共查询到20条相似文献，搜索用时 46 毫秒
1.
Van Oost K Quine TA Govers G De Gryze S Six J Harden JW Ritchie JC McCarty GW Heckrath G Kosmas C Giraldez JV da Silva JR Merckx R 《Science (New York, N.Y.)》2007,318(5850):626-629
Agricultural soil erosion is thought to perturb the global carbon cycle, but estimates of its effect range from a source of 1 petagram per year(-1) to a sink of the same magnitude. By using caesium-137 and carbon inventory measurements from a large-scale survey, we found consistent evidence for an erosion-induced sink of atmospheric carbon equivalent to approximately 26% of the carbon transported by erosion. Based on this relationship, we estimated a global carbon sink of 0.12 (range 0.06 to 0.27) petagrams of carbon per year(-1) resulting from erosion in the world's agricultural landscapes. Our analysis directly challenges the view that agricultural erosion represents an important source or sink for atmospheric CO2. 相似文献
2.
Observed atmospheric concentrations of CO(2) and data on the partial pressures of CO(2) in surface ocean waters are combined to identify globally significant sources and sinks of CO(2). 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 CO(2) are greater in the Northern than in the Southern Hemisphere. The observed differences between the partial pressure of CO(2) 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 CO(2). Therefore, a large amount of the CO(2) is apparently absorbed on the continents by terrestrial ecosystems. 相似文献
3.
Carbon dioxide supersaturation in the surface waters of lakes 总被引：9，自引：0，他引：9
Data on the partial pressure of carbon dioxide (CO(2)) in the surface waters from a large number of lakes (1835) with a worldwide distribution show that only a small proportion of the 4665 samples analyzed (less than 10 percent) were within +/-20 percent of equilibrium with the atmosphere and that most samples (87 percent) were supersaturated. The mean partial pressure of CO(2) averaged 1036 microatmospheres, about three times the value in the overlying atmosphere, indicating that lakes are sources rather than sinks of atmospheric CO(2). On a global scale, the potential efflux of CO(2) from lakes (about 0.14 x 10(15) grams of carbon per year) is about half as large as riverine transport of organic plus inorganic carbon to the ocean. Lakes are a small but potentially important conduit for carbon from terrestrial sources to the atmospheric sink. 相似文献
4.
The oceanic sink for anthropogenic CO2 总被引：6，自引：0，他引：6
Sabine CL Feely RA Gruber N Key RM Lee K Bullister JL Wanninkhof R Wong CS Wallace DW Tilbrook B Millero FJ Peng TH Kozyr A Ono T Rios AF 《Science (New York, N.Y.)》2004,305(5682):367-371
Using inorganic carbon measurements from an international survey effort in the 1990s and a tracer-based separation technique, we estimate a global oceanic anthropogenic carbon dioxide (CO2) sink for the period from 1800 to 1994 of 118 +/- 19 petagrams of carbon. The oceanic sink accounts for approximately 48% of the total fossil-fuel and cement-manufacturing emissions, implying that the terrestrial biosphere was a net source of CO2 to the atmosphere of about 39 +/- 28 petagrams of carbon for this period. The current fraction of total anthropogenic CO2 emissions stored in the ocean appears to be about one-third of the long-term potential. 相似文献
5.
McLean DM 《Science (New York, N.Y.)》1978,200(4345):1060-1062
Since at least the late Mesozoic, the abundance of terrestrial vegetation has been the major factor in atmospheric carbon dioxideloxygen fluctuations. Of modern ecosystem types occupying more than 1 percent of the earth's surface, productivity/area ratios of terrestrial ecosystems (excepting tundra and alpine meadow, desert scrub, and rock, ice, and sand) exceed those of marine ecosystems and probably have done so for much of late Phanerozoic time. Reduction of terrestrial ecosystems during marine transgression would decrease the world primary productivity, thus increasing the atmospheric carbon dioxide concentration and decreasing the oxygen concentration. Regression would produce opposite effects. 相似文献
6.
The global carbon cycle: a test of our knowledge of earth as a system 总被引：21，自引：0，他引：21
Falkowski P Scholes RJ Boyle E Canadell J Canfield D Elser J Gruber N Hibbard K Högberg P Linder S Mackenzie FT Moore B Pedersen T Rosenthal Y Seitzinger S Smetacek V Steffen W 《Science (New York, N.Y.)》2000,290(5490):291-296
Motivated by the rapid increase in atmospheric CO2 due to human activities since the Industrial Revolution, several international scientific research programs have analyzed the role of individual components of the Earth system in the global carbon cycle. Our knowledge of the carbon cycle within the oceans, terrestrial ecosystems, and the atmosphere is sufficiently extensive to permit us to conclude that although natural processes can potentially slow the rate of increase in atmospheric CO2, there is no natural "savior" waiting to assimilate all the anthropogenically produced CO2 in the coming century. Our knowledge is insufficient to describe the interactions between the components of the Earth system and the relationship between the carbon cycle and other biogeochemical and climatological processes. Overcoming this limitation requires a systems approach. 相似文献
7.
Stephens BB Gurney KR Tans PP Sweeney C Peters W Bruhwiler L Ciais P Ramonet M Bousquet P Nakazawa T Aoki S Machida T Inoue G Vinnichenko N Lloyd J Jordan A Heimann M Shibistova O Langenfelds RL Steele LP Francey RJ Denning AS 《Science (New York, N.Y.)》2007,316(5832):1732-1735
Measurements of midday vertical atmospheric CO2 distributions reveal annual-mean vertical CO2 gradients that are inconsistent with atmospheric models that estimate a large transfer of terrestrial carbon from tropical to northern latitudes. The three models that most closely reproduce the observed annual-mean vertical CO2 gradients estimate weaker northern uptake of -1.5 petagrams of carbon per year (Pg C year(-1)) and weaker tropical emission of +0.1 Pg C year(-1) compared with previous consensus estimates of -2.4 and +1.8 Pg C year(-1), respectively. This suggests that northern terrestrial uptake of industrial CO2 emissions plays a smaller role than previously thought and that, after subtracting land-use emissions, tropical ecosystems may currently be strong sinks for CO2. 相似文献
8.
The North Atlantic is believed to represent the largest ocean sink for atmospheric carbon dioxide in the Northern Hemisphere, yet little is known about its temporal variability. We report an 18-year time series of upper-ocean inorganic carbon observations from the northwestern subtropical North Atlantic near Bermuda that indicates substantial variability in this sink. We deduce that the carbon variability at this site is largely driven by variations in winter mixed-layer depths and by sea surface temperature anomalies. Because these variations tend to occur in a basinwide coordinated pattern associated with the North Atlantic Oscillation, it is plausible that the entire North Atlantic Ocean may vary in concert, resulting in a variability of the strength of the North Atlantic carbon sink of about +/-0.3 petagrams of carbon per year (1 petagram = 10(15) grams) or nearly +/-50%. This extrapolation is supported by basin-wide estimates from atmospheric carbon dioxide inversions. 相似文献
9.
L Cheng FL Booker C Tu KO Burkey L Zhou HD Shew TW Rufty S Hu 《Science (New York, N.Y.)》2012,337(6098):1084-1087
The extent to which terrestrial ecosystems can sequester carbon to mitigate climate change is a matter of debate. The stimulation of arbuscular mycorrhizal fungi (AMF) by elevated atmospheric carbon dioxide (CO(2)) has been assumed to be a major mechanism facilitating soil carbon sequestration by increasing carbon inputs to soil and by protecting organic carbon from decomposition via aggregation. We present evidence from four independent microcosm and field experiments demonstrating that CO(2) enhancement of AMF results in considerable soil carbon losses. Our findings challenge the assumption that AMF protect against degradation of organic carbon in soil and raise questions about the current prediction of terrestrial ecosystem carbon balance under future climate-change scenarios. 相似文献
10.
Contribution of increasing CO2 and climate to carbon storage by ecosystems in the United States 总被引：2，自引：0，他引：2
Schimel D Melillo J Tian H McGuire AD Kicklighter D Kittel T Rosenbloom N Running S Thornton P Ojima D Parton W Kelly R Sykes M Neilson R Rizzo B 《Science (New York, N.Y.)》2000,287(5460):2004-2006
The effects of increasing carbon dioxide (CO2) and climate on net carbon storage in terrestrial ecosystems of the conterminous United States for the period 1895-1993 were modeled with new, detailed historical climate information. For the period 1980-1993, results from an ensemble of three models agree within 25%, simulating a land carbon sink from CO2 and climate effects of 0.08 gigaton of carbon per year. The best estimates of the total sink from inventory data are about three times larger, suggesting that processes such as regrowth on abandoned agricultural land or in forests harvested before 1980 have effects as large as or larger than the direct effects of CO2 and climate. The modeled sink varies by about 100% from year to year as a result of climate variability. 相似文献
11.
The extreme warmth of particular intervals of geologic history cannot be simulated with climate models, which are constrained by the geologic proxy record to relatively modest increases in atmospheric carbon dioxide levels. Recent recognition that biological productivity controls the abundance of cloud condensation nuclei (CCN) in the unpolluted atmosphere provides a solution to this problem. Our climate simulations show that reduced biological productivity (low CCN abundance) provides a substantial amplification of CO2-induced warming by reducing cloud lifetimes and reflectivity. If the stress of elevated temperatures did indeed suppress marine and terrestrial ecosystems during these times, this long-standing climate enigma may be solved. 相似文献
12.
Role of land-surface changes in arctic summer warming 总被引：2，自引：0，他引：2
Chapin FS Sturm M Serreze MC McFadden JP Key JR Lloyd AH McGuire AD Rupp TS Lynch AH Schimel JP Beringer J Chapman WL Epstein HE Euskirchen ES Hinzman LD Jia G Ping CL Tape KD Thompson CD Walker DA Welker JM 《Science (New York, N.Y.)》2005,310(5748):657-660
A major challenge in predicting Earth's future climate state is to understand feedbacks that alter greenhouse-gas forcing. Here we synthesize field data from arctic Alaska, showing that terrestrial changes in summer albedo contribute substantially to recent high-latitude warming trends. Pronounced terrestrial summer warming in arctic Alaska correlates with a lengthening of the snow-free season that has increased atmospheric heating locally by about 3 watts per square meter per decade (similar in magnitude to the regional heating expected over multiple decades from a doubling of atmospheric CO2). The continuation of current trends in shrub and tree expansion could further amplify this atmospheric heating by two to seven times. 相似文献
13.
Europe's terrestrial biosphere absorbs 7 to 12% of European anthropogenic CO2 emissions 总被引：2，自引：0，他引：2
Janssens IA Freibauer A Ciais P Smith P Nabuurs GJ Folberth G Schlamadinger B Hutjes RW Ceulemans R Schulze ED Valentini R Dolman AJ 《Science (New York, N.Y.)》2003,300(5625):1538-1542
Most inverse atmospheric models report considerable uptake of carbon dioxide in Europe's terrestrial biosphere. In contrast, carbon stocks in terrestrial ecosystems increase at a much smaller rate, with carbon gains in forests and grassland soils almost being offset by carbon losses from cropland and peat soils. Accounting for non-carbon dioxide carbon transfers that are not detected by the atmospheric models and for carbon dioxide fluxes bypassing the ecosystem carbon stocks considerably reduces the gap between the small carbon-stock changes and the larger carbon dioxide uptake estimated by atmospheric models. The remaining difference could be because of missing components in the stock-change approach, as well as the large uncertainty in both methods. With the use of the corrected atmosphere- and land-based estimates as a dual constraint, we estimate a net carbon sink between 135 and 205 teragrams per year in Europe's terrestrial biosphere, the equivalent of 7 to 12% of the 1995 anthropogenic carbon emissions. 相似文献
14.
Freshwater methane emissions offset the continental carbon sink 总被引：7，自引：0，他引：7
Bastviken D Tranvik LJ Downing JA Crill PM Enrich-Prast A 《Science (New York, N.Y.)》2011,331(6013):50
Inland waters (lakes, reservoirs, streams, and rivers) are often substantial methane (CH(4)) sources in the terrestrial landscape. They are, however, not yet well integrated in global greenhouse gas (GHG) budgets. Data from 474 freshwater ecosystems and the most recent global water area estimates indicate that freshwaters emit at least 103 teragrams of CH(4) year(-1), corresponding to 0.65 petagrams of C as carbon dioxide (CO(2)) equivalents year(-1), offsetting 25% of the estimated land carbon sink. Thus, the continental GHG sink may be considerably overestimated, and freshwaters need to be recognized as important in the global carbon cycle. 相似文献
15.
湿地土壤碳循环研究进展 总被引：1，自引：0，他引：1
湿地是地球上碳储量最大的陆地生态系统,其碳储量约占陆地生态圈总碳量的20%.湿地碳的90%以上储存在湿地土壤中.湿地土壤碳的循环对全球大气碳的收支平衡以及全球气候变化可能产生重大影响.概述了湿地土壤碳素变化与温室气体排放的关系、湿地土壤碳素循环过程及其影响因素等方面的研究进展,提出了进一步研究的问题. 相似文献
16.
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. 相似文献
17.
Le Quéré C Rödenbeck C Buitenhuis ET Conway TJ Langenfelds R Gomez A Labuschagne C Ramonet M Nakazawa T Metzl N Gillett N Heimann M 《Science (New York, N.Y.)》2007,316(5832):1735-1738
Based on observed atmospheric carbon dioxide (CO2) concentration and an inverse method, we estimate that the Southern Ocean sink of CO2 has weakened between 1981 and 2004 by 0.08 petagrams of carbon per year per decade relative to the trend expected from the large increase in atmospheric CO2. We attribute this weakening to the observed increase in Southern Ocean winds resulting from human activities, which is projected to continue in the future. Consequences include a reduction of the efficiency of the Southern Ocean sink of CO2 in the short term (about 25 years) and possibly a higher level of stabilization of atmospheric CO2 on a multicentury time scale. 相似文献
18.
Measurements of the concentrations and carbon-13/carbon-12 isotope ratios of atmospheric carbon dioxide can be used to quantify the net removal of carbon dioxide from the atmosphere by the oceans and terrestrial plants. A study of weekly samples from a global network of 43 sites defined the latitudinal and temporal patterns of the two carbon sinks. A strong terrestrial biospheric sink was found in the temperate latitudes of the Northern Hemisphere in 1992 and 1993, the magnitude of which is roughly half that of the global fossil fuel burning emissions for those years. The challenge now is to identify those processes that would cause the terrestrial biosphere to absorb carbon dioxide in such large quantities. 相似文献
19.
长白山阔叶红松林碳收支特征 总被引：8，自引：0，他引：8
植被-大气间CO2交换研究对准确评价陆地生态系统碳收支有重要意义．该研究采用开路式涡动相关系统对长白山阔叶红松林的C O2交换特征进行了整年连续监测．结果表明,该森林生态系统的碳交换季节变化明显,2003年森林净生态系统碳交换量(NEE)变化范围在-6.37～2.13 g/(m2·d)之间,5—9月均表现为碳汇,其余月份为碳源,其中净碳吸收量与释放量最大的月份分别为6和10月;全年森林净吸收的碳量为-191.3 g/m2,整体表现为一定强度的碳汇．影响NEE的环境因子主要是光合有效辐射(PAR)和土壤温度等,白天NEE对PAR 的响应符合直角双曲线方程,夜间的NEE与5 cm深土壤温度有较好的指数关系．生态系统呼吸释放对温度响应的敏感性(Ｑ10)为3.17． 相似文献
20.
Loss of carbon from the deep sea since the Last Glacial Maximum 总被引：1，自引：0，他引：1
Yu J Broecker WS Elderfield H Jin Z McManus J Zhang F 《Science (New York, N.Y.)》2010,330(6007):1084-1087
Deep-ocean carbonate ion concentrations ([CO(3)(2-)]) and carbon isotopic ratios (δ(13)C) place important constraints on past redistributions of carbon in the ocean-land-atmosphere system and hence provide clues to the causes of atmospheric CO(2) concentration changes. However, existing deep-sea [CO(3)(2-)] reconstructions conflict with one another, complicating paleoceanographic interpretations. Here, we present deep-sea [CO(3)(2-)] for five cores from the three major oceans quantified using benthic foraminiferal boron/calcium ratios since the last glacial period. Combined benthic δ(13)C and [CO(3)(2-)] results indicate that deep-sea-released CO(2) during the early deglacial period (17.5 to 14.5 thousand years ago) was preferentially stored in the atmosphere, whereas during the late deglacial period (14 to 10 thousand years ago), besides contributing to the contemporary atmospheric CO(2) rise, a substantial portion of CO(2) released from oceans was absorbed by the terrestrial biosphere. 相似文献