Enhancement of interdecadal climate variability in the Sahel by vegetationinteraction

The role of naturally varying vegetation in influencing the climate variabi lity in the West African Sahel is explored in a coupled atmosphere-land-veg etation model. The Sahel rainfall variability is influenced by sea-surface temperature variations in the oceans. Land-surface feedback is found to inc rease this variability both on interannual and interdecadal time scales. In teractive vegetation enhances the interdecadal variation substantially but can reduce year-to-year variability because of a phase lag introduced by th e relatively slow vegetation adjustment time. Variations in vegetation acco mpany the changes in rainfall in particular the multidecadal drying trend f rom the 1950s to the 1980s.