Authors: K Maynard JF Royer
Publish Date: 2004/03/10
Volume: 22, Issue: 4, Pages: 343-358
Abstract
The primary goal of this investigation is to focus on a “realistic” scenario for simulating impacts on regional African climate of future deforestation in a greenhousewarmed world Combined effects of plausible landcover change and greenhouse warming are assessed by ‘timeslice’ simulations with an atmospheric general circulation model AGCM for the middle of the twenty first century Three “timeslice” integrations have been performed with the ARPEGEClimat AGCM incorporating a zooming technique to achieve a resolution of about 100 km over Africa A control run for the current climate is forced by observed climatological sea surface temperatures SSTs and the observed vegetation distribution is specified from a new vegetation database in order to improve the geographical distribution and properties of the vegetation cover Future SST changes are derived from a transient coupled atmosphere–ocean simulation for scenario B2 of the International Panel on Climate Change IPCC Future vegetation changes are specified from a simulation of scenario B2 with the Integrated Model to Assess the Global Environment IMAGE developed at the National Institute of Public Health and the Environment in the Netherlands RIVM The results show that land surface processes can locally modulate greenhouse warming effects for African climate with reductions of surface transpiration and small increases of surface temperature Deforestation of tropical Africa has overall only a marginal effect on precipitation because of a compensatory increase in moisture convergence Energy budget analyses show that increases in surface temperature are produced both by increases of greenhouse gases GHG concentration from the increase in downward atmospheric longwave radiation and by African tropical deforestation from the resulting reduction in transpiration This study indicates that realistic landuse changes though of smaller amplitude than greenhouse gas forcing may have a small regional effect in projections of future climateThe authors thank the IMAGE Team at RIVM for providing the IMAGE 22 simulations on CDROM particularly Michiel Schaeffer and Bas Eickhout for their assistance We are grateful to Fabrice Chauvin Hervé Douville Michel Déqué and Robin Clark for their help The software package GrADS http//gradsigesorg/grads/ was used to draw the figures This study has been supported by a grant from European Commission Fifth Framework Programme PROMISE contract EVK2CT1999–00022 and by the French “Programme National d’Etude de la Dynamique du Climat” PNEDC
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