived from the coal burning are larger in the night-time (00:00, 04:00 and 20:00) than in the daytime (08:00, 12:00 and 16:00), and increase with the increase of height. Those derived from the vehicle exhaust decrease with the height increase. The diurnal and height variations of sources reflect the emission and transport characteristics of atmospheric CO2 in Jiading district of Shanghai.

  9. Air exchange rates from atmospheric CO2 daily cycle

    PubMed Central

    Carrilho, João Dias; Mateus, Mário; Batterman, Stuart; da Silva, Manuel Gameiro

    2015-01-01

    We propose a new approach for measuring ventilation air exchange rates (AERs). The method belongs to the class of tracer gas techniques, but is formulated in the light of systems theory and signal processing. Unlike conventional CO2 based methods that assume the outdoor ambient CO2 concentration is constant, the proposed method recognizes that photosynthesis and respiration cycle of plants and processes associated with fuel combustion produce daily, quasi-periodic, variations in the ambient CO2 concentrations. These daily variations, which are within the detection range of existing monitoring equipment, are utilized for estimating ventilation rates without the need of a source of CO2 in the building. Using a naturally-ventilated residential apartment, AERs obtained using the new method compared favorably (within 10%) to those obtained using the conventional CO2 decay fitting technique. The new method has the advantages that no tracer gas injection is needed, and high time resolution results are obtained. PMID:26236090

  10. Air exchange rates from atmospheric CO2 daily cycle.

    PubMed

    Carrilho, João Dias; Mateus, Mário; Batterman, Stuart; da Silva, Manuel Gameiro

    2015-04-01

    We propose a new approach for measuring ventilation air exchange rates (AERs). The method belongs to the class of tracer gas techniques, but is formulated in the light of systems theory and signal processing. Unlike conventional CO2 based methods that assume the outdoor ambient CO2 concentration is constant, the proposed method recognizes that photosynthesis and respiration cycle of plants and processes associated with fuel combustion produce daily, quasi-periodic, variations in the ambient CO2 concentrations. These daily variations, which are within the detection range of existing monitoring equipment, are utilized for estimating ventilation rates without the need of a source of CO2 in the building. Using a naturally-ventilated residential apartment, AERs obtained using the new method compared favorably (within 10%) to those obtained using the conventional CO2 decay fitting technique. The new method has the advantages that no tracer gas injection is needed, and high time resolution results are obtained.

  11. Halloysite Nanotubes Capturing Isotope Selective Atmospheric CO2

    PubMed Central

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

    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 has been explored using an optical cavity-enhanced integrated cavity output spectroscopy. CO2 adsorption/desorption cycling measurements demonstrate that the adsorbent can be regenerated at relatively low temperature and thus, recycled repeatedly to capture atmospheric CO2. The amine grafted halloysite shows excellent stability even in oxidative environments and has high efficacy of CO2 capture, introducing a new route to the adsorption of isotope selective atmospheric CO2. PMID:25736700

  12. Atmospheric Fossil Fuel CO2 Tracing By 14C In Some Chinese Cities

    NASA Astrophysics Data System (ADS)

    Zhou, W.; Niu, Z.; Zhu, Y., Sr.

    2016-12-01

    CO2 plays an important role in global climate as a primary greenhouse gas in the atmosphere. Moreover, it has been shown that more than 70% of global fossil fuel CO2 (CO2ff) emissions are concentrated in urban areas (Duren and Miller, 2012). Our study focuses on atmospheric CO2ff concentrations in 15 Chinese cities using accelerator mass spectrometer (AMS) to measure 14C. Our objectives are: (1) to document atmospheric CO2ff concentrations in a variety of urban environments, (2) to differentiate the spatial-temporal variations in CO2ff among these cities, and (3) to ascertain the factors that control the observed variations. For about two years (winter 2014 to winter 2016), the CO2ff concentrations we observed from all sites varied from 5.1±4.5 ppm to 65.8±39.0 ppm. We observed that inland cities display much higher CO2ff concentrations and overall temporal variations than coastal cities in winter, and that northern cities have higher CO2ff concentrations than those of southern cities in winter. For inland cities relatively high CO2ff values are observed in winter and low values in summer; while seasonal variations are not distinct in the coastal cities. No significant (p > 0.05) differences in CO2ff values are found between weekdays and weekends as was shown previously in Xi'an (Zhou et al., 2014). Diurnal CO2ff variations are plainly evident, with high values between midnight and 4:00 am, and during morning and afternoon rush hours (Niu et al., 2016). The high CO2ff concentrations in northern inland cities in winter results mainly from the substantial consumption of fossil fuels for heating. The high CO2ff concentrations seen in diurnal measurements result mainly from variations in atmospheric dispersion, and from vehicle emissions related to traffic flows. The inter-annual variations in CO2ff in cities could provide a useful reference for local governments to develop policy around the effect of energy conservation and emission reduction strategies.

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

    PubMed

    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

  14. Feedbacks and the coevolution of plants and atmospheric CO2.

    PubMed

    Beerling, David J; Berner, Robert A

    2005-02-01

    The coupled evolution of land plants, CO2, and climate over the last half billion years has maintained atmospheric CO2 concentrations within finite limits, indicating the involvement of a complex network of geophysiological feedbacks. But insight into this important regulatory network is extremely limited. Here we present a systems analysis of the physiological and geochemical processes involved, identifying new positive and negative feedbacks between plants and CO2 on geological time scales. Positive feedbacks accelerated falling CO2 concentrations during the evolution and diversification of terrestrial ecosystems in the Paleozoic and enhanced rising CO2 concentrations across the Triassic-Jurassic boundary during flood basalt eruptions. The existence of positive feedbacks reveals the unexpected destabilizing influence of the biota in climate regulation that led to environmental modifications accelerating rates of terrestrial plant and animal evolution in the Paleozoic.

  15. Feedbacks and the coevolution of plants and atmospheric CO2

    PubMed Central

    Beerling, David J.; Berner, Robert A.

    2005-01-01

    The coupled evolution of land plants, CO2, and climate over the last half billion years has maintained atmospheric CO2 concentrations within finite limits, indicating the involvement of a complex network of geophysiological feedbacks. But insight into this important regulatory network is extremely limited. Here we present a systems analysis of the physiological and geochemical processes involved, identifying new positive and negative feedbacks between plants and CO2 on geological time scales. Positive feedbacks accelerated falling CO2 concentrations during the evolution and diversification of terrestrial ecosystems in the Paleozoic and enhanced rising CO2 concentrations across the Triassic–Jurassic boundary during flood basalt eruptions. The existence of positive feedbacks reveals the unexpected destabilizing influence of the biota in climate regulation that led to environmental modifications accelerating rates of terrestrial plant and animal evolution in the Paleozoic. PMID:15668402

  16. Production and uses of liquefied atmosphere (CO2) on Mars

    NASA Astrophysics Data System (ADS)

    Waldron, R. D.

    Carbon dioxide is universally accessible on Mars, and can be liquefied and separated from residual atmospheric gases by various compress-refrigeration cycles. Liquid CO2, stored under elevated pressures, can be used as a source of high pressure gas for nighttime power generation at a Martian base powered by solar energy during the daytime. Carbon dioxide can also be used for vehicular power. The extractable energy per unit mass of CO2 can exceed that of commercial lead-acid batteries for operating cycles without heat addition. Improved performance is possible using heat input from the ambient atmosphere or thermochemical agents. A unique vehicular application uses pressurized CO2 as a non-combustion low performance propellant for intermediate distance surface transportation. The thermodynamic properties of CO2 are presented with typical operating cycles for the application classes described above.

  17. Production and uses of liquefied atmosphere (CO2) on Mars

    NASA Technical Reports Server (NTRS)

    Waldron, R. D.

    1991-01-01

    Carbon dioxide is universally accessible on Mars, and can be liquefied and separated from residual atmospheric gases by various compress-refrigeration cycles. Liquid CO2, stored under elevated pressures, can be used as a source of high pressure gas for nighttime power generation at a Martian base powered by solar energy during the daytime. Carbon dioxide can also be used for vehicular power. The extractable energy per unit mass of CO2 can exceed that of commercial lead-acid batteries for operating cycles without heat addition. Improved performance is possible using heat input from the ambient atmosphere or thermochemical agents. A unique vehicular application uses pressurized CO2 as a non-combustion low performance propellant for intermediate distance surface transportation. The thermodynamic properties of CO2 are presented with typical operating cycles for the application classes described above.

  18. Spatial response of coastal marshes to increased atmospheric CO2

    PubMed Central

    Ratliff, Katherine M.; Braswell, Anna E.; Marani, Marco

    2015-01-01

    The elevation and extent of coastal marshes are dictated by the interplay between the rate of relative sea-level rise (RRSLR), surface accretion by inorganic sediment deposition, and organic soil production by plants. These accretion processes respond to changes in local and global forcings, such as sediment delivery to the coast, nutrient concentrations, and atmospheric CO2, but their relative importance for marsh resilience to increasing RRSLR remains unclear. In particular, marshes up-take atmospheric CO2 at high rates, thereby playing a major role in the global carbon cycle, but the morphologic expression of increasing atmospheric CO2 concentration, an imminent aspect of climate change, has not yet been isolated and quantified. Using the available observational literature and a spatially explicit ecomorphodynamic model, we explore marsh responses to increased atmospheric CO2, relative to changes in inorganic sediment availability and elevated nitrogen levels. We find that marsh vegetation response to foreseen elevated atmospheric CO2 is similar in magnitude to the response induced by a varying inorganic sediment concentration, and that it increases the threshold RRSLR initiating marsh submergence by up to 60% in the range of forcings explored. Furthermore, we find that marsh responses are inherently spatially dependent, and cannot be adequately captured through 0-dimensional representations of marsh dynamics. Our results imply that coastal marshes, and the major carbon sink they represent, are significantly more resilient to foreseen climatic changes than previously thought. PMID:26644577

  19. Spatial response of coastal marshes to increased atmospheric CO2.

    PubMed

    Ratliff, Katherine M; Braswell, Anna E; Marani, Marco

    2015-12-22

    The elevation and extent of coastal marshes are dictated by the interplay between the rate of relative sea-level rise (RRSLR), surface accretion by inorganic sediment deposition, and organic soil production by plants. These accretion processes respond to changes in local and global forcings, such as sediment delivery to the coast, nutrient concentrations, and atmospheric CO2, but their relative importance for marsh resilience to increasing RRSLR remains unclear. In particular, marshes up-take atmospheric CO2 at high rates, thereby playing a major role in the global carbon cycle, but the morphologic expression of increasing atmospheric CO2 concentration, an imminent aspect of climate change, has not yet been isolated and quantified. Using the available observational literature and a spatially explicit ecomorphodynamic model, we explore marsh responses to increased atmospheric CO2, relative to changes in inorganic sediment availability and elevated nitrogen levels. We find that marsh vegetation response to foreseen elevated atmospheric CO2 is similar in magnitude to the response induced by a varying inorganic sediment concentration, and that it increases the threshold RRSLR initiating marsh submergence by up to 60% in the range of forcings explored. Furthermore, we find that marsh responses are inherently spatially dependent, and cannot be adequately captured through 0-dimensional representations of marsh dynamics. Our results imply that coastal marshes, and the major carbon sink they represent, are significantly more resilient to foreseen climatic changes than previously thought.

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

    NASA Astrophysics Data System (ADS)

    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.

  1. Modeling Atmospheric CO2 Processes to Constrain the Missing Sink

    NASA Technical Reports Server (NTRS)

    Kawa, S. R.; Denning, A. S.; Erickson, D. J.; Collatz, J. C.; Pawson, S.

    2005-01-01

    We report on a NASA supported modeling effort to reduce uncertainty in carbon cycle processes that create the so-called missing sink of atmospheric CO2. Our overall objective is to improve characterization of CO2 source/sink processes globally with improved formulations for atmospheric transport, terrestrial uptake and release, biomass and fossil fuel burning, and observational data analysis. The motivation for this study follows from the perspective that progress in determining CO2 sources and sinks beyond the current state of the art will rely on utilization of more extensive and intensive CO2 and related observations including those from satellite remote sensing. The major components of this effort are: 1) Continued development of the chemistry and transport model using analyzed meteorological fields from the Goddard Global Modeling and Assimilation Office, with comparison to real time data in both forward and inverse modes; 2) An advanced biosphere model, constrained by remote sensing data, coupled to the global transport model to produce distributions of CO2 fluxes and concentrations that are consistent with actual meteorological variability; 3) Improved remote sensing estimates for biomass burning emission fluxes to better characterize interannual variability in the atmospheric CO2 budget and to better constrain the land use change source; 4) Evaluating the impact of temporally resolved fossil fuel emission distributions on atmospheric CO2 gradients and variability. 5) Testing the impact of existing and planned remote sensing data sources (e.g., AIRS, MODIS, OCO) on inference of CO2 sources and sinks, and use the model to help establish measurement requirements for future remote sensing instruments. The results will help to prepare for the use of OCO and other satellite data in a multi-disciplinary carbon data assimilation system for analysis and prediction of carbon cycle changes and carbodclimate interactions.

  2. Modeling Atmospheric CO2 Processes to Constrain the Missing Sink

    NASA Technical Reports Server (NTRS)

    Kawa, S. R.; Denning, A. S.; Erickson, D. J.; Collatz, J. C.; Pawson, S.

    2005-01-01

    We report on a NASA supported modeling effort to reduce uncertainty in carbon cycle processes that create the so-called missing sink of atmospheric CO2. Our overall objective is to improve characterization of CO2 source/sink processes globally with improved formulations for atmospheric transport, terrestrial uptake and release, biomass and fossil fuel burning, and observational data analysis. The motivation for this study follows from the perspective that progress in determining CO2 sources and sinks beyond the current state of the art will rely on utilization of more extensive and intensive CO2 and related observations including those from satellite remote sensing. The major components of this effort are: 1) Continued development of the chemistry and transport model using analyzed meteorological fields from the Goddard Global Modeling and Assimilation Office, with comparison to real time data in both forward and inverse modes; 2) An advanced biosphere model, constrained by remote sensing data, coupled to the global transport model to produce distributions of CO2 fluxes and concentrations that are consistent with actual meteorological variability; 3) Improved remote sensing estimates for biomass burning emission fluxes to better characterize interannual variability in the atmospheric CO2 budget and to better constrain the land use change source; 4) Evaluating the impact of temporally resolved fossil fuel emission distributions on atmospheric CO2 gradients and variability. 5) Testing the impact of existing and planned remote sensing data sources (e.g., AIRS, MODIS, OCO) on inference of CO2 sources and sinks, and use the model to help establish measurement requirements for future remote sensing instruments. The results will help to prepare for the use of OCO and other satellite data in a multi-disciplinary carbon data assimilation system for analysis and prediction of carbon cycle changes and carbodclimate interactions.

  3. Atmospheric CO2 and carbon cycle during the late Holocene

    NASA Astrophysics Data System (ADS)

    Ahn, J.; Brook, E.; Marcott, S. A.

    2015-12-01

    Atmospheric CO2 records during the late Holocene are of great interest because climate boundary conditions for the time interval are similar to those of present and near future. Here we show CO2 records from West Antarctic Ice Sheet (WAIS) Divide ice core that cover the last 2500 years with 10- to 20-year resolutions. The records reveal pre-industrial CO2 variability of ~ 6 ppm on multi-centennial to millennial timescales. We found that the millennial variability is positively correlated with westerly wind stress in the Southern Ocean and the high northern hemispheric climate.

  4. CO2 ice structure and density under Martian atmospheric conditions

    NASA Astrophysics Data System (ADS)

    Mangan, T. P.; Salzmann, C. G.; Plane, J. M. C.; Murray, B. J.

    2017-09-01

    Clouds composed of CO2 ice form throughout the Martian atmosphere. In the mesosphere, CO2 ice clouds are thought to form via heterogeneous ice nucleation on nanoparticles of meteoric origin at temperatures often below 100 K. Lower altitude CO2 ice clouds in the wintertime polar regions form up to around 145 K and lead to the build-up of the polar ice caps. However, the crystal structure and related fundamental properties of CO2 ice under Martian conditions are poorly characterised. Here we present X-ray diffraction (XRD) measurements of CO2 ice, grown via deposition from the vapour phase under temperature and pressure conditions analogous to the Martian mesosphere. A crystalline cubic structure was determined, consistent with the low-pressure polymorph (CO2-I, space group Pa-3 (No. 205)). CO2 deposited at temperatures of 80-130 K and pressures of 0.01-1 mbar was consistent with dry ice and previous literature measurements, thus removing the possibility of a more complicated phase diagram for CO2 in this region. At 80 K, a lattice parameter of 5.578 ± 0.002 Å, cell volume of 173.554 ± 0.19 Å3 and density of 1.684 ± 0.002 g cm-3 was determined. Using these measurements, we determined the thermal expansion of CO2 across 80-130 K that allowed for a fit of CO2 ice density measurements across a larger temperature range (80-195 K) when combined with literature data (CO2 density = 1.72391 - 2.53 × 10-4T - 2.87 × 10-6 T2). Temperature-dependent CO2 density values are used to estimate sedimentation velocities and heterogeneous ice nucleation rates, showing an increase in nucleation rate of up to a factor of 1000 when compared to commonly used literature values. This temperature-dependent equation of state is therefore suggested for use in future studies of Martian mesospheric CO2 clouds. Finally, we discuss the possible shapes of crystals of CO2 ice in the Martian atmosphere and show that a range of shapes including cubes and octahedra as well as a combination of the

  5. Regional and Global Atmospheric CO2 Measurements Using 1.57 Micron IM-CW Lidar

    NASA Technical Reports Server (NTRS)

    Lin, Bing; Obland, Michael; Nehrir, Amin; Browell, Edward; Harrison, F. Wallace; Dobler, Jeremy; Campbell, Joel; Kooi, Susan; Meadows, Byron; Fan, Tai-Fang; hide

    2015-01-01

    Atmospheric CO2 is a critical forcing for the Earth's climate, and knowledge of its distribution and variations influences predictions of the Earth's future climate. Accurate observations of atmospheric CO2 are also crucial to improving our understanding of CO2 sources, sinks and transports. To meet these science needs, NASA is developing technologies for the Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) space mission, which is aimed at global CO2 observations. Meanwhile an airborne investigation of atmospheric CO2 distributions as part of the NASA Suborbital Atmospheric Carbon and Transport â€" America (ACT-America) mission will be conducted with lidar and in situ instrumentation over the central and eastern United States during all four seasons and under a wide range of meteorological conditions. In preparing for the ASCENDS mission, NASA Langley Research Center and Exelis Inc./Harris Corp. have jointly developed and demonstrated the capability of atmospheric CO2 column measurements with an intensity-modulated continuous-wave (IM-CW) lidar. Since 2005, a total of 14 flight campaigns have been conducted. A measurement precision of approx.0.3 ppmv for a 10-s average over desert and vegetated surfaces has been achieved, and the lidar CO2 measurements also agree well with in-situ observations. Significant atmospheric CO2 variations on various spatiotemporal scales have been observed during these campaigns. For example, around 10-ppm CO2 changes were found within free troposphere in a region of about 200A-300 sq km over Iowa during a summer 2014 flight. Results from recent flight campaigns are presented in this paper. The ability to achieve the science objectives of the ASCENDS mission with an IM-CW lidar is also discussed in this paper, along with the plans for the ACT-America aircraft investigation that begins in the winter of 2016.

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

    PubMed

    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.

  7. Atmospheric CO2: Principal Control Knob Governing Earth's Temperature

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

    Ample physical evidence shows that carbon dioxide (CO2) is the single most important climate-relevant greenhouse gas in Earth s atmosphere. This is because CO2, like ozone, N2O, CH4, 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 CO2 and the other noncondensing greenhouse gases, the terrestrial greenhouse would collapse, plunging the global climate into an icebound Earth state.

  8. Does atmospheric CO2 police the rate of chemical weathering?

    NASA Astrophysics Data System (ADS)

    Broecker, Wallace S.; Sanyal, Abhijit

    1998-09-01

    A case is made that in the absence of an effective feedback control on the rate of delivery of CaO to the oceans, the CO2 content of the Earth's atmosphere would have wandered over a large range threatening life either by overheating or by carbon dioxide starvation. In this paper, we defend the suggestion by Walker et al. [1981] that control is exerted by the interaction between the CO2 content of the atmosphere and the continental weathering rates. We contend that in spite of the arguments raised against it [Raymo and Ruddiman, 1992; Edmond and Huh, 1997] the CO2- chemical weathering feedback is the dominant mechanism that stabilizes the atmospheric carbon dioxide content.

  9. Continental-scale variation in controls of summer CO2 in United States lakes

    NASA Astrophysics Data System (ADS)

    Lapierre, Jean-Francois; Seekell, David A.; Filstrup, Christopher T.; Collins, Sarah M.; Emi Fergus, C.; Soranno, Patricia A.; Cheruvelil, Kendra S.

    2017-04-01

    Understanding the broad-scale response of lake CO2 dynamics to global change is challenging because the relative importance of different controls of surface water CO2 is not known across broad geographic extents. Using geostatistical analyses of 1080 lakes in the conterminous United States, we found that lake partial pressure of CO2 (pCO2) was controlled by different chemical and biological factors related to inputs and losses of CO2 along climate, topography, geomorphology, and land use gradients. Despite weak spatial patterns in pCO2 across the study extent, there were strong regional patterns in the pCO2 driver-response relationships, i.e., in pCO2 "regulation." Because relationships between lake CO2 and its predictors varied spatially, global models performed poorly in explaining the variability in CO2 for U.S. lakes. The geographically varying driver-response relationships of lake pCO2 reflected major landscape gradients across the study extent and pointed to the importance of regional-scale variation in pCO2 regulation. These results indicate a higher level of organization for these physically disconnected systems than previously thought and suggest that changes in climate and land use could induce shifts in the main pathways that determine the role of lakes as sources and sinks of atmospheric CO2.

  10. CO2 flux estimation errors associated with moist atmospheric processes

    NASA Astrophysics Data System (ADS)

    Parazoo, N. C.; Denning, A. S.; Kawa, S. R.; Pawson, S.; Lokupitiya, R.

    2012-04-01

    Vertical transport by moist sub-grid scale processes such as deep convection is a well-known source of uncertainty in CO2 source/sink inversion. However, a dynamical link between moist transport, satellite CO2 retrievals, and source/sink inversion has not yet been established. Here we examine the effect of moist processes on (1) synoptic CO2 transport by Version-4 and Version-5 NASA Goddard Earth Observing System Data Assimilation System (NASA-DAS) meteorological analyses, and (2) source/sink inversion. We find that synoptic transport processes, such as fronts and dry/moist conveyors, feed off background vertical CO2 gradients, which are modulated by sub-grid vertical transport. The implication for source/sink estimation is two-fold. First, CO2 variations contained in moist poleward moving air masses are systematically different from variations in dry equatorward moving air. Moist poleward transport is hidden from orbital sensors on satellites, causing a sampling bias, which leads directly to continental scale source/sink estimation errors of up to 0.25 PgC yr-1 in northern mid-latitudes. Second, moist processes are represented differently in GEOS-4 and GEOS-5, leading to differences in vertical CO2 gradients, moist poleward and dry equatorward CO2 transport, and therefore the fraction of CO2 variations hidden in moist air from satellites. As a result, sampling biases are amplified, causing source/sink estimation errors of up to 0.55 PgC yr-1 in northern mid-latitudes. These results, cast from the perspective of moist frontal transport processes, support previous arguments that the vertical gradient of CO2 is a major source of uncertainty in source/sink inversion.

  11. CO2 flux estimation errors associated with moist atmospheric processes

    NASA Astrophysics Data System (ADS)

    Parazoo, N. C.; Denning, A. S.; Kawa, S. R.; Pawson, S.; Lokupitiya, R.

    2012-07-01

    Vertical transport by moist sub-grid scale processes such as deep convection is a well-known source of uncertainty in CO2 source/sink inversion. However, a dynamical link between vertical transport, satellite based retrievals of column mole fractions of CO2, and source/sink inversion has not yet been established. By using the same offline transport model with meteorological fields from slightly different data assimilation systems, we examine sensitivity of frontal CO2 transport and retrieved fluxes to different parameterizations of sub-grid vertical transport. We find that frontal transport feeds off background vertical CO2 gradients, which are modulated by sub-grid vertical transport. The implication for source/sink estimation is two-fold. First, CO2 variations contained in moist poleward moving air masses are systematically different from variations in dry equatorward moving air. Moist poleward transport is hidden from orbital sensors on satellites, causing a sampling bias, which leads directly to small but systematic flux retrieval errors in northern mid-latitudes. Second, differences in the representation of moist sub-grid vertical transport in GEOS-4 and GEOS-5 meteorological fields cause differences in vertical gradients of CO2, which leads to systematic differences in moist poleward and dry equatorward CO2 transport and therefore the fraction of CO2 variations hidden in moist air from satellites. As a result, sampling biases are amplified and regional scale flux errors enhanced, most notably in Europe (0.43 ± 0.35 PgC yr-1). These results, cast from the perspective of moist frontal transport processes, support previous arguments that the vertical gradient of CO2 is a major source of uncertainty in source/sink inversion.

  12. CO2 Flux Estimation Errors Associated with Moist Atmospheric Processes

    NASA Technical Reports Server (NTRS)

    Parazoo, N. C.; Denning, A. S.; Kawa, S. R.; Pawson, S.; Lokupitiya, R.

    2012-01-01

    Vertical transport by moist sub-grid scale processes such as deep convection is a well-known source of uncertainty in CO2 source/sink inversion. However, a dynamical link between vertical transport, satellite based retrievals of column mole fractions of CO2, and source/sink inversion has not yet been established. By using the same offline transport model with meteorological fields from slightly different data assimilation systems, we examine sensitivity of frontal CO2 transport and retrieved fluxes to different parameterizations of sub-grid vertical transport. We find that frontal transport feeds off background vertical CO2 gradients, which are modulated by sub-grid vertical transport. The implication for source/sink estimation is two-fold. First, CO2 variations contained in moist poleward moving air masses are systematically different from variations in dry equatorward moving air. Moist poleward transport is hidden from orbital sensors on satellites, causing a sampling bias, which leads directly to small but systematic flux retrieval errors in northern mid-latitudes. Second, differences in the representation of moist sub-grid vertical transport in GEOS-4 and GEOS-5 meteorological fields cause differences in vertical gradients of CO2, which leads to systematic differences in moist poleward and dry equatorward CO2 transport and therefore the fraction of CO2 variations hidden in moist air from satellites. As a result, sampling biases are amplified and regional scale flux errors enhanced, most notably in Europe (0.43+/-0.35 PgC /yr). These results, cast from the perspective of moist frontal transport processes, support previous arguments that the vertical gradient of CO2 is a major source of uncertainty in source/sink inversion.

  13. Atmospheric Verification of Point Source Fossil Fuel CO2 Emissions

    NASA Astrophysics Data System (ADS)

    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.

  14. Does sedimentary organic delta 13C record variations in quaternary ocean [CO2(aq)]?

    NASA Technical Reports Server (NTRS)

    Rau, G. H.; Froelich, P. N.; Takahashi, T.; Des Marais, D. J.

    1991-01-01

    Ocean surface water [CO2(aq)] variations based on glacial/interglacial changes in sediment delta 13Corg are shown to compare favorably with reconstructions based on ice core [CO2]. In particular, an approximate 80 microatmospheres increase in atmospheric pCO2 during the last glacial-interglacial transition is calculated to correspond to a 3-4 micromolar increase in ocean surface water [CO2(aq)] at atmospheric equilibrium. A widespread marine delta 13Corg decrease of 1-2% accompanied this event and was not preceded by an equivalent isotopic change in surface water total dissolved inorganic carbon. These observations support the hypothesis that [CO2(aq)] influences photosynthetic isotope fractionation between marine inorganic and organic carbon pools, and therefore that plankton/sediment delta 13Corg may serve as a proxy for surface water [CO2(aq)].

  15. Does sedimentary organic delta 13C record variations in quaternary ocean [CO2(aq)]?

    PubMed

    Rau, G H; Froelich, P N; Takahashi, T; Des Marais, D J

    1991-06-01

    Ocean surface water [CO2(aq)] variations based on glacial/interglacial changes in sediment delta 13Corg are shown to compare favorably with reconstructions based on ice core [CO2]. In particular, an approximate 80 microatmospheres increase in atmospheric pCO2 during the last glacial-interglacial transition is calculated to correspond to a 3-4 micromolar increase in ocean surface water [CO2(aq)] at atmospheric equilibrium. A widespread marine delta 13Corg decrease of 1-2% accompanied this event and was not preceded by an equivalent isotopic change in surface water total dissolved inorganic carbon. These observations support the hypothesis that [CO2(aq)] influences photosynthetic isotope fractionation between marine inorganic and organic carbon pools, and therefore that plankton/sediment delta 13Corg may serve as a proxy for surface water [CO2(aq)].

  16. Three dimensional global modeling of atmospheric CO2

    NASA Technical Reports Server (NTRS)

    Fung, I.; Hansen, J.; Rind, D.

    1983-01-01

    A model was developed to study the prospects of extracting information on carbon dioxide sources and sinks from observed CO2 variations. The approach uses a three dimensional global transport model, based on winds from a 3-D general circulation model (GCM), to advect CO2 noninteractively, i.e., as a tracer, with specified sources and sinks of CO2 at the surface. The 3-D model employed is identified and biosphere, ocean and fossil fuel sources and sinks are discussed. Some preliminary model results are presented.

  17. The Effect of CO2 Ice Cap Sublimation on Mars Atmosphere

    NASA Technical Reports Server (NTRS)

    Batterson, Courtney

    2016-01-01

    Sublimation of the polar CO2 ice caps on Mars is an ongoing phenomenon that may be contributing to secular climate change on Mars. The transfer of CO2 between the surface and atmosphere via sublimation and deposition may alter atmospheric mass such that net atmospheric mass is increasing despite seasonal variations in CO2 transfer. My study builds on previous studies by Kahre and Haberle that analyze and compare data from the Phoenix and Viking Landers 1 and 2 to determine whether secular climate change is happening on Mars. In this project, I use two years worth of temperature, pressure, and elevation data from the MSL Curiosity rover to create a program that allows for successful comparison of Curiosity pressure data to Viking Lander pressure data so a conclusion can be drawn regarding whether CO2 ice cap sublimation is causing a net increase in atmospheric mass and is thus contributing to secular climate change on Mars.

  18. Improvement of Atmospheric CO2 Inversion Analysis at JMA

    NASA Astrophysics Data System (ADS)

    Nakamura, T.; Maki, T.; Machida, T.; Matsuda, H.; Sawa, Y.; Niwa, Y.

    2015-12-01

    The Japan Meteorological Agency (JMA) has developed a new inversion system of atmospheric CO2 mole fraction and flux for better understanding of global carbon budget and contribution to global carbon cycle studies. The new system introduces a newly developed on-line atmospheric tracer transport model (GSAM-TM). Its tracer transport process is directly coupled with a low resolution version (TL95) of JMA's operational global numerical weather prediction (NWP) model (JMA_GSM), using mass conservative semi-Lagrangian scheme and Arakawa-Shubert mass flux scheme for vertical convective transportation. It represents mass transportation, mass conservation, and structures of tracer distribution more precisely than JMA's previous transport model (CDTM), which is off-line tracer transport model using semi-Lagrangian scheme and Kuo-based convection scheme with multiplying globally uniform coefficient for mass conservation. The new system also introduces new a priori fluxes for fossil fuel consumption and oceanic CO2 exchange. In this study, we compare CO2 mole fraction field and flux estimates of the new system against that of current annual JMA analysis with CDTM. The new system represents better atmospheric CO2 distribution structure than the current system does especially vertical gradient around tropopause. Due to improvement of fossil fuel CO2 diffusion estimates, analyzed regional budget over Eurasian Continent changed clearly. Budgets for less observation area (South America and Africa) are also changed. Globally averaged atmospheric CO2 budget is not changed significantly. This new system is planned to be operationally implemented in 2016, and we will further improve the CO2 inversion analysis for understanding of carbon cycle.

  19. Cutover peatlands: A persistent source of atmospheric CO2

    NASA Astrophysics Data System (ADS)

    Waddington, J. M.; Warner, K. D.; Kennedy, G. W.

    2002-01-01

    Peatlands represent an important component of the global carbon cycle, storing 23 g C m-2 yr-1. Peatland mining eliminates the carbon sink function of the peatland. In this paper we measure the total ecosystem respiration in a natural, 2 and 3 year (young) and 7 and 8 year (old) postcutover peatland near Sainte-Marguerite-Marie, Québec, during the summers of 1998 and 1999. Although the natural site was a source of CO2 during the dry 1998 study season (138 g C m-2), CO2 emissions were between 260 and 290% higher in the cutover sites (363 and 399 g C m-2 for young and old, respectively). Cutover site CO2 emissions were only 88 and 112 g CO2-C m-2 at the young and old sites during the wet 1999 study season. Total ecosystem respiration was more dependent on the water table position than on changes in the thermal regime or the labile carbon of the peat in a dry summer, but the opposite was the case in a wet summer. CO2 emissions increased with postharvest time regardless of a decrease in labile carbon, demonstrating that cutover peatlands are a large persistent source of atmospheric CO2. Direct measurement of the net ecosystem CO2 exchange in cutover peatlands, as opposed to determining the loss of carbon from bulk density determinations, provides a better understanding of how peat drainage and harvesting operations affect the carbon balance in peatlands.

  20. Acidification of reverse micellar nanodroplets by atmospheric pressure CO2.

    PubMed

    Levinger, Nancy E; Rubenstrunk, Lauren C; Baruah, Bharat; Crans, Debbie C

    2011-05-11

    Water absorption of atmospheric carbon dioxide lowers the solution pH due to carbonic acid formation. Bulk water acidification by CO(2) is well documented, but significantly less is known about its effect on water in confined spaces. Considering its prominence as a greenhouse gas, the importance of aerosols in acid rain, and CO(2)-buffering in cellular systems, surprisingly little information exists about the absorption of CO(2) by nanosized water droplets. The fundamental interactions of CO(2) with water, particularly in nanosized structures, may influence a wide range of processes in our technological society. Here results from experiments investigating the uptake of gaseous CO(2) by water pools in reverse micelles are presented. Despite the small number of water molecules in each droplet, changes in vanadium probes within the water pools, measured using vanadium-51 NMR spectroscopy, indicate a significant drop in pH after CO(2) introduction. Collectively, the pH-dependent vanadium probes show CO(2) dissolves in the nanowater droplets, causing the reverse micelle acidity to increase. © 2011 American Chemical Society

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

    PubMed

    Levin, Ingeborg; Rödenbeck, Christian

    2008-03-01

    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 (CO(2)), also shows large natural concentration variations, which need to be disentangled from anthropogenic signals to assess changes in associated emissions. This is in principle possible for the fossil fuel CO(2) component (FFCO(2)) by high-precision radiocarbon ((14)C) analyses because FFCO(2) is free of radiocarbon. Long-term observations of (14)CO(2) conducted at two sites in south-western Germany do not yet reveal any significant trends in the regional fossil fuel CO(2) component. We rather observe strong inter-annual variations, which are largely imprinted by changes of atmospheric transport as supported by dedicated transport model simulations of fossil fuel CO(2). In this paper, we show that, depending on the remoteness of the site, changes of about 7-26% in fossil fuel emissions in respective catchment areas could be detected with confidence by high-precision atmospheric (14)CO(2) measurements when comparing 5-year averages if these inter-annual variations were taken into account. This perspective constitutes the urgently needed tool for validation of fossil fuel CO(2) emissions changes in the framework of the Kyoto protocol and successive climate initiatives.

  2. Background Error Statistics for Assimilation of Atmospheric CO2

    NASA Astrophysics Data System (ADS)

    Chatterjee, A.; Engelen, R. J.; Kawa, S. R.; Sweeney, C.; Michalak, A. M.

    2012-12-01

    Recent improvements in the CO2 observational density have spurred the development and application of data assimilation systems for extracting information about global CO2 distributions from available observations. A novel application that has been pursued at the European Centre for Medium-Range Weather Forecasts (ECMWF), as part of the Monitoring Atmospheric Composition and Climate (MACC) project, is to use a state-of-the-art 4DVAR system to assimilate CO2 observations, along with meteorological variables to obtain a consistent estimate of atmospheric CO2 concentrations. Global CO2 fields generated in this way enhance the observational database, because the data assimilation procedure uses physical and dynamical laws, along with the available observations, to constrain the analysis. As in any data assimilation framework, the background error covariance matrix plays the critical role of filtering the observed information and propagating it to nearby grid points and levels of the assimilating model. For atmospheric CO2 assimilation, however, the errors in the background are not only impacted by the uncertainties in the CO2 transport but also by the spatial and temporal variability of the carbon exchange at the Earth surface. The background errors cannot be prescribed via traditional forecast-based methods as these fail to account for the uncertainties in the carbon emissions and uptake, resulting in an overall underestimation of the errors. We present a unique approach for characterizing the background error statistics whereby the differences between two CO2 model concentrations are used as a proxy for the statistics of the background errors. The resulting error statistics - 1) vary regionally and seasonally to better capture the changing degree of variability in the background CO2 field, 2) are independent of the observation density, and 3) have a discernible impact on the analysis estimates by allowing observations to adjust predictions over a larger area. In this

  3. Where does CO2 in Antarctica cool the atmosphere ?

    NASA Astrophysics Data System (ADS)

    Schmithüsen, Holger; Notholt, Justus; König-Langlo, Gert; Lemke, Peter; Jung, Thomas

    2016-04-01

    In a recent study we have shown that for the high altitude plateau in Antarctica CO2 causes a surplus in infrared emission to space compared to what is emitted from the surface. This corresponds to a negative greenhouse effect, and is due to the fact that for this region the surface is typically colder than the atmosphere above, opposite to the rest of the world. As a consequence, for this region an increase in CO2 leads to an increase in the energy loss to space, leading to an increase in the negative greenhouse effect. We now studied in more detail the radiative effect of CO2 and compared the results with available measurements from Antarctica. H. Schmithüsen, J. Notholt, G. Köngig-Langlo, T, Jung. How increasing CO2 leads to an increased negative greenhouse effect in Antarctica. Geophysical Research Letters, in press, 2015. doi: 10.1002/2015GL066749.

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

    NASA Technical Reports Server (NTRS)

    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.

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

    NASA Technical Reports Server (NTRS)

    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.

  6. Carbon isotope signature of dissolved inorganic carbon (DIC) in precipitation and atmospheric CO2.

    PubMed

    Górka, Maciej; Sauer, Peter E; Lewicka-Szczebak, Dominika; Jędrysek, Mariusz-Orion

    2011-01-01

    This paper describes results of chemical and isotopic analysis of inorganic carbon species in the atmosphere and precipitation for the calendar year 2008 in Wrocław (SW Poland). Atmospheric air samples (collected weekly) and rainwater samples (collected after rain episodes) were analysed for CO2 and dissolved inorganic carbon (DIC) concentrations and for δ13C composition. The values obtained varied in the ranges: atmospheric CO2: 337-448 ppm; δ13CCO2 from -14.4 to -8.4‰; DIC in precipitation: 0.6-5.5 mg dm(-3); δ13CDIC from -22.2 to +0.2‰. No statistical correlation was observed between the concentration and δ13C value of atmospheric CO2 and DIC in precipitation. These observations contradict the commonly held assumption that atmospheric CO2 controls the DIC in precipitation. We infer that DIC is generated in ambient air temperatures, but from other sources than the measured atmospheric CO2. The calculated isotopic composition of a hypothetical CO2 source for DIC forming ranges from -31.4 to -11.0‰, showing significant seasonal variations accordingly to changing anthropogenic impact and atmospheric mixing processes.

  7. A global coupled Eulerian-Lagrangian model and 1 1 km CO2 surface flux dataset for high-resolution atmospheric CO2 transport simulations

    SciTech Connect

    Ganshin, A; Oda, T; Saito, M; Maksyutov, S; Valsala, V; Andres, Robert Joseph; Fischer, R; Lowry, D; Lukyanov, A; Matsueda, H; Nisbet, E; Rigby, M; Sawa, Y; Toumi, R; Tsuboi, K; Varlagin, A; Zhuravlev, R

    2012-01-01

    Abstract. We designed a method to simulate atmospheric CO2 concentrations at several continuous observation sites around the globe using surface fluxes at a very high spatial resolution. The simulations presented in this study were performed using the Global Eulerian-Lagrangian Coupled Atmospheric model (GELCA), comprising a Lagrangian particle dispersion model coupled to a global atmospheric tracer transport model with prescribed global surface CO2 flux maps at a 1 1 km resolution. The surface fluxes used in the simulations were prepared by assembling the individual components of terrestrial, oceanic and fossil fuel CO2 fluxes. This experimental setup (i.e. a transport model running at a medium resolution, coupled to a high-resolution Lagrangian particle dispersion model together with global surface fluxes at a very high resolution), which was designed to represent high-frequency variations in atmospheric CO2 concentration, has not been reported at a global scale previously. Two sensitivity experiments were performed: (a) using the global transport model without coupling to the Lagrangian dispersion model, and (b) using the coupled model with a reduced resolution of surface fluxes, in order to evaluate the performance of Eulerian-Lagrangian coupling and the role of high-resolution fluxes in simulating high-frequency variations in atmospheric CO2 concentrations. A correlation analysis between observed and simulated atmospheric CO2 concentrations at selected locations revealed that the inclusion of both Eulerian-Lagrangian coupling and highresolution fluxes improves the high-frequency simulations of the model. The results highlight the potential of a coupled Eulerian-Lagrangian model in simulating high-frequency atmospheric CO2 concentrations at many locations worldwide. The model performs well in representing observations of atmospheric CO2 concentrations at high spatial and temporal resolutions, especially for coastal sites and sites located close to sources of

  8. Water Loss from Terrestrial Planets with CO2-rich Atmospheres

    NASA Astrophysics Data System (ADS)

    Wordsworth, R. D.; Pierrehumbert, R. T.

    2013-12-01

    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 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.

  9. Simulation of Atmospheric CO2 Concentrations in California’s South Coast Basin

    NASA Astrophysics Data System (ADS)

    Costigan, K. R.; Dubey, M. K.

    2009-12-01

    Verification of green house gas emission control treaties will require the coupling of measurements and models that can account for sources, sinks, and transport of these gasses. This paper presents an application of the Weather Research and Forecasting Chemistry model (WRF-Chem) to study CO2 transport in California’s South Coast Basin. The model is run for the week of 23-29 March 2008 to correspond with the atmospheric CO2 abundances measured with a ground-based Fourier transform spectrometer (FTS) and reported by Wunch et al. (2009). CO2 emissions used as input for the model are estimated from the Vulcan CO2 inventory (Gurney et al., 2009) and CO2 is treated as a passive tracer in the simulation. In particular, this paper addresses details of the simulation and analysis of the simulated meteorological conditions that may explain some of the observed day-to-day variations in CO2 concentrations.

  10. RISING ATMOSPHERIC CO2 AND CARBON SEQUESTRATION IN FORESTS

    EPA Science Inventory

    Rising CO2 concentrations in the Earth's atmosphere could alter Earth's climate system, but it is thought that higher concentrations may improve plant growth by way of the fertilization effect. Forests, an important part of the Earth's carbon cycle, are postulated to sequester a...

  11. RISING ATMOSPHERIC CO2 AND CARBON SEQUESTRATION IN FORESTS

    EPA Science Inventory

    Rising CO2 concentrations in the Earth's atmosphere could alter Earth's climate system, but it is thought that higher concentrations may improve plant growth by way of the fertilization effect. Forests, an important part of the Earth's carbon cycle, are postulated to sequester a...

  12. Atmospheric CO2 and climate on millennial time scales during the last glacial period.

    PubMed

    Ahn, Jinho; Brook, Edward J

    2008-10-03

    Reconstructions of ancient atmospheric carbon dioxide (CO2) variations help us better understand how the global carbon cycle and climate are linked. We compared CO2 variations on millennial time scales between 20,000 and 90,000 years ago with an Antarctic temperature proxy and records of abrupt climate change in the Northern Hemisphere. CO2 concentration and Antarctic temperature were positively correlated over millennial-scale climate cycles, implying a strong connection to Southern Ocean processes. Evidence from marine sediment proxies indicates that CO2 concentration rose most rapidly when North Atlantic Deep Water shoaled and stratification in the Southern Ocean was reduced. These increases in CO2 concentration occurred during stadial (cold) periods in the Northern Hemisphere, several thousand years before abrupt warming events in Greenland.

  13. CO2 vertical profile retrieval from ground-based IR atmospheric spectra

    NASA Astrophysics Data System (ADS)

    Khosravian, Kobra; Loehnert, Ulrich; Turner, David; Ebell, Kerstin

    2016-04-01

    CO2 vertical profile retrieval from ground-based IR atmospheric spectra In this study, we developed an algorithm for retrieving the CO2 vertical profile from atmospheric ground-based zenith spectra in the mid IR. Providing the CO2 profile from continuous (24h/day) ground-based spectra would be a great potential for studying the carbon cycle, the evaluation of satellite measurements or the assessment of numerical models, which forecast the near-surface CO2 flux. In order to retrieve the CO2 profile, we used observations of the Atmospheric Emitted Radiance Interferometer (AERI) that was installed at the JOYCE (Jülich ObservatorY for Cloud Evolution), Germany in 2012. AERI measures downwelling infrared radiances from 520 cm-1 (3.3 μm) to 3020 cm-1 (19 μm) with a spectral resolution of 1 cm-1 and a temporal resolution of 1 minute. In a first step, we performed sensitivity studies for finding the most-suited spectral bands with highest sensitivity to the mean column amount of CO2 volume mixing ratio (VMR). Then an algorithm, known as AERIoe (Turner and Löhnert 2014), was applied to retrieve the mean column amount of CO2 VMR using simulated radiances in clear sky cases. AERIoe is a variational retrieval algorithm to provide information on Temperature, humidity, trace gases and clouds. The simulated AERI radiances were generated by a line by line radiative transfer model (LBLRTM) using model temperature, humidity and CO2 profile. The retrieval results of mean column amount of CO2 VMR are in good agreement with the true ones. In addition to the mean column amount, we modified AERIoe to retrieve the CO2 vertical profile. First results reveal that there is more than 1 degree of freedom for CO2 profile. We will show results how the retrieval method is refined to optimally exploit the information on the CO2 profile contained in the AERI measurements.

  14. Thermal decomposition of dolomite under CO2-air atmosphere

    NASA Astrophysics Data System (ADS)

    Subagjo, Wulandari, Winny; Adinata, Pratitis Mega; Fajrin, Anita

    2017-01-01

    This paper reports a study on thermal decomposition of dolomite under CO2-air. Calcination was carried out non-isothermally by using thermogravimetry analysis-differential scanning calorimetry (TGA-DSC) with a heating rate of 10°C/minute in an air atmosphere as well as 10 vol% CO2 and 90 vol% air atmosphere from 25 to 950°C. In addition, a thermodynamic modeling was also carried out to simulate dolomite calcination in different level of CO2-air atmosphere by using FactSage® 7.0. The the main constituents of typical dolomite from Gresik, East Java include MgCO3 (magnesite), CaCO3 (calcite), Ca(OH)2, CaO, MgO, and less than 1% of metal impurities. Based on the kinetics analysis from TGA results, it is found that non-isothermal dolomite calcination in 10 vol% CO2 atmosphere is occurred in a two-stage reaction; the first stage is the decomposition of magnesite at 650-740 °C with activation energy of 161.23 kJ/mol, and the second stage is the decomposition of calcite at 775-820 °C with activation energy of 162.46 kJ/mol. The magnesite decomposition is found to follow nucleation reaction mechanism of Avrami Eroveyef (A3), while calcite decomposition follows second order chemical reaction equation. Thermodynamic modeling supports these kinetic analyses. The results of this research give insight to the kinetics of dolomite decomposition in CO2-air atmosphere.

  15. Implications of ``peak oil'' for atmospheric CO2 and climate

    NASA Astrophysics Data System (ADS)

    Kharecha, Pushker A.; Hansen, James E.

    2008-09-01

    Unconstrained CO2 emission from fossil fuel burning has been the dominant cause of observed anthropogenic global warming. The amounts of "proven" and potential fossil fuel reserves are uncertain and debated. Regardless of the true values, society has flexibility in the degree to which it chooses to exploit these reserves, especially unconventional fossil fuels and those located in extreme or pristine environments. If conventional oil production peaks within the next few decades, it may have a large effect on future atmospheric CO2 and climate change, depending upon subsequent energy choices. Assuming that proven oil and gas reserves do not greatly exceed estimates of the Energy Information Administration, and recent trends are toward lower estimates, we show that it is feasible to keep atmospheric CO2 from exceeding about 450 ppm by 2100, provided that emissions from coal, unconventional fossil fuels, and land use are constrained. Coal-fired power plants without sequestration must be phased out before midcentury to achieve this CO2 limit. It is also important to "stretch" conventional oil reserves via energy conservation and efficiency, thus averting strong pressures to extract liquid fuels from coal or unconventional fossil fuels while clean technologies are being developed for the era "beyond fossil fuels". We argue that a rising price on carbon emissions is needed to discourage conversion of the vast fossil resources into usable reserves, and to keep CO2 beneath the 450 ppm ceiling.

  16. Using radiocarbon to investigate soil respiration impacts on atmospheric CO2

    NASA Astrophysics Data System (ADS)

    Phillips, C. L.; LaFranchi, B. W.; McFarlane, K. J.; Desai, A. R.

    2013-12-01

    While soil respiration is believed to represent the largest single source of CO2 emissions on a global scale, there are few tools available to measure soil emissions at large spatial scales. We investigated whether radiocarbon (14C) abundance in CO2 could be used to detect and characterize soil emissions in the atmosphere, taking advantage of the fact that 14C abundance in soil carbon is elevated compared to the background atmosphere, a result of thermonuclear weapons testing during the mid-20th Century (i.e. bomb-C). Working in a temperate hardwood forest in Northern Wisconsin during 2011-12, we made semi-high-frequency measurements of CO2 at nested spatial scales from the soil subsurface to 150 m above ground level. These measurements were used to investigate seasonal patterns in respired C sources, and to evaluate whether variability in soil-respired Δ14C could also be detected in atmospheric measurements. In our ground-level measurements we found large seasonal variation in soil-respired 14CO2 that correlated with soil moisture, which was likely related to root activity. Atmospheric measurements of 14CO2 in the forest canopy (2 to 30m) were used to construct Keeling plots, and these provided larger spatial-scale estimates of respired 14CO2 that largely agreed with the soil-level measurements. In collaboration with the NOAA we also examined temporal patterns of 14CO2 at the Park Falls tall-tower (150m), and found elevated 14CO2 levels during summer months that likely resulted from increased respiration from heterotrophic sources. These results demonstrate that a fingerprint from soil-respired CO2 can be detected in the seasonal patterns of atmospheric 14CO2, even at a regionally-integrating spatial scale far from the soil surface.

  17. A test of sensitivity to convective transport in a global atmospheric CO2 simulation

    NASA Astrophysics Data System (ADS)

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

    2006-11-01

    Two approximations to convective transport have been implemented in an offline chemistry transport model (CTM) to explore the impact on calculated atmospheric CO2 distributions. Global CO2 in the year 2000 is simulated using the CTM 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.

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

    NASA Technical Reports Server (NTRS)

    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.

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

    NASA Technical Reports Server (NTRS)

    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.

  20. Atmospheric CO2 consequences of heavy dependence on coal.

    PubMed Central

    Rotty, R M

    1979-01-01

    Accurate and regular measurements of the concentration of CO2 in the atmosphere during the past 20 years show an accelerating increase. Although clearing of tropical forests has released large amounts of carbon to the atmosphere, evidence is strong that a major contributor is the combustion of fossil fuels. Future energy demands of the world will require extensive further exploitation of fossil fuels, and projections show that without major development of nonfossil fuel alternatives, the atmospheric concentration will double within the next 75 years. Four issues require serious attention. The developing countries will require vastly increased amounts of energy. Major efforts to develop suitable (inexpensive) nonfossil energy sources to meet at least a portion of this demand are required. The distribution of carbon released from fossil fuels and from other anthropogenic sources among the reservoirs of the carbon cycle must be better defined. Uncertainties regarding the effect of the increased concentration of CO2 in the atmosphere on global climate must be reduced. Possible political and social responses to a substantial climate change must be studied in order to more fully understand all of the implication of increased atmospheric CO2. PMID:120253

  1. Atmospheric CO2 consequences of heavy dependence on coal.

    PubMed

    Rotty, R M

    1979-12-01

    Accurate and regular measurements of the concentration of CO2 in the atmosphere during the past 20 years show an accelerating increase. Although clearing of tropical forests has released large amounts of carbon to the atmosphere, evidence is strong that a major contributor is the combustion of fossil fuels. Future energy demands of the world will require extensive further exploitation of fossil fuels, and projections show that without major development of nonfossil fuel alternatives, the atmospheric concentration will double within the next 75 years. Four issues require serious attention. The developing countries will require vastly increased amounts of energy. Major efforts to develop suitable (inexpensive) nonfossil energy sources to meet at least a portion of this demand are required. The distribution of carbon released from fossil fuels and from other anthropogenic sources among the reservoirs of the carbon cycle must be better defined. Uncertainties regarding the effect of the increased concentration of CO2 in the atmosphere on global climate must be reduced. Possible political and social responses to a substantial climate change must be studied in order to more fully understand all of the implication of increased atmospheric CO2.

  2. Vertical distribution of CO2 in the atmospheric boundary layer: Characteristics and impact of meteorological variables

    NASA Astrophysics Data System (ADS)

    Li, Yanli; Deng, Junjun; Mu, Chao; Xing, Zhenyu; Du, Ke

    2014-07-01

    Knowledge of vertical CO2 distribution is important for development of CO2 transport models and calibration/validation of satellite-borne measurements. In this study, vertical profiles of CO2 concentration within 0-1000 m were measured using a tethered balloon at a suburban site in Xiamen, which is undergoing fast urbanization. The characteristics of CO2 vertical distribution were investigated under both stable and convective boundary-layer conditions. The correlation of ground level CO2 concentrations and those at high altitudes decreased with altitude and show significant correlation in the first 300 m with R = 0.78 at 100 m, R = 0.52 at 200 m, R = 0.40 at 300 m (P < 0.01). The correlation keeps almost constant for 300-800 m, and there is no obvious correlation at 800 m, indicating that the impact of ground level CO2 was restricted within the 300 m above the ground. When comparing the vertical profiles obtained at different times during a 24 h period, it was found that CO2 concentration exhibited more obvious diurnal pattern at surface level than at high altitude because of the variation of sources and sinks of CO2 at ground level. Most profiles demonstrated declining trends of CO2 concentration with increasing altitude. The vertical profiles of CO2 were fitted to obtain an empirical equation for estimating CO2 vertical concentration in the lower atmosphere (0-1000 m): y = -75.04 + 1.17 × 109e-x/28.01, R2 = 0.59 (P < 0.05). However, for some cases opposite patterns were observed that the CO2 concentration profiles showed a turning point at a certain altitude or little variation with altitude under certain meteorological conditions. The atmospheric boundary layer depth and atmospheric stability are two major factors controlling the vertical structure of CO2 profile. The results would improve our understanding of the spatial and temporal variation of CO2 in urban environment, which would facilitate using 3-D transport model to study the impacts of CO2 on urban

  3. Evolutionary History of Atmospheric CO2 during the Late Cenozoic from Fossilized Metasequoia Needles

    PubMed Central

    Wang, Yuqing; Momohara, Arata; Wang, Li; Lebreton-Anberrée, Julie; Zhou, Zhekun

    2015-01-01

    The change in ancient atmospheric CO2 concentrations provides important clues for understanding the relationship between the atmospheric CO2 concentration and global temperature. However, the lack of CO2 evolution curves estimated from a single terrestrial proxy prevents the understanding of climatic and environmental impacts due to variations in data. Thus, based on the stomatal index of fossilized Metasequoia needles, we reconstructed a history of atmospheric CO2 concentrations from middle Miocene to late Early Pleistocene when the climate changed dramatically. According to this research, atmospheric CO2 concentration was stabile around 330–350 ppmv in the middle and late Miocene, then it decreased to 278–284 ppmv during the Late Pliocene and to 277–279 ppmv during the Early Pleistocene, which was almost the same range as in preindustrial time. According to former research, this is a time when global temperature decreased sharply. Our results also indicated that from middle Miocene to Pleistocene, global CO2 level decreased by more than 50 ppmv, which may suggest that CO2 decrease and temperature decrease are coupled. PMID:26154449

  4. Evolutionary History of Atmospheric CO2 during the Late Cenozoic from Fossilized Metasequoia Needles.

    PubMed

    Wang, Yuqing; Momohara, Arata; Wang, Li; Lebreton-Anberrée, Julie; Zhou, Zhekun

    2015-01-01

    The change in ancient atmospheric CO2 concentrations provides important clues for understanding the relationship between the atmospheric CO2 concentration and global temperature. However, the lack of CO2 evolution curves estimated from a single terrestrial proxy prevents the understanding of climatic and environmental impacts due to variations in data. Thus, based on the stomatal index of fossilized Metasequoia needles, we reconstructed a history of atmospheric CO2 concentrations from middle Miocene to late Early Pleistocene when the climate changed dramatically. According to this research, atmospheric CO2 concentration was stabile around 330-350 ppmv in the middle and late Miocene, then it decreased to 278-284 ppmv during the Late Pliocene and to 277-279 ppmv during the Early Pleistocene, which was almost the same range as in preindustrial time. According to former research, this is a time when global temperature decreased sharply. Our results also indicated that from middle Miocene to Pleistocene, global CO2 level decreased by more than 50 ppmv, which may suggest that CO2 decrease and temperature decrease are coupled.

  5. Decadal patterns in δ18O of atmospheric CO2

    NASA Astrophysics Data System (ADS)

    Zakem, E.; White, J. W.

    2010-12-01

    The stable oxygen isotope 18O is unique to isotope ecology in that it links the hydrosphere to the carbon cycle. Since land biosphere fluxes are the dominant influences on 18O of atmospheric CO2, particularly on shorter times scales, analysis of atmospheric δ18O trends can provide useful insight into the terrestrial carbon cycle. The isotopic values imprinted by leaf water and soil water exchanges with CO2 out-compete those from ocean exchange, fossil fuel and biomass burning, and stratospheric reactions. The opposing isotopic imprints of photosynthesis and ecosystem respiration therefore control the majority of atmospheric 18O concentration. The resulting seasonal cycle in δ18O data of peaks during early summer, when photosynthesis dominates, and lows during early winter, when respiration dominates, has been clearly established. However, the reasons for the interannual variability of atmospheric 18O remain unknown. Studies have shown that the size and isotopic value of the “retrodiffusion” flux- the CO2 that enters and exits leaves without being fixed by photosynthesis- is a function of stomatal conductance, which is affected by the relative humidity in the surrounding atmosphere. We observe that data from numerous global sites shows a global decadal oscillation in δ18O, suggesting a climatological forcing. We compare decadal trends in δ18O with climate oscillations and the 11-year solar cycle, as well as relative humidity records, examining correlations and proposing associated mechanisms. Understanding the decadal patterns in atmospheric 18O of CO2 will shed light on global terrestrial carbon fluxes and the carbon-water interaction on decadal time scales, potentially helping to scale human versus natural impacts on this coupled system.

  6. Atmospheric correlation time measurements using coherent CO2 lidar

    NASA Technical Reports Server (NTRS)

    Ancellet, G. M.; Menzies, R. T.

    1986-01-01

    A pulsed TEA-CO2 lidar with coherent detection was used to measure the correlation time of backscatter from an ensemble of atmospheric aerosol particles which are illuminated by the pulsed radiation. The correlation time of the backscatter return signal is important in studies of atmospheric turbulence and its effects on optical propagation and backscatter. If the temporal coherence of the pulse is large enough, then the temporal coherence of the return signal is dominated by the turbulence and shear for a variety of interesting atmospheric conditions. Various techniques for correlation time measurement are discussed and evaluated.

  7. Agroecosystem productivity in a warmer and CO2 enriched atmosphere

    NASA Astrophysics Data System (ADS)

    Bernacchi, Carl; Köhler, Iris; Ort, Donald; Long, Steven; Clemente, Thomas

    2017-04-01

    A number of in-field manipulative experiments have been conducted that address the response of key ecosystem services of major agronomic species to rising CO2. Global warming, however, is inextricably linked to rising greenhouse gases in general, of which CO2 is the most dominant. Therefore, agroecosystem functioning in future conditions requires an understanding of plant responses to both rising CO2 and increased temperatures. Few in-field manipulative experiments have been conducted that supplement both heating and CO2 above background concentrations. Here, the results of six years of experimentation using a coupled Free Air CO2 Enrichment (FACE) technology with variable output infrared heating arrays are reported. The manipulative experiment increased temperatures (+ 3.5˚ C) and CO2 (+ 200 μmol mol-1) above background levels for on two major agronomic crop species grown throughout the world, Zea mays (maize) and Glycine max (soybean). The first phase of this research addresses the response of plant physiological parameters to growth in elevated CO2 and warmer temperatures for maize and soybean grown in an open-air manipulative experiment. The results show that any increase in ecosystem productivity associated with rising CO2 is either similar or is offset by growth at higher temperatures, inconsistent with the perceived benefits of higher CO2 plus warmer temperatures on agroecosystem productivity. The second phase of this research addresses the opportunity to genetically modify soybean to allow for improved productivity under high CO2 and warmer temperatures by increasing a key photosynthetic carbon reduction cycle enzyme, SPBase. The results from this research demonstrates that manipulation of the photosynthetic pathway can lead to higher productivity in high CO2 and temperature relative to the wild-type control soybean. Overall, this research advances the understanding of the physiological responses of two major crops, and the impact on ecosystem services

  8. Southern Ocean buoyancy forcing of ocean ventilation and glacial atmospheric CO2

    NASA Astrophysics Data System (ADS)

    Watson, Andrew J.; Vallis, Geoffrey K.; Nikurashin, Maxim

    2015-11-01

    Atmospheric CO2 concentrations over glacial-interglacial cycles closely correspond to Antarctic temperature patterns. These are distinct from temperature variations in the mid to northern latitudes, so this suggests that the Southern Ocean is pivotal in controlling natural CO2 concentrations. Here we assess the sensitivity of atmospheric CO2 concentrations to glacial-interglacial changes in the ocean's meridional overturning circulation using a circulation model for upwelling and eddy transport in the Southern Ocean coupled with a simple biogeochemical description. Under glacial conditions, a broader region of surface buoyancy loss results in upwelling farther to the north, relative to interglacials. The northern location of upwelling results in reduced CO2 outgassing and stronger carbon sequestration in the deep ocean: we calculate that the shift to this glacial-style circulation can draw down 30 to 60 ppm of atmospheric CO2. We therefore suggest that the direct effect of temperatures on Southern Ocean buoyancy forcing, and hence the residual overturning circulation, explains much of the strong correlation between Antarctic temperature variations and atmospheric CO2 concentrations over glacial-interglacial cycles.

  9. Atmospheric CO2 balance: The role of Arctic sea ice

    NASA Astrophysics Data System (ADS)

    Semiletov, Igor; Makshtas, Alexander; Akasofu, Syun-Ichi; Andreas, Edgar L.

    2004-03-01

    Climatic changes in the Northern Hemisphere have led to remarkable environmental changes in the Arctic Ocean, including significant shrinking of sea-ice cover in summer, increased time between sea-ice break-up and freeze-up, and Arctic surface water freshening and warming associated with melting sea-ice, thawing permafrost, and increased runoff [Carmack, 2000; Morison et al., 2000; Semiletov et al., 2000; Serreze et al., 2000]. These changes are commonly attributed to the greenhouse effect resulting from increased carbon dioxide (CO2) concentration. The greenhouse effect should be most pronounced in the Arctic where the largest air CO2 concentrations and winter-summer variations in the world for a clean background environment were detected [Conway et al., 1994; Climate Monitoring and Diagnostics Laboratory Data Archive, http://www.cmdl.noaa.gov/info/ftpdata.html]. Some increased seasonal variation may be a consequence of increasing summer CO2 assimilation by plants in response to higher temperature and longer growing season [Keeling et al., 1996]. Here we show that sea-ice melt ponds and open brine channels form an important spring/summer air CO2 sink that also must be included in any Arctic regional CO2 budget; both the direction and amount of CO2 transfer between air and sea during the open water season may be different from transfer during freezing and thawing, or during winter when CO2 accumulates beneath Arctic sea-ice.

  10. Detection of CO2 leaks from carbon capture and storage sites to the atmosphere with combined CO2 and O2 measurements

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    One of the main issues in carbon capture and storage (CCS) is the possibility of leakage of CO2 from the storage reservoir to the atmosphere, both from a public health and a climate change combat perspective. Detecting these leaks in the atmosphere is difficult due to the rapid mixing of the emitted CO2 with the surrounding air masses and the high natural variability of the atmospheric CO2 concentration. Instead of measuring only the CO2 concentration of the atmosphere, its isotopes or chemical tracers that are released together with the CO2, our method uses O2 measurements in addition to CO2 measurements to detect a leak from a CCS site. CO2 and O2 are coupled in most processes on earth. In photosynthesis, plants take up CO2 and release O2 at the same time. In respiration and fossil fuel burning, O2 is consumed while CO2 is released. In case of a leak from a CCS site, however, there is no relationship between CO2 and O2. A CO2 leak can therefore be distinguished from other sources of CO2 by looking at the atmospheric CO2-O2 ratio. A natural increase of the CO2 concentration is accompanied by a drop in the O2 concentration, while an increase in the CO2 concentration caused by a leak from a CCS site does not have any effect on the O2 concentration. To demonstrate this leak detection strategy we designed and built a transportable CO2 and O2 measurement system, that is capable of measuring the relatively minute (ppm's variations on a 21% concentration) changes in the O2 concentration. The system comprises of three cases that contain the instrumentation and gas handling equipment, the gas cylinders used as reference and calibration gases and a drying system, respectively. Air is pumped to the system from an air inlet that is placed in a small tower in the field. At the conference, we will demonstrate the success of leak detection with our system by showing measurements of several CO2 release experiments, where CO2 was released at a small distance from the air inlet of

  11. Modification of land-atmosphere interactions by CO2 effects

    NASA Astrophysics Data System (ADS)

    Lemordant, Leo; Gentine, Pierre

    2017-04-01

    Plant stomata couple the energy, water and carbon cycles. Increased CO2 modifies the seasonality of the water cycle through stomatal regulation and increased leaf area. As a result, the water saved during the growing season through higher water use efficiency mitigates summer dryness and the impact of potential heat waves. Land-atmosphere interactions and CO2 fertilization together synergistically contribute to increased summer transpiration. This, in turn, alters the surface energy budget and decreases sensible heat flux, mitigating air temperature rise. Accurate representation of the response to higher CO2 levels, and of the coupling between the carbon and water cycles are therefore critical to forecasting seasonal climate, water cycle dynamics and to enhance the accuracy of extreme event prediction under future climate.

  12. Reduced atmospheric CO2 inhibits nitrogen mobilization in Festuca rubra.

    PubMed

    Thornton, Barry; Paterson, Eric; Kingston-Smith, Alison H; Bollard, Andrea L; Pratt, Shona M; Sim, Allan

    2002-09-01

    In defoliated grasses, where photosynthesis is reduced due to removal of leaf material, it is well established that remobilization of nitrogen occurs from both older remaining leaves and roots towards the younger growing leaves. In contrast, little is known about the movement of nitrogen within intact grass plants experiencing prolonged inhibition of photosynthesis. We tested the following hypotheses in Festuca rubra L. ssp. rubra cv. Boreal: that both reduction of the atmospheric CO2 concentration and defoliation (1) induce mobilization of nitrogen from roots and older leaves towards growing leaves and (2) elicit similar directional change in the abundance of proteins in roots and older leaves relevant to the process of nitrogen mobilization including, glutamine synthetase (GS), EC 6.3.1.2; papain, EC 3.4.22.2; chymopapain, EC 3.4.22.6; ribulose bisphosphate carboxylase/oxygenase (Rubisco), EC 4.1.1.39; and the light harvesting complex of photosystem II (LHCPII). After growth at ambient atmospheric CO2 concentration, plants of F. rubra were subject to atmospheres containing either ambient (350 micro l l-1) or deplete (< 20 micro l l-1) CO2. Concurrently, plants were either left intact or defoliated on one occasion. Steady state 15N labelling coupled with a series of destructive harvests over a 7-day period enabled changes in the nitrogen dynamics of the plants to be established. Proteins pertinent to the process of nitrogen mobilization were quantified by immunoblotting. Irrespective of defoliation, plants in ambient CO2 mobilized nitrogen from older to growing leaves. This mobilization was inhibited by deplete CO2. Greater concentration of Rubisco and reduced chymopapain abundance in older remaining leaves of intact plants, in deplete compared with ambient CO2, suggested the inhibition of mobilization was due to inhibition of protein degradation, rather than to the export of degradation products. Both deplete CO2 and defoliation induced nitrogen mobilization from

  13. Implications of 'Peak Oil' for Atmospheric CO2 and Climate

    NASA Astrophysics Data System (ADS)

    Kharecha, P. A.; Hansen, J. E.

    2008-12-01

    Unconstrained CO2 emission from fossil fuel burning has been the dominant cause of observed anthropogenic global warming. The amounts of "proven" and potential fossil fuel reserves are uncertain and debated. Regardless of the true values, society has flexibility in the degree to which it chooses to exploit these reserves, especially unconventional fossil fuels and those located in extreme or pristine environments. If conventional oil production peaks within the next few decades, it may have a large effect on future atmospheric CO2 and climate change, depending upon subsequent energy choices. Assuming that proven oil and gas reserves do not greatly exceed estimates of the Energy Information Administration -- and recent trends are toward lower estimates -- we show that it is feasible to keep atmospheric CO2 from exceeding about 450 ppm by 2100, provided that emissions from coal, unconventional fossil fuels, and land use are constrained. Coal-fired facilities without sequestration must be phased out before midcentury to achieve this CO2 limit. It is also important to "stretch" conventional oil reserves via energy conservation and efficiency, thus averting strong pressures to extract liquid fuels from coal or unconventional fossil fuels while clean technologies are being developed for the era "beyond fossil fuels". We argue that a rising price on carbon emissions is needed to discourage conversion of the vast fossil resources into usable reserves, and to keep CO2 below 450 ppm. It is also plausible that CO2 can be returned below 350 ppm by 2100 or sooner, if more aggressive mitigation measures are enacted, most notably a phase-out of global coal emissions by circa 2030 and large- scale reforestation, primarily in the tropics but also in temperate regions.

  14. Atmospheric verification of anthropogenic CO2 emission trends

    NASA Astrophysics Data System (ADS)

    Francey, Roger J.; Trudinger, Cathy M.; van der Schoot, Marcel; Law, Rachel M.; Krummel, Paul B.; Langenfelds, Ray L.; Paul Steele, L.; Allison, Colin E.; Stavert, Ann R.; Andres, Robert J.; Rödenbeck, Christian

    2013-05-01

    International efforts to limit global warming and ocean acidification aim to slow the growth of atmospheric CO2, guided primarily by national and industry estimates of production and consumption of fossil fuels. Atmospheric verification of emissions is vital but present global inversion methods are inadequate for this purpose. We demonstrate a clear response in atmospheric CO2 coinciding with a sharp 2010 increase in Asian emissions but show persisting slowing mean CO2 growth from 2002/03. Growth and inter-hemispheric concentration difference during the onset and recovery of the Global Financial Crisis support a previous speculation that the reported 2000-2008 emissions surge is an artefact, most simply explained by a cumulative underestimation (~ 9PgC) of 1994-2007 emissions; in this case, post-2000 emissions would track mid-range of Intergovernmental Panel on Climate Change emission scenarios. An alternative explanation requires changes in the northern terrestrial land sink that offset anthropogenic emission changes. We suggest atmospheric methods to help resolve this ambiguity.

  15. Infrared polarization spectroscopy of CO 2 at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Alwahabi, Z. T.; Li, Z. S.; Zetterberg, J.; Aldén, M.

    2004-04-01

    Polarisation spectroscopy (PS) was used to probe CO 2 gas concentration in a CO 2/N 2 binary mixture at atmospheric pressure and ambient temperature. The CO 2 molecules were probed by a direct laser excitation to an overtone and combination vibrational state. The tuneable narrow linewidth infrared laser radiation at 2 μm was obtained by Raman shifting of the output from a single-longitudinal-mode pulsed alexandrite laser-system to the second Stokes component in a H 2 gas cell. Infrared polarisation spectroscopy (IRPS) and time-resolved infrared laser-induced fluorescence (IRLIF) spectra were collected. A linear dependence of the IRPS signal on the CO 2 mole fraction has been found. This indicates that the IRPS signal is only weakly affected by the molecular collisions and that the inter- and intra- molecular energy transfer processes do not strongly influence the molecular alignment at the time scale of the measurements. Thus IRPS holds great potential for quantitative instantaneous gas concentration diagnostics in general. This is especially important for molecules which do not posses an accessible optical transition such as CO, CO 2 and N 2O. In addition, an accurate experimental method to measure the extinction ratio of the IR polarisers employed in this study has been developed and applied. With its obvious merits as simplicity, easy alignment and high accuracy, the method can be generalized to all spectral regions, different polarisers and high extinction ratios.

  16. Biomass burial and storage to reduce atmospheric CO2

    NASA Astrophysics Data System (ADS)

    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.

  17. Leveraging atmospheric CO2 observations to constrain the climate sensitivity of terrestrial ecosystems

    NASA Astrophysics Data System (ADS)

    Keppel-Aleks, G.

    2015-12-01

    A significant challenge in understanding, and therefore modeling, the response of terrestrial carbon cycling to climate and environmental drivers is that vegetation varies on spatial scales of order a few kilometers whereas Earth system models (ESMs) are run with characteristic length scales of order 100 km. Atmospheric CO2 provides a constraint on carbon fluxes at spatial scales compatible with the resolution of ESMs due to the fact that atmospheric mixing renders a single site representative of fluxes within a large spatial footprint. The variations in atmospheric CO2 at both seasonal and interannual timescales largely reflect terrestrial influence. I discuss the use of atmospheric CO2 observations to benchmark model carbon fluxes over a range of spatial scales. I also discuss how simple models can be used to test functional relationships between the CO2 growth rate and climate variations. In particular, I show how atmospheric CO2 provides constraints on ecosystem sensitivity to climate drivers in the tropics, where tropical forests and semi-arid ecosystems are thought to account for much of the variability in the contemporary carbon sink.

  18. Effects of atmospheric CO2 enrichment on soil CO2 efflux in a young longleaf pine system

    Treesearch

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

    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...

  19. Seasonal variation of CO2 saturation in the Gulf of Bothnia: Indications of marine net heterotrophy

    NASA Astrophysics Data System (ADS)

    Algesten, Grete; Wikner, Johan; Sobek, Sebastian; Tranvik, Lars J.; Jansson, Mats

    2004-12-01

    Seasonal variation of pCO2 and primary and bacterioplankton production were measured in the Gulf of Bothnia during an annual cycle. Surface water was supersaturated with CO2 on an annual basis, indicating net heterotrophy and a source of CO2 to the atmosphere. However, the Gulf of Bothnia oscillated between being a sink and a source of CO2 over the studied period, largely decided by temporal variation in bacterial respiration (BR) and primary production (PP) in the water column above the pycnocline. The calculated annual respiration-production balance (BR-PP) was very similar to the estimated CO2 emission from the Gulf of Bothnia, which indicates that these processes were major determinants of the exchange of CO2 between water and atmosphere. The southern basin (the Bothnian Sea) had a lower net release of CO2 to the atmosphere than the northern Bothnian Bay (7.1 and 9.7 mmol C m-2 d-1, respectively), due to higher primary production, which to a larger extent balanced respiration in this basin.

  20. Paleo-CO2 variation trends and the Cretaceous greenhouse climate

    NASA Astrophysics Data System (ADS)

    Wang, Yongdong; Huang, Chengmin; Sun, Bainian; Quan, Cheng; Wu, Jingyu; Lin, Zhicheng

    2014-02-01

    The Cretaceous was one of the most remarkable periods in geological history, with a "greenhouse" climate and several important geological events. Reconstructions of atmospheric CO2 using proxies are crucial for understanding the Cretaceous "greenhouse." In this paper we summarize the major approaches for reconstructing CO2 based on paleobotanical or geochemical data, and synthesize the CO2 variations throughout the Cretaceous. The results show that atmospheric CO2 levels remained relatively high throughout the Cretaceous, but were lower in the early Cretaceous, highest in the mid-Cretaceous and gradually declined during the late Cretaceous. However, this overall trend was interrupted by several rapid changes associated with ocean anoxic events (OAEs) and the end-Cretaceous catastrophic event. New data on paleo-CO2 levels from paleobotanical and paleosol evidences support not only the overall trends indicated by geochemical models, but provide more precise records of the short-term fluctuations related to brief episodes of climate change. Temporal resolution within the long quiet magnetic period in the middle Cretaceous is one of the obstacles preventing us from a more comprehensive understanding of the CO2 climate linkage. But new paleo-CO2 determinations and climatic data from stratigraphic sections of sediments intercalated with datable volcanic rocks will allow a better understanding of the relationships between fluctuations of atmospheric CO2, climate change, and geological events.

  1. Influence of atmospheric circulation on regional 14CO2 differences

    NASA Astrophysics Data System (ADS)

    Hua, Quan; Barbetti, Mike

    2007-10-01

    Detailed analyses of published 14C data from tree rings and atmospheric CO2 samples for the northern tropics in Asia (India, Thailand, and Vietnam) and Africa (Ethiopia) have been performed for the heavily bomb-influenced period 1963-1967 A.D. The results show that the Asian summer monsoon and Intertropical Convergence Zone (ITCZ) position influenced atmospheric 14CO2 over the study area. Similar analyses of atmospheric records for northern and western Europe, northwestern Africa, and the northeastern United States and tree ring data for east Asia show that the Northern Hemisphere distribution of bomb 14C for 1963-1967 depended on atmospheric circulation controlled by the seasonal positions of Hadley cell boundaries and the ITCZ. The distribution of 14C did not have a simple latitudinal dependence. This work shows that the seasonal atmospheric circulation patterns are crucial for the description of atmospheric 14C gradients during the bomb peak period. These principles can be applied to the interpretation of the small intrahemispheric 14C offsets of the remote past.

  2. Evolutionary context for understanding and manipulating plant responses to past, present and future atmospheric [CO2].

    PubMed

    Leakey, Andrew D B; Lau, Jennifer A

    2012-02-19

    Variation in atmospheric [CO(2)] is a prominent feature of the environmental history over which vascular plants have evolved. Periods of falling and low [CO(2)] in the palaeo-record appear to have created selective pressure for important adaptations in modern plants. Today, rising [CO(2)] is a key component of anthropogenic global environmental change that will impact plants and the ecosystem goods and services they deliver. Currently, there is limited evidence that natural plant populations have evolved in response to contemporary increases in [CO(2)] in ways that increase plant productivity or fitness, and no evidence for incidental breeding of crop varieties to achieve greater yield enhancement from rising [CO(2)]. Evolutionary responses to elevated [CO(2)] have been studied by applying selection in controlled environments, quantitative genetics and trait-based approaches. Findings to date suggest that adaptive changes in plant traits in response to future [CO(2)] will not be consistently observed across species or environments and will not be large in magnitude compared with physiological and ecological responses to future [CO(2)]. This lack of evidence for strong evolutionary effects of elevated [CO(2)] is surprising, given the large effects of elevated [CO(2)] on plant phenotypes. New studies under more stressful, complex environmental conditions associated with climate change may revise this view. Efforts are underway to engineer plants to: (i) overcome the limitations to photosynthesis from today's [CO(2)] and (ii) benefit maximally from future, greater [CO(2)]. Targets range in scale from manipulating the function of a single enzyme (e.g. Rubisco) to adding metabolic pathways from bacteria as well as engineering the structural and functional components necessary for C(4) photosynthesis into C(3) leaves. Successfully improving plant performance will depend on combining the knowledge of the evolutionary context, cellular basis and physiological integration

  3. Evolutionary context for understanding and manipulating plant responses to past, present and future atmospheric [CO2

    PubMed Central

    Leakey, Andrew D. B.; Lau, Jennifer A.

    2012-01-01

    Variation in atmospheric [CO2] is a prominent feature of the environmental history over which vascular plants have evolved. Periods of falling and low [CO2] in the palaeo-record appear to have created selective pressure for important adaptations in modern plants. Today, rising [CO2] is a key component of anthropogenic global environmental change that will impact plants and the ecosystem goods and services they deliver. Currently, there is limited evidence that natural plant populations have evolved in response to contemporary increases in [CO2] in ways that increase plant productivity or fitness, and no evidence for incidental breeding of crop varieties to achieve greater yield enhancement from rising [CO2]. Evolutionary responses to elevated [CO2] have been studied by applying selection in controlled environments, quantitative genetics and trait-based approaches. Findings to date suggest that adaptive changes in plant traits in response to future [CO2] will not be consistently observed across species or environments and will not be large in magnitude compared with physiological and ecological responses to future [CO2]. This lack of evidence for strong evolutionary effects of elevated [CO2] is surprising, given the large effects of elevated [CO2] on plant phenotypes. New studies under more stressful, complex environmental conditions associated with climate change may revise this view. Efforts are underway to engineer plants to: (i) overcome the limitations to photosynthesis from today's [CO2] and (ii) benefit maximally from future, greater [CO2]. Targets range in scale from manipulating the function of a single enzyme (e.g. Rubisco) to adding metabolic pathways from bacteria as well as engineering the structural and functional components necessary for C4 photosynthesis into C3 leaves. Successfully improving plant performance will depend on combining the knowledge of the evolutionary context, cellular basis and physiological integration of plant responses to varying

  4. The BErkeley Atmospheric CO2 Observation Network: initial evaluation

    NASA Astrophysics Data System (ADS)

    Shusterman, Alexis A.; Teige, Virginia E.; Turner, Alexander J.; Newman, Catherine; Kim, Jinsol; Cohen, Ronald C.

    2016-10-01

    With the majority of the world population residing in urban areas, attempts to monitor and mitigate greenhouse gas emissions must necessarily center on cities. However, existing carbon dioxide observation networks are ill-equipped to resolve the specific intra-city emission phenomena targeted by regulation. Here we describe the design and implementation of the BErkeley Atmospheric CO2 Observation Network (BEACO2N), a distributed CO2 monitoring instrument that utilizes low-cost technology to achieve unprecedented spatial density throughout and around the city of Oakland, California. We characterize the network in terms of four performance parameters - cost, reliability, precision, and systematic uncertainty - and find the BEACO2N approach to be sufficiently cost-effective and reliable while nonetheless providing high-quality atmospheric observations. First results from the initial installation successfully capture hourly, daily, and seasonal CO2 signals relevant to urban environments on spatial scales that cannot be accurately represented by atmospheric transport models alone, demonstrating the utility of high-resolution surface networks in urban greenhouse gas monitoring efforts.

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

    PubMed

    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.

  6. [Effects of elevated atmospheric CO2 on plant, herbivorous insect, and its natural enemy: a review].

    PubMed

    Xie, Hai-Cui; Wang, Zhen-Ying; He, Kang-Lai

    2013-12-01

    Since the industrial revolution, the huge consumption of fossil fuels and unduly destruction of natural habitats by human activities have led to the ever-increasing concentration of atmospheric CO2. To study the adaptation mechanisms of plant, herbivorous insect, and its natural enemy within agricultural ecosystems to the elevated atmospheric CO2 concentration is of significance in deciphering the damage pattern of agricultural pest occurrence and controlling the pest occurrence and in mitigating the CO2 emission from agricultural ecosystems. This paper reviewed the research progress on the effects of elevated atmospheric CO2 on the host plant, herbivorous insect, and its natural enemy in agro-ecosystem, with the focuses on the improvement of related research methods, the variation patterns of host plant primary and secondary metabolites induced by elevated atmospheric CO2, the effects of the elevated CO2 on the growth and development, population density, and behaviors of herbivorous insect, and the biology and predation and/or parasitism rates of natural enemy. The future research frontiers in this research area were also discussed.

  7. Simulation and Observation of Global Atmospheric CO2 from 2009-2010

    NASA Astrophysics Data System (ADS)

    Denning, A.; O'Dell, C. W.; Baker, D. F.; Parazoo, N.; McKeown, R.; Baker, I. T.; Kawa, S. R.; Doney, S. C.

    2011-12-01

    We compare global variations in atmospheric CO2 concentrations using a comprehensive model of surface carbon cycling and atmospheric transport to retrievals of column CO2 mole fraction from near-infrared spectroscopy from the GOSAT mission. Surface carbon exchanges due to photosynthesis, respiration, decomposition, biomass burning, fossil fuel combustion, and air-sea gas exchange are computed every hour. These fluxes are used as input to a global atmospheric tranport model to obtain three-dimensional fields of CO2, which are sampled at the time and location of quality-screened GOSAT data retrieved by the Atmospheric Carbon Observations from Space (ACOS) team. The system is operated on a 0.5° x 0.67° grid (dx ~ 50 km), providing global mesoscale coverage, and has good skill at replicating diurnal, synoptic, and seasonal variations over vegetated land surfaces. It is driven by meteorological output from the NASA Goddard EOS Data Assimilation System. Surface weather from the system drives calculations of terrestrial ecosystem metabolism (radiation, precipitation, humidity, temperature) and air-sea gas exchange (wind), with other input data coming from satellite data products. Simulated spatial patterns and seasonal variations of simulated and observed column CO2 exhibit broad agreement, but some offsets in latitude and seasonal variations are noted. These are attributed to both model and satellite retrieval errors.

  8. The Stable Isotopic Composition of Atmospheric CO2

    NASA Astrophysics Data System (ADS)

    Yakir, D.

    2003-12-01

    When a bean leaf was sealed in a closed chamber under a lamp (Rooney, 1988), in two hours the atmospheric CO2 in the microcosm reached an isotopic steady state with a 13C abundance astonishingly similar to the global mean value of atmospheric CO2 at that time (-7.5‰ in the δ13C notation introduced below). Almost concurrently, another research group sealed a suspension of asparagus cells in a different type of microcosm in which within about two hours the atmospheric O2 reached an isotopic steady state with 18O enrichment relative to water in the microcosm that was, too, remarkably similar to the global-scale offset between atmospheric O2 and mean ocean water (21‰ versus 23.5‰ in the δ18O notation introduced below; Guy et al., 1987). These classic experiments capture some of the foundations underlying the isotopic composition of atmospheric CO2 and O2. First, in both cases the biological system rapidly imposed a unique isotopic value on the microcosms' atmosphere via their massive photosynthetic and respiratory exchange of CO2 and O2. Second, in both cases the biological system acted on materials with isotopic signals previously formed by the global carbon and hydrological cycles. That is, the bean leaf introduced its previously formed organic matter (the source of the CO2 respired into microcosm's atmosphere), and the asparagus cells were introduced complete with local tap water (from which photosynthesis released molecular oxygen). Therefore, while the isotopic composition of the biological system used was slave to long-term processes, intense metabolic processes centered on few specific enzymes (Yakir, 2002) dictated the short-term atmospheric composition.In a similar vein, on geological timescales of millions of years, the atmosphere and its isotopic composition are integral parts of essentially a single dynamic ocean-atmosphere-biosphere system. This dynamic system exchanges material, such as carbon and oxygen, with the sediments and the lithosphere via

  9. Interannual Variability In the Atmospheric CO2 Rectification Over Boreal Forests Based On A Coupled Ecosystem-Atmosphere Model

    NASA Astrophysics Data System (ADS)

    Chen, B.; Chen, J. M.; Worthy, D.

    2004-05-01

    Ecosystem CO2 exchange and the planetary boundary layer (PBL) are correlated diurnally and seasonally. The simulation of this atmospheric rectifier effect is important in understanding the global CO2 distribution pattern. A 12-year (1990-1996, 1999-2003), continuous CO2 measurement record from Fraserdale, Ontario (located ~150 km north of Timmons), along with a coupled Vertical Diffusion Scheme (VDS) and ecosystem model (Boreal Ecosystem Productivity Simulator, BEPS), is used to investigate the interannual variability in this effect over a boreal forest region. The coupled model performed well in simulating CO2 vertical diffusion processes. Simulated annual atmospheric rectifier effects, (including seasonal and diurnal), quantified as the variation in the mean CO2 concentration from the surface to the top of the PBL, varied from 2.8 to 4.1 ppm, even though the modeled seasonal variations in the PBL depth were similar throughout the 12-year period. The differences in the interannual rectifier effect primarily resulted from changes in the biospheric CO2 uptake and heterotrophic respiration. Correlations in the year-to year variations of the CO2 rectification were found with mean annual air temperatures, simulated gross primary productivity (GPP) and heterotrophic respiration (Rh) (r2=0.5, 0.46, 0.42, respectively). A small increasing trend in the CO2 rectification was also observed. The year-to-year variation in the vertical distribution of the monthly mean CO2 mixing ratios (reflecting differences in the diurnal rectifier effect) was related to interannual climate variability, however, the seasonal rectifier effects were found to be more sensitive to climate variability than the diurnal rectifier effects.

  10. Water relations in grassland and desert ecosystems exposed to elevated atmospheric CO2.

    PubMed

    Morgan, J A; Pataki, D E; Körner, C; Clark, H; Del Grosso, S J; Grünzweig, J M; Knapp, A K; Mosier, A R; Newton, P C D; Niklaus, P A; Nippert, J B; Nowak, R S; Parton, W J; Polley, H W; Shaw, M R

    2004-06-01

    Atmospheric CO2 enrichment may stimulate plant growth directly through (1) enhanced photosynthesis or indirectly, through (2) reduced plant water consumption and hence slower soil moisture depletion, or the combination of both. Herein we describe gas exchange, plant biomass and species responses of five native or semi-native temperate and Mediterranean grasslands and three semi-arid systems to CO2 enrichment, with an emphasis on water relations. Increasing CO2 led to decreased leaf conductance for water vapor, improved plant water status, altered seasonal evapotranspiration dynamics, and in most cases, periodic increases in soil water content. The extent, timing and duration of these responses varied among ecosystems, species and years. Across the grasslands of the Kansas tallgrass prairie, Colorado shortgrass steppe and Swiss calcareous grassland, increases in aboveground biomass from CO2 enrichment were relatively greater in dry years. In contrast, CO2-induced aboveground biomass increases in the Texas C3/C4 grassland and the New Zealand pasture seemed little or only marginally influenced by yearly variation in soil water, while plant growth in the Mojave Desert was stimulated by CO2 in a relatively wet year. Mediterranean grasslands sometimes failed to respond to CO2-related increased late-season water, whereas semiarid Negev grassland assemblages profited. Vegetative and reproductive responses to CO2 were highly varied among species and ecosystems, and did not generally follow any predictable pattern in regard to functional groups. Results suggest that the indirect effects of CO2 on plant and soil water relations may contribute substantially to experimentally induced CO2-effects, and also reflect local humidity conditions. For landscape scale predictions, this analysis calls for a clear distinction between biomass responses due to direct CO2 effects on photosynthesis and those indirect CO2 effects via soil moisture as documented here.

  11. Atmospheric CO2 Reconstructions from Polar Ice: What Do High-Resolution CO2 Records and δ13CO2 Analyses Tell Us about Past Climate and Global Carbon Cycle Processes?

    NASA Astrophysics Data System (ADS)

    Schmitt, J.; Eggleston, S.; Marcott, S. A.; Brook, E.; Chappellaz, J. A.; Köhler, P.; Joos, F.; Fischer, H.

    2014-12-01

    Today, a monitoring network measures atmospheric CO2 at high temporal and spatial resolution. Atmospheric transport models then calculate regional CO2 source and sink fluxes. Prior to this instrumental period, archived air, firn air, and air trapped in polar ice are the only direct atmospheric archives to reconstruct past CO2 changes. Only ice from Antarctica allows reliable CO2 measurements, either from classical ice cores or outcropping ice, while Greenland records are subject to in situ production. They provide high-resolution and high-precision CO2 reconstructions up to 800,000 years back in time. Ice core records have revealed an intimate connection between CO2 variations and major changes in Earth's climate and have fundamentally shaped the community's view of the global carbon cycle. Knowing the concentration of past atmospheric CO2 and the other greenhouse gases is key to provide the radiative forcing for climate simulations. Ice core reconstructions broadly fulfilled this task. On the contrary, we are far from a coherent understanding of the mechanisms driving these changes. Analyzing phase relations between CO2, other ice-core derived species, and proxies from marine sediment cores allow for the identification of factors likely responsible for the observed CO2 changes. Specifically, the strength of the Atlantic overturning circulation and Southern Ocean upwelling are thought to be key players. However, the observed CO2 changes cannot uniquely be related to a specific process. Here, stable carbon isotope analysis on CO2 extracted from ice provides additional constraints as any process leads to isotope fractionation of the reservoir. Analytical progress during the last decade affords us with a growing data set on this long-awaited parameter. This presentation provides a state-of-the-art overview on ice-based CO2 and its carbon isotopic signature focusing both on the long-term orbital changes as well as rapid changes documented during the last deglaciation.

  12. Changes in atmospheric CO2 - Influence of the marine biota at high latitude

    NASA Technical Reports Server (NTRS)

    Knox, F.; Mcelroy, M. B.

    1984-01-01

    Approximately half of the nitrogen and phosphorus entering deep waters of the contemporary ocean are transported from the surface in inorganic form as preformed nutrients. A simple model for ocean chemistry is presented and shown to account for the present level of atmospheric CO2. Fluctuations in preformed nutrients, modulated by changes in insolation and circulation at high latitudes, can result in significant variations in CO2. It is suggested that these changes may account for the apparent control on climate exercised by secular variations in the orbital parameters of the earth.

  13. Changes in atmospheric CO2 - Influence of the marine biota at high latitude

    NASA Technical Reports Server (NTRS)

    Knox, F.; Mcelroy, M. B.

    1984-01-01

    Approximately half of the nitrogen and phosphorus entering deep waters of the contemporary ocean are transported from the surface in inorganic form as preformed nutrients. A simple model for ocean chemistry is presented and shown to account for the present level of atmospheric CO2. Fluctuations in preformed nutrients, modulated by changes in insolation and circulation at high latitudes, can result in significant variations in CO2. It is suggested that these changes may account for the apparent control on climate exercised by secular variations in the orbital parameters of the earth.

  14. Relating Nimbus-7 37 GHz data to global land-surface evaporation, primary productivity and the atmospheric CO2 concentration

    NASA Technical Reports Server (NTRS)

    Choudhury, B. J.

    1988-01-01

    Global observations at 37 GHz by the Nimbus-7 SMMR are related to zonal variations of land surface evaporation and primary productivity, as well as to temporal variations of atmospheric CO2 concentration. The temporal variation of CO2 concentration and the zonal variations of evaporation and primary productivity are shown to be highly correlated with the satellite sensor data. The potential usefulness of the 37-GHz data for global biospheric and climate studies is noted.

  15. Relating Nimbus-7 37 GHz data to global land-surface evaporation, primary productivity and the atmospheric CO2 concentration

    NASA Technical Reports Server (NTRS)

    Choudhury, B. J.

    1988-01-01

    Global observations at 37 GHz by the Nimbus-7 SMMR are related to zonal variations of land surface evaporation and primary productivity, as well as to temporal variations of atmospheric CO2 concentration. The temporal variation of CO2 concentration and the zonal variations of evaporation and primary productivity are shown to be highly correlated with the satellite sensor data. The potential usefulness of the 37-GHz data for global biospheric and climate studies is noted.

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

    NASA Astrophysics Data System (ADS)

    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

  17. Scrutinizing the carbon cycle and CO2 residence time in the atmosphere

    NASA Astrophysics Data System (ADS)

    Harde, Hermann

    2017-05-01

    Climate scientists presume that the carbon cycle has come out of balance due to the increasing anthropogenic emissions from fossil fuel combustion and land use change. This is made responsible for the rapidly increasing atmospheric CO2 concentrations over recent years, and it is estimated that the removal of the additional emissions from the atmosphere will take a few hundred thousand years. Since this goes along with an increasing greenhouse effect and a further global warming, a better understanding of the carbon cycle is of great importance for all future climate change predictions. We have critically scrutinized this cycle and present an alternative concept, for which the uptake of CO2 by natural sinks scales proportional with the CO2 concentration. In addition, we consider temperature dependent natural emission and absorption rates, by which the paleoclimatic CO2 variations and the actual CO2 growth rate can well be explained. The anthropogenic contribution to the actual CO2 concentration is found to be 4.3%, its fraction to the CO2 increase over the Industrial Era is 15% and the average residence time 4 years.

  18. Atmospheric CO2 Over the Last 1000 Years: WAIS Divide Ice Core Record

    NASA Astrophysics Data System (ADS)

    Ahn, J.; Brook, E. J.

    2009-04-01

    How atmospheric CO2 varied over the last thousands years is of great interest because we may see not only natural, but also anthropogenic variations (Ruddiman, Climatic Change, 2003). The Law Dome ice cores reveal decadal to centennial variations in CO2 over the last 2000 years (MacFarling Meure et al., Geophys. Res. Lett., 2006). However, these variations have not yet been well confirmed in other ice core records. Here we use a newly drilled WAIS Divide ice core, which is ideal for this purpose because WAIS Divide has relatively high snow accumulation rate and small gas age distribution that allow us to observe decadal CO2 variations with minimal damping. We have started an extensive study of CO2 in WAIS Divide core. So far we have obtained data for 960-1940 A.D. from the WDC05-A core drilled in 2005-2006. 344 ice samples from 103 depths were analyzed and the standard error of the mean is ~0.8 ppm on average. Ancient air in 8~12 g of bubbly ice is liberated by crushing with steel pins at -35 °C and trapped in stainless steel tubes at -262 °C. CO2 mixing ratio in the extracted air is precisely determined using a gas chromatographic method. Details of the high-precision methods are described in Ahn et al. (J. of Glaciology, in press). Our new results show preindustrial atmospheric CO2 variability of ~ 10 ppm. The most striking feature of the record is a rapid atmospheric CO2 decrease of 7~8 ppm within ~20 years at ~ 1600 A.D. Considering the larger smoothing of gas records in the WAIS Divide relative to Law Dome, our results confirm the atmospheric CO2 decrease of ~10 ppm in Law Dome records observed at this time. However, this event is not significant in the Dronning Maud Land ice core (Siegenthaler et al., Tellus, 2005), probably due to more extensive smoothing of gas records in the core. Similar rapid changes of CO2 at other times in the WAIS Divide record need to be confirmed with higher resolution studies. We also found that our WAIS Divide CO2 data are

  19. Lidar Observations of Atmospheric CO2 Column During 2014 Summer Flight Campaigns

    NASA Technical Reports Server (NTRS)

    Lin, Bing; Harrison, F. Wallace; Fan, Tai-Fang

    2015-01-01

    Advanced knowledge in atmospheric CO2 is critical in reducing large uncertainties in predictions of the Earth' future climate. Thus, Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) from space was recommended by the U.S. National Research Council to NASA. As part of the preparation for the ASCENDS mission, NASA Langley Research Center (LaRC) and Exelis, Inc. have been collaborating in development and demonstration of the Intensity-Modulated Continuous-Wave (IM-CW) lidar approach for measuring atmospheric CO2 column from space. Airborne laser absorption lidars such as the Multi-Functional Fiber Laser Lidar (MFLL) and ASCENDS CarbonHawk Experiment Simulator (ACES) operating in the 1.57 micron CO2 absorption band have been developed and tested to obtain precise atmospheric CO2 column measurements using integrated path differential absorption technique and to evaluate the potential of the space ASCENDS mission. This presentation reports the results of our lidar atmospheric CO2 column measurements from 2014 summer flight campaign. Analysis shows that for the 27 Aug OCO-2 under flight over northern California forest regions, significant variations of CO2 column approximately 2 ppm) in the lower troposphere have been observed, which may be a challenge for space measurements owing to complicated topographic condition, heterogeneity of surface reflection and difference in vegetation evapotranspiration. Compared to the observed 2011 summer CO2 drawdown (about 8 ppm) over mid-west, 2014 summer drawdown in the same region measured was much weak (approximately 3 ppm). The observed drawdown difference could be the results of the changes in both meteorological states and the phases of growing seasons. Individual lidar CO2 column measurements of 0.1-s integration were within 1-2 ppm of the CO2 estimates obtained from on-board in-situ sensors. For weak surface reflection conditions such as ocean surfaces, the 1- s integrated signal-to-noise ratio (SNR) of

  20. Mixing ratio and carbon isotopic composition investigation of atmospheric CO2 in Beijing, China

    NASA Astrophysics Data System (ADS)

    Pang, J.; Wen, X.; Sun, X.

    2016-12-01

    The stable isotope composition of atmospheric CO2 can be used as a tracer in the study of urban carbon cycles, which are affected by anthropogenic and biogenic CO2 components. Continuous measurements of the mixing ratio and δ13C of atmospheric CO2 were conducted in Beijing from Nov. 15, 2012 to Mar. 8, 2014 including two heating seasons and a vegetative season. Both δ13C and the isotopic composition of source CO2 (δ13CS) were depleted in the heating seasons and enriched in the vegetative season. The diurnal variations in the CO2 mixing ratio and δ13C contained two peaks in the heating season, which are due to the effects of morning rush hour traffic. Seasonal and diurnal patterns of the CO2 mixing ratio and δ13C were affected by anthropogenic emissions and biogenic activity. Assuming that the primary CO2 sources at night (22:00-04:00) were coal and natural gas combustion during heating seasons I and II, an isotopic mass balance analysis indicated that coal combustion had average contributions of 83.83 ± 14.11% and 86.84 ± 12.27% and that natural gas had average contributions of 16.17 ± 14.11% and 13.16 ± 12.27%, respectively. The δ13C of background CO2 in air was the main error source in the isotopic mass balance model. Both the mixing ratio and δ13C of atmospheric CO2 had significant linear relationships with the air quality index (AQI) and can be used to indicate local air pollution conditions. Energy structure optimization, for example, reducing coal consumption, will improve the local air conditions in Beijing.

  1. Decrease in CO2 efflux from northern hardwater lakes with increasing atmospheric warming.

    PubMed

    Finlay, Kerri; Vogt, Richard J; Bogard, Matthew J; Wissel, Björn; Tutolo, Benjamin M; Simpson, Gavin L; Leavitt, Peter R

    2015-03-12

    Boreal lakes are biogeochemical hotspots that alter carbon fluxes by sequestering particulate organic carbon in sediments and by oxidizing terrestrial dissolved organic matter to carbon dioxide (CO2) or methane through microbial processes. At present, such dilute lakes release ∼1.4 petagrams of carbon annually to the atmosphere, and this carbon efflux may increase in the future in response to elevated temperatures and increased hydrological delivery of mineralizable dissolved organic matter to lakes. Much less is known about the potential effects of climate changes on carbon fluxes from carbonate-rich hardwater and saline lakes that account for about 20 per cent of inland water surface area. Here we show that atmospheric warming may reduce CO2 emissions from hardwater lakes. We analyse decadal records of meteorological variability, CO2 fluxes and water chemistry to investigate the processes affecting variations in pH and carbon exchange in hydrologically diverse lakes of central North America. We find that the lakes have shifted progressively from being substantial CO2 sources in the mid-1990s to sequestering CO2 by 2010, with a steady increase in annual mean pH. We attribute the observed changes in pH and CO2 uptake to an atmospheric-warming-induced decline in ice cover in spring that decreases CO2 accumulation under ice, increases spring and summer pH, and enhances the chemical uptake of CO2 in hardwater lakes. Our study suggests that rising temperatures do not invariably increase CO2 emissions from aquatic ecosystems.

  2. Mixing ratio and carbon isotopic composition investigation of atmospheric CO2 in Beijing, China.

    PubMed

    Pang, Jiaping; Wen, Xuefa; Sun, Xiaomin

    2016-01-01

    The stable isotope composition of atmospheric CO2 can be used as a tracer in the study of urban carbon cycles, which are affected by anthropogenic and biogenic CO2 components. Continuous measurements of the mixing ratio and δ(13)C of atmospheric CO2 were conducted in Beijing from Nov. 15, 2012 to Mar. 8, 2014 including two heating seasons and a vegetative season. Both δ(13)C and the isotopic composition of source CO2 (δ(13)CS) were depleted in the heating seasons and enriched in the vegetative season. The diurnal variations in the CO2 mixing ratio and δ(13)C contained two peaks in the heating season, which are due to the effects of morning rush hour traffic. Seasonal and diurnal patterns of the CO2 mixing ratio and δ(13)C were affected by anthropogenic emissions and biogenic activity. Assuming that the primary CO2 sources at night (22:00-04:00) were coal and natural gas combustion during heating seasons I and II, an isotopic mass balance analysis indicated that coal combustion had average contributions of 83.83±14.11% and 86.84±12.27% and that natural gas had average contributions of 16.17±14.11% and 13.16±12.27%, respectively. The δ(13)C of background CO2 in air was the main error source in the isotopic mass balance model. Both the mixing ratio and δ(13)C of atmospheric CO2 had significant linear relationships with the air quality index (AQI) and can be used to indicate local air pollution conditions. Energy structure optimization, for example, reducing coal consumption, will improve the local air conditions in Beijing. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. Implications of high amplitude atmospheric CO2 fluctuations on past millennium climate change

    NASA Astrophysics Data System (ADS)

    van Hoof, Thomas; Kouwenberg, Lenny; Wagner-Cremer, Friederike; Visscher, Henk

    2010-05-01

    Stomatal frequency analysis of leaves of land plants preserved in peat and lake deposits can provide a proxy record of pre-industrial atmospheric CO2 concentration complementary to measurements in Antarctic ice cores. Stomatal frequency based CO2 trends from the USA and NW European support the presence of significant CO2 variability during the first half of the last millennium (Kouwenberg et al., 2005; Wagner et al., 2004; van Hoof et al., 2008). The timing of the most significant perturbation in the stomata records (1200 AD) is in agreement with an observed CO2 fluctuation in the D47 Antarctic ice-core record (Barnola et al., 1995; van Hoof et al., 2005). The amplitude of the stomatal frequency based CO2 changes (> 34ppmv) exceeds the maximum amplitude of CO2 variability in the D47 ice core (< 10 ppmv). A modelling experiment taking into account firn-densification based smoothing processes in the D47 ice core proved, however, that the amplitude difference between the stomata record and the D47 ice-core can be explained by natural smoothing processes in the ice (van Hoof et al., 2005). This observation gives credence to the existence of high-amplitude CO2 fluctuations during the last millennium and suggests that high resolution ice core CO2 records should be regarded as a smoothed representation of the atmospheric CO2 signal. In the present study, potential marine and terrestrial sources and sinks associated with the observed atmospheric CO2 perturbation will be discussed. The magnitude of the observed CO2 variability implies that inferred changes in CO2 radiative forcing are of a similar magnitude as variations ascribed to other forcing mechanisms (e.g. solar forcing and volcanism), therefore challenging the IPCC concept of CO2 as an insignificant preindustrial climate forcing factor. References Barnola J.M., M. Anklin, J. Porcheron, D. Raynaud, J. Schwander and B. Stauffer 1995. CO2 evolution during the last millennium as recorded by Antarctic and Greenland ice

  4. Observations of Atmospheric Δ(14)CO2 at the Global and Regional Background Sites in China: Implication for Fossil Fuel CO2 Inputs.

    PubMed

    Niu, Zhenchuan; Zhou, Weijian; Cheng, Peng; Wu, Shugang; Lu, Xuefeng; Xiong, Xiaohu; Du, Hua; Fu, Yunchong

    2016-11-15

    Six months to more than one year of atmospheric Δ(14)CO2 were measured in 2014-2015 at one global background site in Waliguan (WLG) and four regional background sites at Shangdianzi (SDZ), Lin'an (LAN), Longfengshan (LFS) and Luhuitou (LHT), China. The objectives of the study are to document the Δ(14)CO2 levels at each site and to trace the variations in fossil fuel CO2 (CO2ff) inputs at regional background sites. Δ(14)CO2 at WLG varied from 7.1 ± 2.9‰ to 32.0 ± 3.2‰ (average 17.1 ± 6.8‰) in 2015, with high values generally in autumn/summer and low values in winter/spring. During the same period, Δ(14)CO2 values at the regional background sites were found to be significantly (p < 0.05) lower than those at WLG, indicating different levels of CO2ff inputs at those sites. CO2ff concentrations at LAN (12.7 ± 9.6 ppm) and SDZ (11.5 ± 8.2 ppm) were significantly (p < 0.05) higher than those at LHT (4.6 ± 4.3 ppm) in 2015. There were no significant (p > 0.05) seasonal differences in CO2ff concentrations for the regional sites. Regional sources contributed in part to the CO2ff inputs at LAN and SDZ, while local sources dominated the trend observed at LHT. These data provide a preliminary understanding of atmospheric Δ(14)CO2 and CO2ff inputs for a range of Chinese background sites.

  5. Sensitivity of the marine carbonate cycle to atmospheric CO2

    NASA Astrophysics Data System (ADS)

    Gangstø, R.; Joos, F.; Gehlen, M.

    2010-09-01

    Ocean acidification might reduce the ability of calcifying plankton to produce and maintain their shells of calcite, or of aragonite, the more soluble form of CaCO3. In addition to possibly large biological impacts, reduced CaCO3 production corresponds to a negative feedback on atmospheric CO2. In order to explore the sensitivity of the ocean carbon cycle to increasing concentrations of atmospheric CO2, we use the new biogeochemical Bern3D/PISCES model. The model reproduces the large scale distributions of biogeochemical tracers. With a range of sensitivity studies, we explore the effect of (i) using different parameterizations of CaCO3 production fitted to available laboratory and field experiments, of (ii) letting calcite and aragonite be produced by auto- and heterotrophic plankton groups, and of (iii) using carbon emissions from the range of the most recent IPCC Representative Concentration Pathways (RCP). Under a high-emission scenario, the CaCO3 production of all the model versions decreases from ~1 Pg C yr-1 to between 0.36 and 0.82 Pg C yr-1 by the year 2100. By the year 2500, the ratio of open water CaCO3 dissolution to production stabilizes at a value that is 30-50% higher than at pre-industrial times when carbon emissions are set to zero after 2100. Despite the wide range of parameterizations, model versions and scenarios included in our study, the changes in CaCO3 production and dissolution resulting from ocean acidification provide only a small feedback on atmospheric CO2 of 1-11 ppm by the year 2100.

  6. Assessing factors underlying variation of CO2 emissions in boreal lakes vs. reservoirs.

    PubMed

    Tadonléké, Rémy D; Marty, Jérôme; Planas, Dolors

    2012-02-01

    Reservoirs and lakes were compared to test the hypothesis that they are similar with respect to factors driving the variation in CO(2) emissions to the atmosphere. Understanding this variation is necessary for the assessment of the contribution of these freshwater ecosystems to the global carbon cycle. This study, in contrast to previous ones, included analyses of the relationships between CO(2) emissions and microbial communities. Pooled data (lakes and reservoirs) showed that variations in CO(2) emissions were strongly related to variations in temperature, dissolved organic matter (DOM) quality, and bacterial production (BP). Results also showed that lakes were characterized by higher water temperature, lower DOM quality, larger size of Daphnia, and enriched δ(13) C zooplankton compared to reservoirs. Moreover, interactions within plankton communities and relationships between CO(2) emissions and zooplankton δ(13) C signatures differed in lakes vs. reservoirs, indicating among-system type differences in food web structure and carbon cycling. As a result of these ecosystem-type characteristics, CO(2) emission variation was mainly explained by temperature and BP in lakes, and by DOM quality and the ratio of phytoplankton biomass to microheterotroph biomass in reservoirs. These results showed that differences in temperature and DOM quality between lakes and reservoirs translate into differences in microbial interactions and ultimately in the importance of factors driving CO(2) emissions to the atmosphere. They indicated that considering microbial communities and environmental variables such as temperature and DOM quality can help improve our understanding of the variation in CO(2) emissions from freshwater ecosystems. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

  7. [Open-path online monitoring of ambient atmospheric CO2 based on laser absorption spectrum].

    PubMed

    He, Ying; Zhang, Yu-Jun; Kan, Rui-Feng; Xia, Hui; Geng, Hui; Ruan, Jun; Wang, Min; Cui, Xiao-Juan; Liu, Wen-Qing

    2009-01-01

    With the conjunction of tunable diode laser absorption spectroscopy technology (TDLAS) and the open long optical path technology, the system designing scheme of CO2 on-line monitoring based on near infrared tunable diode laser absorption spectroscopy technology was discussed in detail, and the instrument for large-range measurement was set up. By choosing the infrared absorption line of CO2 at 1.57 microm whose line strength is strong and suitable for measurement, the ambient atmospheric CO2 was measured continuously with a 30 s temporal resolution at an suburb site in the autumn of 2007. The diurnal atmospheric variations of CO2 and continuous monitoring results were presented. The results show that the variation in CO2 concentration has an obvious diurnal periodicity in suburb where the air is free of interference and contamination. The general characteristic of diurnal variation is that the concentration is low in the daytime and high at night, so it matches the photosynthesis trend. The instrument can detect gas concentration online with high resolution, high sensitivity, high precision, short response time and many other advantages, the monitoring requires no gas sampling, the calibration is easy, and the detection limit is about 4.2 x 10(-7). It has been proved that the system and measurement project are feasible, so it is an effective method for gas flux continuous online monitoring of large range in ecosystem based on TDLAS technology.

  8. Deep Sea Memory of High Atmospheric CO2 Concentration

    NASA Astrophysics Data System (ADS)

    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

  9. An Assessment of Biases in Satellite CO2 Measurements Using Atmospheric Inversion

    NASA Astrophysics Data System (ADS)

    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

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

    NASA Astrophysics Data System (ADS)

    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

  11. Atmospheric observations inform CO2 flux responses to enviroclimatic drivers

    NASA Astrophysics Data System (ADS)

    Fang, Yuanyuan; Michalak, Anna M.

    2015-05-01

    Understanding the response of the terrestrial biospheric carbon cycle to variability in enviroclimatic drivers is critical for predicting climate-carbon interactions. Here we apply an atmospheric-inversion-based framework to assess the relationships between the spatiotemporal patterns of net ecosystem CO2 exchange (NEE) and those of enviroclimatic drivers. We show that those relationships can be directly observed at 1° × 1° 3-hourly resolution from atmospheric CO2 measurements for four of seven large biomes in North America, namely, (i) boreal forests and taiga; (ii) temperate coniferous forests; (iii) temperate grasslands, savannas, and shrublands; and (iv) temperate broadleaf and mixed forests. We find that shortwave radiation plays a dominant role during the growing season over all four biomes. Specific humidity and precipitation also play key roles and are associated with decreased CO2 uptake (or increased release). The explanatory power of specific humidity is especially strong during transition seasons, while that of precipitation appears during both the growing and dormant seasons. We further find that the ability of four prototypical terrestrial biospheric models (TBMs) to represent the spatiotemporal variability of NEE improves as the influence of radiation becomes more dominant, implying that TBMs have a better skill in representing the impact of radiation relative to other drivers. Even so, we show that TBMs underestimate the strength of the relationship to radiation and do not fully capture its seasonality. Furthermore, the TBMs appear to misrepresent the relationship to precipitation and specific humidity at the examined scales, with relationships that are not consistent in terms of sign, seasonality, or significance relative to observations. More broadly, we demonstrate the feasibility of directly probing relationships between NEE and enviroclimatic drivers at scales with no direct measurements of NEE, opening the door to the study of emergent

  12. Recent Widespread Tree Growth Decline Despite Increasing Atmospheric CO2

    PubMed Central

    Silva, Lucas C. R.; Anand, Madhur; Leithead, Mark D.

    2010-01-01

    Background The synergetic effects of recent rising atmospheric CO2 and temperature are expected to favor tree growth in boreal and temperate forests. However, recent dendrochronological studies have shown site-specific unprecedented growth enhancements or declines. The question of whether either of these trends is caused by changes in the atmosphere remains unanswered because dendrochronology alone has not been able to clarify the physiological basis of such trends. Methodology/Principal Findings Here we combined standard dendrochronological methods with carbon isotopic analysis to investigate whether atmospheric changes enhanced water use efficiency (WUE) and growth of two deciduous and two coniferous tree species along a 9° latitudinal gradient across temperate and boreal forests in Ontario, Canada. Our results show that although trees have had around 53% increases in WUE over the past century, growth decline (measured as a decrease in basal area increment – BAI) has been the prevalent response in recent decades irrespective of species identity and latitude. Since the 1950s, tree BAI was predominantly negatively correlated with warmer climates and/or positively correlated with precipitation, suggesting warming induced water stress. However, where growth declines were not explained by climate, WUE and BAI were linearly and positively correlated, showing that declines are not always attributable to warming induced stress and additional stressors may exist. Conclusions Our results show an unexpected widespread tree growth decline in temperate and boreal forests due to warming induced stress but are also suggestive of additional stressors. Rising atmospheric CO2 levels during the past century resulted in consistent increases in water use efficiency, but this did not prevent growth decline. These findings challenge current predictions of increasing terrestrial carbon stocks under climate change scenarios. PMID:20657763

  13. Recent widespread tree growth decline despite increasing atmospheric CO2.

    PubMed

    Silva, Lucas C R; Anand, Madhur; Leithead, Mark D

    2010-07-21

    The synergetic effects of recent rising atmospheric CO(2) and temperature are expected to favor tree growth in boreal and temperate forests. However, recent dendrochronological studies have shown site-specific unprecedented growth enhancements or declines. The question of whether either of these trends is caused by changes in the atmosphere remains unanswered because dendrochronology alone has not been able to clarify the physiological basis of such trends. Here we combined standard dendrochronological methods with carbon isotopic analysis to investigate whether atmospheric changes enhanced water use efficiency (WUE) and growth of two deciduous and two coniferous tree species along a 9 degrees latitudinal gradient across temperate and boreal forests in Ontario, Canada. Our results show that although trees have had around 53% increases in WUE over the past century, growth decline (measured as a decrease in basal area increment--BAI) has been the prevalent response in recent decades irrespective of species identity and latitude. Since the 1950s, tree BAI was predominantly negatively correlated with warmer climates and/or positively correlated with precipitation, suggesting warming induced water stress. However, where growth declines were not explained by climate, WUE and BAI were linearly and positively correlated, showing that declines are not always attributable to warming induced stress and additional stressors may exist. Our results show an unexpected widespread tree growth decline in temperate and boreal forests due to warming induced stress but are also suggestive of additional stressors. Rising atmospheric CO2 levels during the past century resulted in consistent increases in water use efficiency, but this did not prevent growth decline. These findings challenge current predictions of increasing terrestrial carbon stocks under climate change scenarios.

  14. Interannual variability in the atmospheric CO2 rectification over a boreal forest region

    NASA Astrophysics Data System (ADS)

    Chen, Baozhang; Chen, Jing M.; Worthy, Douglas E. J.

    2005-08-01

    Ecosystem CO2 exchange with the atmosphere and the planetary boundary layer (PBL) dynamics are correlated diurnally and seasonally. The strength of this kind of covariation is quantified as the rectifier effect, and it affects the vertical gradient of CO2 and thus the global CO2 distribution pattern. An 11-year (1990-1996, 1999-2002), continuous CO2 record from Fraserdale, Ontario (49°52'29.9″N, 81°34'12.3″W), along with a coupled vertical diffusion scheme (VDS) and ecosystem model named Boreal Ecosystem Productivity Simulator (BEPS), are used to investigate the interannual variability of the rectifier effect over a boreal forest region. The coupled model performed well (r2 = 0.70 and 0.87, at 40 m at hourly and daily time steps, respectively) in simulating CO2 vertical diffusion processes. The simulated annual atmospheric rectifier effect varies from 3.99 to 5.52 ppm, while the diurnal rectifying effect accounted for about a quarter of the annual total (22.8˜28.9%).The atmospheric rectification of CO2 is not simply influenced by terrestrial source and sink strengths, but by seasonal and diurnal variations in the land CO2 flux and their interaction with PBL dynamics. Air temperature and moisture are found to be the dominant climatic factors controlling the rectifier effect. The annual rectifier effect is highly correlated with annual mean temperature (r2 = 0.84), while annual mean air relative humidity can explain 51% of the interannual variation in rectification. Seasonal rectifier effect is also found to be more sensitive to climate variability than diurnal rectifier effect.

  15. Precise measurements of the total concentration of atmospheric CO2 and 13CO2/12CO2 isotopic ratio using a lead-salt laser diode spectrometer.

    PubMed

    Croizé, Laurence; Mondelain, Didier; Camy-Peyret, Claude; Delmotte, Marc; Schmidt, Martina

    2008-04-01

    We have developed a tunable diode laser spectrometer, called SIMCO (spectrometer for isotopic measurements of CO(2)), for determining the concentrations of (12)CO(2) and (13)CO(2) in atmospheric air, from which the total concentration of CO(2) and the isotopic composition (expressed in delta units) delta(13)CO(2) are calculated. The two concentrations are measured using a pair of lines around 2290.1 cm(-1), by fitting a line profile model, taking into account the confinement narrowing effect to achieve a better accuracy. Using the Allan variance, we have demonstrated (for an integration time of 25 s) a precision of 0.1 ppmv for the total CO(2) concentration and of 0.3[per thousand] for delta(13)CO(2). The performances on atmospheric air have been tested during a 3 days campaign by comparing the SIMCO instrument with a gas chromatograph (GC) for the measurement of the total CO(2) concentration and with an isotopic ratio mass spectrometer (MS) for the isotopic composition. The CO(2) concentration measurements of SIMCO are in very good agreement with the GC data with a mean difference of Delta(CO(2))=0.16+/-1.20 ppmv for a comparison period of 45 h and the linearity of the concentration between the two instruments is also very good (slope of correlation: 0.9996+/-0.0003) over the range between 380 and 415 ppmv. For delta(13)CO(2), the comparison with the MS data shows a larger mean difference of Delta(delta(13)CO(2))=(-1.9+/-1.2)[per thousand], which could be partly related to small residual fluctuations of the overall SIMCO instrument response.

  16. Response of plants' water use efficiency to increasing atmospheric CO2 concentration.

    PubMed

    Wang, Guoan; Feng, Xiahong

    2012-08-21

    This study assesses plants' adaptation to the elevated atmospheric CO(2) concentrations (c(a)) using 83 tree-ring δ(13)C series from the mid- to high-latitudes of the northern hemisphere. We found that the variation of Δ with the atmospheric CO(2) concentration is nonlinear and that the range of Δ change is relatively small. After 1950, the mean increase in Δ is 0.43‰, corresponding to the average coefficient of Δ-c(a) relationship to be about 0.006‰/ ppmv CO(2). In contrast to the changes in Δ, intercellular CO(2) concentration (c(i)) and intrinsic water-use efficiency (W(i)) both increase linearly with c(a). For the past two and a half centuries, changes in the intercellular CO(2) concentration (c(i)) and intrinsic water-use efficiency (W(i)) are, on average, both about 30%, while the mean change of the c(i)/c(a) ratio is 3%. Most changes have occurred after 1950. W(i) responds to c(a) linearly with sensitivities ranging from 0.06 to 0.6 μmol CO(2)/mmol H(2)O ppmv(-1), and an average 0.33 μmol CO(2)/mmol H(2)O ppmv(-1) during the past 50 years. Statistical analysis shows that the increase in c(a) accounts for 98% of the W(i) variation. The remaining small variance is explained by altitude and temperature. Trees at higher elevations show slightly higher increase in W(i), and they are also more sensitive to the CO(2) increase than trees at lower altitudes. Trees growing at low temperature environments are slightly more sensitive to CO(2) increase than those at higher temperature sites. No significant relationship between precipitation and plants' W(i) response to the atmospheric CO(2) increase is found with these data. Although the temperature and altitude both impact the W(i) response to elevated CO(2), the size of the impact is physically small and can be omitted from ecological models.

  17. Seasonal, diel, and tidal CO2 variation in the Bay of Fundy

    NASA Astrophysics Data System (ADS)

    Horwitz, Rachel; Burt, William J.; Hay, Alex; Thomas, Helmuth

    2017-04-01

    Anthropogenic CO2 emissions acidify the oceans and have potentially adverse effects for ecosystems, living marine resources, and the fisheries and mariculture industries that depend on them. Assessing the vulnerability of these resources to ocean acidification requires a detailed understanding of both the system's natural variability and its response to the ocean's uptake of anthropogenic CO2. A cabled-to-shore observatory was installed in Grand Passage, a tidal channel in the Bay of Fundy, Nova Scotia. Measurements from a CO2 sensor, CTD, and ADCP provide year-long time series of pCO2, temperature, salinity, and currents. The dominant seasonal cycle of pCO2 indicates a spring bloom in April and May, and net respiration from November through March. This seasonal cycle is modulated by a large diel cycle in summertime, and by equal contributions from diel and tidal variation in winter. The oceanic CO2 partial pressure (pCO2) is higher than the atmospheric pCO2 for most of the year, indicating an annual average balance between respiration and outgassing at this site. Further analysis aims to link observations in this tidal channel to the larger Bay of Fundy - Gulf of Maine carbon system.

  18. Multiple Proxy Estimates of Atmospheric CO2 from an Early Paleocene Rainforest

    NASA Astrophysics Data System (ADS)

    Kowalczyk, J.; Royer, D. L.; Miller, I.; Franks, P.

    2016-12-01

    As atmospheric CO2 continues to increase, we enter a climate state whose analogue in terms of CO2 concentration is found millions of years ago. Knowledge of this ancient climate is only accessible via proxy reconstructions. However, many proxy methods suffer from large uncertainties and/or systematic biases. This is illustrated in a compilation of atmospheric CO2 estimates over the Cenozoic from different proxy methods that shows two-fold scatter for many time-slices (Beerling and Royer, 2011, Nature Geoscience 4: 418 - 420). It is unclear how much of this scatter is due to true CO2 variation and how much is due to proxy model biases. Therefore, to increase understanding of and confidence in proxy methods, multi-proxy comparison studies are greatly needed. Here we present results from one such comparison study, the first of its kind for land-based proxies. Using plant fossils from the unusually diverse early Paleocene (64.5 Ma) Castle Rock rainforest, we generate CO2 estimates from four proxy methods: the traditional stomatal index, two newer models based on gas-exchange in C3 plants, and a model based on liverwort photosynthesis. Median estimates range from 470 to 832 ppm, indicating that much of the scatter in the Beerling and Royer (2011) compilation could be due to proxy model biases. We also present sensitivity analyses for the multi-parameter proxy methods, providing a helpful guide to model users by highlighting parameters that contribute most to uncertainty in estimated CO2.

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

    NASA Astrophysics Data System (ADS)

    Yakir, Dan

    2011-07-01

    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‰ trend between 1880 and 2000, compared with - 1.45 and - 1.57‰ 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.

  20. Evaluation of the sinks and sources of atmospheric CO2 by artificial upwelling.

    PubMed

    Pan, Yiwen; Fan, Wei; Huang, Ting-Hsuan; Wang, Shu-Lun; Chen, Chen-Tung Arthur

    2015-04-01

    Artificial upwelling is considered a promising way to reduce the accumulation of anthropogenic carbon dioxide in the atmosphere. This practice could transport nutrient-rich deep water to the euphotic zone, enhance phytoplankton growth and consequently increase organic carbon exportation to the deep ocean via the biological pump. However, only a few studies quantitatively assess changes in oceanic CO2 uptake resulting from artificial upwelling. This article uses a simulation to examine the effect of hypothetical artificial upwelling-induced variations of CO2 fugacity in seawater (fCO2) using observed carbon and nutrient data from 14 stations, ranging from 21 to 43°N, in the West Philippine Sea (WPS), the East China Sea (ECS) and the Sea of Japan. Calculations are based on two basic assumptions: First, a near-field mixing of a nutrient-rich deep-ocean water plume in a stratified ocean environment is assumed to form given the presence of an artificial upwelling devise with appropriate technical parameters. Second, it is assumed that photosynthesis of marine phytoplankton could deplete all available nutrients following the stoichiometry of the modified Redfield ratio C/H/O/N/S/P=103.1/181.7/93.4/11.7/2.1/1. Results suggest artificial upwelling has significant effects on regional changes in sea-air differences (ΔfCO2sea-air) and the carbon sequestration potential (ΔfCO2mixed-amb). Large variations of ΔfCO2sea-air and ΔfCO2mixed-amb are shown to be associated with different regions, seasons and technical parameters of the artificial upwelling device. With proper design, it is possible to reverse the contribution of artificial upwelling from a strong CO2 source to sink. Thus, artificial upwelling has the potential to succeed as a geoengineering technique to sequester anthropogenic CO2, with appropriate technical parameters in the right region and season.

  1. Modeling global atmospheric CO2 with improved emission inventories and CO2 production from the oxidation of other carbon species

    NASA Astrophysics Data System (ADS)

    Nassar, R.; Jones, D. B. A.; Suntharalingam, P.; Chen, J. M.; Andres, R. J.; Wecht, K. J.; Yantosca, R. M.; Kulawik, S. S.; Bowman, K. W.; Worden, J. R.; Machida, T.; Matsueda, H.

    2010-12-01

    The use of global three-dimensional (3-D) models with satellite observations of CO2 in inverse modeling studies is an area of growing importance for understanding Earth's carbon cycle. Here we use the GEOS-Chem model (version 8-02-01) CO2 mode with multiple modifications in order to assess their impact on CO2 forward simulations. Modifications include CO2 surface emissions from shipping (~0.19 Pg C yr-1), 3-D spatially-distributed emissions from aviation (~0.16 Pg C yr-1), and 3-D chemical production of CO2 (~1.05 Pg C yr-1). Although CO2 chemical production from the oxidation of CO, CH4 and other carbon gases is recognized as an important contribution to global CO2, it is typically accounted for by conversion from its precursors at the surface rather than in the free troposphere. We base our model 3-D spatial distribution of CO2 chemical production on monthly-averaged loss rates of CO (a key precursor and intermediate in the oxidation of organic carbon) and apply an associated surface correction for inventories that have counted emissions of CO2 precursors as CO2. We also explore the benefit of assimilating satellite observations of CO into GEOS-Chem to obtain an observation-based estimate of the CO2 chemical source. The CO assimilation corrects for an underestimate of atmospheric CO abundances in the model, resulting in increases of as much as 24% in the chemical source during May-June 2006, and increasing the global annual estimate of CO2 chemical production from 1.05 to 1.18 Pg C. Comparisons of model CO2 with measurements are carried out in order to investigate the spatial and temporal distributions that result when these new sources are added. Inclusion of CO2 emissions from shipping and aviation are shown to increase the global CO2 latitudinal gradient by just over 0.10 ppm (~3%), while the inclusion of CO2 chemical production (and the surface correction) is shown to decrease the latitudinal gradient by about 0.40 ppm (~10%) with a complex spatial structure

  2. Modeling global atmospheric CO2 with improved emission inventories and CO2 production from the oxidation of other carbon species

    SciTech Connect

    Nassar, Ray; Jones, DBA; Suntharalingam, P; Chen, j.; Andres, Robert Joseph; Wecht, K. J.; Yantosca, R. M.; Kulawik, SS; Bowman, K; Worden, JR; Machida, T; Matsueda, H

    2010-01-01

    The use of global three-dimensional (3-D) models with satellite observations of CO2 in inverse modeling studies is an area of growing importance for understanding Earth s carbon cycle. Here we use the GEOS-Chem model (version 8-02-01) CO2 mode with multiple modifications in order to assess their impact on CO2 forward simulations. Modifications include CO2 surface emissions from shipping (0.19 PgC yr 1), 3-D spatially-distributed emissions from aviation (0.16 PgC yr 1), and 3-D chemical production of CO2 (1.05 PgC yr 1). Although CO2 chemical production from the oxidation of CO, CH4 and other carbon gases is recognized as an important contribution to global CO2, it is typically accounted for by conversion from its precursors at the surface rather than in the free troposphere. We base our model 3-D spatial distribution of CO2 chemical production on monthly-averaged loss rates of CO (a key precursor and intermediate in the oxidation of organic carbon) and apply an associated surface correction for inventories that have counted emissions of CO2 precursors as CO2. We also explore the benefit of assimilating satellite observations of CO into GEOS-Chem to obtain an observation-based estimate of the CO2 chemical source. The CO assimilation corrects for an underestimate of atmospheric CO abundances in the model, resulting in increases of as much as 24% in the chemical source during May June 2006, and increasing the global annual estimate of CO2 chemical production from 1.05 to 1.18 Pg C. Comparisons of model CO2 with measurements are carried out in order to investigate the spatial and temporal distributions that result when these new sources are added. Inclusion of CO2 emissions from shipping and aviation are shown to increase the global CO2 latitudinal gradient by just over 0.10 ppm (3%), while the inclusion of CO2 chemical production (and the surface correction) is shown to decrease the latitudinal gradient by about 0.40 ppm (10%) with a complex spatial structure

  3. Role of Southern Ocean stratification in glacial atmospheric CO2 reduction

    NASA Astrophysics Data System (ADS)

    Kobayashi, H.; Oka, A.

    2014-12-01

    Paleoclimate proxy data at the glacial period shows high salinity of more than 37.0 psu in the deep South Atlantic. At the same time, data also indicate that the residence time of the water mass was more than 3000 years. These data implies that the stratification by salinity was stronger in the deep Southern Ocean (SO) in the Last Glacial Maximum (LGM). Previous studies using Ocean General Circulation Model (OGCM) fail to explain the low glacial atmospheric carbon dioxide (CO2) concentration at LGM. The reproducibility of salinity and water mass age is considered insufficient in these OGCMs, which may in turn affect the reproducibility of the atmospheric CO2concentration. In coarse-resolution OGCMs, The deep water is formed by unrealistic open-ocean deep convection in the SO. Considering these facts, we guessed previous studies using OGCM underestimated the salinity and water mass age at LGM. This study investigate the role of the enhanced stratification in the glacial SO on the variation of atmospheric CO2 concentration by using OGCM. In order to reproduce the recorded salinity of the deep water, relaxation of salinity toward value of recorded data is introduced in our OGCM simulations. It was found that deep water formation in East Antarctica is required for explaining the high salinity in the South Atlantic. In contrast, it is difficult to explain the glacial water mass age, even if we assume the situation vertical mixing is very weak in the SO. Contrary to previous estimate, the high salinity of the deep SO resulted in increase of Antarctic Bottom water (AABW) flow and decrease the residence time of carbon in the deep ocean, which increased atmospheric CO2 concentration. On the other hand, the weakening of the vertical mixing in the SO contributed to increase the vertical gradient of dissolved inorganic carbon (DIC), which decreased atmospheric CO2 concentration. Adding the contribution of the enhanced stratification in the glacial SO, we obtained larger

  4. Isotopic disequilibrium during uptake of atmospheric CO2 into mine process waters: implications for CO2 sequestration.

    PubMed

    Wilson, Siobhan A; Barker, Shaun L L; Dipple, Gregory M; Atudorei, Viorel

    2010-12-15

    Dypingite, a hydrated Mg-carbonate mineral, was precipitated from high-pH, high salinity solutions to investigate controls on carbon fixation and to identify the isotopic characteristics of mineral sequestration in mine tailings. δ(13)C values of dissolved inorganic carbon content and synthetic dypingite are significantly more negative than those predicted for equilibrium exchange of CO(2) gas between the atmosphere and solution. The measured δ(13)C of aqueous carbonate species is consistent with a kinetic fractionation that results from a slow diffusion of atmospheric CO(2) into solution. During dypingite precipitation, dissolved inorganic carbon concentrations decrease and δ(13)C values become more negative, indicating that the rate of CO(2) uptake into solution was outpaced by the rate of carbon fixation within the precipitate. This implies that CO(2) gas uptake is rate-limiting to CO(2) fixation. δ(13)C of carbonate mineral precipitates in mine tailings and of DIC in mine process waters display similar (13)C-depletions that are inconsistent with equilibrium fractionation. Thus, the rate of carbon fixation in mine tailings may also be limited by supply of CO(2). Carbon sequestration could be accelerated by increasing the partial pressure of CO(2) in tailings ponds or by using chemicals that enhance the uptake of gaseous CO(2) into aqueous solution.

  5. Modeling global atmospheric CO2 with improved emission inventories and CO2 production from the oxidation of other carbon species

    NASA Astrophysics Data System (ADS)

    Nassar, R.; Jones, D. B. A.; Suntharalingam, P.; Chen, J. M.; Andres, R. J.; Wecht, K. J.; Yantosca, R. M.; Kulawik, S. S.; Bowman, K. W.; Worden, J. R.; Machida, T.; Matsueda, H.

    2010-07-01

    The use of global three-dimensional (3-D) models with satellite observations of CO2 in inverse modeling studies is an area of growing importance for understanding Earth's carbon cycle. Here we use the GEOS-Chem model (version 8-02-01) CO2 simulation with multiple modifications in order to assess their impact on CO2 forward simulations. Modifications include CO2 surface emissions from shipping (~0.19 Pg C/yr), 3-D spatially-distributed emissions from aviation (~0.16 Pg C/yr), and 3-D chemical production of CO2 (~1.05 Pg C/yr). Although CO2 chemical production from the oxidation of CO, CH4 and other carbon gases is recognized as an important contribution to global CO2, it is typically accounted for by conversion from its precursors at the surface rather than in the free troposphere. We base our model 3-D spatial distribution of CO2 chemical production on monthly-averaged loss rates of CO (a key precursor and intermediate in the oxidation of organic carbon) and apply an associated surface correction for inventories that have counted emissions of carbon precursor as CO2. We also explore the benefit of assimilating satellite observations of CO into GEOS-Chem to obtain an observation-based estimate of the CO2 chemical source. The CO assimilation corrects for an underestimate of atmospheric CO abundances in the model, resulting in increases of as much as 24% in the chemical source during May-June 2006, and increasing the global annual estimate of CO2 chemical production from 1.05 to 1.18 Pg C. Comparisons of model CO2 with measurements are carried out in order to investigate the spatial and temporal distributions that result when these new sources are added. Inclusion of CO2 emissions from shipping and aviation are shown to increase the global CO2 latitudinal gradient by just over 0.10 ppm (~3%), while the inclusion of CO2 chemical production (and the surface correction) is shown to decrease the latitudinal gradient by about 0.40 ppm (~10%) with a complex spatial

  6. Sustained effects of atmospheric [CO2] and nitrogen availability on forest soil CO2 efflux

    Treesearch

    A. Christopher Oishi; Sari Palmroth; Kurt H. Johnsen; Heather R. McCarthy; Ram. Oren

    2014-01-01

    Soil CO2 efflux (Fsoil) is the largest source of carbon from forests and reflects primary productivity as well as how carbon is allocated within forest ecosystems. Through early stages of stand development, both elevated [CO2] and availability of soil nitrogen (N; sum of mineralization, deposition, and fixation) have been shown to increase gross primary productivity,...

  7. The Potential Impacts of Nutrient and CO2 Variations on Ecosystem Oxidative Ratio

    NASA Astrophysics Data System (ADS)

    Gallagher, M. E.; Hockaday, W. C.; Masiello, C. A.; Snapp, S.; Polley, W.; McSwiney, C. P.; Baldock, J.

    2009-12-01

    A fraction of fossil fuel carbon dioxide (CO2) emissions are being taken up by the terrestrial biosphere and the oceans. One particularly effective way of determining the sizes of these terrestrial biosphere and ocean carbon sinks is based on the measurements of changes in atmospheric oxygen (O2) and CO2 concentrations (Keeling et al. 1996). This method of carbon apportionment requires knowledge of total fossil fuel CO2 emissions, atmospheric O2 and CO2 concentrations, and the value of the terrestrial biosphere oxidative ratio (OR), which has historically been assumed to be constant at 1.10 (e.g. Prentice et al. 2001). OR is the ratio of moles of O2 per mole of CO2 in gas exchanges between the terrestrial biosphere and the atmosphere. An incorrect estimation of the biosphere’s OR results in misapportionment of CO2 between the terrestrial biosphere and ocean carbon sinks (Randerson et al. 2006). Understanding how OR can vary with changing environmental properties is therefore essential to accurately estimate the size of the terrestrial carbon sink. We estimate OR through its relationship with organic carbon oxidation state (Cox) measurements made using a 13C nuclear magnetic resonance spectrometer and a CHNSO elemental analyzer (Masiello et al. 2008; Hockaday et al. 2009). It is clear that ecosystem OR values frequently deviate from the assumed 1.10 (Masiello et al., 2008; Hockaday et al., 2009). Here we review what mechanisms drive shifts in OR, including: fire, climate (precipitation and temperature), land use change, atmospheric CO2 concentrations, and nutrient supply. We present data on the impact of nitrogen supply and elevated CO2 on ecosystem OR at two different field sites. We measure the effect of nitrogen supply on an agricultural ecosystem at the Kellogg Biological Station-Living Field Laboratory (KBS-LFL) in Michigan over a fertilization gradient (0 to 202 kg N/ha). We also measured the effect of atmospheric CO2 variation on ecosystem OR at a grassland

  8. Reservoir timescales for anthropogenic CO2 in the atmosphere

    PubMed

    O'Neill, B C; Gaffin, S R; Tubiello, F N; Oppenheimer, M

    1994-11-01

    Non-steady state timescales are complicated and their application to specific geophysical systems requires a common theoretical foundation. We first extend reservoir theory by quantifying the difference between turnover time and transit time (or residence time) for time-dependent systems under any mixing conditions. We explicitly demonstrate the errors which result from assuming these timescales are equal, which is only true at steady state. We also derive a new response function which allows the calculation of age distributions and timescales for well-mixed reservoirs away from steady state, and differentiate between timescales based on gross and net fluxes. These theoretical results are particularly important to tracer-calibrated "box models" currently used to study the carbon cycle, which usually approximate reservoirs as well-mixed. We then apply the results to the important case of anthropogenic CO2 in the atmosphere, since timescales describing its behavior are commonly used but ambiguously defined. All relevant timescales, including lifetime, transit time, and adjustment time, are precisely defined and calculated from data and models. Apparent discrepancies between the current, empirically determined turnover time of 30-60 years and longer model-derived estimates of expected lifetime and adjustment time are explained within this theoretical framework. We also discuss the results in light of policy issues related to global warming, in particular since any comparisons of the "lifetimes" of different greenhouse gases (CO2, CH4, N2O, CFC's etc.) must use a consistent definition to be meaningful.

  9. Sustained effects of atmospheric [CO2] and nitrogen availability on forest soil CO2 efflux.

    PubMed

    Oishi, A Christopher; Palmroth, Sari; Johnsen, Kurt H; McCarthy, Heather R; Oren, Ram

    2014-04-01

    Soil CO2 efflux (Fsoil ) is the largest source of carbon from forests and reflects primary productivity as well as how carbon is allocated within forest ecosystems. Through early stages of stand development, both elevated [CO2] and availability of soil nitrogen (N; sum of mineralization, deposition, and fixation) have been shown to increase gross primary productivity, but the long-term effects of these factors on Fsoil are less clear. Expanding on previous studies at the Duke Free-Air CO2 Enrichment (FACE) site, we quantified the effects of elevated [CO2] and N fertilization on Fsoil using daily measurements from automated chambers over 10 years. Consistent with previous results, compared to ambient unfertilized plots, annual Fsoil increased under elevated [CO2] (ca. 17%) and decreased with N (ca. 21%). N fertilization under elevated [CO2] reduced Fsoil to values similar to untreated plots. Over the study period, base respiration rates increased with leaf productivity, but declined after productivity saturated. Despite treatment-induced differences in aboveground biomass, soil temperature and water content were similar among treatments. Interannually, low soil water content decreased annual Fsoil from potential values - estimated based on temperature alone assuming nonlimiting soil water content - by ca. 0.7% per 1.0% reduction in relative extractable water. This effect was only slightly ameliorated by elevated [CO2]. Variability in soil N availability among plots accounted for the spatial variability in Fsoil , showing a decrease of ca. 114 g C m(-2) yr(-1) per 1 g m(-2) increase in soil N availability, with consistently higher Fsoil in elevated [CO2] plots ca. 127 g C per 100 ppm [CO2] over the +200 ppm enrichment. Altogether, reflecting increased belowground carbon partitioning in response to greater plant nutritional needs, the effects of elevated [CO2] and N fertilization on Fsoil in this stand are sustained beyond the early stages of stand development and

  10. Agricultural green revolution as a driver of increasing atmospheric CO2 seasonal amplitude

    SciTech Connect

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

    2014-11-20

    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 256N and 606N and the high-latitude natural vegetation between 506N and 706 N. The long-term trend of seasonal amplitude increase is 0.311 ± 0.027 percent 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 1961–1970

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

    PubMed

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

    2014-11-20

    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

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

    NASA Astrophysics Data System (ADS)

    Ahn, J.; Brook, E.; Buizert, C.

    2013-12-01

    The abrupt cooling event 8200 years ago (8.2 ka event) is the most prominent centennial scale climate event during the Holocene and was likely caused by a reduction in the Atlantic meridional overturning circulation (AMOC). Atmospheric CO2 records for this event may help us understand climate-carbon cycle feedbacks under interglacial conditions, which are important for understanding future climate, but existing ice core records do not provide enough detail and natural smoothing of the CO2 time series by diffusion and gradual bubble close-off in the firn layer (unconsolidated snow layer in the top of ice sheets) limits their resolution. Studies of leaf stomata records suggest a CO2 decrease of up to ~25 ppm during the 8.2 ka event, but relatively large uncertainties in reconstructed CO2 levels from leaves and dating make firm conclusions difficult. 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. The relatively high snow accumulation rate at Siple Dome results minimizes smoothing relative to other records and the timing of the 8.2 ka event is precisely constrained by a CH4 record from the same core. We observe a small, ~2 ppm, increase of atmospheric CO2 during the 8.2 ka event. The increase is not remarkable when compared to other centennial variations in the Holocene that are not linked to large temperature changes. Our results imply that the sensitivity of atmospheric CO2 to the primarily northern hemisphere cooling of the 8.2 ka event was limited.

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

    NASA Astrophysics Data System (ADS)

    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

  14. New constraints on atmospheric CO2 concentration for the Phanerozoic

    NASA Astrophysics Data System (ADS)

    Franks, Peter J.; Royer, Dana L.; Beerling, David J.; Van de Water, Peter K.; Cantrill, David J.; Barbour, Margaret M.; Berry, Joseph A.

    2014-07-01

    Earth's atmospheric CO2 concentration (ca) for the Phanerozoic Eon is estimated from proxies and geochemical carbon cycle models. Most estimates come with large, sometimes unbounded uncertainty. Here, we calculate tightly constrained estimates of ca using a universal equation for leaf gas exchange, with key variables obtained directly from the carbon isotope composition and stomatal anatomy of fossil leaves. Our new estimates, validated against ice cores and direct measurements of ca, are less than 1000 ppm for most of the Phanerozoic, from the Devonian to the present, coincident with the appearance and global proliferation of forests. Uncertainties, obtained from Monte Carlo simulations, are typically less than for ca estimates from other approaches. These results provide critical new empirical support for the emerging view that large (~2000-3000 ppm), long-term swings in ca do not characterize the post-Devonian and that Earth's long-term climate sensitivity to ca is greater than originally thought.

  15. Marine biological controls on atmospheric CO2 and climate

    NASA Technical Reports Server (NTRS)

    Mcelroy, M. B.

    1983-01-01

    It is argued that the ocean is losing N gas faster than N is being returned to the ocean, and that replenishment of the N supply in the ocean usually occurs during ice ages. Available N from river and estruarine transport and from rainfall after formation by lightning are shown to be at a rate too low to compensate for the 10,000 yr oceanic lifetime of N. Ice sheets advance and transfer moraine N to the ocean, lower the sea levels, erode the ocean beds, promote greater biological productivity, and reduce CO2. Ice core samples have indicated a variability in the atmospheric N content that could be attributed to the ice age scenario.

  16. Impact of Error in Atmospheric State on Column CO2 Retrievals from a Laser CO2 Sounder

    NASA Astrophysics Data System (ADS)

    Mao, J.; Ramanathan, A. K.; Abshire, J. B.; Kawa, S. R.

    2016-12-01

    NASA Goddard is developing an integrated-path, differential absorption (IPDA) lidar approach to measure global atmospheric column CO2 concentrations from space as a candidate for NASA's Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) mission. This pulsed laser approach uses a step-locked laser diode source and a high-efficiency detector to measure atmospheric column CO2 absorption at multiple wavelengths across a CO2 line centered at 1572.335 nm with minimum temperature sensitivity. Atmospheric states from a global numerical forecast and data assimilation model are used as ancillary data to produce the best retrievals of column-averaged CO2 mixing ratio with regards to dry air. Retrieval error, both bias and random error, depends on uncertainties of atmospheric states for atmospheric radiative transfer calculations that are then used to fit measured CO2 absorption line shape for retrievals. Temperature data uncertainty, for example, can modify air density as well as absorption line intensity and line shape, which could cause significant error in radiative transfer calculations and then in column CO2mixing ratio retrievals. Uncertainty in atmospheric pressure and water vapor could also further increase retrieval error. We use atmospheric temperature profiles from Atmospheric InfraRed Sounder retrievals and the European Center for Medium range Weather Forecasting Model to assess temperature impact on spaceborne measurement of ASCENDS using our Goddard IPDA approach. We find the temperature differences produce a small impact on optical depth measurements on our CO2 line. Uncertainty in the atmospheric surface pressure could cause greater impact, implying a requirement for accurate dry air column density information in addition to laser ranging capability. We use data from the 2014 and 2016 ASCENDS airborne science campaigns to evaluate the atmospheric impact on our column CO2 concentration retrievals using the Goddard GEOS-5 meteorological

  17. Quantifying the magnitude, spatiotemporal variation and age of aquatic CO2 fluxes in western Greenland

    NASA Astrophysics Data System (ADS)

    Long, H. E.; Waldron, S.; Hoey, T.; Garnett, M.; Newton, J.

    2014-12-01

    High latitude regions are experiencing accelerated atmospheric warming, and understanding the terrestrial response to this is of crucial importance as: a) there is a large store of carbon (C) in permafrost soils which may be released and feedback to climate change; and, b) ice sheet melt in this region is accelerating, and whilst this will cause albedo and heat flux changes, the role of this in atmospheric gas release is poorly known. To understand how sensitive arctic environments may respond to future warming, we need measurements that document current C flux rates and help to understand C cycling pathways. Although it has been widely hypothesised that arctic regions may become increasingly significant C sources, the contribution of aquatic C fluxes which integrate catchment-wide sources has been little studied. Using a floating chamber method we directly measured CO2 fluxes from spatially distributed freshwaters (ice sheet melt, permafrost melt, and lakes/ponds) in the Kangerlussuaq region of western Greenland during the early part of the summer 2014 melt season. Fluxes from freshwaters with permafrost sources were in the range -3.15 to +1.28 μmol CO2 m-2 s-1. Fluxes from a river draining the ice sheet and the Russell Glacier were between -2.19 and +4.31 μmol CO2 m-2 s-1. These ranges show the systems can be both sources (efflux) and sinks (influx) of CO2. Most freshwater data worldwide shows CO2 efflux and so recording aquatic systems being a CO2­ ­sink is unusual. Our data show spatial and temporal variations that are related to hydraulic as well as biogeochemical processes. Additionally, where we recorded CO2 efflux we collected effluxed CO2 for radiocarbon analysis. The measured age of the released gas will help to identify the sources and dominant transport processes of CO­2 (e.g. entrained modern atmospheric CO2, or old CO2 trapped during ice formation released through ice melt, or CO2 derived from respiration of soil and sediment organic matter

  18. CO2 Exsolution from CO2 Saturated Water: Core-Scale Experiments and Focus on Impacts of Pressure Variations.

    PubMed

    Xu, Ruina; Li, Rong; Ma, Jin; Jiang, Peixue

    2015-12-15

    For CO2 sequestration and utilization in the shallow reservoirs, reservoir pressure changes are due to the injection rate changing, a leakage event, and brine withdrawal for reservoir pressure balance. The amounts of exsolved CO2 which are influenced by the pressure reduction and the subsequent secondary imbibition process have a significant effect on the stability and capacity of CO2 sequestration and utilization. In this study, exsolution behavior of the CO2 has been studied experimentally using a core flooding system in combination with NMR/MRI equipment. Three series of pressure variation profiles, including depletion followed by imbibitions without or with repressurization and repetitive depletion and repressurization/imbibition cycles, were designed to investigate the exsolution responses for these complex pressure variation profiles. We found that the exsolved CO2 phase preferentially occupies the larger pores and exhibits a uniform spatial distribution. The mobility of CO2 is low during the imbibition process, and the residual trapping ratio is extraordinarily high. During the cyclic pressure variation process, the first cycle has the largest contribution to the amount of exsolved CO2. The low CO2 mobility implies a certain degree of self-sealing during a possible reservoir depletion.

  19. Assessing filtering of mountaintop CO2 mixing ratios for application to inverse models of biosphere-atmosphere carbon exchange

    NASA Astrophysics Data System (ADS)

    Brooks, B.-G. J.; Desai, A. R.; Stephens, B. B.; Bowling, D. R.; Burns, S. P.; Watt, A. S.; Heck, S. L.; Sweeney, C.

    2011-09-01

    There is a widely recognized need to improve our understanding of biosphere-atmosphere carbon exchanges in areas of complex terrain including the United States Mountain West. CO2 fluxes over mountainous terrain are difficult to measure often due to unusual and complicated influences associated with atmospheric transport in complex terrain. Using five years of CO2 mixing ratio observations from the Regional Atmospheric Continuous CO2 Network in the Rocky Mountains (Rocky RACCOON), five statistical (subsetting) filters are used to investigate a range of approaches for identifying regionally representative CO2 mixing ratios. Test results from three filters indicate that subsets based on short-term variance and local CO2 gradients across tower inlet heights retain nine-tenths of the total observations and are able to define representative diurnal variability and seasonal cycles even for difficult-to-model sites where the influence of local fluxes is much larger than regional mixing ratio variations. Test results from two other filters that consider measurements from previous and following days using spline fitting or sliding windows are overly selective. Case study examples showed that even when standardized to common subset sizes these windowing-filters rejected measurements representing synoptic changes in CO2, which suggests that they are not well suited to filtering continental CO2 measurements. We present a novel CO2 lapse rate filter that uses CO2 differences between levels in the model atmosphere to constrain subsets of site measurements that are representative on model scales.

  20. Coupled micrometeorological and biological processes on atmospheric CO 2 concentrations at the land-ocean boundary, NE coast of India

    NASA Astrophysics Data System (ADS)

    Ganguly, D.; Dey, M.; Chowdhury, C.; Pattnaik, A. A.; Sahu, B. K.; Jana, T. K.

    2011-07-01

    This study reveals that land-sea breezes, atmospheric stability and influence of net ecosystem metabolism for the conversion of organic carbon to atmospheric CO 2 are the major driving forces behind the variation of atmospheric CO 2 at the land-ocean boundary, northeast coast of India. The seasonal variation of partial pressure of CO 2 (pCO 2) and its efflux from the coastal water were several fold higher in the pre-monsoon (1807.9 ± 757.03 μ atm; 579.03 ± 172.9 μM m -2 h -1) than in the monsoon (1070.5 ± 328.5 μ atm; 258.96 ± 185.65 μM m -2 h -1) and the post-monsoon (615.7 ± 121.6 μ atm; 53.27 ± 19.24 μM m -2 h -1). The mean photic zone productivity to column respiration ratio was 0.12 ± 0.08, revealing predominance of heterotrophic processes. Community respiration was at minimum during monsoon (38.82 ± 8.63 mM C m -2 d -1) but was at maximum (173.8 ± 111.8 mM C m -2 d -1) during pre-monsoon and intermittent (125.07 ± 11.97 mM C m -2 d -1) during post-monsoon. Diurnal variations of atmospheric CO 2 concentration were determined by local air circulations and atmospheric stability. Seasonal variations of atmospheric CO 2 bear a significant signature of biological processes occurring in the coastal water by means of air-sea exchange, markedly affected by the net ecosystem metabolism. Important predictors of coastal atmospheric CO 2 in decreasing order of explained variability are wind direction, stability, CO 2 efflux and wind velocity.

  1. Atmospheric Modeling and Verification of Point Source Fossil Fuel CO2 Emissions

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    Emissions from large point sources (electricity generation and large-scale industry) of fossil fuel CO2 (CO2ff) emissions are currently determined from self-reported "bottom-up" inventory data, with an uncertainty of about 20% for individual power plants. As the world moves towards a regulatory environment, there is a need for independent, objective measurements of these emissions both to improve the accuracy of and to verify the reported amounts. "Top-down" atmospheric methods have the potential to independently constrain point source emissions, combining observations with atmospheric transport modeling to derive emission estimates. We use the Kapuni Gas Treatment Plant to examine methodologies and model sensitivities for atmospheric monitoring of point source fossil fuel CO2 (CO2ff) emissions. The Kapuni plant, located in rural New Zealand, removes and vents CO2 from locally extracted natural gas at a rate of ~0.1 Tg carbon per year. We measured the CO2ff content in three different types of observations: air samples collected in flasks over a period of a few minutes, sodium hydroxide solution exposed the atmosphere, and grass samples from the surrounding farmland, the latter two representing ~1 week integrated averages. We use the WindTrax Lagrangian plume dispersion model to compare these atmospheric observations with "expected" values given the emissions reported by the Kapuni plant. The model has difficulty accurately capturing the short-term variability in the flask samples but does well in representing the longer-term averages from grass samples, suggesting that passive integrated-sampling methods have the potential to monitor long-term emissions. Our results indicate that using this method, point source emissions can be verified to within about 30%. Further improvements in atmospheric transport modelling are needed to reduce uncertainties. In view of this, we discuss model strengths and weaknesses and explore model sensitivity to meteorological conditions

  2. Atmospheric Mixing of CO2 above Carbon Storage Sites: Coupling Physics Based Models within a CO2 Sequestration System Modeling Framework

    NASA Astrophysics Data System (ADS)

    Stauffer, P. H.; Olsen, S. C.; Viswanathan, H. S.; Dubey, M. K.; Guthrie, G. D.; Pawar, R. J.

    2006-12-01

    The Zero Emissions Research and Technology (ZERT) project at the Los Alamos National Laboratory is studying the injection of CO2 into geologic repositories. We are formulating the problem as science based decision framework that can address issues of risk, cost, and technical requirements at all stages of the sequestration process. The framework, called CO2-PENS , is implemented in a system model that is capable of performing stochastic simulations to address uncertainty in different geologic sequestration scenarios. In this talk we examine the changes atmospheric concentrations directly above a potential repository caused by diffuse CO2 leakage that migrates to the atmosphere from the repository. We present an atmospheric mixing model that accounts for local surface effects, local climate data, and daily variations in the mixing layer thickness. We compare model results to field data collected at a controlled flux tower experiment. We next show how the atmospheric mixing model can provide estimates of uncertainty when used from within the CO2- PENS framework. Finally, we discuss data needs and future work needed to make the atmospheric component more flexible so that it can quickly be applied to any potential repository.

  3. Modelling of stomatal density response to atmospheric CO2.

    PubMed

    Konrad, W; Roth-Nebelsick, A; Grein, M

    2008-08-21

    Stomatal density tends to vary inversely with changes in atmospheric CO(2) concentration (C(a)). This phenomenon is of significance due to: (i) the current anthropogenic rise in C(a) and its impact on vegetation, and (ii) the potential applicability for reconstructing palaeoatmospheric C(a) by using fossil plant remains. It is generally assumed that the inverse change of stomatal density with C(a) represents an adaptation of epidermal gas conductance to varying C(a). Reconstruction of fossil C(a) by using stomatal density is usually based on empirical curves which are obtained by greenhouse experiments or the study of herbarium material. In this contribution, a model describing the stomatal density response to changes in C(a) is introduced. It is based on the diffusion of water vapour and CO(2), photosynthesis and an optimisation principle concerning gas exchange and water availability. The model considers both aspects of stomatal conductance: degree of stomatal aperture and stomatal density. It is shown that stomatal aperture and stomatal density response can be separated with stomatal aperture representing a short-term response and stomatal density a long-term response. The model also demonstrates how the stomatal density response to C(a) is modulated by environmental factors. This in turn implies that reliable reconstructions of ancient C(a) require additional information concerning temperature and humidity of the considered sites. Finally, a sensitivity analysis was carried out for the relationship between stomatal density and C(a) in order to identify critical parameters (= small parameter changes lead to significant changes of the results). Stomatal pore geometry (pore size and depth) represents a critical parameter. In palaeoclimatic studies, pore geometry should therefore also be considered.

  4. Atmospheric Variability of CO2 impact on space observation Requirements

    NASA Astrophysics Data System (ADS)

    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

  5. A Climactic Feedback? Variations in Mid-Ocean Ridge CO2 Emissions Driven by Glacial Cycles

    NASA Astrophysics Data System (ADS)

    Burley, J. M.; Katz, R. F.; Huybers, P. J.

    2015-12-01

    Changes in sea level associated with glacial cycles affect the pressure beneath a mid-ocean ridge (MOR) [1,2,3]. Pressure controls the depth of first melting, and therefore the rate of change of pressure controls the rate of change of the depth of first melting. The changing depth of first melting alters the effective rate at which mantle, and thus CO2, enters the melting region. Melt then transports CO2 to the ridge axis, where it enters the climate system. We calculate that the lag between sea level change and consequent variation in MOR CO2 emissions is 40-120 kyrs[4], similar to the timescale of glacial cycles. Could these variations in MOR CO2 emissions feed back on climate and lead to ice-age pacing at a small multiple of the obliquity period? [5]To test this hypothesis we begin with a climate model comprised of a global energy balance and a 1D ice sheet. The ice sheet flows under its own weight, accumulates due to precipitation, and melts in response to the local energy balance[6]. This model broadly replicates Early Pleistocene 40 kyr glacial cycles. We extend the model to include a variable greenhouse effect, according to atmospheric CO2, and variable MOR CO2 emissions driven by sea level. The lag between sea level change and MOR CO2 emissions is controlled by mantle permeability. If this model does not demonstrate MOR CO2 emissions altering glacial cycles, it would suggest this hypothesised feedback mechanism can be rejected. References[1] Huybers & Langmuir 2009; 10.1016/j.epsl.2009.07.014[2] Lund & Asimow 2011; 10.1029/2011GC003693[3] Crowley et al 2015; 10.1126/science.1261508[4] Burley & Katz 2015; 10.1016/j.epsl.2015.06.031[5] Huybers (in prep.)[6] Huybers & Tziperman 2008; 10.1029/2007PA001463

  6. Climate impacts on rising atmospheric CO2 from long-term time-series of CO2 and O2

    NASA Astrophysics Data System (ADS)

    Keeling, R. F.; Rafelski, L. E.; Piper, S. C.

    2009-04-01

    The long-term time series of atmospheric CO2 and O2 concentrations from the Scripps Institution of oceanography now span 51 and 19 years, respectively. These time series will be presented together with the ice-core CO2 records and discussed in terms of the processes controlling the atmospheric CO2 rise, particularly the sensitivity of the natural sinks for CO2 in the land and ocean to climate changes. The CO2 record provides constraints on the sensitivity of the land sinks to climate. The CO2 rise can be expressed as an anomaly relative to the trend expected from fossil-fuel burning, land use emissions, and uptake by the land biosphere and oceans, with the latter two processes depicted by simple reservoir models (land sink driven by CO2 fertilization). Despite uncertainties, the anomaly computed this way shows an evident link with global land temperature, with both the anomaly and temperature trend showing breaks in slope around 1940 and 1980. Climate effects on the land biosphere may thus explain two otherwise puzzling features in the CO2 record: the plateau in growth in the 1940s and the persistent high growth after 1980. The implied effect of warming on CO2 suggested by this decadal variability is too small to be a significant climate feedback, however. Additional constraints on the climate sensitivity of ocean sinks can be obtained by combining the CO2 and O2 records. The ocean CO2 sink that would have been obtained in the absence of climate change is quite well constrained based on ocean observations of chlorofluorocarbons. This sink can be compared to the sink computed from the global O2 budget, assuming the oceans have not been a long-term source or sink for O2. The comparison reveals a significant discrepancy, which suggests that climate changes are impacting some combination of the long-term O2 and CO2 fluxes. The climate effect is qualitatively consistent with ocean models, which predict that warming will reduce oceanic uptake of CO2 and induce oceanic

  7. Seasonal Variation of CO2 in the Gulf of Bothnia: Indications for Net Heterotrophy

    NASA Astrophysics Data System (ADS)

    Algesten, G.; Wikner, J.; Sobek, S.; Tranvik, L. J.; Jansson, M.

    2004-05-01

    Marine systems have been considered to be in carbon balance with the atmosphere, which means that primary production equals total respiration within the system. However, recent studies indicate that large parts of the ocean, especially oligotrophic marine systems, are net heterotrophic and, thus, a source of CO2 to the atmosphere. Net heterotrophy implies that organic carbon is transported to low-productive areas, either by redistribution of organic carbon (OC) from more productive marine zones or by input of terrestrial OC via rivers. This study was conducted in the Gulf of Bothnia, which is situated between Sweden and Finland in northern Europe. It is a brackish water body with two major basins (Bothnian Bay and Bothnian Sea). The Gulf receives a high input of OC from Swedish and Finnish rivers, but also from the adjacent more productive water body of the Baltic Proper. Previous studies on carbon balance in the Gulf of Bothnia have indicated that the system is net heterotrophic. We therefore employed, for the first time, direct estimates of CO2 saturation to assess the net ecosystem exchange in the two major basins of the Gulf of Bothnia during one year. Primary and bacterial production (PP and BP) was also measured in order to calculate the respiration-production balance in the Gulf of Bothnia. On an annual basis the surface water was supersaturated with CO2, indicating net heterotrophy. The Gulf of Bothnia oscillated between being a sink and a source of CO2 over the studied period, largely decided by the temporal variation in bacterial respiration (BR) and primary production in the water column above the pycnocline. Calculated annual respiration-production balance (BR-PP) was very similar to the estimated CO2 emission from the Gulf of Bothnia, indicating that these processes were the major determinants of the exchange of CO2 between water and atmosphere. The southern basin (Bothnian Sea) had a lower net release of CO2 to the atmosphere than the northern

  8. Temporal variations in CO2 and CO at Ahmedabad in western India

    NASA Astrophysics Data System (ADS)

    Chandra, N.; Lal, S.; Venkataramani, S.; Patra, P. K.; Sheel, V.

    2015-11-01

    About 70 % of the anthropogenic CO2 is emitted from the megacities and urban areas of the world. In-situ simultaneous measurements of carbon dioxide (CO2) and carbon monoxide (CO) have been made using a state-of-the-art laser based cavity ring down spectroscopy technique at Ahmedabad, an urban site in western India, from November 2013 to May 2015 with a break during March to June 2014. Annual average concentrations of CO2 and CO have been found to be 413.0 ± 13.7 ppm and 0.50 ± 0.37 ppm respectively. Both the species show strong seasonality, with lower concentrations of 400.3 ± 6.8 ppm and 0.19 ± 0.13 ppm, respectively during the south-west monsoon, and higher values of 419.6 ± 22.8 ppm and 0.72 ± 0.68 ppm, respectively in autumn (SON). Strong diurnal variations are also observed for both the species. The common factors for diurnal cycles of CO2 and CO are the vertical mixing and rush hour traffic, while the influence of biospheric fluxes is also seen in CO2 diurnal cycle. Using CO and CO2 covariation, we differentiate the anthropogenic and biospheric components of CO2 and found that significant contributions of biospheric respiration and anthropogenic emission in the late night (00:00-05:00 IST) and evening rush hours (18:00-22:00 IST) respectively. We compute total yearly emission of CO to be 69.2 ± 0.07 Gg for the study region using the observed CO : CO2 correlation slope and bottom-up CO2 emission inventory. This calculated emission of CO is 52 % larger than the estimated emission of CO by the EDGAR inventory. The observations of CO2 have been compared with an atmospheric chemistry transport model (i.e., ACTM), which incorporates various components of CO2 fluxes. ACTM is able to capture the basic variabilities, but both diurnal and seasonal amplitudes are largely underestimated compared to the observations. We attribute this underestimation by model to uncertainties in terrestrial biosphere fluxes and coarse model resolution. The fossil fuel signal from

  9. Venus - On the phase variation of CO2 line profiles

    NASA Technical Reports Server (NTRS)

    Macy, W., Jr.; Trafton, L.; Barker, E.

    1977-01-01

    The shapes of Venus' CO2 profiles are found to vary with solar phase angle. High-resolution spectra of the P16 and P14 lines in the 8689- and 7820-A bands, respectively, are presented for phase angles ranging from 6 to 158 deg. The scattering mean free path at 80 mbar, approximately the effective pressure, is 1.7 km. Use of the van de Hulst (1974) similarity relations with simple parametric scattering models is inadequate to separate effects due to the scattering phase function from those due to inhomogeneities in depth when one attempts to determine the atmospheric structure by fitting a family of such models over a wide range of phase angles.

  10. An Assessment of the Ability of Potential Satellite Instruments to Resolve Spatial and Temporal Variability of Atmospheric CO2

    NASA Technical Reports Server (NTRS)

    Andrews, A.; Bhartia, Pawan (Technical Monitor)

    2002-01-01

    Sufficiently precise satellite observations with adequate spatial and temporal resolution would substantially increase our knowledge of the atmospheric CO2 distribution and would undoubtedly lead to reduced uncertainty in estimates of the global carbon budget. An overview of possible strategies for measuring CO2 from space will be presented, including IR and nearby measurements, active sensors and broad band and narrow band passive sensors. The ability of potential satellite instruments with a variety of orbits, horizontal resolution and vertical weighting functions to capture the variation in atmospheric CO2 mixing ratios will be illustrated using a combination of surface data, aircraft data and model results.

  11. An Assessment of the Ability of Potential Satellite Instruments to Resolve Spatial and Temporal Variability of Atmospheric CO2

    NASA Technical Reports Server (NTRS)

    Andrews, A.; Bhartia, Pawan (Technical Monitor)

    2002-01-01

    Sufficiently precise satellite observations with adequate spatial and temporal resolution would substantially increase our knowledge of the atmospheric CO2 distribution and would undoubtedly lead to reduced uncertainty in estimates of the global carbon budget. An overview of possible strategies for measuring CO2 from space will be presented, including IR and nearby measurements, active sensors and broad band and narrow band passive sensors. The ability of potential satellite instruments with a variety of orbits, horizontal resolution and vertical weighting functions to capture the variation in atmospheric CO2 mixing ratios will be illustrated using a combination of surface data, aircraft data and model results.

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

    NASA Astrophysics Data System (ADS)

    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. CO2 emission of Indonesian fires in 2015 estimated from satellite-derived atmospheric CO2 concentrations

    NASA Astrophysics Data System (ADS)

    Heymann, J.; Reuter, M.; Buchwitz, M.; Schneising, O.; Bovensmann, H.; Burrows, J. P.; Massart, S.; Kaiser, J. W.; Crisp, D.

    2017-02-01

    Indonesia experienced an exceptional number of fires in 2015 as a result of droughts related to the recent El Niño event and human activities. These fires released large amounts of carbon dioxide (CO2) into the atmosphere. Emission databases such as the Global Fire Assimilation System version 1.2 and the Global Fire Emission Database version 4s estimated the CO2 emission to be approximately 1100 MtCO2 in the time period from July to November 2015. This emission was indirectly estimated by using parameters like burned area, fire radiative power, and emission factors. In the study presented in this paper, we estimate the Indonesian fire CO2 emission by using the column-averaged dry air mole fraction of CO2, XCO2, derived from measurements of the Orbiting Carbon Observatory-2 satellite mission. The estimated CO2 emission is 748 ± 209 MtCO2, which is about 30% lower than provided by the emission databases.

  14. Diurnal variations in CO2 flux from peatland floodplains: Implications for models of ecosystem respiration

    NASA Astrophysics Data System (ADS)

    Goulsbra, Claire; Rickards, Nathan; Brown, Sarah; Evans, Martin; Boult, Stephen; Alderson, Danielle

    2016-04-01

    Peatlands are important terrestrial carbon stores, and within these environments, floodplains have been identified as hotspots of carbon processing, potentially releasing substantial amounts of CO2 into the atmosphere. Previous monitoring campaigns have shown that such CO2 release from ecosystem respiration is linked not only to soil temperature and water table depth, but also to CO2 sequestration via primary productivity, thought to be because the root exudates produced during photosynthesis stimulate microbial activity. This suggests that extrapolation models that are parameterised on data collected during day light hours, when vegetation is photosynthesising, may overestimate ecosystem respiration rates at night, which has important implications for estimates of annual CO2 flux and carbon budgeting. To investigate this hypothesis, monitoring data is collected on the CO2 flux from UK peatland floodplains over the full diurnal cycle. This is done via ex-situ manual data collection from mesocosms using an infra-red gas analyser, and the in-situ automated collection of CO2 concentration data from boreholes within the peat using GasClams®. Preliminary data collected during the summer months suggest that night time respiration is suppressed compared to that during the day, and that the significant predictors of respiration are different when examining day and night time data. This highlights the importance of incorporating diurnal variations into models of ecosystem respiration.

  15. CO2 leakage monitoring and analysis to understand the variation of CO2 concentration in vadose zone by natural effects

    NASA Astrophysics Data System (ADS)

    Joun, Won-Tak; Ha, Seung-Wook; Kim, Hyun Jung; Ju, YeoJin; Lee, Sung-Sun; Lee, Kang-Kun

    2017-04-01

    Controlled ex-situ experiments and continuous CO2 monitoring in the field are significant implications for detecting and monitoring potential leakage from CO2 sequestration reservoir. However, it is difficult to understand the observed parameters because the natural disturbance will fluctuate the signal of detections in given local system. To identify the original source leaking from sequestration reservoir and to distinguish the camouflaged signal of CO2 concentration, the artificial leakage test was conducted in shallow groundwater environment and long-term monitoring have been performed. The monitoring system included several parameters such as pH, temperature, groundwater level, CO2 gas concentration, wind speed and direction, atmospheric pressure, borehole pressure, and rainfall event etc. Especially in this study, focused on understanding a relationship among the CO2 concentration, wind speed, rainfall and pressure difference. The results represent that changes of CO2 concentration in vadose zone could be influenced by physical parameters and this reason is helpful in identifying the camouflaged signal of CO2 concentrations. The 1-D column laboratory experiment also was conducted to understand the sparking-peak as shown in observed data plot. The results showed a similar peak plot and could consider two assumptions why the sparking-peak was shown. First, the trapped CO2 gas was escaped when the water table was changed. Second, the pressure equivalence between CO2 gas and water was broken when the water table was changed. These field data analysis and laboratory experiment need to advance due to comprehensively quantify local long-term dynamics of the artificial CO2 leaking aquifer. Acknowledgement Financial support was provided by the "R&D Project on Environmental Management of Geologic CO2 Storage" from the KEITI (Project Number: 2014001810003)

  16. Atmospheric CO2 and CH4 Measurement Network on Towers in Siberia

    NASA Astrophysics Data System (ADS)

    Shimoyama, K.; Machida, T.; Shinohara, A.; Maksyutov, S.; Arshinov, M.; Davydov, D.; Fofonov, A.; Krasnov, O.; Fedoseev, N.; Belan, B.; Belan, H.; Inoue, G.

    2006-12-01

    In order to estimate CO2 and CH4 fluxes at regional to sub-continental scale by an inverse model, a network of tall towers for atmospheric CO2 and CH4 measurements has been established over a region of thousand square kilometers in west Siberia. In-situ continuous measurements have been conducted at 6 stations: Berezorechka (56.17N, 84.33E) since 2002, Parabel (58.25N, 82.40E) and Igrim (63.20N, 64.48E) since 2004, Demyanskoe (59.78N, 70.87E) and Noyabrsk (63.43N, 76.76E) since 2005, and Yakutsk (62.83N, 129.35E) in east Siberia since 2005. Over next two years, installations of 4 more stations are planned. This study provides some results of observation from this network. Seasonal cycles of CO2 showed quite similar trends in growing season (May to September) among the west Siberian sites. The remarkable decrease of CO2 concentration occurred in early May and the seasonal minimum was observed between July and August. On the other hand, the short-term (from several days to week) variations in CO2 concentrations were quite different among the sites, particularly during the growing season. Rather large variation of more than 25 ppm within a week was observed during winter. The changes in CO2 concentrations at the nearby sites were almost identical. Monthly mean values of CO2 during the growing season were relatively higher at the northern sites than at southern sites. These observational results evidentially reflected the regional characteristics of CO2 flux variation, transportation, and mixing process. Daily cycles of CH4 in summer showed nocturnal increase and diurnal decrease which was due to emission of CH4 from wetland accumulated over night, and diurnal convective mixing. Relatively high concentrations of CH4 were observed in winter and summer. Because there is one of the world's vastest wetland in western Siberia, the peak of CH4 in summer implies the significant role of CH4 emissions from the west Siberian wetland to the atmosphere. On the other hand, an

  17. Airborne Double Pulsed 2-Micron IPDA Lidar for Atmospheric CO2 Measurement

    NASA Technical Reports Server (NTRS)

    Yu, Jirong; Petros, Mulugeta; Refaat, Tamer; Singh, Upendra

    2015-01-01

    We have developed an airborne 2-micron Integrated Path Differential Absorption (IPDA) lidar for atmospheric CO2 measurements. The double pulsed, high pulse energy lidar instrument can provide high-precision CO2 column density measurements.

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

    NASA Astrophysics Data System (ADS)

    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

  19. Assumption Centred Modelling of Ecosystem Responses to CO2 at Six US Atmospheric CO2 Enrichment Experiments.

    NASA Astrophysics Data System (ADS)

    Walker, A. P.; De Kauwe, M. G.; Medlyn, B. E.; Zaehle, S.; Luus, K. A.; Ryan, E.; Xia, J.; Norby, R. J.

    2015-12-01

    Plant photosynthetic rates increase and stomatal apertures decrease in response to elevated atmospheric CO[2] (eCO2), increasing both plant carbon (C) availability and water use efficiency. These physiological responses to eCO2 are well characterised and understood, however the ecological effects of these responses as they cascade through a suite of plant and ecosystem processes are complex and subject to multiple interactions and feedbacks. Therefore the response of the terrestrial carbon sink to increasing atmospheric CO[2] remains the largest uncertainty in global C cycle modelling to date, and is a huge contributor to uncertainty in climate change projections. Phase 2 of the FACE Model-Data Synthesis (FACE-MDS) project synthesises ecosystem observations from five long-term Free-Air CO[2] Enrichment (FACE) experiments and one open top chamber (OTC) experiment to evaluate the assumptions of a suite of terrestrial ecosystem models. The experiments are: The evergreen needleleaf Duke Forest FACE (NC), the deciduous broadleaf Oak Ridge FACE (TN), the prairie heating and FACE (WY), and the Nevada desert FACE, and the evergreen scrub oak OTC (FL). An assumption centered approach is being used to analyse: the interaction between eCO2 and water limitation on plant productivity; the interaction between eCO2 and temperature on plant productivity; whether increased rates of soil decomposition observed in many eCO2 experiments can account for model deficiencies in N uptake shown during Phase 1 of the FACE-MDS; and tracing carbon through the ecosystem to identify the exact cause of changes in ecosystem C storage.

  20. Seasonal change in CO2 and H2O exchange between grassland and atmosphere

    NASA Astrophysics Data System (ADS)

    Saigusa, N.; Liu, S.; Oikawa, T.; Watanabe, T.

    1996-03-01

    The seasonal change in CO2 flux over an artificial grassland was analyzed from the ecological and meteorological point of view. This grassland contains C3 and C4 plants; the three dominant species belonging to the Gramineae; Festuca elatior (C3) dominated in early spring, and Imperata cylindrica (C4) and Andropogon virginicus (C4) grew during early summer and became dominant in mid-summer. CO2 flux was measured by the gradient method, and the routinely observed data for the surface-heat budget were used to analyze the CO2 and H2O exchange between the grassland and atmosphere. From August to October in 1993, CO2 flux was reduced to around half under the same solar-radiation conditions, while H2O flux decreased 20% during the same period. The monthly values of water use efficiency, i.e., ratio of CO2 flux to H2O flux decreased from 5.8 to 3.3 mg CO2/g H2O from August to October, the Bowen ratio increased from 0.20 to 0.30, and the ratio of the bulk latent heat transfer coefficient CE to the sensible heat transfer coefficient CH was maintained around 0.40-0.50. The increase in the Bowen ratio was explained by the decrease in air temperature from 22.3 °C in August to 16.6 °C in October without considering biological effects such as stomatal closure on the individual leaves. The nearly constant CE/CH ratios suggested that the contribution ratio of canopy resistance to aerodynamic resistance did not change markedly, although the meteorological conditions changed seasonally. The decrease in the water use efficiency, however, suggested that the photosynthetic rate decreased for individual leaves from August to October under the same radiation conditions. Diurnal variations of CO2 exchange were simulated by the multi-layer canopy model taking into account the differences in the stomatal conductance and photosynthetic pathway between C3 and C4 plants. The results suggested that C4 plants played a major role in the CO2 exchange in August, the contribution of C4 plants

  1. Assessing filtering of mountaintop CO2 mole fractions for application to inverse models of biosphere-atmosphere carbon exchange

    NASA Astrophysics Data System (ADS)

    Brooks, B.-G. J.; Desai, A. R.; Stephens, B. B.; Bowling, D. R.; Burns, S. P.; Watt, A. S.; Heck, S. L.; Sweeney, C.

    2012-02-01

    There is a widely recognized need to improve our understanding of biosphere-atmosphere carbon exchanges in areas of complex terrain including the United States Mountain West. CO2 fluxes over mountainous terrain are often difficult to measure due to unusual and complicated influences associated with atmospheric transport. Consequently, deriving regional fluxes in mountain regions with carbon cycle inversion of atmospheric CO2 mole fraction is sensitive to filtering of observations to those that can be represented at the transport model resolution. Using five years of CO2 mole fraction observations from the Regional Atmospheric Continuous CO2 Network in the Rocky Mountains (Rocky RACCOON), five statistical filters are used to investigate a range of approaches for identifying regionally representative CO2 mole fractions. Test results from three filters indicate that subsets based on short-term variance and local CO2 gradients across tower inlet heights retain nine-tenths of the total observations and are able to define representative diel variability and seasonal cycles even for difficult-to-model sites where the influence of local fluxes is much larger than regional mole fraction variations. Test results from two other filters that consider measurements from previous and following days using spline fitting or sliding windows are overly selective. Case study examples showed that these windowing-filters rejected measurements representing synoptic changes in CO2, which suggests that they are not well suited to filtering continental CO2 measurements. We present a novel CO2 lapse rate filter that uses CO2 differences between levels in the model atmosphere to select subsets of site measurements that are representative on model scales. Our new filtering techniques provide guidance for novel approaches to assimilating mountain-top CO2 mole fractions in carbon cycle inverse models.

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

    PubMed

    Zhang, Han; Cao, Long

    2016-02-03

    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.

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

    PubMed Central

    Zhang, Han; Cao, Long

    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 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. PMID:26838480

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

    USDA-ARS?s Scientific Manuscript database

    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...

  5. Soil CO2 flux in response to elevated atmospheric CO2 and nitrogen fertilization: patterns and methods

    Treesearch

    James M. Vose; Katherine J. Elliott; D.W. Johnson

    1995-01-01

    The evolution of carbon dioxide (CO2) from soils is due to the metabolic activity of roots, mycorrhizae, and soil micro- and macro-organisms. Although precise estimates of carbon (C) recycled to the atmosphere from belowground sources are unavailable, Musselman and Fox (1991) propose that the belowground contribution exceeds 100 Pg y-1...

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

    NASA Astrophysics Data System (ADS)

    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

  7. Deploying CRDS instruments at a geological CO2 storage site: an overlap experiment to compare atmospheric CO2 measurements with a high precision NDIR instrument (Invited)

    NASA Astrophysics Data System (ADS)

    Loh, Z. M.; Steele, P.; Etheridge, D. M.; van der Schoot, M.; Krummel, P. B.; Spencer, D.

    2010-12-01

    We are conducting atmospheric monitoring at a demonstration geological CO2 storage facility, the CO2CRC Otway Project in south-west, Victoria, Australia (http://www.co2crc.com.au/otway/). The atmospheric monitoring is being developed to detect and quantify potential leakage, though most of the variations in CO2 at Otway are due to ecological fluxes. At this site we have been making continuous measurements of CO2 with a high-precision non-dispersive infrared analyzer system (Da Costa and Steele, 1999; Francey and Steele, 2003) since January 2007, and in November 2009 we added two wavelength-scanned cavity ring-down spectrometers (CRDS) (Picarro Inc.), providing continuous measurements of 12CO2, 12CH4, H2O and 12/13CO2. In this paper, we will use one year of overlapping data for these instruments to compare their relative precisions, stabilities and calibration regimes. In addition, we compare their usefulness for the purpose of monitoring for potential leakage from geological storage. For instance, while we believe that the NDIR instrument provides superior precision and stability, this performance is achieved through a rigorous calibration protocol (6 calibration standards run over 2-3 days each month) and a quality assurance regime which takes up 25% of each hour. When looking for signals from local emissions, such as potential leakage from geological storage with a limited number of measurement locations, we believe the increased temporal coverage from CRDS instruments is an important advantage, along with the capacity to measure multiple relevant species simultaneously. We give an example of the increased sensitivity to leak detection gained by simultaneous measurement of CH4 and CO2. Da Costa, G. A. and Steele, L. P. (1999). A low-flow analyser system for making measurements of atmospheric CO2. In: Report of the ninth WMO Meeting of Experts on Carbon Dioxide Concentration and Related Tracer Measurement Techniques (Environmental Pollution Monitoring and Research

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

    NASA Astrophysics Data System (ADS)

    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

  9. [Effects of nitrogen fertilization on wheat leaf photosynthesis under elevated atmospheric CO2 concentration].

    PubMed

    Yu, Xian-feng; Zhang, Xu-cheng; Guo, Tian-wen; Yu, Jia

    2010-09-01

    In this paper, the effects of nitrogen (N) fertilization on the wheat leaf photosynthesis under long-term elevated atmospheric CO2 concentration (760 micromol x mol(-1)) was studied, based on the measurements of photosynthetic gas exchange parameters and light intensity-photosynthetic rate response curves at jointing stage. Under the long-term elevated atmospheric CO2 concentration, applying sufficient N could increase the wheat leaf photosynthetic rate (Pn), transpiration rate (Tr), and instantaneous water use efficiency (WUEi). Comparing with those under ambient atmospheric CO2 concentration, the Po and WUEi under the elevated atmospheric CO2 concentration increased, while the stomatal conductance (Gs) and intercellular CO2 concentration (Ci) decreased. With the increase of light flux intensity, the Pn and WUEi under the elevated atmospheric CO2 concentration were higher those under ambient atmospheric CO2 concentration, Gs was in adverse, while Ci and Tr had less change. At high fertilization rate of N, the Gs was linearly positively correlated with Pn, Tr, and WUEi, and the Gs and Ci had no correlation with each other under the elevated atmospheric CO2 concentration but negatively correlated under ambient atmospheric CO2 concentration. At low fertilization rate of N, the Gs had no correlations with Pn and WUEi but linearly positively correlated with Ci and Tr. It was suggested that under the elevated atmospheric CO2 concentration, the wheat leaf Pn at low N fertilization rate was limited by non-stomatal factor.

  10. The future of the carbon cycle: review, calcification response, ballast and feedback on atmospheric CO2.

    PubMed

    Barker, S; Higgins, J A; Elderfield, H

    2003-09-15

    The operation of the carbon cycle forms an important part of the processes relevant to future changes in atmospheric carbon dioxide. The balance of carbon between terrestrial and oceanic reservoirs is an important factor and here we focus in particular on the oceans. Future changes in the carbon cycle that may affect air-sea partitioning of CO(2) are difficult to quantify but the palaeoceanographic record and modern observational studies provide important evidence of what variations might occur. These include changes in surface nutrient use, the oceanic inventory of nutrients, and the elemental composition and rain-rate ratio of marine particles. Recent work has identified two inter-linked processes of potential importance that we consider in some detail: the response of marine calcification to changes in surface water CO(2) and the association of particulate organic carbon with ballast minerals, in particular biogenic calcite. We review evidence from corals, coccolithophores and foraminifera, which suggests that the response of reduced calcification provides a negative feedback on rising atmospheric CO(2). We then use a box model to demonstrate how the calcification response may affect the organic carbon rain rate through the ballast effect. The ballast effect on export fluxes of organic and inorganic carbon acts to counteract the negative calcification response to increased CO(2). Thus, two oceanic buffers exert a significant control on ocean-atmosphere carbonate chemistry: the thermodynamic CO(2) buffer; and the ballast/calcification buffer. Just how tightly coupled the rain-rate ratio of CaCO(3)/C(org) is to fluxes of ballast minerals is an important question for future research.

  11. Effects of explicit atmospheric convection at high CO2.

    PubMed

    Arnold, Nathan P; Branson, Mark; Burt, Melissa A; Abbot, Dorian S; Kuang, Zhiming; Randall, David A; Tziperman, Eli

    2014-07-29

    The effect of clouds on climate remains the largest uncertainty in climate change predictions, due to the inability of global climate models (GCMs) to resolve essential small-scale cloud and convection processes. We compare preindustrial and quadrupled CO2 simulations between a conventional GCM in which convection is parameterized and a "superparameterized" model in which convection is explicitly simulated with a cloud-permitting model in each grid cell. We find that the global responses of the two models to increased CO2 are broadly similar: both simulate ice-free Arctic summers, wintertime Arctic convection, and enhanced Madden-Julian oscillation (MJO) activity. Superparameterization produces significant differences at both CO2 levels, including greater Arctic cloud cover, further reduced sea ice area at high CO2, and a stronger increase with CO2 of the MJO.

  12. Effects of explicit atmospheric convection at high CO2

    PubMed Central

    Arnold, Nathan P.; Branson, Mark; Burt, Melissa A.; Abbot, Dorian S.; Kuang, Zhiming; Randall, David A.; Tziperman, Eli

    2014-01-01

    The effect of clouds on climate remains the largest uncertainty in climate change predictions, due to the inability of global climate models (GCMs) to resolve essential small-scale cloud and convection processes. We compare preindustrial and quadrupled CO2 simulations between a conventional GCM in which convection is parameterized and a “superparameterized” model in which convection is explicitly simulated with a cloud-permitting model in each grid cell. We find that the global responses of the two models to increased CO2 are broadly similar: both simulate ice-free Arctic summers, wintertime Arctic convection, and enhanced Madden–Julian oscillation (MJO) activity. Superparameterization produces significant differences at both CO2 levels, including greater Arctic cloud cover, further reduced sea ice area at high CO2, and a stronger increase with CO2 of the MJO. PMID:25024204

  13. Is guava phenolic metabolism influenced by elevated atmospheric CO2?

    PubMed

    Mendes de Rezende, Fernanda; Pereira de Souza, Amanda; Silveira Buckeridge, Marcos; Maria Furlan, Cláudia

    2015-01-01

    Seedlings of Psidium guajava cv. Pedro Sato were distributed into four open-top chambers: two with ambient CO(2) (∼390 ppm) and two with elevated CO(2) (∼780 ppm). Monthly, five individuals of each chamber were collected, separated into root, stem and leaves and immediately frozen in liquid nitrogen. Chemical parameters were analyzed to investigate how guava invests the surplus carbon. For all classes of phenolic compounds analyzed only tannins showed significant increase in plants at elevated CO(2) after 90 days. There was no significant difference in dry biomass, but the leaves showed high accumulation of starch under elevated CO(2). Results suggest that elevated CO(2) seems to be favorable to seedlings of P. guajava, due to accumulation of starch and tannins, the latter being an important anti-herbivore substance.

  14. Influence of Fossil Fuel Emissions on CO2 Flux Estimation by Atmospheric Inversions

    NASA Astrophysics Data System (ADS)

    Saeki, T.; Patra, P. K.; van der Laan-Luijkx, I. T.; Peters, W.

    2015-12-01

    Top-down approaches (or atmospheric inversions) using atmospheric transport models with CO2 observations are an effective way to estimate carbon fluxes at global and regional scales. CO2 flux estimation by Bayesian inversions require a priori knowledge of terrestrial biosphere and oceanic fluxes and fossil fuel (FF) CO2 emissions. In most inversion frameworks, FF CO2 is assumed to be a known quantity because FF CO2 based on world statistics are thought to be more reliable than natural CO2 fluxes. However different databases of FF CO2 emissions may have different temporal and spatial variations especially at locations where statistics are not so accurate. In this study, we use 3 datasets of fossil fuel emissions in inversion estimations and evaluate the sensitivity of the optimized CO2 fluxes to FF emissions with two different inverse models, JAMSTEC's ACTM and CarbonTracker Europe (CTE). Interannually varying a priori FF CO2 emissions were based on 1) CDIAC database, 2) EDGARv4.2 database, and 3) IEA database, with some modifications. Biosphere and oceanic fluxes were optimized. Except for FF emissions, other conditions were kept the same in our inverse experiments. The three a priori FF emissions showed ~5% (~0.3GtC/yr) differences in their global total emissions in the early 2000's and the differences reached ~9% (~0.9 GtC/yr) in 2010. This resulted in 0.5-1 GtC/yr (2001-2011) and 0.3-0.6 GtC/yr (2007-2011) differences in the estimated global total emissions for the ACTM and CTE inversions, respectively. Regional differences in the FF emissions were relatively large in East Asia (~0.5 GtC/yr for ACTM and ~0.3 GtC/yr for CTE) and Europe (~0.3 GtC/yr for ACTM). These a priori flux differences caused differences in the estimated biosphere fluxes for ACTM in East Asia and Europe and also their neighboring regions such as West Asia, Boreal Eurasia, and North Africa. The main differences in the biosphere fluxes for CTE were found in Asia and the Americas.

  15. Intraspecific variation in juvenile tree growth under elevated CO2 alone and with O3: a meta-analysis.

    PubMed

    Resco de Dios, Víctor; Mereed, Tessema E; Ferrio, Juan Pedro; Tissue, David T; Voltas, Jordi

    2016-06-01

    Atmospheric carbon dioxide (CO2) concentrations are expected to increase throughout this century, potentially fostering tree growth. A wealth of studies have examined the variation in CO2 responses across tree species, but the extent of intraspecific variation in response to elevated CO2 (eCO2) has, so far, been examined in individual studies and syntheses of published work are currently lacking. We conducted a meta-analysis on the effects of eCO2 on tree growth (height, stem biomass and stem volume) and photosynthesis across genotypes to examine whether there is genetic variation in growth responses to eCO2 and to understand their dependence on photosynthesis. We additionally examined the interaction between the responses to eCO2 and ozone (O3), another global change agent. Most of the published studies so far have been conducted in juveniles and in Populus spp., although the patterns observed were not species dependent. All but one study reported significant genetic variation in stem biomass, and the magnitude of intraspecific variation in response to eCO2 was similar in magnitude to previous analyses on interspecific variation. Growth at eCO2 was predictable from growth at ambient CO2 (R(2) = 0.60), and relative rankings of genotype performance were preserved across CO2 levels, indicating no significant interaction between genotypic and environmental effects. The growth response to eCO2 was not correlated with the response of photosynthesis (P > 0.1), and while we observed 57.7% average increases in leaf photosynthesis, stem biomass and volume increased by 36 and 38.5%, respectively, and height only increased by 9.5%, suggesting a predominant role for carbon allocation in ultimately driving the response to eCO2 Finally, best-performing genotypes under eCO2 also responded better under eCO2 and elevated O3 Further research needs include widening the study of intraspecific variation beyond the genus Populus and examining the interaction between eCO2 and

  16. Carbon sequestration and atmospheric CO2 removal: climate consequence and long-term commitment

    NASA Astrophysics Data System (ADS)

    Cao, L.; Caldeira, K.

    2010-12-01

    A variety of methods have been proposed to remove anthropogenic CO2 from the atmosphere and thus mitigate climate change, such as biospheric carbon sequestration, carbon sequestration through enhanced ocean and land weathering, and direct carbon capture from ambient air. Although these proposed methods differ substantially in their physical, chemical, and biological implementations, the ultimate outcome of all schemes is to remove anthropogenic CO2 from the atmosphere. However, the climate effect of atmospheric CO2 removal has not been studied. Here we use an Earth system model to investigate the response of the coupled climate-carbon system to an idealized removal of anthropogenic CO2 from the atmosphere. We use idealized scenarios in our analysis to facilitate exploration of the basic response of the coupled climate-carbon cycle system to proposed methods of removing anthropogenic CO2. In our extreme and idealized simulations, anthropogenic CO2 emissions are halted and all anthropogenic CO2 is removed from the atmosphere at year 2050 under the IPCC A2 CO2 emission scenario. In our simulations a one-time removal of all anthropogenic CO2 in the atmosphere reduces surface air temperature by 0.8°C within a few years, but 1°C surface warming above pre-industrial levels lasts for several centuries. In other words, a one-time removal of 100% excess CO2 from the atmosphere offsets less than 50% of the warming experienced at the time of removal. To maintain atmospheric CO2 and temperature at low levels, not only does anthropogenic CO2 in the atmosphere need to be removed, but anthropogenic CO2 stored in the ocean and land needs to be removed as well when it outgasses to the atmosphere. Our study indicts that the amount of CO2 that would need to be removed from the atmosphere, either by biological means or other means, could be much greater than the desired reduction in atmospheric CO2 concentrations, and may exceed the total burden of excess atmospheric CO2 at the time

  17. CO2 photodissociation and vibrational excitation in the planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Slanger, T. G.

    1974-01-01

    The principal subjects of investigation were the determination of the CO2 photodissociation quantum yields at the wavelengths from 1200 A to 1500 A, and the efficiency of electronic-to-vibrational energy transfer in the systems 0(1D) + CO, N2, CO2 yields 0(3P) + CO N2, CO2 vibrational energies. Measurements on the photodissociation quantum yield of CO2 in the 1200-1500 A region show that it is wavelength dependent, and for the six atomic line sources used, the quantum yield varied from 0.2 to 0.8. The data appear to fit the interpretation of stable CO2 bound states mixed with repulsive or predissociating states, since the low quantum yields coincide with the maximum structure in the CO2 absorption spectrum. The first reliable measurements were made on the efficiency of electronic-to-vibrational energy transfer in the systems 0(1D)-CO and 0(1D)-N2, using a uv resonance fluorescence technique. The 0(1D)-CO2 interaction was investigated by infrared techniques.

  18. Tropical epiphytes in a CO 2-rich atmosphere

    NASA Astrophysics Data System (ADS)

    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.

  19. Comparison of CO2 fluxes estimated using atmospheric and oceanic inversions, and role of fluxes and their interannual variability in simulating atmospheric CO2 concentrations

    NASA Astrophysics Data System (ADS)

    Patra, P. K.; Mikaloff Fletcher, S. E.; Ishijima, K.; Maksyutov, S.; Nakazawa, T.

    2006-07-01

    We use a time-dependent inverse (TDI) model to estimate regional sources and sinks of atmospheric CO2 from 64 and then 22 regions based on atmospheric CO2 observations at 87 stations. The air-sea fluxes from the 64-region atmospheric-CO2 inversion are compared with fluxes from an analogous ocean inversion that uses ocean interior observations of dissolved inorganic carbon (DIC) and other tracers and an ocean general circulation model (OGCM). We find that, unlike previous atmospheric inversions, our flux estimates in the southern hemisphere are generally in good agreement with the results from the ocean inversion, which gives us added confidence in our flux estimates. In addition, a forward tracer transport model (TTM) is used to simulate the observed CO2 concentrations using (1) estimates of fossil fuel emissions and a priori estimates of the terrestrial and oceanic fluxes of CO2, and (2) two sets of TDI model corrected fluxes. The TTM simulations of TDI model corrected fluxes show improvements in fitting the observed interannual variability in growth rates and seasonal cycles in atmospheric CO2. Our analysis suggests that the use of interannually varying (IAV) meteorology and a larger observational network have helped to capture the regional representation and interannual variabilities in CO2 fluxes realistically.

  20. Evidence for CO2 Ice Formation and CO2 Gas Depletion in the South Polar Winter Atmosphere of Mars from Mars Climate Sounder Measurements

    NASA Astrophysics Data System (ADS)

    Kleinboehl, A.; Patel, P.; Schofield, J. T.; Kass, D. M.; Hayne, P. O.; McCleese, D. J.

    2016-09-01

    New 2D retrievals from MCS data show south polar winter atmospheric temperatures below the CO2 frost point, consistent with CO2 gas removal through condensation. Limb emission features suggest CO2 ice occurrence correlated with CO2 gas depletion.

  1. Impact of oceanic circulation changes on atmospheric δ13CO2

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    δ13CO2 measured in Antarctic ice cores provides constraints on oceanic and terrestrial carbon cycle processes linked with millennial-scale and glacial/interglacial changes in atmospheric CO2. However, the interpretation of δ13CO2 is not straightforward. Using two Earth system models of intermediate complexity 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 ocean 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 upwelling 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.

  2. Low atmospheric CO2 levels during the Little Ice Age due to cooling-induced terrestrial uptake

    NASA Astrophysics Data System (ADS)

    Rubino, M.; Etheridge, D. M.; Trudinger, C. M.; Allison, C. E.; Rayner, P. J.; Enting, I.; Mulvaney, R.; Steele, L. P.; Langenfelds, R. L.; Sturges, W. T.; Curran, M. A. J.; Smith, A. M.

    2016-09-01

    Low atmospheric carbon dioxide (CO2) concentration during the Little Ice Age has been used to derive the global carbon cycle sensitivity to temperature. Recent evidence confirms earlier indications that the low CO2 was caused by increased terrestrial carbon storage. It remains unknown whether the terrestrial biosphere responded to temperature variations, or there was vegetation re-growth on abandoned farmland. Here we present a global numerical simulation of atmospheric carbonyl sulfide concentrations in the pre-industrial period. Carbonyl sulfide concentration is linked to changes in gross primary production and shows a positive anomaly during the Little Ice Age. We show that a decrease in gross primary production and a larger decrease in ecosystem respiration is the most likely explanation for the decrease in atmospheric CO2 and increase in atmospheric carbonyl sulfide concentrations. Therefore, temperature change, not vegetation re-growth, was the main cause of the increased terrestrial carbon storage. We address the inconsistency between ice-core CO2 records from different sites measuring CO2 and δ13CO2 in ice from Dronning Maud Land (Antarctica). Our interpretation allows us to derive the temperature sensitivity of pre-industrial CO2 fluxes for the terrestrial biosphere (γL = -10 to -90 Pg C K-1), implying a positive climate feedback and providing a benchmark to reduce model uncertainties.

  3. Variation in Quantum Yield for CO2 Uptake among C3 and C4 Plants 1

    PubMed Central

    Ehleringer, James; Pearcy, Robert W.

    1983-01-01

    The quantum yield for CO2 uptake was measured on a number of C3 and C4 monocot and dicot species. Under normal atmospheric conditions (330 microliters per liter CO2, 21% O2) and a leaf temperature of 30°C, the average quantum yields (moles CO2 per einstein) were as follows: 0.052 for C3 dicots, 0.053 for C3 grasses, 0.053 for NAD-malic enzyme type C4 dicots, 0.060 for NAD-malic enzyme type C4 grasses, 0.064 for phosphoenolpyruvate carboxykinase type C4 grasses, 0.061 for NADP-malic enzyme C4 dicots, and 0.065 for NADP-malic enzyme type C4 grasses. The quantum yield under normal atmospheric conditions was temperature dependent in C3 species, but apparently not in C4 species. Light and temperature conditions during growth appeared not to influence quantum yield. The significance of variation in the quantum yields of C4 plants was discussed in terms of CO2 leakage from the bundle sheath cells and suberization of apoplastic regions of the bundle sheath cells. PMID:16663257

  4. Modeling of collision induced absorption spectra of CO2-CO2 pairs for planetary atmosphere of Venus

    NASA Technical Reports Server (NTRS)

    Borysow, Aleksandra

    1995-01-01

    The objective of the proposal was to model the rototranslational and rotovibrational collision induced absorption spectral bands of importance for the radiative transfer analysis of the atmosphere of Venus. Our main task has involved CO2 pairs. The approach is not straightforward: whereas computational techniques to compute CIA spectra of small linear molecules exist, and were successfully applied to molecules like H2 or N2, they fail when applied to large molecules like CO2. For small molecules one can safely assume that the interaction potential is isotropic. The same approximation does not work for CO2, and when employed, it gives an incorrect band shape and only 50 percent of the CIA intensity.

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

    PubMed

    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.

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

    NASA Astrophysics Data System (ADS)

    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

  7. Speculations on Cold, Dense Atmospheres, Faint Suns, and CO2 Rain

    NASA Astrophysics Data System (ADS)

    Hecht, M. H.

    2016-09-01

    If the early Mars atmosphere was sufficiently dense (>5 bar), liquid CO2 would have been a stable state. The result would be a mixed-phased system, with CO2 rain, lakes, rivers, and maybe oceans, with CO2 frost and snow in colder spots.

  8. Implications of elevated atmospheric CO2 on plant growth and water relations

    USDA-ARS?s Scientific Manuscript database

    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 result in less water use. Competitio...

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

    PubMed

    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.

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

    NASA Astrophysics Data System (ADS)

    Cao, Long; Zhang, Han; Zheng, Meidi; Wang, Shuangjing

    2014-01-01

    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.

  11. Detection of near-atmospheric concentrations of CO2 by an olfactory subsystem in the mouse.

    PubMed

    Hu, Ji; Zhong, Chun; Ding, Cheng; Chi, Qiuyi; Walz, Andreas; Mombaerts, Peter; Matsunami, Hiroaki; Luo, Minmin

    2007-08-17

    Carbon dioxide (CO2) is an important environmental cue for many organisms but is odorless to humans. It remains unclear whether the mammalian olfactory system can detect CO2 at concentrations around the average atmospheric level (0.038%). We demonstrated the expression of carbonic anhydrase type II (CAII), an enzyme that catabolizes CO2, in a subset of mouse olfactory neurons that express guanylyl cyclase D (GC-D+ neurons) and project axons to necklace glomeruli in the olfactory bulb. Exposure to CO2 activated these GC-D+ neurons, and exposure of a mouse to CO2 activated bulbar neurons associated with necklace glomeruli. Behavioral tests revealed CO2 detection thresholds of approximately 0.066%, and this sensitive CO2 detection required CAII activity. We conclude that mice detect CO2 at near-atmospheric concentrations through the olfactory subsystem of GC-D+ neurons.

  12. The 2009-2010 step in atmospheric CO2 inter-hemispheric difference

    NASA Astrophysics Data System (ADS)

    Francey, R. J.; Frederiksen, J. S.

    2015-09-01

    The annual average CO2 difference between baseline data from Mauna Loa and the Southern Hemisphere increased by ∼ 0.8 μmol mol-1 (0.8 ppm) between 2009 and 2010, a step unprecedented in over 50 years of reliable data. We find no evidence for coinciding, sufficiently large and rapid, source/sink changes. A statistical anomaly is unlikely due to the highly systematic nature of the variation in observations. An explanation for the step, and the subsequent 5 year stability in this north-south difference, involves inter-hemispheric atmospheric exchange variation. The selected data describing this episode provide a critical test for studies that employ atmospheric transport models that interpret global carbon budgets and inform management of anthropogenic emissions.

  13. Atmospheric CO2 content in the last 120,000 years: The phosphate-extraction model.

    NASA Astrophysics Data System (ADS)

    Keir, R. S.; Berger, W. H.

    1983-07-01

    Broecker [1982] has proposed that during the retreat of the Wisconsin ice sheets, atmospheric CO2 increased because of the extraction of phosphorus from the ocean as sea level rose. Using a time-dependent box-model, we examine the consequences of the phosphate extraction hypothesis over the last 120,000 years, assuming that δ18O change in core V28-238 is analogous to sea level variation. The model takes into account the total CO2 and alkalinity balance in the deep sea and in an `upper' reservoir consisting of the surface ocean and atmosphere, which are assumed to be in equilibrium. Dissolution of deep-sea calcium carbonate sediment is assumed to respond to the supply of particulate carbonate from the `upper' box and to the dissolved carbonate-ion concentration of the deep sea. Assuming 1015 mole of phosphorus and 1017 mole of carbon were extracted during deglaciation, the predicted increase in pCO2 is 54 ppm. Variation of pCO2 follows the ice-volume forcing function with a 1000 yr lag, which is the input residence time of water in the deep sea. The accumulation (supply minus dissolution) of CaCO3 and the percent preservation (accumulation over supply) follow the derivative of the ice-volume function. Both are similar to the solution index and percent fragments of core V28-238. In addition, unusually good preservation is predicted during deglaciation due to carbon extraction. If phosphorus but not carbon is assumed to be extracted, the accumulation of CaCO3 varies little, remaining near a value equivalent to the river input.

  14. Overestimation of closed-chamber soil CO2 effluxes at low atmospheric turbulence

    NASA Astrophysics Data System (ADS)

    Brændholt, Andreas; Steenberg Larsen, Klaus; Ibrom, Andreas; Pilegaard, Kim

    2017-03-01

    Soil respiration (Rs) is an important component of ecosystem carbon balance, and accurate quantification of the diurnal and seasonal variation of Rs is crucial for a correct interpretation of the response of Rs to biotic and abiotic factors, as well as for estimating annual soil CO2 efflux rates. In this study, we measured Rs hourly for 1 year by automated closed chambers in a temperate Danish beech forest. The data showed a clear diurnal pattern of Rs across all seasons with higher rates during night-time than during daytime. However, further analysis showed a clear negative relationship between flux rates and friction velocity (u∗) above the canopy, suggesting that Rs was overestimated at low atmospheric turbulence throughout the year due to non-steady-state conditions during measurements. Filtering out data at low u∗ values removed or even inverted the observed diurnal pattern, such that the highest effluxes were now observed during daytime, and also led to a substantial decrease in the estimated annual soil CO2 efflux. By installing fans to produce continuous turbulent mixing of air around the soil chambers, we tested the hypothesis that overestimation of soil CO2 effluxes during low u∗ can be eliminated if proper mixing of air is ensured, and indeed the use of fans removed the overestimation of Rs rates during low u∗. Artificial turbulent air mixing may thus provide a method to overcome the problems of using closed-chamber gas-exchange measurement techniques during naturally occurring low atmospheric turbulence conditions. Other possible effects from using fans during soil CO2 efflux measurements are discussed. In conclusion, periods with low atmospheric turbulence may provide a significant source of error in Rs rates estimated by the use of closed-chamber techniques and erroneous data must be filtered out to obtain unbiased diurnal patterns, accurate relationships to biotic and abiotic factors, and before estimating Rs fluxes over longer timescales.

  15. Inter-annual changes in detritus-based food chains can enhance plant growth response to elevated atmospheric CO2.

    PubMed

    Hines, Jes; Eisenhauer, Nico; Drake, Bert G

    2015-12-01

    Elevated atmospheric CO2 generally enhances plant growth, but the magnitude of the effects depend, in part, on nutrient availability and plant photosynthetic pathway. Due to their pivotal role in nutrient cycling, changes in abundance of detritivores could influence the effects of elevated atmospheric CO2 on essential ecosystem processes, such as decomposition and primary production. We conducted a field survey and a microcosm experiment to test the influence of changes in detritus-based food chains on litter mass loss and plant growth response to elevated atmospheric CO2 using two wetland plants: a C3 sedge (Scirpus olneyi) and a C4 grass (Spartina patens). Our field study revealed that organism's sensitivity to climate increased with trophic level resulting in strong inter-annual variation in detritus-based food chain length. Our microcosm experiment demonstrated that increased detritivore abundance could not only enhance decomposition rates, but also enhance plant growth of S. olneyi in elevated atmospheric CO2 conditions. In contrast, we found no evidence that changes in the detritus-based food chains influenced the growth of S. patens. Considered together, these results emphasize the importance of approaches that unite traditionally subdivided food web compartments and plant physiological processes to understand inter-annual variation in plant production response to elevated atmospheric CO2. © 2015 John Wiley & Sons Ltd.

  16. Projected land photosynthesis constrained by changes in the seasonal cycle of atmospheric CO2.

    PubMed

    Wenzel, Sabrina; Cox, Peter M; Eyring, Veronika; Friedlingstein, Pierre

    2016-10-27

    Uncertainties in the response of vegetation to rising atmospheric CO2 concentrations contribute to the large spread in projections of future climate change. Climate-carbon cycle models generally agree that elevated atmospheric CO2 concentrations will enhance terrestrial gross primary productivity (GPP). However, the magnitude of this CO2 fertilization effect varies from a 20 per cent to a 60 per cent increase in GPP for a doubling of atmospheric CO2 concentrations in model studies. Here we demonstrate emergent constraints on large-scale CO2 fertilization using observed changes in the amplitude of the atmospheric CO2 seasonal cycle that are thought to be the result of increasing terrestrial GPP. Our comparison of atmospheric CO2 measurements from Point Barrow in Alaska and Cape Kumukahi in Hawaii with historical simulations of the latest climate-carbon cycle models demonstrates that the increase in the amplitude of the CO2 seasonal cycle at both measurement sites is consistent with increasing annual mean GPP, driven in part by climate warming, but with differences in CO2 fertilization controlling the spread among the model trends. As a result, the relationship between the amplitude of the CO2 seasonal cycle and the magnitude of CO2 fertilization of GPP is almost linear across the entire ensemble of models. When combined with the observed trends in the seasonal CO2 amplitude, these relationships lead to consistent emergent constraints on the CO2 fertilization of GPP. Overall, we estimate a GPP increase of 37 ± 9 per cent for high-latitude ecosystems and 32 ± 9 per cent for extratropical ecosystems under a doubling of atmospheric CO2 concentrations on the basis of the Point Barrow and Cape Kumukahi records, respectively.

  17. Projected land photosynthesis constrained by changes in the seasonal cycle of atmospheric CO2

    NASA Astrophysics Data System (ADS)

    Wenzel, Sabrina; Cox, Peter M.; Eyring, Veronika; Friedlingstein, Pierre

    2016-10-01

    Uncertainties in the response of vegetation to rising atmospheric CO2 concentrations contribute to the large spread in projections of future climate change. Climate-carbon cycle models generally agree that elevated atmospheric CO2 concentrations will enhance terrestrial gross primary productivity (GPP). However, the magnitude of this CO2 fertilization effect varies from a 20 per cent to a 60 per cent increase in GPP for a doubling of atmospheric CO2 concentrations in model studies. Here we demonstrate emergent constraints on large-scale CO2 fertilization using observed changes in the amplitude of the atmospheric CO2 seasonal cycle that are thought to be the result of increasing terrestrial GPP. Our comparison of atmospheric CO2 measurements from Point Barrow in Alaska and Cape Kumukahi in Hawaii with historical simulations of the latest climate-carbon cycle models demonstrates that the increase in the amplitude of the CO2 seasonal cycle at both measurement sites is consistent with increasing annual mean GPP, driven in part by climate warming, but with differences in CO2 fertilization controlling the spread among the model trends. As a result, the relationship between the amplitude of the CO2 seasonal cycle and the magnitude of CO2 fertilization of GPP is almost linear across the entire ensemble of models. When combined with the observed trends in the seasonal CO2 amplitude, these relationships lead to consistent emergent constraints on the CO2 fertilization of GPP. Overall, we estimate a GPP increase of 37 ± 9 per cent for high-latitude ecosystems and 32 ± 9 per cent for extratropical ecosystems under a doubling of atmospheric CO2 concentrations on the basis of the Point Barrow and Cape Kumukahi records, respectively.

  18. A passive sampling method for radiocarbon analysis of atmospheric CO 2 using molecular sieve

    NASA Astrophysics Data System (ADS)

    Garnett, Mark H.; Hartley, Iain P.

    2010-03-01

    Radiocarbon ( 14C) analysis of atmospheric CO 2 can provide information on CO 2 sources and is potentially valuable for validating inventories of fossil fuel-derived CO 2 emissions to the atmosphere. We tested zeolite molecular sieve cartridges, in both field and laboratory experiments, for passively collecting atmospheric CO 2. Cartridges were exposed to the free atmosphere in two configurations which controlled CO 2 trapping rate, allowing collection of sufficient CO 2 in between 1.5 and 10 months at current levels. 14C results for passive samples were within measurement uncertainty of samples collected using a pump-based system, showing that the method collected samples with 14C contents representative of the atmosphere. δ 13C analysis confirmed that the cartridges collected representative CO 2 samples, however, fractionation during passive trapping means that δ 13C values need to be adjusted by an amount which we have quantified. Trapping rate was proportional to atmospheric CO 2 concentration, and was not affected by exposure time unless this exceeded a threshold. Passive sampling using molecular sieve cartridges provides an easy and reliable method to collect atmospheric CO 2 for 14C analysis.

  19. Vertical and horizontal soil CO2 transport and its exchanges with the atmosphere

    NASA Astrophysics Data System (ADS)

    Sánchez-Cañete, Enrique P.; Serrano-Ortíz, Penélope; Kowalski, Andrew S.; Curiel Yuste, Jorge; Domingo, Francisco; Oyonarte, Cecilio

    2015-04-01

    The CO2 efflux from soils to the atmosphere constitutes one of the major fluxes of the terrestrial carbon cycle and is a key determinant for sources and sinks of CO2 in land-atmosphere exchanges. Because of their large global magnitude, even small changes in soil CO2 effluxes directly affect the atmospheric CO2 content. Despite much research, models of soil CO2 efflux rates are highly uncertain, with the positive or negative feedbacks between underground carbon pools and fluxes and their temperature sensitivities in future climate scenarios largely unknown. Now it is necessary to change the point of view regarding CO2 exchange studies from an inappropriately conceived static system in which all respired CO2 is directly emitted by molecular processes to the atmosphere, to a dynamic system with gas transport by three different processes: convection, advection and molecular diffusion. Here we study the effects of wind-induced advection on the soil CO2 molar fraction during two years in a shrubland plateau situated in the Southeast of Spain. A borehole and two subterranean profiles (vertical and horizontal) were installed to study CO2 transport in the soil. Exchanges with the atmosphere were measured by an eddy covariance tower. In the vertical profile, two CO2 sensors (GMP-343, Vaisala) were installed at 0.15m and 1.5m along with soil temperature and humidity probes. The horizontal profile was designed to measure horizontal movements in the soil CO2 molar fraction due to down-gradient CO2 from the plant, where the majority CO2 is produced, towards bare soil. Three CO2 sensors (GMM-222, Vaisala) were installed, the first below plant (under-plant), the second in bare soil separated 25 cm from the first sensor (near-plant) and the third in bare soil at 25 cm from the second sensor (bare soil). The results show how the wind induces the movement of subterranean air masses both horizontally and vertically, affecting atmospheric CO2 exchanges. The eddy covariance tower

  20. Vertical variations in wood CO2 efflux for live emergent trees in a Bornean tropical rainforest.

    PubMed

    Katayama, Ayumi; Kume, Tomonori; Komatsu, Hikaru; Ohashi, Mizue; Matsumoto, Kazuho; Ichihashi, Ryuji; Kumagai, Tomo'omi; Otsuki, Kyoichi

    2014-05-01

    Difficult access to 40-m-tall emergent trees in tropical rainforests has resulted in a lack of data related to vertical variations in wood CO2 efflux, even though significant variations in wood CO2 efflux are an important source of errors when estimating whole-tree total wood CO2 efflux. This study aimed to clarify vertical variations in wood CO2 efflux for emergent trees and to document the impact of the variations on the whole-tree estimates of stem and branch CO2 efflux. First, we measured wood CO2 efflux and factors related to tree morphology and environment for seven live emergent trees of two dipterocarp species at four to seven heights of up to ∼ 40 m for each tree using ladders and a crane. No systematic tendencies in vertical variations were observed for all the trees. Wood CO2 efflux was not affected by stem and air temperature, stem diameter, stem height or stem growth. The ratios of wood CO2 efflux at the treetop to that at breast height were larger in emergent trees with relatively smaller diameters at breast height. Second, we compared whole-tree stem CO2 efflux estimates using vertical measurements with those based on solely breast height measurements. We found similar whole-tree stem CO2 efflux estimates regardless of the patterns of vertical variations in CO2 efflux because the surface area in the canopy, where wood CO2 efflux often differed from that at breast height, was very small compared with that at low stem heights, resulting in little effect of the vertical variations on the estimate. Additionally, whole-tree branch CO2 efflux estimates using measured wood CO2 efflux in the canopy were considerably different from those measured using only breast height measurements. Uncertainties in wood CO2 efflux in the canopy did not cause any bias in stem CO2 efflux scaling, but affected branch CO2 efflux.

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

    PubMed

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

    2014-05-15

    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.

  2. Frequency-doubled CO2 lidar measurement and diode laser spectroscopy of atmospheric CO2

    NASA Technical Reports Server (NTRS)

    Bufton, J. L.; Itabe, T.; Strow, L. L.; Korb, C. L.; Gentry, B. M.; Weng, C. Y.

    1983-01-01

    A lidar instrument based on pulsed frequency-doubled carbon-dioxide lasers has been used at 4.88 microns for remote sensing of atmospheric carbon dioxide. A tunable-diode laser spectrometer provided the high-resolution spectroscopic data on carbon-dioxide line strength and line broadening needed for an accurate differential absorption measurement. Initial field measurements are presented, and instrument improvements necessary for accurate carbon dioxide measurement are discussed.

  3. Linking emissions of fossil fuel CO2 and other anthropogenic trace gases using atmospheric 14CO2

    NASA Astrophysics Data System (ADS)

    Miller, John B.; Lehman, Scott J.; Montzka, Stephen A.; Sweeney, Colm; Miller, Benjamin R.; Karion, Anna; Wolak, Chad; Dlugokencky, Ed J.; Southon, John; Turnbull, Jocelyn C.; Tans, Pieter P.

    2012-04-01

    Atmospheric CO2 gradients are usually dominated by the signal from net terrestrial biological fluxes, despite the fact that fossil fuel combustion fluxes are larger in the annual mean. Here, we use a six year long series of 14CO2 and CO2 measurements obtained from vertical profiles at two northeast U.S. aircraft sampling sites to partition lower troposphere CO2 enhancements (and depletions) into terrestrial biological and fossil fuel components (Cbio and Cff). Mean Cff is 1.5 ppm, and 2.4 ppm when we consider only planetary boundary layer samples. However, we find that the contribution of Cbio to CO2 enhancements is large throughout the year, and averages 60% in winter. Paired observations of Cff and the lower troposphere enhancements (Δgas) of 22 other anthropogenic gases (CH4, CO, halo- and hydrocarbons and others) measured in the same samples are used to determine apparent emission ratios for each gas. We then scale these ratios by the well known U.S. fossil fuel CO2 emissions to provide observationally based estimates of national emissions for each gas and compare these to "bottom up" estimates from inventories. Correlations of Δgas with Cff for almost all gases are statistically significant with median r2for winter, summer and the entire year of 0.59, 0.45, and 0.42, respectively. Many gases exhibit statistically significant winter:summer differences in ratios that indicate seasonality of emissions or chemical destruction. The variability of ratios in a given season is not readily attributable to meteorological or geographic variables and instead most likely reflects real, short-term spatiotemporal variability of emissions.

  4. Synthesis inversion of atmospheric CO2 using the NIRE chemical transport model

    NASA Astrophysics Data System (ADS)

    Taguchi, Shoichi

    Seasonal variations of CO2 emissions from the land biota and oceans are retrieved by use of an inverse method. Concentrations of CO2, computed by an atmospheric chemical transport model (NIRE-CTM-93), are fitted to the observed CO2 concentrations in terms of annual mean concentrations between 1984 to 1985, one-year period components, half-year components, and a global trend averaged over the years 1979 to 1996. The emissions due to fossil fuel combustion, those from land biota consisting of thirteen land areas, and those from the ocean consisting of twelve oceanic areas, are considered. The problem is solved by a least squares method, using singular value decomposition. A prior estimate of the emissions due to fossil fuel combustion is used as a tight constraint. When the annual mean emission, the net flux from the land biota during the growing season, and the net flux from the ocean are loosely constrained to zero, the solution indicates that areas consist of two groups. That is, those areas with relatively reliable estimates and those without. No reliable estimates are obtained for Africa, tropical and South America, tropical Asia, the tropical and the South Atlantic Ocean, and the western tropical Pacific. A reasonable global budget is not obtained due to unreliable estimates. The amplitude of the seasonal variations over middle-latitude North America is found to be less than that of some tropical land areas.

  5. Effect of atmospheric CO2 levels on nutrients in cheatgrass tissue

    USDA-ARS?s Scientific Manuscript database

    Rising atmospheric CO2 has resulted in declining tissue nutrient concentrations and leaf biochemicals, which has potential ramifications for animal nutrition, herbivory and litter decomposition rates. We investigated the interacting effects of atmospheric CO2 concentrations (270, 320, 370, and 420 p...

  6. [CO2 Budget and Atmospheric Rectification (COBRA) Over North America

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The purpose of the CO2 Budget and Rectification Airborne (COBRA) study was to assess terrestrial sources and sinks of carbon dioxide using an air-borne study. The study was designed to address the measurement gap between plot-scale direct flux measurements and background hemispheric-scale constraints and to refine techniques for measuring terrestrial fluxes at regional to continental scales. The initial funded effort (reported on here) was to involve two air-borne campaigns over North America, one in summer and one in winter. Measurements for COBRA (given the acronym C02BAR in the initial proposal) were conducted from the University of North Dakota Citation 11, a twin-engine jet aircraft capable of profiling from the surface to 12 km and cruising for up to 4 hours and 175m/s. Onboard instrumentation measured concentrations of CO2, CO, and H2O, and meteorological parameters at high rates. In addition, two separate flask sampling systems collected discrete samples for laboratory analysis of CO2,CO, CH4, N2O, SF6, H2, 13CO2, C18O16O,O2/N2, and Ar/N2. The project involved a collaboration between a number of institutions, including (but not limited to) Harvard, NOAA-CMDL, the University of North Dakota, and Scripps.

  7. [CO2 Budget and Atmospheric Rectification (COBRA) Over North America

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The purpose of the CO2 Budget and Rectification Airborne (COBRA) study was to assess terrestrial sources and sinks of carbon dioxide using an air-borne study. The study was designed to address the measurement gap between plot-scale direct flux measurements and background hemispheric-scale constraints and to refine techniques for measuring terrestrial fluxes at regional to continental scales. The initial funded effort (reported on here) was to involve two air-borne campaigns over North America, one in summer and one in winter. Measurements for COBRA (given the acronym C02BAR in the initial proposal) were conducted from the University of North Dakota Citation 11, a twin-engine jet aircraft capable of profiling from the surface to 12 km and cruising for up to 4 hours and 175m/s. Onboard instrumentation measured concentrations of CO2, CO, and H2O, and meteorological parameters at high rates. In addition, two separate flask sampling systems collected discrete samples for laboratory analysis of CO2,CO, CH4, N2O, SF6, H2, 13CO2, C18O16O,O2/N2, and Ar/N2. The project involved a collaboration between a number of institutions, including (but not limited to) Harvard, NOAA-CMDL, the University of North Dakota, and Scripps.

  8. On the potential of the ICOS atmospheric CO2 measurement network for estimating the biogenic CO2 budget of Europe

    NASA Astrophysics Data System (ADS)

    Kadygrov, N.; Broquet, G.; Chevallier, F.; Rivier, L.; Gerbig, C.; Ciais, P.

    2015-11-01

    We present a performance assessment of the European Integrated Carbon Observing System (ICOS) atmospheric network for constraining European biogenic CO2 fluxes (hereafter net ecosystem exchange, NEE). The performance of the network is assessed in terms of uncertainty in the fluxes, using a state-of-the-art mesoscale variational atmospheric inversion system assimilating hourly averages of atmospheric data to solve for NEE at 6 h and 0.5° resolution. The performance of the ICOS atmospheric network is also assessed in terms of uncertainty reduction compared to typical uncertainties in the flux estimates from ecosystem models, which are used as prior information by the inversion. The uncertainty in inverted fluxes is computed for two typical periods representative of northern summer and winter conditions in July and in December 2007, respectively. These computations are based on a observing system simulation experiment (OSSE) framework. We analyzed the uncertainty in a 2-week-mean NEE as a function of the spatial scale with a focus on the model native grid scale (0.5°), the country scale and the European scale (including western Russia and Turkey). Several network configurations, going from 23 to 66 sites, and different configurations of the prior uncertainties and atmospheric model transport errors are tested in order to assess and compare the improvements that can be expected in the future from the extension of the network, from improved prior information or transport models. Assimilating data from 23 sites (a network comparable to present-day capability) with errors estimated from the present prior information and transport models, the uncertainty reduction on a 2-week-mean NEE should range between 20 and 50 % for 0.5° resolution grid cells in the best sampled area encompassing eastern France and western Germany. At the European scale, the prior uncertainty in a 2-week-mean NEE is reduced by 50 % (66 %), down to ~ 43 Tg C month-1 (26 Tg C month-1) in July

  9. Long-term spatial and temporal variation of CO2 partial pressure in the Yellow River, China

    NASA Astrophysics Data System (ADS)

    Ran, L.; Lu, X. X.; Richey, J. E.; Sun, H.; Han, J.; Yu, R.; Liao, S.; Yi, Q.

    2015-02-01

    Carbon transport in river systems is an important component of the global carbon cycle. Most rivers of the world act as atmospheric CO2 sources due to high riverine CO2 partial pressure (pCO2). By determining the pCO2 from alkalinity and pH, we investigated its spatial and temporal variation in the Yellow River watershed using historical water chemistry records (1950s-1984) and recent sampling along the mainstem (2011-2012). Except the headwater region where the pCO2 was lower than the atmospheric equilibrium (i.e. 380 μatm), river waters in the remaining watershed were supersaturated with CO2. The average pCO2 for the watershed was estimated at 2810 ± 1985 μatm, which is 7-fold the atmospheric equilibrium. As a result of severe soil erosion and dry climate, waters from the Loess Plateau in the middle reaches had higher pCO2 than that from the upper and lower reaches. From a seasonal perspective, the pCO2 varied from about 200 μatm to > 30 000 μatm with higher pCO2 usually occurring in the dry season and lower pCO2 in the wet season (at 73% of the sampling sites), suggesting the dilution effect of water. While the pCO2 responded exponentially to total suspended solids (TSS) export when the TSS concentration was less than 100 kg m-3, it decreased slightly and remained stable if the TSS concentration exceeded 100 kg m-3. This stable pCO2 is largely due to gully erosion that mobilizes subsoils characterized by low organic carbon for decomposition. In addition, human activities have changed the pCO2 dynamics. Particularly, flow regulation by dams can diversely affect the temporal changes of pCO2, depending on the physiochemical properties of the regulated waters and adopted operation scheme. Given the high pCO2 in the Yellow River waters, large potential for CO2 evasion is expected and warrants further investigation.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

    Qin, X.; Lei, L.; Kawasaki, M.; Oohasi, M.; Zeng, Z.

    2014-03-01

    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.

  12. H2O and CO2 exchange between a sphagnum mire ecosystem and the atmosphere

    NASA Astrophysics Data System (ADS)

    Olchev, Alexander; Volkova, Elena; Karataeva, Tatiana; Novenko, Elena

    2013-04-01

    The modern climatic conditions are strongly influenced by both internal variability of climatic system, and various external natural and anthropogenic factors (IPCC 2007). Significant increase of concentration of greenhouse gases in the atmosphere and especially the growth of atmospheric CO2 due to human activity are considered as the main factors that are responsible for modern global warming and climate changes. A significant part of anthropogenic CO2 is absorbed from the atmosphere by land biota and especially by vegetation cover. However, it is still not completely clear what is the role of different land ecosystems and especially forests and mires in global cycles of H2O and CO2 and what is a sensitivity of these ecosystems to climate changes. Within the framework of this study the spatial and temporal variability of H2O and CO2 fluxes between a mire ecosystem and the atmosphere was described using results of the field measurements and modeling approach. For the study a mire ecosystem located in Tula region in European part of Russia was selected. The selected mire has karst origin, depth of peat float is 2.5-3.0 m (depth of depression is more than 10 meter), area is about 1 ha. The mire vegetation is characterized by sedge and sphagnum mosses cover. The mire is surrounded by broad-leaved forest of about 20 meter high. To describe the temporal and spatial patterns of H2O and CO2 fluxes within selected mire the chamber method was applied. The measurement were carried out along transect from mire edge to center from June to September of 2012. For measurements the transparent ventilated chambers combined with portable infrared CO2/H2O analyzer LI-840 (Li-Cor, USA) was used. To estimate the gross primary production and respiration of different type of vegetation within the mire the measurements were conducted both under actual light conditions and artificial shading. Results of the experimental studies showed that the maximal CO2 fluxes was observed in central

  13. Temporal variations in air permeability and soil CO2 flux in volcanic ash soils (island of Vulcano, Italy)

    NASA Astrophysics Data System (ADS)

    Camarda, Marco; Prano, Vincenzo; Cappuzzo, Santo; Gurrieri, Sergio; Valenza, Mariano

    2017-08-01

    Air permeability is a major physical factor affecting the advective transport of a gas through the soil, and variations in this parameter can strongly influence the emission of endogenous gases from the soil to the atmosphere. In this paper, we illustrated a new and simple method for measuring in situ air permeability based on the measurement of air pressure inside a special probe inserted into the soil. The method was designed and developed primarily to study the relationship between air permeability and the soil CO2 flux in an active volcanic area. The method was used for continuous monitoring of the air permeability at two different locations on the island of Vulcano. At the same time, the values of the atmospheric pressure, temperature, rain, and volumetric water content of the soil were also acquired to investigate their effect on soil air permeability and soil CO2 flux. The results showed that during the monitoring period, soil air permeability exhibited minor variations at each site, while larger variations in the soil CO2 flux were recorded. The effect of soil air permeability on soil CO2 flux was negligible at both sites, whereas a strong dependence of soil CO2 flux on volumetric water content and on atmospheric pressure was found. Furthermore, the variation in air permeability recorded at both sites was much lower than that predicted using some well-known predictive models, showing that the relationship among different soil transport parameters is more complex in real field conditions than would be expected by semiempirical models.

  14. Variations in net CO2 flux across a tropical savanna landscape due to spatial variations in hydrology and land use

    NASA Astrophysics Data System (ADS)

    Arruda, P. H. Z. D.; Vourlitis, G. L.; Santanna, F. B.; Lobo, F. D. A., Sr.; Nogueira, J. D. S.; Pinto-Jr, O. B.

    2016-12-01

    The savanna vegetation of Brazil (Cerrado) accounts for 20-25% of the land cover of Brazil; however, large spatial variations in vegetation type, hydrology, and land use presumably result in large spatial and temporal variations in ecosystem mass and energy exchange. We used eddy covariance to measure the net ecosystem CO2 exchange (NEE) of grass-dominated Cerrado (campo sujo) over three years and partitioned the flux footprint into three sectors that varied with respect to seasonal hydrology (flooded vs. upland) and land use (mowed vs. unmowed). We hypothesized that spatial variations in hydrology and land use would cause spatial variations in the direction and magnitude of net ecosystem CO2 exchange (NEE). Average daily NEE during the wet season for the flooded and unmowed upland sectors ranged between -0.75- -3.25 umol m-2 s-1, while NEE fluxes for the mowed sector ranged between -0.60- +1.50 umol m-2 s-1 (negative values indicate net ecosystem CO2 uptake). Thus, over the 3 year study period the mowed sector was a not source of CO2 to the atmosphere while the flooded and upland sectors were net CO2 sinks during the wet season. In contrast, both upland and flooded sectors were net sources of CO2 to the atmosphere during the dry season while the mowed sector was approximately in balance. Mowing savanna grasses during the dry season caused net daytime NEE (a proxy for net photosynthesis) to increase significantly compared to the flooded and upland surfaces; however, mowed areas had lower daytime NEE during the wet season compared to the other sectors. Nighttime rates of NEE (a proxy for ecosystem respiration) were similar for all sectors regardless of season and land use. Thus, differences in NEE due to seasonal variations in hydrology and land use acted to alter photosynthetic C gain rather than respiration. Our results indicate that the NEE of grass-dominated Cerrado is very sensitive to land management practices that alter leaf area index and photosynthetic C

  15. Quantifying the drivers of ocean-atmosphere CO2 fluxes

    NASA Astrophysics Data System (ADS)

    Lauderdale, Jonathan M.; Dutkiewicz, Stephanie; Williams, Richard G.; Follows, Michael J.

    2016-07-01

    A mechanistic framework for quantitatively mapping the regional drivers of air-sea CO2 fluxes at a global scale is developed. The framework evaluates the interplay between (1) surface heat and freshwater fluxes that influence the potential saturated carbon concentration, which depends on changes in sea surface temperature, salinity and alkalinity, (2) a residual, disequilibrium flux influenced by upwelling and entrainment of remineralized carbon- and nutrient-rich waters from the ocean interior, as well as rapid subduction of surface waters, (3) carbon uptake and export by biological activity as both soft tissue and carbonate, and (4) the effect on surface carbon concentrations due to freshwater precipitation or evaporation. In a steady state simulation of a coarse-resolution ocean circulation and biogeochemistry model, the sum of the individually determined components is close to the known total flux of the simulation. The leading order balance, identified in different dynamical regimes, is between the CO2 fluxes driven by surface heat fluxes and a combination of biologically driven carbon uptake and disequilibrium-driven carbon outgassing. The framework is still able to reconstruct simulated fluxes when evaluated using monthly averaged data and takes a form that can be applied consistently in models of different complexity and observations of the ocean. In this way, the framework may reveal differences in the balance of drivers acting across an ensemble of climate model simulations or be applied to an analysis and interpretation of the observed, real-world air-sea flux of CO2.

  16. Seasonal Variations in CO2 Flux among Arctic Plant Communities in Northern Alaska

    NASA Astrophysics Data System (ADS)

    Kade, A.; Bret-Harte, M. S.

    2010-12-01

    In the context of accelerated warming trends and the potential impacts on net carbon exchange (NEE) from high-latitude systems, we investigated CO2 fluxes of distinct arctic plant communities at the Imnavait Creek watershed in northern Alaska. The goals of this study were to (a) characterize the plant communities found within the footprint of three eddy covariance towers located along a toposequence, (b) study the seasonal variations in plot-level CO2 flux among the vegetation types and (c) relate the plot-level flux measurements to the eddy covariance data. We mapped the vegetation within the footprint of three eddy covariance towers that were installed along a hill slope and selected the major plant communities to measure gross ecosystem productivity (GPP), ecosystem respiration (ER) and NEE during six measurement campaigns from June 2009 to April 2010. We measured midday CO2 concentrations in ecosystem light-response curves with a portable infrared gas analyzer connected to a small clear chamber during the summer and used CO2 concentrations measured at the base of the snow pack to estimate diffusional CO2 flux to the atmosphere during the winter. We scaled plot-level CO2-flux data to the eddy covariance measurements by simply weighting the contribution of the dominant vegetation types according to their mapped percentage cover. The three sites were dominated by frost-disturbed dry heath tundra and moist acidic tundra (MAT) on the hilltop, MAT at mid-slope and MAT and mossy wet sedge tundra in the valley bottom. During the height of the growing season, GEP at 600 μmol/m2/s of light was generally greater at the mid-slope and valley-bottom sites (8.0-9.6 μmol CO2/m2/s), while the dry heath community showed consistently the lowest GEP values (3.3 μmol CO2/m2/s). Similarly, ER was persistently highest in the wet sedge tundra and usually lowest in the dry heath tundra and ridge-top MAT. This resulted in relatively similar NEE values across vegetation types with the

  17. Characteristics of the atmospheric electric field and correlation with CO2 at a rural site in southern Balkans

    NASA Astrophysics Data System (ADS)

    Kastelis, Nikolaos; Kourtidis, Konstantinos

    2016-01-01

    In the current work, 4 years of atmospheric electric field observations at a rural site near Xanthi, Greece, are presented for 2011-2014. The site is situated in an area with very high radon fluxes and high thunderstorm activity. The annual variation is consistent with that at other Northern Hemisphere continental stations, with maxima (minima) occurring during the cold (warm) months. The diurnal variation of the atmospheric electric field both for fair weather (FW) and all weather is found to exhibit a double-peak structure corresponding to local effects and global thunderstorm activity. Comparison with the Carnegie curve shows that nighttime hours and winter months are preferable for observing the Global Electric Circuit at the Xanthi site. Finally, it is shown that atmospheric CO2 measurements can be effectively utilized as a stratification proxy, indicating conditions of potential radon trapping, whereas CO2 was found to anticorrelate with the atmospheric electric field during such conditions.

  18. Reconstructing atmospheric CO2 during the Plio-Pleistocene transition by fossil Typha.

    PubMed

    Bai, Yun-Jun; Chen, Li-Qun; Ranhotra, Parminder S; Wang, Qing; Wang, Yu-Fei; Li, Cheng-Sen

    2015-02-01

    The Earth has undergone a significant climate switch from greenhouse to icehouse during the Plio-Pleistocene transition (PPT) around 2.7-2.4 million years ago (Ma), marked by the intensification of the Northern Hemisphere glaciation (NHG) ~2.7 Ma. Evidence based on oceanic CO2 [(CO2)aq], supposed to be in close equilibrium with the atmospheric CO2 [(CO2)atm], suggests that the CO2 decline might drive such climate cooling. However, the rarity of direct evidence from [CO2]atm during the interval prevents determination of the atmospheric CO2 level and further assessment on the impact of its fluctuation. Here, we reconstruct the [CO2]atm level during 2.77-2.52 Ma based on a new developed proxy of stomatal index on Typha orientalis leaves from Shanxi, North China, and depict the first [CO2]atm curve over the past 5 Ma by using stomata-based [CO2]atm data. Comparisons of the terrestrial-based [CO2]atm and the existed marine-based [CO2]aq curves show a similar general trend but with different intensity of fluctuations. Our data reveal that the high peak of [CO2]atm occurred at 2.77-2.52 Ma with a lower [CO2]aq background. The subsequent sharp fall in [CO2]atm level might be responsible for the intensification of the NHG based on their general temporal synchronism. These findings shed a significant light for our understanding toward the [CO2]atm changes and its ecological impact since 5 Ma.

  19. Quantifying the magnitude and spatiotemporal variation of aquatic CO2 fluxes in a sub-tropical karst catchment, Southwest China

    NASA Astrophysics Data System (ADS)

    Ding, Hu; Waldron, Susan; Newton, Jason; Garnett, Mark H.

    2017-04-01

    The role played by rivers in regional and global C budgets is receiving increasing attention. A large portion of the carbon transported via inland waters is returned to the atmosphere by carbon dioxide evasion from rivers and lakes. Karst landscapes represent an important C store on land, and are also considered to play an important role in climate regulation by consuming atmospheric CO2 during chemical weathering. However, we cannot be certain how effective this sink is if we do not know how efficiently the rivers draining karst landscapes remobilise weathered C to the atmosphere as CO2. pCO2 in karst waters is generally greater than atmospheric equilibrium, indicating that there can be a net CO2 efflux to the atmosphere. However, measurement confirming this and quantifying flux rates has been rarely conducted. Using a floating chamber method, in 2016 we directly measured CO2 fluxes from spatially distributed freshwaters (springs, sinkholes, streams and reservoirs/ponds) in the Houzhai Catchment, a karst region in SW China. Fluxes ranged from -0.5 to +267.4 μmol CO2 m-2s-1, and most sites showed seasonal variations with higher CO2 efflux rates in the wet (April - September) than dry season (October - March). There was a significant positive relationship between CO2 efflux and flow velocity, indicating that hydraulic controls on CO2 efflux from flowing water are important, while for water with little movement (sinkholes and reservoirs/ponds), pCO2 appears a more important control on efflux rates. Conditions similar to this study area may exist in many sub-tropical rivers that drain karst landscapes in South China. These waters are rich in DIC which can be an order of magnitude greater than some non-karst catchments. The large DIC pool has the potential to be a considerable source of free CO2 to the atmosphere. Considering that carbonate lithology covers a significant part of the Earth's surface, CO2 evasion in fluvial water from these regions is expected to

  20. A multiscale and multidisciplinary investigation of ecosystem-atmosphere CO2 exchange over the rocky mountains of colorado

    USGS Publications Warehouse

    Sun, Jielun; Oncley, S.P.; Burns, Sean P.; Stephens, B.B.; Lenschow, D.H.; Campos, T.; Monson, Russell K.; Schimel, D.S.; Sacks, W.J.; De Wekker, S. F. J.; Lai, C.-T.; Lamb, B.; Ojima, D.; Ellsworth, P.Z.; Sternberg, L.S.L.; Zhong, S.; Clements, C.; Moore, D.J.P.; Anderson, D.E.; Watt, A.S.; Hu, Jiawen; Tschudi, M.; Aulenbach, S.; Allwine, E.; Coons, T.

    2010-01-01

    A field study combined with modeling investigation demonstrated that the organization of CO2 transport by mountain terrain strongly affects the regional CO2 budget. Atmospheric dynamics can lead to complicated flows generated by inhomogeneous landscapes, topography or synoptic weather systems. The field campaign conducted of a ground deployment, the Carbon in the Mountain Experiment (CME04), and an aircraft deployment of the national Center for Atmospheric Research (NCAR) C-130, the Airborne Carbon in the Mountains Experiment (ACME04) over the period of spring to fall of 2004 to cover the seasonal variation of ecosystem-atmosphere carbon exchange. The role of the mountain circulation in CO2 transport can be played over seemingly flat terrain by mesoscale flows generated by various physical processes. The three dimensional observation strategy considered can also be applied over flat terrain.

  1. [Contribution of wheat rhizosphere respiration to soil respiration under elevated atmospheric CO2 and nitrogen application].

    PubMed

    Kou, Tai-ji; Xu, Xiao-feng; Zhu, Jian-guo; Xie, Zu-bin; Guo, Da-yong; Miao, Yan-fang

    2011-10-01

    With the support of free-air carbon dioxide enrichment (FACE) system and by using isotope 13C technique, and through planting wheat (Triticum aestivum L., C3 crop) on a soil having been planted with maize (Zea mays L., C4 crop) for many years, this paper studied the effects of elevated atmospheric CO2 and nitrogen application on the delta 13C value of soil emitted CO2 and the wheat rhizosphere respiration. With the growth of wheat, the delta 13C value of soil emitted CO2 had a gradual decrease. Elevated atmospheric CO2 concentration (200 micromol mol(-1)) decreased the delta 13C value of emitted CO2 at booting and heading stages significantly when the nitrogen application rate was 250 kg hm(-2) (HN), and at jointing and booting stages significantly when the nitrogen application rate was 150 kg hm(-2) (LN). Nevertheless, the elevated atmospheric CO2 promoted the proportions of wheat rhizosphere respiration to soil respiration at booting and heading stages significantly. From jointing stage to maturing stage, the proportions of wheat rhizosphere respiration to soil respiration were 24%-48% (HN) and 21%-48% (LN) under elevated atmospheric CO2, and 20%-36% (HN) and 19%-32% (LN) under ambient atmospheric CO2. Under both elevated and ambient atmospheric CO2 concentrations, the delta 13C value of emitted CO2 and the rhizosphere respiration had different responses to the increased nitrogen application rate, and there was a significant interactive effect of atmospheric CO2 concentration and nitrogen application rate on the wheat rhizosphere respiration at jointing stage.

  2. Climate change and the middle atmosphere. I - The doubled CO2 climate

    NASA Technical Reports Server (NTRS)

    Rind, D.; Prather, M. J.; Suozzo, R.; Balachandran, N. K.

    1990-01-01

    The effect of doubling the atmospheric content of CO2 on the middle-atmosphere climate is investigated using the GISS global climate model. In the standard experiment, the CO2 concentration is doubled both in the stratosphere and troposphere, and the SSTs are increased to match those of the doubled CO2 run of the GISS model. Results show that the doubling of CO2 leads to higher temperatures in the troposphere, and lower temperatures in the stratosphere, with a net result being a decrease of static stability for the atmosphere as a whole. The middle atmosphere dynamical differences found were on the order of 10-20 percent of the model values for the current climate. These differences, along with the calculated temperature differences of up to about 10 C, may have a significant impact on the chemistry of the future atmosphere, including that of stratospheric ozone, the polar ozone 'hole', and basic atmospheric composition.

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

    PubMed Central

    Thomson, David J.

    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 temperature during the last century is at least 20 times the SD of the residual temperature series left when the effects of CO2 and changes in solar irradiance are subtracted. PMID:11607747

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

    PubMed

    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. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Synchronous change of atmospheric CO2 and Antarctic temperature during the last deglacial warming.

    PubMed

    Parrenin, F; Masson-Delmotte, V; Köhler, P; Raynaud, D; Paillard, D; Schwander, J; Barbante, C; Landais, A; Wegner, A; Jouzel, J

    2013-03-01

    Understanding the role of atmospheric CO2 during past climate changes requires clear knowledge of how it varies in time relative to temperature. Antarctic ice cores preserve highly resolved records of atmospheric CO2 and Antarctic temperature for the past 800,000 years. Here we propose a revised relative age scale for the concentration of atmospheric CO2 and Antarctic temperature for the last deglacial warming, using data from five Antarctic ice cores. We infer the phasing between CO2 concentration and Antarctic temperature at four times when their trends change abruptly. We find no significant asynchrony between them, indicating that Antarctic temperature did not begin to rise hundreds of years before the concentration of atmospheric CO2, as has been suggested by earlier studies.

  6. Deep CO2 soil inhalation / exhalation induced by synoptic pressure changes and atmospheric tides in a carbonated semiarid steppe

    NASA Astrophysics Data System (ADS)

    Sánchez-Cañete, E. P.; Kowalski, A. S.; Serrano-Ortiz, P.; Pérez-Priego, O.; Domingo, F.

    2013-10-01

    Knowledge of all the mechanisms and processes involved in soil CO2 emissions is essential to close the global carbon cycle. Apart from molecular diffusion, the main physical component of such CO2 exchange is soil ventilation. Advective CO2 transport, through soil or snow, has been correlated with the wind speed, friction velocity or pressure (p). Here we examine variations in subterranean CO2 molar fractions (χc) over two years within a vertical profile (1.5 m) in a semiarid ecosystem, as influenced by short-timescale p changes. Analyses to determine the factors involved in the variations in subterranean χc were differentiated between the growing period and the dry period. In both periods it was found that variations in deep χc (0.5-1.5 m) were due predominantly to static p variations and not to wind or biological influences. Within a few hours, the deep χc can vary by fourfold, showing a pattern with two cycles per day, due to p oscillations caused by atmospheric tides. By contrast, shallow χc (0.15 m) generally has one cycle per day as influenced by biological factors like soil water content and temperature in both periods, while the wind was an important factor in shallow χc variations only during the dry period. Evidence of emissions was registered in the atmospheric boundary layer by eddy covariance during synoptic pressure changes when subterranean CO2 was released; days with rising barometric pressure - when air accumulated belowground, including soil-respired CO2 - showed greater ecosystem uptake than days with falling pressure. Future assessments of the net ecosystem carbon balance should not rely exclusively on Fick's law to calculate soil CO2 effluxes from profile data.

  7. Tree growth variation in the tropical forest: understanding effects of temperature, rainfall and CO2.

    PubMed

    Schippers, Peter; Sterck, Frank; Vlam, Mart; Zuidema, Pieter A

    2015-01-28

    Tropical forest responses to climatic variability have important consequences for global carbon cycling, but are poorly understood. As empirical, correlative studies cannot disentangle the interactive effects of climatic variables on tree growth, we used a tree growth model (IBTREE) to unravel the climate effects on different physiological pathways and in turn on stem growth variation. We parameterized the model for canopy trees of Toona ciliata (Meliaceae) from a Thai monsoon forest and compared predicted and measured variation from a tree-ring study over a 30-year period. We used historical climatic variation of minimum and maximum day temperature, precipitation and carbon dioxide (CO2 ) in different combinations to estimate the contribution of each climate factor in explaining the inter-annual variation in stem growth. Running the model with only variation in maximum temperature and rainfall yielded stem growth patterns that explained almost 70% of the observed inter-annual variation in stem growth. Our results show that maximum temperature had a strong negative effect on the stem growth by increasing respiration, reducing stomatal conductance and thus mitigating a higher transpiration demand, and - to a lesser extent - by directly reducing photosynthesis. Although stem growth was rather weakly sensitive to rain, stem growth variation responded strongly and positively to rainfall variation owing to the strong inter-annual fluctuations in rainfall. Minimum temperature and atmospheric CO2 concentration did not significantly contribute to explaining the inter-annual variation in stem growth. Our innovative approach - combining a simulation model with historical data on tree-ring growth and climate - allowed disentangling the effects of strongly correlated climate variables on growth through different physiological pathways. Similar studies on different species and in different forest types are needed to further improve our understanding of the sensitivity of

  8. The effect of anthropogenic emissions corrections on the seasonal cycle of atmospheric CO2

    NASA Astrophysics Data System (ADS)

    Brooks, B. J.; Hoffman, F. M.; Mills, R. T.; Erickson, D. J.; Blasing, T. J.

    2009-12-01

    A previous study (Erickson et al. 2008) approximated the monthly global emission estimates of anthropogenic CO2 by applying a 2-harmonic Fourier expansion with coefficients as a function of latitude to annual CO2 flux estimates derived from United States data (Blasing et al. 2005) that were extrapolated globally. These monthly anthropogenic CO2 flux estimates were used to model atmospheric concentrations using the NASA GEOS-4 data assimilation system. Local variability in the amplitude of the simulated CO2 seasonal cycle were found to be on the order of 2-6 ppmv. Here we used the same Fourier expansion to seasonally adjust the global annual fossil fuel CO2 emissions from the SRES A2 scenario. For a total of four simulations, both the annual and seasonalized fluxes were advected in two configurations of the NCAR Community Atmosphere Model (CAM) used in the Carbon-Land Model Intercomparison Project (C-LAMP). One configuration used the NCAR Community Land Model (CLM) coupled with the CASA‧ (carbon only) biogeochemistry model and the other used CLM coupled with the CN (coupled carbon and nitrogen cycles) biogeochemistry model. All four simulations were forced with observed sea surface temperatures and sea ice concentrations from the Hadley Centre and a prescribed transient atmospheric CO2 concentration for the radiation and land forcing over the 20th century. The model results exhibit differences in the seasonal cycle of CO2 between the seasonally corrected and uncorrected simulations. Moreover, because of differing energy and water feedbacks between the atmosphere model and the two land biogeochemistry models, features of the CO2 seasonal cycle were different between these two model configurations. This study reinforces previous findings that suggest that regional near-surface atmospheric CO2 concentrations depend strongly on the natural sources and sinks of CO2, but also on the strength of local anthropogenic CO2 emissions and geographic position. This work further

  9. Photosynthetic adaptations to low atmospheric CO2 evels of the Late Pleistocene

    SciTech Connect

    Sage, R.F.

    1995-06-01

    The Pleistocene was a period where atmospheric CO2 level fell to its lowest point (180 ppm) of the past 200 million years. At these low levels. photosynthesis in C3 plants is strongly limited by the availability of CO2 for the carboxylation reaction of Rubisco, and by photorespiration, which becomes extensive above 20{degrees}C. A reduction of CO2 to 180 ppm results in a mean 50% decline in photosynthesis relative to the rate at 350 ppm CO2. Plants can potentially adapt to low atmospheric CO2 by either increasing the specificity of Rubisco for CO2, minimizing leaf temperature, or through faster CO2 delivery to the chloroplast. Of these mechanisms, the facilitation of CO2 delivery (via C4, HCO3-1 pumping, or carbonic anhydrase) has been the most effective. Differences in Rubisco specificity for CO2 are not pronounced in organisms containing chloroplasts, indicating little evolutionary advancement in Rubisco in recent geological times. Avoidance of elevated leaf temperature through morphological, temporal, or stomatal adjustments has been of limited value, and usually involves a significant cost. Given the pronounced reduction in photosyntheticpotential because of low CO2 during the Pleistocene, it is not readily apparent how C3 species were able to maintain widespread dominance in the presence of CO2-concentrating species such as C4 plants. Paleo-ecological surveys indicate they did, however. Possible mechanisms for ecological success of C3 plants during the Pleistocene will be discussed.

  10. Rapid Cenozoic glaciation of Antarctica induced by declining atmospheric CO2.

    PubMed

    DeConto, Robert M; Pollard, David

    2003-01-16

    The sudden, widespread glaciation of Antarctica and the associated shift towards colder temperatures at the Eocene/Oligocene boundary (approximately 34 million years ago) (refs 1-4) is one of the most fundamental reorganizations of global climate known in the geologic record. The glaciation of Antarctica has hitherto been thought to result from the tectonic opening of Southern Ocean gateways, which enabled the formation of the Antarctic Circumpolar Current and the subsequent thermal isolation of the Antarctic continent. Here we simulate the glacial inception and early growth of the East Antarctic Ice Sheet using a general circulation model with coupled components for atmosphere, ocean, ice sheet and sediment, and which incorporates palaeogeography, greenhouse gas, changing orbital parameters, and varying ocean heat transport. In our model, declining Cenozoic CO2 first leads to the formation of small, highly dynamic ice caps on high Antarctic plateaux. At a later time, a CO2 threshold is crossed, initiating ice-sheet height/mass-balance feedbacks that cause the ice caps to expand rapidly with large orbital variations, eventually coalescing into a continental-scale East Antarctic Ice Sheet. According to our simulation the opening of Southern Ocean gateways plays a secondary role in this transition, relative to CO2 concentration.

  11. Southern Ocean acidification: A tipping point at 450-ppm atmospheric CO2

    PubMed Central

    McNeil, Ben I.; Matear, Richard J.

    2008-01-01

    Southern Ocean acidification via anthropogenic CO2 uptake is expected to be detrimental to multiple calcifying plankton species by lowering the concentration of carbonate ion (CO32−) to levels where calcium carbonate (both aragonite and calcite) shells begin to dissolve. Natural seasonal variations in carbonate ion concentrations could either hasten or dampen the future onset of this undersaturation of calcium carbonate. We present a large-scale Southern Ocean observational analysis that examines the seasonal magnitude and variability of CO32− and pH. Our analysis shows an intense wintertime minimum in CO32− south of the Antarctic Polar Front and when combined with anthropogenic CO2 uptake is likely to induce aragonite undersaturation when atmospheric CO2 levels reach ≈450 ppm. Under the IPCC IS92a scenario, Southern Ocean wintertime aragonite undersaturation is projected to occur by the year 2030 and no later than 2038. Some prominent calcifying plankton, in particular the Pteropod species Limacina helicina, have important veliger larval development during winter and will have to experience detrimental carbonate conditions much earlier than previously thought, with possible deleterious flow-on impacts for the wider Southern Ocean marine ecosystem. Our results highlight the critical importance of understanding seasonal carbon dynamics within all calcifying marine ecosystems such as continental shelves and coral reefs, because natural variability may potentially hasten the onset of future ocean acidification. PMID:19022908

  12. Southern Ocean acidification: a tipping point at 450-ppm atmospheric CO2.

    PubMed

    McNeil, Ben I; Matear, Richard J

    2008-12-02

    Southern Ocean acidification via anthropogenic CO(2) uptake is expected to be detrimental to multiple calcifying plankton species by lowering the concentration of carbonate ion (CO(3)(2-)) to levels where calcium carbonate (both aragonite and calcite) shells begin to dissolve. Natural seasonal variations in carbonate ion concentrations could either hasten or dampen the future onset of this undersaturation of calcium carbonate. We present a large-scale Southern Ocean observational analysis that examines the seasonal magnitude and variability of CO(3)(2-) and pH. Our analysis shows an intense wintertime minimum in CO(3)(2-) south of the Antarctic Polar Front and when combined with anthropogenic CO(2) uptake is likely to induce aragonite undersaturation when atmospheric CO(2) levels reach approximately 450 ppm. Under the IPCC IS92a scenario, Southern Ocean wintertime aragonite undersaturation is projected to occur by the year 2030 and no later than 2038. Some prominent calcifying plankton, in particular the Pteropod species Limacina helicina, have important veliger larval development during winter and will have to experience detrimental carbonate conditions much earlier than previously thought, with possible deleterious flow-on impacts for the wider Southern Ocean marine ecosystem. Our results highlight the critical importance of understanding seasonal carbon dynamics within all calcifying marine ecosystems such as continental shelves and coral reefs, because natural variability may potentially hasten the onset of future ocean acidification.

  13. Three-Dimensional Tracer Model Study of Atmospheric CO2 - Response to Seasonal Exchanges with the Terrestrial Biosphere

    NASA Technical Reports Server (NTRS)

    Fung, I.; Prentice, K.; Matthews, E.; Lerner, J.; Russell, G.

    1983-01-01

    A three-dimensional tracer transport model is used to investigate the annual cycle of atmospheric CO2 concentration produced by seasonal exchanges with the terrestrial biosphere. The tracer model uses winds generated by a global general circulation model to advect and convect CO2; no explicit diffusion coefficients are employed. A biospheric exchange function constructed from a map of net primary productivity, and Azevedo's (1982) seasonality of CO2 uptake and release closely simulates the annual cycles at coastal stations. The results show that zonal homogeneity in surface CO2 concentrations can never be achieved at mid-latitudes where the time scale for zonal mixing is longer than the time scale for biospheric exchange. Analysis of the zonal mean balance in the lower troposphere reveals that atmospheric transport processes may alter the CO2 response to local biospheric exchanges by 50% or more. Hence year-to-year variation of the annual CO2 cycle may result from the natural variability of the atmospheric circulation as well as from changes in the sources and sinks.

  14. Atmospheric CO2 and abrupt climate change in Antarctic warming events 3 and 4 (65 ~ 48 kyrBP)

    NASA Astrophysics Data System (ADS)

    Ahn, J.; Brook, E. J.

    2006-12-01

    Understanding phase relationship between atmospheric CO2 and abrupt climate change (e.g., Dansgaard- Oeschger [D-O] and Heinrich events) in the last glacial period has been hampered by uncertain chronology of CO2 records from Antarctic ice cores. We developed a new extraction/analytical system to measure CO2 in ice cores, and are using it to examine millennial variations of atmospheric CO2 in the Byrd ice core, which has an age scale well synchronized to Greenland cores using CH4 records. Duplicate measurements of the Byrd ice show average standard error of the mean and pooled standard deviation of 1.55 and 1.98 ppm CO2, respectively. Our preliminary data cover Antarctic warming events A3 and A4, the onset of which precedes D-O events 14 and 17. For A3 and A4 the initial CO2 rise precedes the corresponding D-O events by 2 and 4 kyrs, respectively. CO2 reaches final interstadial levels during A4 approximately 2 kyrs before the onset of D-O 17, but the CO2 rise during A3 is more abrupt, with over half of the ~17 ppm change occurring in a <600 year step immediately preceding D-O event 14. Further high time-resolution measurements of CO2 concentration in the Byrd ice core are in progress and may help us understand the carbon cycle, teleconnection of climate-related factors such as CH4 and biological productivity recorded in marine sediments and temperatures in northern and southern hemispheres, and the chronology of other Antarctic ice cores using CO2 as a correlation tool.

  15. Characterizing Uncertainties in Atmospheric Inversions of Fossil Fuel CO2 Emissions in California

    NASA Astrophysics Data System (ADS)

    Brophy, K. J.; Graven, H. D.; Manning, A.; Arnold, T.; Fischer, M. L.; Jeong, S.; Cui, X.; Parazoo, N.

    2016-12-01

    In 2006 California passed a law requiring greenhouse gas emissions be reduced to 1990 levels by 2020, equivalent to a 20% reduction over 2006-2020. Assessing compliance with greenhouse gas mitigation policies requires accurate determination of emissions, particularly for CO2 emitted by fossil fuel combustion (ffCO2). We found differences in inventory-based ffCO2 flux estimates for California total emissions of 11% (standard deviation relative to the mean), and even larger differences on some smaller sub-state levels. Top-down studies may be useful for validating ffCO2 flux estimates, but top-down studies of CO2 typically focus on biospheric CO2 fluxes and they are not yet well-developed for ffCO2. Implementing top-down studies of ffCO2 requires observations of a fossil fuel combustion tracer such as 14C to distinguish ffCO2 from biospheric CO2. However, even if a large number of 14C observations are available, multiple other sources of uncertainty will contribute to the uncertainty in posterior ffCO2 flux estimates. With a Bayesian inverse modelling approach, we use simulated atmospheric observations of ffCO2 at a network of 11 tower sites across California in an observing system simulation experiment to investigate uncertainties. We use four different prior ffCO2 flux estimates, two different atmospheric transport models, different types of spatial aggregation, and different assumptions for observational and model transport uncertainties to investigate contributions to posterior ffCO2 emission uncertainties. We show how various sources of uncertainty compare and which uncertainties are likely to limit top-down estimation of ffCO2 fluxes in California.

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

    NASA Astrophysics Data System (ADS)

    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.

  17. Ten Years of Robust Sources and Sinks of Atmospheric CO2 inferred from 13CO2 and pCO2 Measurements in the NOAA/CMDL Network

    NASA Astrophysics Data System (ADS)

    White, J. W.; Miller, J. B.; Tans, P. P.; Conway, T. J.

    2003-12-01

    Prediction of future climate is dependent upon the trajectory of the rising concentration of carbon dioxide, which is, in turn, dependent upon the operation of both the terrestrial and oceanic components of the carbon cycle. Because the uptake of carbon in the oceans and land operates via different mechanisms, it is useful to calculate separately the uptake (or release) by each. Atmospheric measurements of CO2 concentrations and the relative carbon-13 content offer the possibility to resolve oceanic and terrestrial carbon fluxes at relatively high spatial and temporal resolution. Even though the global totals of oceanic and terrestrial uptake derived using d13C are somewhat uncertain, we will show that both the spatial and temporal patterns are robust. Since 1990, nearly 90,000 d13CO2 measurements have been made on air collected from more than 60 globally distributed sites in the NOAA/CMDL air sampling network. When combined with measurements of CO2 made on the same air, these data allow us to calculate the oceanic and terrestrial contributions to the total surface uptake of CO2 as a function of space and time. The most prominent result of our analysis is the large and sustained uptake of carbon in the temperate Northern Hemisphere (TNH), punctuated by periods of enhanced uptake centered around 1992 and 1997. The mean size of the uptake in the TNH is ~3+/-1 GTonC/yr, roughly half the size of the total fossil fuel flux to the atmosphere. The earlier period of enhanced uptake may be associated with the eruption of Mt. Pinatubo in 1991. The reasons for the enhanced terrestrial uptake in 1997 are less clear. The next result that stands out is the large release of carbon from the tropical biosphere that occurred during the 1997-1998 El Nino. The 1998 terrestrial flux in the tropics is about 2 to 3 GTon C more than the 1991-1997 mean. Coinciding with the SST transition typical of El Nino, we also estimate that tropical oceanic fluxes rose 2 by GtonC, sustained for two

  18. A data driven model for the impact of IFT and density variations on CO2 storage capacity in geologic formations

    NASA Astrophysics Data System (ADS)

    Nomeli, Mohammad A.; Riaz, Amir

    2017-09-01

    Carbon dioxide (CO2) storage in depleted hydrocarbon reservoirs and deep saline aquifers is one of the most promising solutions for decreasing CO2 concentration in the atmosphere. One of the important issues for CO2 storage in subsurface environments is the sealing efficiency of low-permeable cap-rocks overlying potential CO2 storage reservoirs. Though we focus on the effect of IFT in this study as a factor influencing sealing efficiency or storage capacity, other factors such as interfacial interactions, wettability, pore radius and interfacial mass transfer also affect the mobility and storage capacity of CO2 phase in the pore space. The study of the variation of IFT is however important because the pressure needed to penetrate a pore depends on both the pore size and the interfacial tension. Hence small variations in IFT can affect flow across a large population of pores. A novel model is proposed to find the IFT of the ternary systems (CO2/brine-salt) in a range of temperatures (300-373 K), pressures (50-250 bar), and up to 6 molal salinity applicable to CO2 storage in geological formations through a multi-variant non-linear regression of experimental data. The method uses a general empirical model for the quaternary system CO2/brine-salts that can be made to coincide with experimental data for a variety of solutions. We introduce correction parameters into the model, which compensates for uncertainties, and enforce agreement with experimental data. The results for IFT show a strong dependence on temperature, pressure, and salinity. The model has been found to describe the experimental data in the appropriate parameter space with reasonable precision. Finally, we use the new model to evaluate the effects of formation depth on the actual efficiency of CO2 storage. The results indicate that, in the case of CO2 storage in deep subsurface environments as a global-warming mitigation strategy, CO2 storage capacity increases with reservoir depth.

  19. [Influence of elevated atmospheric CO2 on rhizosphere microbes and arbuscular mycorrhizae].

    PubMed

    Chen, Jing; Chen, Xin; Tang, Jianjun

    2004-12-01

    The changes of microbial communities in rhizosphere and the formation of mycorrhizae play an important role in affecting the dynamics of plant communities and terrestrial ecosystems. This paper summarized and discussed the effects of elevated atmospheric CO2 on them. Under elevated atmospheric CO2, the carbohydrates accumulated in root systems increased, and the rhizospheric environment and its microbial communities as well as the formation of mycorrhizae changed. It is suggested that the researches in the future should be focused on the effects of rhizosphere microbes and arbuscular mycorrhizae on regulating the carbon dynamics of plant communities and terrestrial ecosystems under elevated atmospheric CO2.

  20. Shock-induced CO2 loss from CaCO3: Implications for early planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Lange, M. A.; Ahrens, T. J.

    1984-01-01

    Recovered samples from shock recovery experiments on single crystal calcite were subjected to thermogravimetric analysis to determine the amount of post-shock CO2, the decarbonization interval and the activation energy, for the removal of remaining CO2 in shock-loaded calcite. Comparison of post-shock CO2 with that initially present determines shock-induced CO2 loss as a function of shock pressure. Incipient to complete CO2 loss occurs over a pressure range of approximately 10 to approximately 70 GPa. Optical and scanning electron microscopy reveal structural changes, which are related to the shock-loading. The occurrence of dark, diffuse areas, which can be resolved as highly vesicular areas as observed with a scanning electron microscope are interpreted as representing quenched partial melts, into which shock-released CO2 was injected. The experimental results are used to constrain models of shock-produced, primary CO2 atmospheres on the accreting terrestrial planets.

  1. Winds induce CO2 exchange with the atmosphere and vadose zone transport in a karstic ecosystem

    NASA Astrophysics Data System (ADS)

    Sánchez-Cañete, Enrique P.; Oyonarte, Cecilio; Serrano-Ortiz, Penélope; Curiel Yuste, Jorge; Pérez-Priego, Oscar; Domingo, Francisco; Kowalski, Andrew S.

    2016-08-01

    Research on the subterranean CO2 dynamics has focused individually on either surface soils or bedrock cavities, neglecting the interaction of both systems as a whole. In this regard, the vadose zone contains CO2-enriched air (ca. 5% by volume) in the first meters, and its exchange with the atmosphere can represent from 10 to 90% of total ecosystem CO2 emissions. Despite its importance, to date still lacking are reliable and robust databases of vadose zone CO2 contents that would improve knowledge of seasonal-annual aboveground-belowground CO2 balances. Here we study 2.5 years of vadose zone CO2 dynamics in a semiarid ecosystem. The experimental design includes an integrative approach to continuously measure CO2 in vertical and horizontal soil profiles, following gradients from surface to deep horizons and from areas of net biological CO2 production (under plants) to areas of lowest CO2 production (bare soil), as well as a bedrock borehole representing karst cavities and ecosystem-scale exchanges. We found that CO2 followed similar seasonal patterns for the different layers, with the maximum seasonal values of CO2 delayed with depth (deeper more delayed). However, the behavior of CO2 transport differed markedly among layers. Advective transport driven by wind induced CO2 emission both in surface soil and bedrock, but with negligible effect on subsurface soil, which appears to act as a buffer impeding rapid CO2 exchanges. Our study provides the first evidence of enrichment of CO2 under plant, hypothesizing that CO2-rich air could come from root zone or by transport from deepest layers through cracks and fissures.

  2. Horizontal displacement of carbon associated with agriculture and its impacts on atmospheric CO2

    NASA Astrophysics Data System (ADS)

    Ciais, P.; Bousquet, P.; Freibauer, A.; Naegler, T.

    2007-06-01

    The growth of crops represents a sink of atmospheric CO2, whereas biomass is consumed by humans and housed animals, yielding respiratory sources of CO2. This process induces a lateral displacement of carbon and creates geographic patterns of CO2 sources and sinks at the surface of the globe. We estimated the global carbon flux harvested in croplands to be 1290 TgC/yr. Most of this carbon is transported into domestic trade, whereas a small fraction (13%) enters into international trade circuits. We then calculated the global patterns of CO2 fluxes associated with food and feedstuff trade, using country-based agricultural statistics and activity maps of human and housed animal population densities. The CO2 flux maps show regional dipoles of sources and sinks in Asia and North America. The effect of these fluxes on atmospheric CO2 was simulated using a global atmospheric transport model. The mean latitudinal CO2 gradients induced by the displacement of crop products are fairly small (≈0.2 ppm) compared with observations (4-5 ppm), indicating that this process has a only a small influence in explaining the latitudinal distribution of CO2 fluxes. On the other hand, the simulated longitudinal mean atmospheric CO2 gradients at northern midlatitudes (≈ up to 0.5 ppm) are comparable to the ones measured between atmospheric stations, suggesting that CO2 fluxes from crop products trade are an important component of continental- and regional-scale CO2 budgets. Thus they should be accounted for as prior information in regional inversions.

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

    NASA Astrophysics Data System (ADS)

    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

  4. 12CO2 emission from different metabolic pathways measured in illuminated and darkened C3 and C4 leaves at low, atmospheric and elevated CO2 concentration.

    PubMed

    Pinelli, Paola; Loreto, Francesco

    2003-07-01

    The detection of 12CO2 emission from leaves in air containing 13CO2 allows simple and fast determination of the CO2 emitted by different sources, which are separated on the basis of their labelling velocity. This technique was exploited to investigate the controversial effect of CO2 concentration on mitochondrial respiration. The 12CO2 emission was measured in illuminated and darkened leaves of one C4 plant and three C3 plants maintained at low (30-50 ppm), atmospheric (350-400 ppm) and elevated (700-800 ppm) CO2 concentration. In C3 leaves, the 12CO2 emission in the light (Rd) was low at ambient CO2 and was further quenched in elevated CO2, when it was often only 20-30% of the 12CO2 emission in the dark, interpreted as the mitochondrial respiration in the dark (Rn). Rn was also reduced in elevated CO2. At low CO2, Rd was often 70-80% of Rn, and a burst of 12CO2 was observed on darkening leaves of Mentha sativa and Phragmites australis after exposure for 4 min to 13CO2 in the light. The burst was partially removed at low oxygen and was never observed in C4 leaves, suggesting that it may be caused by incomplete labelling of the photorespiratory pool at low CO2. This pool may be low in sclerophyllous leaves, as in Quercus ilex where no burst was observed. Rd was inversely associated with photosynthesis, suggesting that the Rd/Rn ratio reflects the refixation of respiratory CO2 by photosynthesizing leaves rather than the inhibition of mitochondrial respiration in the light, and that CO2 produced by mitochondrial respiration in the light is mostly emitted at low CO2, and mostly refixed at elevated CO2. In the leaves of the C4 species Zea mays, the 12CO2 emission in the light also remained low at low CO2, suggesting efficient CO2 refixation associated with sustained photosynthesis in non-photorespiratory conditions. However, Rn was inhibited in CO2-free air, and the velocity of 12CO2 emission after darkening was inversely associated with the CO2 concentration. The

  5. Stomatal frequency adjustment of four conifer species to historical changes in atmospheric CO2.

    PubMed

    Kouwenberg, Lenny L R; McElwain, Jennifer C; Kürschner, Wolfram M; Wagner, Friederike; Beerling, David J; Mayle, Francis E; Visscher, Henk

    2003-04-01

    The species-specific inverse relation between atmospheric CO(2) concentration and stomatal frequency for many woody angiosperm species is being used increasingly with fossil leaves to reconstruct past atmospheric CO(2) levels. To extend our limited knowledge of the responsiveness of conifer needles to CO(2) fluctuations, the stomatal frequency response of four native North American conifer species (Tsuga heterophylla, Picea glauca, Picea mariana, and Larix laricina) to a range of historical CO(2) mixing ratios (290 to 370 ppmV) was analyzed. Because of the specific mode of leaf development and the subsequent stomatal patterning in conifer needles, the stomatal index of these species was not affected by CO(2). In contrast, a new measure of stomatal frequency, based on the number of stomata per millimeter of needle length, decreased significantly with increasing CO(2). For Tsuga heterophylla, the stomatal frequency response to CO(2) changes in the last century is validated through assessment of the influence of other biological and environmental variables. Because of their sensitive response to CO(2), combined with a high preservation capacity, fossil needles of Tsuga heterophylla, Picea glauca, P. mariana, and Larix laricina have great potential for detecting and quantifying past atmospheric CO(2) fluctuations.

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

    USGS Publications Warehouse

    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.; 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.

  7. Increases in atmospheric CO2 have little influence on transpiration of a temperate forest canopy.

    PubMed

    Tor-ngern, Pantana; Oren, Ram; Ward, Eric J; Palmroth, Sari; McCarthy, Heather R; Domec, Jean-Christophe

    2015-01-01

    Models of forest energy, water and carbon cycles assume decreased stomatal conductance with elevated atmospheric CO2 concentration ([CO2]) based on leaf-scale measurements, a response not directly translatable to canopies. Where canopy-atmosphere are well-coupled, [CO2 ]-induced structural changes, such as increasing leaf-area index (LD), may cause, or compensate for, reduced mean canopy stomatal conductance (GS), keeping transpiration (EC) and, hence, runoff unaltered. We investigated GS responses to increasing [CO2] of conifer and broadleaved trees in a temperate forest subjected to 17-yr free-air CO2 enrichment (FACE; + 200 μmol mol(-1)). During the final phase of the experiment, we employed step changes of [CO2] in four elevated-[CO2 ] plots, separating direct response to changing [CO2] in the leaf-internal air-space from indirect effects of slow changes via leaf hydraulic adjustments and canopy development. Short-term manipulations caused no direct response up to 1.8 × ambient [CO2], suggesting that the observed long-term 21% reduction of GS was an indirect effect of decreased leaf hydraulic conductance and increased leaf shading. Thus, EC was unaffected by [CO2] because 19% higher canopy LD nullified the effect of leaf hydraulic acclimation on GS . We advocate long-term experiments of duration sufficient for slow responses to manifest, and modifying models predicting forest water, energy and carbon cycles accordingly.

  8. Analysing Atmospheric CO2/CH4 Variability to Derive a Prior Covariance Matrices for CO2 Retrieval From Spectroscopic Data

    NASA Astrophysics Data System (ADS)

    Eguchi, N.; Nakatsuka, Y.; Saito, R.; Maksyutov, S.

    2008-12-01

    We report derivation of the prior error covariance matrices for use in gas concentration retrieval from GOSAT spectroscopic data. Concentration profiles of CO2 and CH4 simulated with forward tracer transport model are used for retrieval, so the estimate of model error will be used as uncertainty of the retrieval prior. The error estimate for the single shot simulated concentration is composed of three components: (1) interannual variability, (2) seasonal cycle bias in the model, (3) synoptic scale variability. We processed available observation data at limited number of available sites at surface and in free troposphere to construct the fields of the seasonal and interannual error components. For obtaining components (2) and (3), we simulated CO2 and CH4 concentration for troposphere by running a transport model for 2 years at 1 by 1 degree horizontal resolution and 15 vertical levels. Error of the estimated concentration (i.e. component (2) above) is estimated as a mean misfit between observed concentration and simulated one where the observations are available and extrapolated value is used where there are no observations. To obtain component (3), short time variations were extracted from the simulated concentrations with high pass filter with 14-day window. From this short-term variability, seasonally varying monthly mean covariance matrices of the concentration profile were derived. Combined uncertainty at level of several ppm's for CO2 will provide relatively weak constrain to retrieved concentration.

  9. Variations of anthropogenic CO2 in urban area deduced by radiocarbon concentration in modern tree rings.

    PubMed

    Rakowski, Andrzej Z; Nakamura, Toshio; Pazdur, Anna

    2008-10-01

    Radiocarbon concentration in the atmosphere is significantly lower in areas where man-made emissions of carbon dioxide occur. This phenomenon is known as Suess effect, and is caused by the contamination of clean air with non-radioactive carbon from fossil fuel combustion. The effect is more strongly observed in industrial and densely populated urban areas. Measurements of carbon isotope concentrations in a study area can be compared to those from areas of clear air in order to estimate the amount of carbon dioxide emission from fossil fuel combustion by using a simple mathematical model. This can be calculated using the simple mathematical model. The result of the mathematical model followed in this study suggests that the use of annual rings of trees to obtain the secular variations of 14C concentration of atmospheric CO2 can be useful and efficient for environmental monitoring and modeling of the carbon distribution in local scale.

  10. Atmospheric CO2 and O3 alter competition for soil nitrogen in developing forests

    Treesearch

    Donald R. Zak; Mark E. Kubiske; Kurt S. Pregitzer; Andrew J. Burton

    2012-01-01

    Plant growth responses to rising atmospheric CO2 and O3 vary among genotypes and between species, which could plausibly influence the strength of competitive interactions for soil N. Ascribable to the size-symmetric nature of belowground competition, we reasoned that differential growth responses to CO2...

  11. [Effect of atmospheric CO2 enrichment on soil microbes and related factors].

    PubMed

    Li, Yang; Huang, Guohong; Shi, Yi

    2003-12-01

    This paper summarized the effects of atmospheric CO2 enrichment on soil microbes and their related factors, including soil microflora, soil respiration, soil microbial biomass, and higher plant-microbe symbiosis. The factors related to soil microbic activity such as litter decomposition, root exudates, soil nutrient availability, nutrient use efficiency and soil fauna were also affected by the CO2 enrichment.

  12. Modeling plant-atmosphere carbon and water fluxes along a CO2 gradient

    USDA-ARS?s Scientific Manuscript database

    At short time scales (hourly to daily), plant photosynthesis and transpiration respond nonlinearly to atmospheric CO2 concentration and vapor pressure deficit, depending on plant water status and thus soil moisture. Modeling vegetation and soil responses to different values of CO2 at multiple time s...

  13. Impacts of elevated atmospheric CO2 and O3 on Paper Birch (Betula papyrifera): reproductive fitness

    Treesearch

    Joseph N.T. Darbah; Mark E. Kubiske; Neil Nelson; Elina Oksanen; Elina Vaapavuori; David F. Karnosky

    2007-01-01

    Atmospheric CO2 and tropospheric O3 are rising in many regions of the world. Little is known about how these two commonly co-occurring gases will affect reproductive fitness of important forest tree species. Here, we report on the long-term effects of CO2 and O3 for paper birch...

  14. Fungal community responses to past and future atmospheric CO2 differ by soil type

    USDA-ARS?s Scientific Manuscript database

    Soils sequester and release substantial atmospheric carbon, but the biological responses of soils to rising CO2 are not well understood. We studied fungal communities in a grassland ecosystem exposed to a preindustrial-to-future CO2 gradient (250-500 ppm) on two soil types, a black clay and a sandy...

  15. Grasses and Gases: Impacts of Atmospheric CO2 Enrichment on Grasslands

    USDA-ARS?s Scientific Manuscript database

    The concentration of carbon dioxide (CO2) gas in the atmosphere has increased by about 40% since the beginning of the Industrial revolution 200 years ago to the current level of 380 parts per million (ppm). Fossil fuel consumption and changes in land use account for much of this increase in CO2. A...

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

    As one of the main greenhouse gases in the atmosphere, CO2 has 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 CO2 accurately. 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 CO2 at 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.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    USDA-ARS?s Scientific Manuscript database

    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 (...

  19. Responses of Plant Respiration to Pleistocene Changes in Atmospheric CO2 Concentrations

    NASA Astrophysics Data System (ADS)

    Blanc-Betes, E.; Gonzalez-Meler, M.; Gomez-Casanovas, N.; Ward, J. K.

    2008-12-01

    Vegetation plays a crucial role on the terrestrial C cycling through the processes of photosynthesis and respiration. At a global scale, these two processes are essential components of the C cycle, because 30% to 70% of the CO2 fixed by photosynthesis is released back to the atmosphere each year by plant respiration. Therefore, small changes in these two fluxes can have a significant impact on atmospheric CO2 concentration. Changes in CO2 concentrations in the atmosphere have prompted plant evolutionary responses that have resulted in novel physiological photosynthetic adaptations such as the photosynthetic C oxidation pathway or the rise of C4-photosynthesis. However, little is known about the role of respiration on the nature of plant acclimation and adaptation to different CO2 scenarios when the photosynthesis-to-respiration ratio is low. Plant respiration is further complicated by the presence of the alternative pathway that burns photosynthate without producing chemical energy (ATP). Here, we explore the effects of Pleistocene levels of CO2 on plant respiration and on the activity of the alternative pathway. We concentrated in plants that have a low photosynthesis-to-respiration ratio such as plants grown in shade and CAM plants, and on Arabidopsis thaliana plants that were selected at Pleistocene CO2 levels (200ppm), current (360ppm) and projected (680 ppm) atmospheric levels of CO2. Our results, indicate that regardless of the overall respiration response to CO2 levels the activity of the alternative pathway was inversely correlated with atmospheric CO2 concentration in all plants. Because alternative pathway activity is not coupled to ATP production and does not support maintenance or growth processes as effectively as normal respiration, plants exposed to Pleistocene CO2 levels will run respiration more efficiently than plants exposed to current or higher CO2 levels. The effectiveness of respiration can either play a survival role at low CO2 levels, or

  20. CO2 greenhouse in the early martian atmosphere: SO2 inhibits condensation

    NASA Technical Reports Server (NTRS)

    Yung, Y. L.; Nair, H.; Gerstell, M. F.

    1997-01-01

    Many investigators of the early martian climate have suggested that a dense carbon dioxide atmosphere was present and warmed the surface above the melting point of water (J.B. Pollack, J.F. Kasting, S.M. Richardson, and K. Poliakoff 1987. Icarus 71, 203-224). However, J.F. Kasting (1991. Icarus 94, 1-13) pointed out that previous thermal models of the primitive martian atmosphere had not considered the condensation of CO2. When this effect was incorporated, Kasting found that CO2 by itself is inadequate to warm the surface. SO2 absorbs strongly in the near UV region of the solar spectrum. While a small amount of SO2 may have a negligible effect by itself on the surface temperature, it may have significantly warmed the middle atmosphere of early Mars, much as ozone warms the terrestrial stratosphere today. If this region is kept warm enough to inhibit the condensation of CO2, then CO2 remains a viable greenhouse gas. Our preliminary radiative modeling shows that the addition of 0.1 ppmv of SO2 in a 2 bar CO2 atmosphere raises the temperature of the middle atmosphere by approximately 10 degrees, so that the upper atmosphere in a 1 D model remains above the condensation temperature of CO2. In addition, this amount of SO2 in the atmosphere provides an effective UV shield for a hypothetical biosphere on the martian surface.

  1. CO 2Greenhouse in the Early Martian Atmosphere: SO 2Inhibits Condensation

    NASA Astrophysics Data System (ADS)

    Yung, Y. L.; Nair, H.; Gerstell, M. F.

    1997-11-01

    Many investigators of the early martian climate have suggested that a dense carbon dioxide atmosphere was present and warmed the surface above the melting point of water (J. B. Pollack, J. F. Kasting, S. M. Richardson, and K. Poliakoff 1987.Icarus71,203-224). However, J. F. Kasting (1991.Icarus94,1-13) pointed out that previous thermal models of the primitive martian atmosphere had not considered the condensation of CO2. When this effect was incorporated, Kasting found that CO2by itself is inadequate to warm the surface. SO2absorbs strongly in the near UV region of the solar spectrum. While a small amount of SO2may have a negligible effect by itself on the surface temperature, it may have significantly warmed the middle atmosphere of early Mars, much as ozone warms the terrestrial stratosphere today. If this region is kept warm enough to inhibit the condensation of CO2, then CO2remains a viable greenhouse gas. Our preliminary radiative modeling shows that the addition of 0.1 ppmv of SO2in a 2 bar CO2atmosphere raises the temperature of the middle atmosphere by approximately 10 degrees, so that the upper atmosphere in a 1D model remains above the condensation temperature of CO2. In addition, this amount of SO2in the atmosphere provides an effective UV shield for a hypothetical biosphere on the martian surface.

  2. CO2 greenhouse in the early martian atmosphere: SO2 inhibits condensation

    NASA Technical Reports Server (NTRS)

    Yung, Y. L.; Nair, H.; Gerstell, M. F.

    1997-01-01

    Many investigators of the early martian climate have suggested that a dense carbon dioxide atmosphere was present and warmed the surface above the melting point of water (J.B. Pollack, J.F. Kasting, S.M. Richardson, and K. Poliakoff 1987. Icarus 71, 203-224). However, J.F. Kasting (1991. Icarus 94, 1-13) pointed out that previous thermal models of the primitive martian atmosphere had not considered the condensation of CO2. When this effect was incorporated, Kasting found that CO2 by itself is inadequate to warm the surface. SO2 absorbs strongly in the near UV region of the solar spectrum. While a small amount of SO2 may have a negligible effect by itself on the surface temperature, it may have significantly warmed the middle atmosphere of early Mars, much as ozone warms the terrestrial stratosphere today. If this region is kept warm enough to inhibit the condensation of CO2, then CO2 remains a viable greenhouse gas. Our preliminary radiative modeling shows that the addition of 0.1 ppmv of SO2 in a 2 bar CO2 atmosphere raises the temperature of the middle atmosphere by approximately 10 degrees, so that the upper atmosphere in a 1 D model remains above the condensation temperature of CO2. In addition, this amount of SO2 in the atmosphere provides an effective UV shield for a hypothetical biosphere on the martian surface.

  3. Implications of a Changing Arctic on Summertime Surface Seawater pCO2 Variations in the Eastern Canadian Arctic

    NASA Astrophysics Data System (ADS)

    Burgers, T.; Miller, L. A.; Thomas, H.; Else, B. G. T.; Gosselin, M.; Papakyriakou, T. N.

    2015-12-01

    Arctic marine carbonate chemistry and rates of air-sea CO2 exchange are anticipated to be affected by current changes in sea-ice structure and extent, freshwater inputs, ocean circulation patterns, and the seasonality of phytoplankton blooms. This study examines how such changes will impact rates of air-sea CO2 exchange in northern Baffin Bay, Nares Strait, and the eastern Canadian Arctic Archipelago. This complex oceanographic region includes the North Water polynya; one of the most biologically productive areas in the Arctic Ocean, and the convergence site of the warm West Greenland Current with cold exported Arctic waters. Continuous measurements of atmospheric and surface seawater CO2 (pCO2) were collected onboard the Canadian Coast Guard Ship Amundsen during its 2013 and 2014 summer cruises. Surface seawater pCO2 displayed considerable variability (145 - 389 ppm), but never exceeded atmospheric concentrations. Calculated CO2 fluxes ranged from 0 to -45 mmol m-2 day-1 (oceanic uptake), and were estimated using the Sweeney et al. (2007) parameterization with in-situ wind speed measurements. Ancillary measurements of chlorophyll a reveal low productivity in surface waters during mid-summer with isolated sub-surface blooms. This is likely the result of nutrient limitation within the highly stratified polar mixed layer (PML). Measurements of stable oxygen isotope ratios (δ18O) and total alkalinity were used to estimate freshwater inputs (sea-ice melt vs. meteoric water) to the PML. These and in-situ observations of sea ice cover were used to interpret seawater pCO2 variations. Surface waters influenced by sea-ice melt exhibit lower pCO2 than those influenced by meteoric water. The results of this investigation shed light on the future role of this region as a summertime sink of atmospheric CO2.

  4. The response of coastal surface ocean pH to naturally changing atmospheric pCO2

    NASA Astrophysics Data System (ADS)

    Chrystal, A.; Zimdahl, N.; Paytan, A.

    2013-12-01

    Average global surface ocean pH is rapidly decreasing in response to increasing atmospheric pCO2 concentrations. The rate of acidification may be elevated in regions of strong coastal upwelling due to the combined impacts of atmospheric pCO2 and upwelling of deep water with a respired carbon signature. Since coastal upwelling regions support economically important fisheries, it is important that we understand the significance of these changes. Of essence is an understanding of the scale of regional pH change associated with natural atmospheric pCO2 oscillations at multiple time scales. Reconstructions of past pH variations from boron isotopes (δ11B) of planktonic foraminifera or other carbonate secreting organisms will provide valuable insight into the natural variability in pH regime in the ecologically and economically important California margin region, and facilitate predictions of pH response in this and other coastal upwelling systems. In this study, we will analyze δ11B in the tests of surface-dwelling planktic foraminifera (G. bulloides) to reconstruct surface water pH. We will compare surface water pH with ice-core atmospheric pCO2 records from the last several glacial cycles to better understand the natural pH response to changing atmospheric pCO2 in a coastal upwelling system. We will present a comparison between glacial and interglacial samples from site 1012 (East Cortez Basin). We hope to produce a record of high enough time resolution that the rate of pH change associated with atmospheric pCO2 changes can also be assessed, but in some sections of the core low foraminiferal abundances may force a reduction in record resolution.

  5. Regional Atmospheric CO2 Inversion Reveals Seasonal and Geographic Differences in Amazon Net Biome Exchange

    NASA Technical Reports Server (NTRS)

    Alden, Caroline B.; Miller, John B.; Gatti, Luciana V.; Gloor, Manuel M.; Guan, Kaiyu; Michalak, Anna M.; van der Laan-Luijkx, Ingrid; Touma, Danielle; Andrews, Arlyn; Basso, Luana G.; hide

    2016-01-01

    Understanding tropical rainforest carbon exchange and its response to heat and drought is critical for quantifying the effects of climate change on tropical ecosystems, including global climate carbon feedbacks. Of particular importance for the global carbon budget is net biome exchange of CO2 with the atmosphere (NBE), which represents nonfire carbon fluxes into and out of biomass and soils. Subannual and sub-Basin Amazon NBE estimates have relied heavily on process-based biosphere models, despite lack of model agreement with plot-scale observations. We present a new analysis of airborne measurements that reveals monthly, regional-scale (Approx.1-8 x 10(exp -6) km2) NBE variations. We develop a regional atmospheric CO2 inversion that provides the first analysis of geographic and temporal variability in Amazon biosphere-atmosphere carbon exchange and that is minimally influenced by biosphere model-based first guesses of seasonal and annual mean fluxes. We find little evidence for a clear seasonal cycle in Amazon NBE but do find NBE sensitivity to aberrations from long-term mean climate. In particular, we observe increased NBE (more carbon emitted to the atmosphere) associated with heat and drought in 2010, and correlations between wet season NBE and precipitation (negative correlation) and temperature (positive correlation). In the eastern Amazon, pulses of increased NBE persisted through 2011, suggesting legacy effects of 2010 heat and drought. We also identify regional differences in postdrought NBE that appear related to long-term water availability. We examine satellite proxies and find evidence for higher gross primary productivity (GPP) during a pulse of increased carbon uptake in 2011, and lower GPP during a period of increased NBE in the 2010 dry season drought, but links between GPP and NBE changes are not conclusive. These results provide novel evidence of NBE sensitivity to short-term temperature and moisture extremes in the Amazon, where monthly and sub

  6. Regional atmospheric CO2 inversion reveals seasonal and geographic differences in Amazon net biome exchange.

    PubMed

    Alden, Caroline B; Miller, John B; Gatti, Luciana V; Gloor, Manuel M; Guan, Kaiyu; Michalak, Anna M; van der Laan-Luijkx, Ingrid T; Touma, Danielle; Andrews, Arlyn; Basso, Luana S; Correia, Caio S C; Domingues, Lucas G; Joiner, Joanna; Krol, Maarten C; Lyapustin, Alexei I; Peters, Wouter; Shiga, Yoichi P; Thoning, Kirk; van der Velde, Ivar R; van Leeuwen, Thijs T; Yadav, Vineet; Diffenbaugh, Noah S

    2016-10-01

    Understanding tropical rainforest carbon exchange and its response to heat and drought is critical for quantifying the effects of climate change on tropical ecosystems, including global climate-carbon feedbacks. Of particular importance for the global carbon budget is net biome exchange of CO2 with the atmosphere (NBE), which represents nonfire carbon fluxes into and out of biomass and soils. Subannual and sub-Basin Amazon NBE estimates have relied heavily on process-based biosphere models, despite lack of model agreement with plot-scale observations. We present a new analysis of airborne measurements that reveals monthly, regional-scale (~1-8 × 10(6)  km(2) ) NBE variations. We develop a regional atmospheric CO2 inversion that provides the first analysis of geographic and temporal variability in Amazon biosphere-atmosphere carbon exchange and that is minimally influenced by biosphere model-based first guesses of seasonal and annual mean fluxes. We find little evidence for a clear seasonal cycle in Amazon NBE but do find NBE sensitivity to aberrations from long-term mean climate. In particular, we observe increased NBE (more carbon emitted to the atmosphere) associated with heat and drought in 2010, and correlations between wet season NBE and precipitation (negative correlation) and temperature (positive correlation). In the eastern Amazon, pulses of increased NBE persisted through 2011, suggesting legacy effects of 2010 heat and drought. We also identify regional differences in postdrought NBE that appear related to long-term water availability. We examine satellite proxies and find evidence for higher gross primary productivity (GPP) during a pulse of increased carbon uptake in 2011, and lower GPP during a period of increased NBE in the 2010 dry season drought, but links between GPP and NBE changes are not conclusive. These results provide novel evidence of NBE sensitivity to short-term temperature and moisture extremes in the Amazon, where monthly and sub

  7. Net uptake of atmospheric CO2 by coastal submerged aquatic vegetation

    PubMed Central

    Tokoro, Tatsuki; Hosokawa, Shinya; Miyoshi, Eiichi; Tada, Kazufumi; Watanabe, Kenta; Montani, Shigeru; Kayanne, Hajime; Kuwae, Tomohiro

    2014-01-01

    ‘Blue Carbon’, which is carbon captured by marine living organisms, has recently been highlighted as a new option for climate change mitigation initiatives. In particular, coastal ecosystems have been recognized as significant carbon stocks because of their high burial rates and long-term sequestration of carbon. However, the direct contribution of Blue Carbon to the uptake of atmospheric CO2 through air-sea gas exchange remains unclear. We performed in situ measurements of carbon flows, including air-sea CO2 fluxes, dissolved inorganic carbon changes, net ecosystem production, and carbon burial rates in the boreal (Furen), temperate (Kurihama), and subtropical (Fukido) seagrass meadows of Japan from 2010 to 2013. In particular, the air-sea CO2 flux was measured using three methods: the bulk formula method, the floating chamber method, and the eddy covariance method. Our empirical results show that submerged autotrophic vegetation in shallow coastal waters can be functionally a sink for atmospheric CO2. This finding is contrary to the conventional perception that most near-shore ecosystems are sources of atmospheric CO2. The key factor determining whether or not coastal ecosystems directly decrease the concentration of atmospheric CO2 may be net ecosystem production. This study thus identifies a new ecosystem function of coastal vegetated systems; they are direct sinks of atmospheric CO2. PMID:24623530

  8. Net uptake of atmospheric CO2 by coastal submerged aquatic vegetation.

    PubMed

    Tokoro, Tatsuki; Hosokawa, Shinya; Miyoshi, Eiichi; Tada, Kazufumi; Watanabe, Kenta; Montani, Shigeru; Kayanne, Hajime; Kuwae, Tomohiro

    2014-06-01

    'Blue Carbon', which is carbon captured by marine living organisms, has recently been highlighted as a new option for climate change mitigation initiatives. In particular, coastal ecosystems have been recognized as significant carbon stocks because of their high burial rates and long-term sequestration of carbon. However, the direct contribution of Blue Carbon to the uptake of atmospheric CO2 through air-sea gas exchange remains unclear. We performed in situ measurements of carbon flows, including air-sea CO2 fluxes, dissolved inorganic carbon changes, net ecosystem production, and carbon burial rates in the boreal (Furen), temperate (Kurihama), and subtropical (Fukido) seagrass meadows of Japan from 2010 to 2013. In particular, the air-sea CO2 flux was measured using three methods: the bulk formula method, the floating chamber method, and the eddy covariance method. Our empirical results show that submerged autotrophic vegetation in shallow coastal waters can be functionally a sink for atmospheric CO2. This finding is contrary to the conventional perception that most near-shore ecosystems are sources of atmospheric CO2. The key factor determining whether or not coastal ecosystems directly decrease the concentration of atmospheric CO2 may be net ecosystem production. This study thus identifies a new ecosystem function of coastal vegetated systems; they are direct sinks of atmospheric CO2.

  9. Dissolved inorganic carbon and stable carbon isotopic evolution of neutral mine drainage interacting with atmospheric CO2(g).

    PubMed

    Abongwa, Pride Tamasang; Atekwana, Eliot Anong; Puckette, James

    2016-03-01

    We investigated the spatial variations in the concentrations of dissolved inorganic carbon (DIC), the stable carbon isotopic composition (δ(13)C) of DIC and the δ(13)C of carbonate precipitated from neutral mine drainage interacting with the atmospheric CO2(g). We assessed the chemical, DIC and δ(13)CDIC evolution of the mine drainage and the δ(13)C evolution of carbonate precipitates for a distance of 562 m from the end of an 8 km tunnel that drains a mine. Our results show that as the mine drainage interacts with atmospheric CO2(g) the outgassing of CO2 due to the high initial partial pressure of CO2 (pCO2) causes the DIC to evolve under kinetic conditions followed by equilibration and then under equilibrium conditions. The carbonate evolution was characterized by spatial increases in pH, decreasing concentrations of Ca(2+) and DIC and by the precipitation of carbonate. The δ(13)CDIC showed a larger enrichment from the tunnel exit to 38 m, moderate continuous enrichment to 318 m and almost no enrichment to 562 m. On the other hand, the δ(13)C of the carbonate precipitates also showed large enrichment from the tunnel exit to 38 m, moderate enrichment to 318 m after which the δ(13)C remained nearly constant. The enrichment in the δ(13)C of the DIC and the carbonate precipitates from 0 to 38 m from kinetic fractionation caused by CO2(g) outgassing was followed by a mix of kinetic fractionation and equilibrium fractionation controlled by carbon exchange between DIC and atmospheric CO2(g) to 318 m and then by equilibrium fractionation from 318 to 562 m. From the carbonate evolution in this neutral mine drainage, we estimated that 20% of the carbon was lost via CO2 outgassing, 12% was sequestered in sediments in the drainage ponds from calcite precipitation and the remainder 68% was exported to the local stream.

  10. River sequesters atmospheric carbon and limits the CO2 degassing in karst area, southwest China.

    PubMed

    Zhang, Tao; Li, Jianhong; Pu, Junbing; Martin, Jonathan B; Khadka, Mitra B; Wu, Feihong; Li, Li; Jiang, Feng; Huang, Siyu; Yuan, Daoxian

    2017-12-31

    CO2 fluxes across water-air interfaces of river systems play important roles in regulating the regional and global carbon cycle. However, great uncertainty remains as to the contribution of these inland water bodies to the global carbon budget. Part of the uncertainty stems from limited understanding of the CO2 fluxes at diurnal and seasonal frequencies caused by aquatic metabolism. Here, we measured surface water characteristics (temperature, pH, and DO, DIC, Ca(2+) concentrations) and CO2 fluxes across the air-water interface at two transects of Guijiang River, southwest China to assess the seasonal and diurnal dynamics of fluvial carbon cycling and its potential role in regional and global carbon budgets. The two transects had differing bedrock; DM transect is underlain by carbonate and detrital rock and PY is underlain by pure carbonate. Our results show that the river water both degasses CO2 to and absorbs CO2 from the atmosphere in both summer and winter, but the degassing and absorption varied between the two transects. Further, CO2 fluxes evolve through diurnal cycles. At DM, the river evaded CO2 from early morning through noon and absorbed CO2 from afternoon through early morning. At PY in summer, the CO2 evasion decreased during the daytime and increased at night while in winter at night, CO2 uptake increased in the morning and decreased in the afternoon but remained relatively stable at night. Although the river is a net source of carbon to the atmosphere (~15mMm(-2)day(-1)), the evasion rate is the smallest of all reported world's inland water bodies reflecting sequestration of atmospheric carbon through the carbonate dissolution and high primary productivity. These results emphasize the need of seasonal and diurnal monitoring of CO2 fluxes across water-air interface, particularly in highly productive rivers, to reduce uncertainty in current estimates of global riverine CO2 emission. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Speleothems as proxy for the carbon isotope composition of atmospheric CO2

    NASA Astrophysics Data System (ADS)

    Baskaran, M.; Krishnamurthy, R. V.

    1993-12-01

    We have measured the stable isotope ratios of carbon in a suite of recent cave deposits (less than 200 years) from the San Saba County, Texas, USA. The methodology for dating these deposits using excess Pb-210 was recently established (Baskaran and Iliffe, 1993). The carbon isotope ratios of these samples, spanning the time period approximately 1800-1990 AD, reflect the carbon isotope ratio of atmospheric CO2 for the same period. The pathways by which the delta C-13 of atmospheric CO2 is imprinted on these speleothems can be explained using a model developed by Cerling (1984). The results suggest that the carbon isotope ratios of speleothems can be used to develop long-term, high-resolution chronologies of the delta C-13 of atmospheric CO2 and, by implication, the concentration of the atmospheric CO2.

  12. Bioenergy from forestry and changes in atmospheric CO2: reconciling single stand and landscape level approaches.

    PubMed

    Cherubini, Francesco; Guest, Geoffrey; Strømman, Anders H

    2013-11-15

    Analyses of global warming impacts from forest bioenergy systems are usually conducted either at a single stand level or at a landscape level, yielding findings that are sometimes interpreted as contrasting. In this paper, we investigate and reconcile the scales at which environmental impact analyses of forest bioenergy systems are undertaken. Focusing on the changes caused in atmospheric CO2 concentration of forest bioenergy systems characterized by different initial states of the forest, we show the features of the analyses at different scales and depict the connections between them. Impacts on atmospheric CO2 concentration at a single stand level are computed through impulse response functions (IRF). Results at a landscape level are elaborated through direct application of IRFs to the emission profile, so to account for the fluxes from all the stands across time and space. Impacts from fossil CO2 emissions are used as a benchmark. At a landscape level, forest bioenergy causes an increase in atmospheric CO2 concentration for the first decades that is similar to the impact from fossil CO2, but then the dynamics clearly diverge because while the impact from fossil CO2 continues to rise that from bioenergy stabilizes at a certain level. These results perfectly align with those obtained at a single stand for which characterization factors have been developed. In the hypothetical case of a sudden cessation of emissions, the change caused in atmospheric CO2 concentration from biogenic CO2 emissions reverses within a couple of decades, while that caused by fossil CO2 emissions remains considerably higher for centuries. When counterfactual aspects like the additional sequestration that would have occurred in the forest if not harvested and the theoretical displacement of fossil CO2 are included in the analysis, results can widely differ, as the CO2 debt at a landscape level ranges from a few years to several centuries (depending on the underlying assumptions considered

  13. Variation of pCO2 in ocean surface water in response to the passage of a hurricane

    NASA Astrophysics Data System (ADS)

    Huang, Peisheng; Imberger, JöRg

    2010-10-01

    The temporal and spatial variations of pCO2 in the ocean surface layer in response to the passage of Hurricane Frances (2004) were investigated with a coupled three-dimensional hydrodynamic and carbon model. The results showed that the sea surface temperature cooling was the dominant cause of the decrease of surface pCO2, while the entrainment of water with higher CO2 levels partially offset the cooling-induced decrease. The surface distribution of pCO2 was thus found to mimic the physical deepening processes, with a "right bias" to the hurricane track. The impact of the hurricane on the local air-sea CO2 exchange extended to about 100 km on both sides of the hurricane track. The whole passage of Hurricane Frances was estimated to have caused a CO2 efflux of about 3.504-10.363 Tg (1 Tg = 1012 g) C from ocean to the atmosphere. Globally, hurricanes in 2004 were estimated to have released a CO2 efflux of 0.047-0.141 Pg (1 Pg = 1015 g) C in total when extrapolating from Hurricane Frances. Under our assumptions, the CO2 efflux caused by the passages of global hurricanes should have increased by about 71.2%-75.0% in past decades.

  14. Acetylene fuel from atmospheric CO2 on Mars

    NASA Technical Reports Server (NTRS)

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-01-01

    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 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.

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

    NASA Astrophysics Data System (ADS)

    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.

  17. Species characteristics and intraspecific variation in growth and photosynthesis of Cryptomeria japonica under elevated O3 and CO2.

    PubMed

    Hiraoka, Yuichiro; Iki, Taiichi; Nose, Mine; Tobita, Hiroyuki; Yazaki, Kenichi; Watanabe, Atsushi; Fujisawa, Yoshitake; Kitao, Mitsutoshi

    2017-03-21

    In order to predict the effects of future atmospheric conditions on forest productivity, it is necessary to clarify the physiological responses of major forest tree species to high concentrations of ozone (O3) and carbon dioxide (CO2). Furthermore, intraspecific variation of these responses should also be examined in order to predict productivity gains through tree improvements in the future. We investigated intraspecific variation in growth and photosynthesis of Cryptomeria japonica D. Don, a major silviculture species in Japan, in response to elevated concentrations of O3 (eO3) and CO2 (eCO2), separately and in combination. Cuttings of C. japonica were grown and exposed to two levels of O3 (ambient and twice-ambient levels) in combination with two levels of CO2 (ambient and 550 µmol mol-1 in the daytime) for two growing seasons in a free-air CO2 enrichment experiment. There was no obvious negative effect of eO3 on growth or photosynthetic traits of the C. japonica clones, but a positive effect was observed for annual height increments in the first growing season. Dry mass production and the photosynthetic rate increased under eCO2 conditions, while the maximum carboxylation rate decreased. Significant interaction effects of eO3 and eCO2 on growth and photosynthetic traits were not observed. Clonal effects on growth and photosynthetic traits were significant, but the interactions between clones and O3 and/or CO2 treatments were not. Spearman's rank correlation coefficients between growth traits under ambient conditions and for each treatment were significantly positive, implying that clonal ranking in growth abilities might not be affected by either eO3 or eCO2. The knowledge obtained from this study will be helpful for species selection in afforestation programs, to continue and to improve current programs involving this species, and to accurately predict the CO2 fixation capacity of Japanese forests.

  18. Carbon residence time dominates uncertainty in terrestrial vegetation responses to future climate and atmospheric CO2.

    PubMed

    Friend, Andrew D; Lucht, Wolfgang; Rademacher, Tim T; Keribin, Rozenn; Betts, Richard; Cadule, Patricia; Ciais, Philippe; Clark, Douglas B; Dankers, Rutger; Falloon, Pete D; Ito, Akihiko; Kahana, Ron; Kleidon, Axel; Lomas, Mark R; Nishina, Kazuya; Ostberg, Sebastian; Pavlick, Ryan; Peylin, Philippe; Schaphoff, Sibyll; Vuichard, Nicolas; Warszawski, Lila; Wiltshire, Andy; Woodward, F Ian

    2014-03-04

    Future climate change and increasing atmospheric CO2 are expected to cause major changes in vegetation structure and function over large fractions of the global land surface. Seven global vegetation models are used to analyze possible responses to future climate simulated by a range of general circulation models run under all four representative concentration pathway scenarios of changing concentrations of greenhouse gases. All 110 simulations predict an increase in global vegetation carbon to 2100, but with substantial variation between vegetation models. For example, at 4 °C of global land surface warming (510-758 ppm of CO2), vegetation carbon increases by 52-477 Pg C (224 Pg C mean), mainly due to CO2 fertilization of photosynthesis. Simulations agree on large regional increases across much of the boreal forest, western Amazonia, central Africa, western China, and southeast Asia, with reductions across southwestern North America, central South America, southern Mediterranean areas, southwestern Africa, and southwestern Australia. Four vegetation models display discontinuities across 4 °C of warming, indicating global thresholds in the balance of positive and negative influences on productivity and biomass. In contrast to previous global vegetation model studies, we emphasize the importance of uncertainties in projected changes in carbon residence times. We find, when all seven models are considered for one representative concentration pathway × general circulation model combination, such uncertainties explain 30% more variation in modeled vegetation carbon change than responses of net primary productivity alone, increasing to 151% for non-HYBRID4 models. A change in research priorities away from production and toward structural dynamics and demographic processes is recommended.

  19. Carbon residence time dominates uncertainty in terrestrial vegetation responses to future climate and atmospheric CO2

    PubMed Central

    Friend, Andrew D.; Lucht, Wolfgang; Rademacher, Tim T.; Keribin, Rozenn; Betts, Richard; Cadule, Patricia; Ciais, Philippe; Clark, Douglas B.; Dankers, Rutger; Falloon, Pete D.; Ito, Akihiko; Kahana, Ron; Kleidon, Axel; Lomas, Mark R.; Nishina, Kazuya; Ostberg, Sebastian; Pavlick, Ryan; Peylin, Philippe; Schaphoff, Sibyll; Vuichard, Nicolas; Warszawski, Lila; Wiltshire, Andy; Woodward, F. Ian

    2014-01-01

    Future climate change and increasing atmospheric CO2 are expected to cause major changes in vegetation structure and function over large fractions of the global land surface. Seven global vegetation models are used to analyze possible responses to future climate simulated by a range of general circulation models run under all four representative concentration pathway scenarios of changing concentrations of greenhouse gases. All 110 simulations predict an increase in global vegetation carbon to 2100, but with substantial variation between vegetation models. For example, at 4 °C of global land surface warming (510–758 ppm of CO2), vegetation carbon increases by 52–477 Pg C (224 Pg C mean), mainly due to CO2 fertilization of photosynthesis. Simulations agree on large regional increases across much of the boreal forest, western Amazonia, central Africa, western China, and southeast Asia, with reductions across southwestern North America, central South America, southern Mediterranean areas, southwestern Africa, and southwestern Australia. Four vegetation models display discontinuities across 4 °C of warming, indicating global thresholds in the balance of positive and negative influences on productivity and biomass. In contrast to previous global vegetation model studies, we emphasize the importance of uncertainties in projected changes in carbon residence times. We find, when all seven models are considered for one representative concentration pathway × general circulation model combination, such uncertainties explain 30% more variation in modeled vegetation carbon change than responses of net primary productivity alone, increasing to 151% for non-HYBRID4 models. A change in research priorities away from production and toward structural dynamics and demographic processes is recommended. PMID:24344265

  20. A 2-Micron Pulsed Integrated Path Differential Absorption Lidar Development For Atmospheric CO2 Concentration Measurements

    NASA Technical Reports Server (NTRS)

    Yu, Jirong; Petros, Mulugeta; Reithmaier, Karl; Bai, Yingxin; Trieu, Bo C.; Refaat, Tamer F.; Kavaya, Michael J.; Singh, Upendra N.

    2012-01-01

    A 2-micron pulsed, Integrated Path Differential Absorption (IPDA) lidar instrument for ground and airborne atmospheric CO2 concentration measurements via direct detection method is being developed at NASA Langley Research Center. This instrument will provide an alternate approach to measure atmospheric CO2 concentrations with significant advantages. A high energy pulsed approach provides high-precision measurement capability by having high signal-to-noise level and unambiguously eliminates the contamination from aerosols and clouds that can bias the IPDA measurement.

  1. Climatic effects of enhanced CO2 levels in Mars early atmosphere

    NASA Technical Reports Server (NTRS)

    Kasting, James F.

    1987-01-01

    Results are presented of one-dimensional radiation convection modeling of the early Mars atmosphere. Up to 5 bars of CO2 would have been required to raise the surface temperature (orbitally and globally averaged) above the freezing point, although at the equator at perihelion, 1 bar would have sufficed. Such an atmospheric CO2 invertory, the author argued, is not inconsistent with any known constraint on Mars' degassed volatile inventory.

  2. A Pilot Study to Evaluate California's Fossil Fuel CO2 Emissions Using Atmospheric Observations

    NASA Astrophysics Data System (ADS)

    Graven, H. D.; Fischer, M. L.; Lueker, T.; Guilderson, T.; Brophy, K. J.; Keeling, R. F.; Arnold, T.; Bambha, R.; Callahan, W.; Campbell, J. E.; Cui, X.; Frankenberg, C.; Hsu, Y.; Iraci, L. T.; Jeong, S.; Kim, J.; LaFranchi, B. W.; Lehman, S.; Manning, A.; Michelsen, H. A.; Miller, J. B.; Newman, S.; Paplawsky, B.; Parazoo, N.; Sloop, C.; Walker, S.; Whelan, M.; Wunch, D.

    2016-12-01

    Atmospheric CO2 concentration is influenced by human activities and by natural exchanges. Studies of CO2 fluxes using atmospheric CO2 measurements typically focus on natural exchanges and assume that CO2 emissions by fossil fuel combustion and cement production are well-known from inventory estimates. However, atmospheric observation-based or "top-down" studies could potentially provide independent methods for evaluating fossil fuel CO2 emissions, in support of policies to reduce greenhouse gas emissions and mitigate climate change. Observation-based estimates of fossil fuel-derived CO2 may also improve estimates of biospheric CO2 exchange, which could help to characterize carbon storage and climate change mitigation by terrestrial ecosystems. We have been developing a top-down framework for estimating fossil fuel CO2 emissions in California that uses atmospheric observations and modeling. California is implementing the "Global Warming Solutions Act of 2006" to reduce total greenhouse gas emissions to 1990 levels by 2020, and it has a diverse array of ecosystems that may serve as CO2 sources or sinks. We performed three month-long field campaigns in different seasons in 2014-15 to collect flask samples from a state-wide network of 10 towers. Using measurements of radiocarbon in CO2, we estimate the fossil fuel-derived CO2 present in the flask samples, relative to marine background air observed at coastal sites. Radiocarbon (14C) is not present in fossil fuel-derived CO2 because of radioactive decay over millions of years, so fossil fuel emissions cause a measurable decrease in the 14C/C ratio in atmospheric CO2. We compare the observations of fossil fuel-derived CO2 to simulations based on atmospheric modeling and published fossil fuel flux estimates, and adjust the fossil fuel flux estimates in a statistical inversion that takes account of several uncertainties. We will present the results of the top-down technique to estimate fossil fuel emissions for our field

  3. Regional and Local Carbon Flux Information from a Continuous Atmospheric CO2 Network in the Rocky Mountains

    NASA Astrophysics Data System (ADS)

    Heck, S. L.; Stephens, B.; Watt, A.

    2007-12-01

    We will present preliminary carbon flux estimates from the Regional Atmospheric Continuous CO2 Network in the Rocky Mountains (Rocky RACCOON). In order to improve our understanding of regional carbon fluxes in the Rocky Mountain West, we have developed and deployed autonomous, inexpensive, and robust CO2 analyzers (AIRCOA) at five sites throughout Colorado and Utah, and plan additional deployments on the Navajo Reservation, Arizona in September 2007 and atop Mount Kenya, Africa in November 2007. We have used a one- dimensional CO2 budget equation, following Bakwin et al. (2004), to estimate regional monthly-mean fluxes from our continuous CO2 concentrations. These comparisons between our measurements and estimates of free- tropospheric background concentrations reveal regional-scale CO2 flux signals that are generally consistent with one another across the Rocky RACCOON sites. We will compare the timing and magnitude of these estimates with expectations from local-scale eddy-correlation flux measurements and bottom-up ecosystem models. We will also interpret the differences in monthly-mean flux signals between our sites in terms of their varying upwind areas of influence and inferred regional variations in CO2 fluxes. Our measurements will be included in future CarbonTracker assimilation runs and other planned model-data fusion efforts. However, questions still exist concerning the ability of these models to accurately represent the various influences on CO2 concentrations in continental boundary layers, and at mountaintop sites in particular. We will present an analysis of the diurnal cycles in CO2 concentration and CO2 variability at our sites, and compare these to various model estimates. Several of our sites near major population centers reflect the influence of industrial CO2 sources in afternoon upslope flows, with CO2 concentration increasing and variable in the mid to late afternoon. Other more remote sites show more consistent and decreasing CO2

  4. Recent pause in the growth rate of atmospheric CO2 due to enhanced terrestrial carbon uptake

    NASA Astrophysics Data System (ADS)

    Keenan, Trevor F.; Prentice, I. Colin; Canadell, Josep G.; Williams, Christopher A.; Wang, Han; Raupach, Michael; Collatz, G. James

    2016-11-01

    Terrestrial ecosystems play a significant role in the global carbon cycle and offset a large fraction of anthropogenic CO2 emissions. The terrestrial carbon sink is increasing, yet the mechanisms responsible for its enhancement, and implications for the growth rate of atmospheric CO2, remain unclear. Here using global carbon budget estimates, ground, atmospheric and satellite observations, and multiple global vegetation models, we report a recent pause in the growth rate of atmospheric CO2, and a decline in the fraction of anthropogenic emissions that remain in the atmosphere, despite increasing anthropogenic emissions. We attribute the observed decline to increases in the terrestrial sink during the past decade, associated with the effects of rising atmospheric CO2 on vegetation and the slowdown in the rate of warming on global respiration. The pause in the atmospheric CO2 growth rate provides further evidence of the roles of CO2 fertilization and warming-induced respiration, and highlights the need to protect both existing carbon stocks and regions, where the sink is growing rapidly.

  5. Recent pause in the growth rate of atmospheric CO2 due to enhanced terrestrial carbon uptake.

    PubMed

    Keenan, Trevor F; Prentice, I Colin; Canadell, Josep G; Williams, Christopher A; Wang, Han; Raupach, Michael; Collatz, G James

    2016-11-08

    Terrestrial ecosystems play a significant role in the global carbon cycle and offset a large fraction of anthropogenic CO2 emissions. The terrestrial carbon sink is increasing, yet the mechanisms responsible for its enhancement, and implications for the growth rate of atmospheric CO2, remain unclear. Here using global carbon budget estimates, ground, atmospheric and satellite observations, and multiple global vegetation models, we report a recent pause in the growth rate of atmospheric CO2, and a decline in the fraction of anthropogenic emissions that remain in the atmosphere, despite increasing anthropogenic emissions. We attribute the observed decline to increases in the terrestrial sink during the past decade, associated with the effects of rising atmospheric CO2 on vegetation and the slowdown in the rate of warming on global respiration. The pause in the atmospheric CO2 growth rate provides further evidence of the roles of CO2 fertilization and warming-induced respiration, and highlights the need to protect both existing carbon stocks and regions, where the sink is growing rapidly.

  6. Recent pause in the growth rate of atmospheric CO2 due to enhanced terrestrial carbon uptake

    DOE PAGES

    Keenan, Trevor F.; Prentice, I. Colin; Canadell, Josep G.; ...

    2016-11-08

    Terrestrial ecosystems play a significant role in the global carbon cycle and offset a large fraction of anthropogenic CO2 emissions. The terrestrial carbon sink is increasing, yet the mechanisms responsible for its enhancement, and implications for the growth rate of atmospheric CO2, remain unclear. Here using global carbon budget estimates, ground, atmospheric and satellite observations, and multiple global vegetation models, we report a recent pause in the growth rate of atmospheric CO2, and a decline in the fraction of anthropogenic emissions that remain in the atmosphere, despite increasing anthropogenic emissions. We also attribute the observed decline to increases in themore » terrestrial sink during the past decade, associated with the effects of rising atmospheric CO2 on vegetation and the slowdown in the rate of warming on global respiration. Furthermore, the pause in the atmospheric CO2 growth rate provides further evidence of the roles of CO2 fertilization and warming-induced respiration, and highlights the need to protect both existing carbon stocks and regions, where the sink is growing rapidly.« less

  7. Recent pause in the growth rate of atmospheric CO2 due to enhanced terrestrial carbon uptake

    PubMed Central

    Keenan, Trevor F; Prentice, I. Colin; Canadell, Josep G; Williams, Christopher A; Wang, Han; Raupach, Michael; Collatz, G. James

    2016-01-01

    Terrestrial ecosystems play a significant role in the global carbon cycle and offset a large fraction of anthropogenic CO2 emissions. The terrestrial carbon sink is increasing, yet the mechanisms responsible for its enhancement, and implications for the growth rate of atmospheric CO2, remain unclear. Here using global carbon budget estimates, ground, atmospheric and satellite observations, and multiple global vegetation models, we report a recent pause in the growth rate of atmospheric CO2, and a decline in the fraction of anthropogenic emissions that remain in the atmosphere, despite increasing anthropogenic emissions. We attribute the observed decline to increases in the terrestrial sink during the past decade, associated with the effects of rising atmospheric CO2 on vegetation and the slowdown in the rate of warming on global respiration. The pause in the atmospheric CO2 growth rate provides further evidence of the roles of CO2 fertilization and warming-induced respiration, and highlights the need to protect both existing carbon stocks and regions, where the sink is growing rapidly. PMID:27824333

  8. Intermediate time scale response of atmospheric CO2 following prescribed fire in a longleaf pine forest

    NASA Astrophysics Data System (ADS)

    Viner, B.; Parker, M.; Maze, G.; Varnedoe, P.; Leclerc, M.; Starr, G.; Aubrey, D.; Zhang, G.; Duarte, H.

    2016-10-01

    Fire plays an essential role in maintaining the structure and function of longleaf pine ecosystems. While the effects of fire on carbon cycle have been measured in previous studies for short periods during a burn and for multiyear periods following the burn, information on how carbon cycle is influenced by such changes over the span of a few weeks to months has yet to be quantified. We have analyzed high-frequency measurements of CO2 concentration and flux, as well as associated micrometeorological variables, at three levels of the tall Aiken AmeriFlux tower during and after a prescribed burn. Measurements of the CO2 concentration and vertical fluxes were examined as well as calculated net ecosystem exchange (NEE) for periods prior to and after the burn. Large spikes in both CO2 concentration and CO2 flux during the fire and increases in atmospheric CO2 concentration and reduced CO2 flux were observed for several weeks following the burn, particularly below the forest canopy. Both CO2 measurements and NEE were found to return to their preburn states within 60-90 days following the burn when no statistical significance was found between preburn and postburn NEE. This study examines the micrometeorological conditions during a low-intensity prescribed burn and its short-term effects on local CO2 dynamics in a forested environment by identifying observable impacts on local measurements of atmospheric CO2 concentration and fluxes.

  9. Intermediate time scale response of atmospheric CO2 following prescribed fire in a longleaf pine forest

    DOE PAGES

    Viner, Brian; Parker, M.; Maze, G.; ...

    2016-10-12

    Fire plays an essential role in maintaining the structure and function of longleaf pine ecosystems. While the effects of fire on carbon cycle have been measured in previous studies for short periods during a burn and for multiyear periods following the burn, information on how carbon cycle is influenced by such changes over the span of a few weeks to months has yet to be quantified. We have analyzed high-frequency measurements of CO2 concentration and flux, as well as associated micrometeorological variables, at three levels of the tall Aiken AmeriFlux tower during and after a prescribed burn. Measurements of themore » CO2 concentration and vertical fluxes were examined as well as calculated net ecosystem exchange (NEE) for periods prior to and after the burn. Large spikes in both CO2 concentration and CO2 flux during the fire and increases in atmospheric CO2 concentration and reduced CO2 flux were observed for several weeks following the burn, particularly below the forest canopy. Both CO2 measurements and NEE were found to return to their preburn states within 60–90 days following the burn when no statistical significance was found between preburn and postburn NEE. Furthermore, this study examines the micrometeorological conditions during a low-intensity prescribed burn and its short-term effects on local CO2 dynamics in a forested environment by identifying observable impacts on local measurements of atmospheric CO2 concentration and fluxes.« less

  10. Fungal Community Responses to Past and Future Atmospheric CO2 Differ by Soil Type.

    PubMed

    Procter, Andrew C; Ellis, J Christopher; Fay, Philip A; Polley, H Wayne; Jackson, Robert B

    2014-12-01

    Soils sequester and release substantial atmospheric carbon, but the contribution of fungal communities to soil carbon balance under rising CO2 is not well understood. Soil properties likely mediate these fungal responses but are rarely explored in CO2 experiments. We studied soil fungal communities in a grassland ecosystem exposed to a preindustrial-to-future CO2 gradient (250 to 500 ppm) in a black clay soil and a sandy loam soil. Sanger sequencing and pyrosequencing of the rRNA gene cluster revealed that fungal community composition and its response to CO2 differed significantly between soils. Fungal species richness and relative abundance of Chytridiomycota (chytrids) increased linearly with CO2 in the black clay (P < 0.04, R(2) > 0.7), whereas the relative abundance of Glomeromycota (arbuscular mycorrhizal fungi) increased linearly with elevated CO2 in the sandy loam (P = 0.02, R(2) = 0.63). Across both soils, decomposition rate was positively correlated with chytrid relative abundance (r = 0.57) and, in the black clay soil, fungal species richness. Decomposition rate was more strongly correlated with microbial biomass (r = 0.88) than with fungal variables. Increased labile carbon availability with elevated CO2 may explain the greater fungal species richness and Chytridiomycota abundance in the black clay soil, whereas increased phosphorus limitation may explain the increase in Glomeromycota at elevated CO2 in the sandy loam. Our results demonstrate that soil type plays a key role in soil fungal responses to rising atmospheric CO2.

  11. CO2 deficit in temperate forest soils receiving high atmospheric N-deposition.

    PubMed

    Fleischer, Siegfried

    2003-02-01

    Evidence is provided for an internal CO2 sink in forest soils, that may have a potential impact on the global CO2-budget. Lowered CO2 fraction in the soil atmosphere, and thus lowered CO2 release to the aboveground atmosphere, is indicated in high N-deposition areas. Also at forest edges, especially of spruce forest, where additional N-deposition has occurred, the soil CO2 is lowered, and the gradient increases into the closed forest. Over the last three decades the capacity of the forest soil to maintain the internal sink process has been limited to a cumulative supply of approximately 1000 and 1500 kg N ha(-1). Beyond this limit the internal soil CO2 sink becomes an additional CO2 source, together with nitrogen leaching. This stage of "nitrogen saturation" is still uncommon in closed forests in southern Scandinavia, however, it occurs in exposed forest edges which receive high atmospheric N-deposition. The soil CO2 gradient, which originally increases from the edge towards the closed forest, becomes reversed.

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

    NASA Technical Reports Server (NTRS)

    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 (<1%) has yet to be achieved. Given the elevated Delta(sup 13)C values measured in 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.

  13. Measurements of atmospheric transmittance of CO2 laser radiation

    NASA Astrophysics Data System (ADS)

    Aref'ev, V. N.

    1991-02-01

    The field measurement of transmission of 12C1602, 12C1802 and 2 13C160 laser at 62 wavelenghts in the 9.2-11.2.~m spectral range are presented. The measurements were made on a O.2-2.0 km horizontal path using a tunable CO laser. The results were compared with the compu- 2 ted molecular absorptions. Mather a good agreement has been found. Under sufficient visibility (disregarding aerozol attenuation ) atmospheric water vapour is the main extinction component within 10-13 tm and in the range of 8-10 im other small constituents are important.

  14. The relationship of global green leaf biomass to atmospheric CO2 concentrations

    NASA Technical Reports Server (NTRS)

    Tucker, C. J.; Fung, Inez Y.; Keeling, C. D.; Gammon, R. H.

    1985-01-01

    Advanced very high resolution radiometer data from NOAA's polar orbiting meteorological satellite have been obtained globally for a 21 month period, processed to produce a green leaf biomass spectral vegetative index for the entire terrestrial surface by month, zonally aggregated by latitude, and compared to atmospheric CO2 concentrations from observing stations. A strong inverse association was found between the monthly Pt. Barrow CO2 concentrations and the vegetation index measurements from 50 deg N to 80 deg N, between the monthly Mauna Loa CO2 concentrations and the vegetation index measurements from 10 deg N to 30 deg N, 10 deg N to 80 deg N, and the global total, and between the globally averaged CO2 concentrations and the globally averaged vegetation index. No relationships between atmospheric CO2 concentrations and the vegetative index measurements from any latitude zone or combinations of zones were found for the South Pole station.

  15. Interannual physiological responses of glacial trees to changes in atmospheric [CO2] since the Last Glacial Maximum

    NASA Astrophysics Data System (ADS)

    Gerhart, L. M.; Harris, J. M.; Ward, J. K.

    2009-12-01

    During the Last Glacial Maximum, atmospheric [CO2] were as low as 180 ppm and have currently risen to a modern value of 385 ppm as a result of fossil fuel combustion and deforestation. In order to understand how changing [CO2] influenced the physiology of trees over the last 50,000 years, we analyzed carbon isotope ratios of individual tree rings from juniper wood specimens from the Rancho La Brea tar pits in southern California and kauri wood specimens from peat bogs in New Zealand (North Island). Modern trees from different altitudes were compared to account for changes in precipitation and temperature through time in order to isolate the effects of changing [CO2]. We hypothesized that over the last 50,000 years, the ratio of ci (intracellular [CO2]) to ca (atmospheric [CO2]) would be maintained within each species. Consequently, ci values would be significantly lower in glacial trees due to lower ca levels during the LGM. In addition, we hypothesized that low [CO2] (which does not vary between years during the LGM) dominated tree physiology during the LGM as evidenced by low levels of inter-annual variation in ci/ca ratios relative to modern trees (which are known to respond to high frequency variation in water and temperature between years). In both kauri and juniper trees, mean ci/ca values remained constant throughout 50,000 years despite major climatic and [CO2] changes, indicating that there is a long-term physiological set point in these species. Limitations on the ci values of glacial junipers suggest that 90 ppm CO2 represents a survival compensation point for this species. In addition, glacial trees showed very low inter-annual variation in ci/ca values compared to modern trees. This suggests that glacial tree physiology may have been dominated by low CO2 that was constant between years, whereas modern trees may be dominated by climatic factors that vary substantially between years. Consequently, while each species maintained mean ci/ca values over time

  16. Physiological responses during short-term acclimation to increasing atmospheric CO2 concentration in Pinus nigra

    NASA Astrophysics Data System (ADS)

    Maseyk, K. S.; Biron, P.; Richard, P.; Canale, L.; Bariac, T.

    2010-12-01

    The response of plants to increasing atmospheric CO2 concentrations is a key element shaping future biogeochemical cycles. While leaf scale manipulations of CO2 concentration provide us with a wealth of information on the biochemical response of leaf photosynthesis, these responses do not necessarily translate to whole plant responses at higher CO2 concentrations. Evidence from free air enrichment studies show different responses of plant gas exchange parameters in their degree of acclimation to long-term increases in atmospheric CO2, relative to those predicted from the instantaneous responses of leaf-level measurements. However, free air enrichment studies are also limited by the fact that they represent a single step change in CO2 and it is therefore of interest to understand how physiological responses derived from leaf-scale increases in CO2 compare to those from exposing the whole plant to increases CO2 across a range of elevated CO2 concentrations. Here we report on a study into the short-term leaf level physiological responses to CO2 concentration of small (1.5m) Pinus nigra trees that were maintained at different CO2 concentrations, therefore allowing potential whole-plant feedback effects to be incorporated into the responses. The trees were maintained at 20°C and 50-60% RH at three ambient CO2 concentrations (Ca of 380 ppm, 500 ppm, 800 ppm) for ~10 days each in a 10m3 growth chamber. The response of gas exchange parameters (assimilation rate, A, stomatal conductance, gs, internal CO2 concentration, Ci, transpiration, E) to leaf level changes in CO2 were measured at each ambient CO2 concentration, allowing the instantaneous response to be compared to the ‘acclimated’ response (i.e. that at the ambient concentration). Typical A-Ci response curves were seen at all CO2 concentrations, with saturation at Ci above 800ppm and Ca above 1500 ppm. However, even over this short period, assimilation rates at a given CO2 concentration deceased with increasing

  17. Theoretical operational life study of the closed-cycle transversely excited atmospheric CO2 laser

    NASA Astrophysics Data System (ADS)

    Hokazono, Hirokazu; Obara, Minoru; Midorikawa, Katsumi; Tashiro, Hideo

    1991-05-01

    The operational characteristics of a high-power closed-cycle transversely excited atmospheric CO2 laser are investigated kinetically. The fractional CO2/N2, molecules decomposition, and concentration of minor impurities accumulated in the laser gas mixture are calculated theoretically as a function of shots and number of repetitive discharge pulses. It is shown that the laser output peak power decreases in proportion to the fractional CO2 decomposition, while nitrogen oxides are found to show little effect on the operational E/N. The theoretical model employed specifies that a trace of water vapor in the laser chamber suppresses the CO2 decomposition due to fact that CO2 reforming is enhanced by OH radicals. As far as ultraviolet preionization is concerned, its absorption depth of the laser gas mixture decreases as the CO2 decomposition increases.

  18. NUCLEAR POWERED CO2 CAPTURE FROM THE ATMOSPHERE

    SciTech Connect

    Sherman, S

    2008-09-22

    A process for capturing CO{sub 2} from the atmosphere was recently proposed. This process uses a closed cycle of sodium and calcium hydroxide, carbonate, and oxide transformations to capture dilute CO{sub 2} from the atmosphere and to generate a concentrated stream of CO{sub 2} that is amenable to sequestration or subsequent chemical transformations. In one of the process steps, a fossil-fueled lime kiln is needed, which reduces the net CO{sub 2} capture of the process. It is proposed to replace the fossil-fueled lime kiln with a modified kiln heated by a high-temperature nuclear reactor. This will have the effect of eliminating the use of fossil fuels for the process and increasing the net CO{sub 2} capture. Although the process is suitable to support sequestration, the use of a nuclear power source for the process provides additional capabilities, and the captured CO{sub 2} may be combined with nuclear-produced hydrogen to produce liquid fuels via Fischer-Tropsch synthesis or other technologies. Conceivably, such plants would be carbon-neutral, and could be placed virtually anywhere without being tied to fossil fuel sources or geological sequestration sites.

  19. Climatic consequences of very high CO2 levels in Earth's early atmosphere

    NASA Technical Reports Server (NTRS)

    Katsing, J. F.

    1986-01-01

    Earth has approximately 60 bars of carbon dioxide tied up in carbonate rocks, or roughly 2/3 the amount of CO2 of the atmosphere of Venus. Two different lines of evidence, one based on thermodynamics and the other on geochemical cycles, indicate that a substantial fraction of thes CO2 may have resided in the atmosphere during the first few hundred million years of the Earth's history. A natural question which arises is whether this much CO2 would have resulted in a runaway greenhouse effect. One dimensional radiative/convective model calculations presented showed that the surface temperature of a hypothetical primitive atmosphere containing 20 bars of CO2 was less than 100 C; thus no runaway greenhouse effect would have occurred. The climatic stability of the early atmosphere is a consequence of three factors: reduced solar luminosity at that time, an increase in planetary albedo caused by Rayleigh scattering by CO2, and the stabilizing effects of a moist convection. The latter two factors are sufficient to prevent a CO2 induced runaway greenhouse effect on the present Earth as well, for CO2 levels up to 100 bars. Further studies are being undertaken to determine whether a runaway greenhouse effect could have occurred during the latter stages of the accretion process and, if so, whether it would have collapsed one the influx of material slowed down.

  20. Development of a Coherent Differential Absorption Lidar for Range Resolved Atmospheric CO2 Measurements

    NASA Technical Reports Server (NTRS)

    Yu, Jirong; Petros, Mulgueta; Chen, Songsheng; Bai, Yingxin; Petzar, Paul J.; Trieu, Bo. C.; Koch, Grady J.; Beyon, Jeffery J.; Singh, Upendra N.

    2010-01-01

    A pulsed, 2-m coherent Differential Absorption Lidar (DIAL) / Integrated Path Differential Absorption (IPDA) transceiver, developed under the Laser Risk Reduction Program (LRRP) at NASA, is integrated into a fully functional lidar instrument. This instrument will measure atmospheric CO2 profiles (by DIAL) initially from a ground platform, and then be prepared for aircraft installation to measure the atmospheric CO2 column densities in the atmospheric boundary layer (ABL) and lower troposphere. The airborne prototype CO2 lidar can measure atmospheric CO2 column density in a range bin of 1km with better than 1.5% precision at horizontal resolution of less than 50km. It can provide the image of the pooling of CO2 in lowlying areas and performs nighttime mass balance measurements at landscape scale. This sensor is unique in its capability to study the vertical ABL-free troposphere exchange of CO2 directly. It will allow the investigators to pursue subsequent in science-driven deployments, and provides a unique tool for Active Sensing of CO2 Emissions over Night, Days, and Seasons (ASCENDS) validation that was strongly advocated in the recent ASCENDS Workshop.