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REGIONAL BIOSPHERIC CARBON FLUXES AS INFERRED FROM ATMOSPHERIC CO 2 MEASUREMENTS
Author(s) -
Ciais P.,
Peylin P.,
Bousquet P.
Publication year - 2000
Publication title -
ecological applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.864
H-Index - 213
eISSN - 1939-5582
pISSN - 1051-0761
DOI - 10.1890/1051-0761(2000)010[1574:rbcfai]2.0.co;2
Subject(s) - environmental science , northern hemisphere , atmospheric sciences , biosphere , carbon sink , southern hemisphere , ecosystem , terrestrial ecosystem , atmospheric carbon cycle , carbon cycle , carbon dioxide in earth's atmosphere , biome , equator , sink (geography) , climatology , latitude , tropics , ocean gyre , carbon flux , climate change , geography , oceanography , geology , subtropics , ecology , cartography , geodesy , biology
Land ecosystems are currently absorbing ∼30% of fossil CO 2 emissions. However, the role of land ecosystems as sources or sinks of carbon in response to human perturbation is not well understood. One key issue is to better diagnose the flux of carbon exchanged between continents and the atmosphere at the regional level. We have analyzed the constraints that today's unevenly distributed global network of atmospheric CO 2 measurements put on one's ability to understand and pinpoint biospheric CO 2 fluxes. We constructed an inverse model using atmospheric CO 2 observations and atmospheric transport to infer the mean spatial distribution of CO 2 terrestrial fluxes. CO 2 fluxes can be inferred over large regions of the globe, such as continents or large ocean gyres. The target period for the inversion procedure is 1985–1995. The inversion produces a global ocean uptake of 1.5 ± 0.5 Pg C/yr and a global land sink of 1.3 ± 1.5 Pg C/yr (1 Pg = 10 15 g = 10 9 metric tons = 1 Gt). There is a net terrestrial carbon uptake at northern mid‐latitudes (2.1 ± 1.3 Pg C/yr) and a net release in the tropics (1.1 ± 1 Pg C/yr). In the Southern Hemisphere, at least over South America and Africa, our results indicate that tropical deforestation either has been overestimated or is currently offset by other sinks. However, the sparse spatial coverage of atmospheric observations around the Equator does not allow us to partition the inferred fluxes between South America and Africa separately. In the Northern Hemisphere, where more stations are available, we obtain an uptake of 0.5 ± 0.6 Pg C/yr over North America, 0.3 ± 0.8 Pg C/yr over Europe, and 1.3 ± 0.8 Pg C/yr over Siberia. We analyze uncertainties in these estimates in the light of the atmospheric measurements and the transport model that we used.