Global ocean carbon uptake: magnitude, variability and trends

[摘要] The globally integrated sea–air anthropogenic carbon dioxide (CO₂) fluxfrom 1990 to 2009 is determined from models and data-based approaches aspart of the Regional Carbon Cycle Assessment and Processes (RECCAP) project.Numerical methods include ocean inverse models, atmospheric inverse models,and ocean general circulation models with parameterized biogeochemistry(OBGCMs). The median value of different approaches shows good agreement inaverage uptake. The best estimate of anthropogenic CO₂ uptake for thetime period based on a compilation of approaches is −2.0 Pg C yr⁻¹.The interannual variability in the sea–air flux is largely driven bylarge-scale climate re-organizations and is estimated at0.2 Pg C yr⁻¹ for the two decades with some systematic differencesbetween approaches. The largest differences between approaches are seen inthe decadal trends. The trends range from −0.13(Pg C yr⁻¹) decade⁻¹ to −0.50 (Pg C yr⁻¹) decade⁻¹for the two decades under investigation. The OBGCMs and the data-basedsea–air CO₂ flux estimates show appreciably smaller decadal trends thanestimates based on changes in carbon inventory suggesting that methodscapable of resolving shorter timescales are showing a slowing of the rate ofocean CO₂ uptake. RECCAP model outputs for five decades show similardifferences in trends between approaches.

[学科分类] 地球化学与岩石