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Projected increase in continental runoff due to plant responses to increasing carbon dioxide

Betts, Richard A.; Boucher, Olivier; Collins, Matthew; Cox, Peter M.; Falloon, Peter D.; Gedney, Nicola; Hemming, Deborah L.; Huntingford, Chris; Jones, Chris D.; Sexton, David M.H.; Webb, Mark J.. 2007 Projected increase in continental runoff due to plant responses to increasing carbon dioxide. Nature, 448 (7157). 1037-1042. 10.1038/nature06045

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Abstract/Summary

In addition to influencing climatic conditions directly through radiative forcing, increasing carbon dioxide concentration influences the climate system through its effects on plant physiology1. Plant stomata generally open less widely under increased carbon dioxide concentration2, which reduces transpiration1, 3, 4, 5, 6 and thus leaves more water at the land surface7. This driver of change in the climate system, which we term 'physiological forcing', has been detected in observational records of increasing average continental runoff over the twentieth century8. Here we use an ensemble of experiments with a global climate model that includes a vegetation component to assess the contribution of physiological forcing to future changes in continental runoff, in the context of uncertainties in future precipitation. We find that the physiological effect of doubled carbon dioxide concentrations on plant transpiration increases simulated global mean runoff by 6 per cent relative to pre-industrial levels; an increase that is comparable to that simulated in response to radiatively forced climate change (11 6 per cent). Assessments of the effect of increasing carbon dioxide concentrations on the hydrological cycle that only consider radiative forcing9, 10, 11 will therefore tend to underestimate future increases in runoff and overestimate decreases. This suggests that freshwater resources may be less limited than previously assumed under scenarios of future global warming, although there is still an increased risk of drought. Moreover, our results highlight that the practice of assessing the climate-forcing potential of all greenhouse gases in terms of their radiative forcing potential relative to carbon dioxide does not accurately reflect the relative effects of different greenhouse gases on freshwater resources.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.1038/nature06045
Programmes: CEH Programmes pre-2009 publications > Water
CEH Programmes pre-2009 publications > Biogeochemistry > CC01B Land-surface Feedbacks in the Climate System > CC01.7 Land carbon cycle feedbacks on climate change
CEH Sections: Harding (to 31.07.11)
ISSN: 0028-0836
NORA Subject Terms: Meteorology and Climatology
Ecology and Environment
Atmospheric Sciences
Date made live: 01 Oct 2007 15:18
URI: http://nora.nerc.ac.uk/id/eprint/898

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