Global Carbon Sinks and Their Variability Inferred from Atmospheric [O.sub.2] and [[Delta].sup.13]C

• Published in: Science (American Association for the Advancement of Science) Vol. 287; no. 5462; p. 2467
• Main Authors: Battle, M, Bender, M.L, Tans, P.P, White, J.W.C, Ellis, J.T, Conway, T, Francey, R.J
• Format: Journal Article
• Language: English
• Published: American Association for the Advancement of Science 31-03-2000
• Subjects: Atmospheric carbon dioxide; Carbon content; Carbon dioxide; Composition; Measurement; Soil carbon; Soils
• ISSN: 0036-8075

Recent time-series measurements of atmospheric [O.sub.2] show that the land biosphere and world oceans annually sequestered 1.4 [+ or -] 0.8 and 2.0 [+ or -] 0.6 gigatons of carbon, respectively, between mid-1991 and mid-1997. The rapid storage of carbon by the land biosphere from 1991 to 1997 contrasts with the 1980s, when the land biosphere was approximately neutral Comparison with measurements of [[Delta].sup.13][CO.sub.2] implies an isotopic flux of 89 [+ or -] 21 gigatons of carbon per mil per year, in agreement with model- and inventory-based estimates of this flux. Both the [[Delta].sup.13]C and the [O.sub.2] data show significant interannual variability in carbon storage over the period of record. The genera[ agreement of the independent estimates from [O.sub.2] and [[Delta].sup.13]C is a robust signal of variable carbon uptake by both the land biosphere and the oceans.