Influences of precipitation changes and direct CO2 effects on streamflow

Wigley, T.M.L. and Jones, P.D. (1985) Influences of precipitation changes and direct CO2 effects on streamflow. Nature, 314 (6007). pp. 149-152.

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Increasing atmospheric carbon dioxide concentrations are expected1 to cause major changes in the world's climate over the next 50–100 yr. The impact of such changes on water resources, through changing precipitation and evaporation, will, however, be complicated by the direct effects of increasing CO2 on vegetation. In controlled environment experiments, higher CO2 levels cause the stomata of plants to close down, decreasing their rate of transpiration and increasing their water use efficiency2. Reduced evapotranspiration would make more water available as runoff and could tend to offset the effects of any CO2-induced reductions in precipitation or enhance the effects of precipitation increases. We consider here, in a simple but revealing analysis, the relative sensitivity of runoff to these two processes, changes in precipitation and changes in evapotranspiration. We show that, for low runoff ratios, small changes in precipitation may cause large changes in runoff. The magnitude and direction of these changes is, however, strongly dependent on the magnitude of the direct CO2 effect on plant evapotranspiration

Item Type: Article
Author Affiliation: Climatic Research Unit, School of Environmental Sciences, University of East Anglia, Norwich NR4 7TJ, UK
Subjects: Plant Protection > Pesticides
Divisions: General
Depositing User: Mr B Krishnamurthy
Date Deposited: 25 Jul 2011 09:08
Last Modified: 25 Jul 2011 09:08
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