Publication Date:
2014-03-14
Description:
Oceanic uptake and long-term storage of atmospheric carbon dioxide (CO 2 ) are strongly driven by the marine ‘biological pump’, i.e. sinking of biotically fixed inorganic carbon and nutrients from the surface into the deep ocean [ Sarmiento and Bender , 1994; Volk and Hoffert , 1985]. Sinking velocity of marine particles depends on seawater viscosity, which is strongly controlled by temperature [ Sharqawy et al. , 2010]. Consequently, marine particle flux is accelerated as ocean temperatures increase under global warming [ Bach et al. , 2012]. Here we show that this previously overlooked 'viscosity effect' could have profound impacts on marine biogeochemical cycling and carbon uptake over the next centuries to millennia. In our global-warming simulation, the viscosity effect accelerates particle sinking by up to 25%, thereby effectively reducing the portion of organic matter that is respired in the surface ocean. Accordingly, the biological carbon pump's efficiency increases, enhancing the sequestration of atmospheric CO 2 into the ocean. This effect becomes particularly important on longer timescales when warming reaches the ocean interior. At the end of our simulation (4000 AD) oceanic carbon uptake is 17% higher, atmospheric CO 2 concentration is 180 ppm lower, and the increase in global average surface temperature is 8% weaker when considering the viscosity effect. Consequently, the viscosity effect could act as a long-term negative feedback mechanism in the global climate system.
Print ISSN:
0886-6236
Electronic ISSN:
1944-9224
Topics:
Biology
,
Chemistry and Pharmacology
,
Geography
,
Geosciences
,
Physics
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