Impact of changes in diffuse radiation on the global land carbon sink

Mercado, Lina M. ORCID:; Bellouin, Nicolas; Sitch, Stephen; Boucher, Olivier; Huntingford, Chris ORCID:; Wild, Martin; Cox, Peter M.. 2009 Impact of changes in diffuse radiation on the global land carbon sink. Nature, 458. 1014-1017.

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Plant photosynthesis tends to increase with irradiance. However, recent theoretical and observational studies have demonstrated that photosynthesis is also more efficient under diffuse light conditions1–5. Changes in cloud cover or atmospheric aerosol loadings, arising from either volcanic or anthropogenic emissions, alter both the total photosynthetically active radiation reaching the surface and the fraction of this radiation which is diffuse, with uncertain overall effects on global plant productivity and the land carbon sink. Here we estimate the impact of variations in diffuse fraction on the land carbon sink using a global model modified to account for the effects of variations in both direct and diffuse radiation on canopy photosynthesis. We estimate that variations in diffuse fraction, associated largely with the ‘global dimming’ period6–8, enhanced the land carbon sink by approximately one-quarter between 1960 and 1999. However, under a climate mitigation scenario for the twenty-first century in which sulphate aerosols decline before atmospheric CO2 is stabilized, this ‘diffuse-radiation’ fertilisation effect declines rapidly to near zero by the end of the twenty-first century.

Item Type: Publication - Article
Digital Object Identifier (DOI):
Programmes: CEH Programmes pre-2009 publications > Biogeochemistry
UKCEH and CEH Sections/Science Areas: Harding (to July 2011)
ISSN: 0028-0836
Additional Keywords: global dimming and brightenning, land carbon sink, photosynthesis
NORA Subject Terms: Ecology and Environment
Earth Sciences
Date made live: 27 May 2009 10:39 +0 (UTC)

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