Simulated response of the ocean carbon cycle to anthropogenic climate warming

• Published in: Nature (London) Vol. 393; no. 6682; pp. 245 - 249
• Main Authors: Sarmiento, J.L, Hughes, T.M.C, Stouffer, R.J, Manabe, S
• Format: Journal Article
• Language: English
• Published: London Nature Publishing 21.05.1998; Nature Publishing Group
• Subjects: biogeochemical cycles; Carbon; carbon dioxide; carbon sequestration; Earth sciences; Earth, ocean, space; Emissions; Engineering and environment geology. Geothermics; Exact sciences and technology; global warming; Greenhouse effect; Marine; Marine and continental quaternary; marine environment; Oceans; Pollution, environment geology; simulation models; Surficial geology; PS, Antarctic Ocean; carbon dioxide; atmospheric emission; stratification; simulation; greenhouse effect; climate warming; carbon cycle; transport; pollution; human activity; climate modification; Antarctic Ocean; ocean circulation
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/30455

A 1995 report of the Intergovernmental Panel on Climate Change provides a set of illustrative anthropogenic CO2 emission models leading to stabilization of atmospheric CO2 concentrations ranging from 350 to 1,000 p.p.m. Ocean carbon-cycle models used in calculating these scenarios assume that oceanic circulation and biology remain unchanged through time. Here we examine the importance of this assumption by using a coupled atmosphere-ocean model of global warming for the period 1765 to 2065. We find a large potential modification to the ocean carbon sink in a vast region of the Southern Ocean where increased rainfall leads to surface freshening and increased stratification. The increased stratification reduces the downward flux of carbon and the loss of heat to the atmosphere, both of which decrease the oceanic uptake of anthropogenic CO2 relative to a constant-climate control scenario. Changes in the formation, transport and cycling of biological material may counteract the reduced uptake, but the response of the biological community to the climate change is difficult to predict on present understanding. Our simulation suggests that such physical and biological changes might already be occurring, and that they could substantially affect the ocean carbon sink over the next few decades.