Letter abstract


Nature Geoscience 2, 630 - 635 (2009)
Published online: 30 August 2009 | doi:10.1038/ngeo612

Subject Category: Oceanography

The impact of remineralization depth on the air–sea carbon balance

Eun Young Kwon1, François Primeau2 & Jorge L. Sarmiento1

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As particulate organic carbon rains down from the surface ocean it is respired back to carbon dioxide and released into the ocean's interior. The depth at which this sinking carbon is converted back to carbon dioxide—known as the remineralization depth—depends on the balance between particle sinking speeds and their rate of decay. A host of climate-sensitive factors can affect this balance, including temperature1, oxygen concentration2, stratification, community composition3, 4 and the mineral content of the sinking particles5. Here we use a three-dimensional global ocean biogeochemistry model to show that a modest change in remineralization depth can have a substantial impact on atmospheric carbon dioxide concentrations. For example, when the depth at which 63% of sinking carbon is respired increases by 24 m globally, atmospheric carbon dioxide concentrations fall by 10–27 ppm. This reduction in atmospheric carbon dioxide concentration results from the redistribution of remineralized carbon from intermediate waters to bottom waters. As a consequence of the reduced concentration of respired carbon in upper ocean waters, atmospheric carbon dioxide is preferentially stored in newly formed North Atlantic Deep Water. We suggest that atmospheric carbon dioxide concentrations are highly sensitive to the potential changes in remineralization depth that may be caused by climate change.

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  1. Atmospheric and Oceanic Sciences Program, Princeton University, New Jersey 08544, USA
  2. Department of Earth System Science, University of California, Irvine, California 92697, USA

Correspondence to: Eun Young Kwon1 e-mail: ekwon@princeton.edu



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