Sub-saharan desertification and productivity are linked to hemispheric climate variability


and present address: The Agricultural University of Norway, Noragric-Centre for International Environment and Development Studies, PO 5001, N-1432 Ås, Norway, tel + 47/22-854795, fax + 47/64-940760, e-mail
1Present address: Department of Biology, The Pennsylvania State University, 208 Mueller Lab, University Park, PA 16802, USA


Vegetation productivity and desertification in sub-Saharan Africa may be influenced by global climate variability attributable to the North Atlantic Oscillation (NAO) and El Niño Southern Oscillation (ENSO). Combined and individual effects of the NAO and ENSO indices revealed that 75% of the interannual variation in the area of Sahara Desert was accounted for by the combined effects, with most variance attributable to the NAO. Effects were shown in the latitudinal variation on the 200 mm isocline, which was influenced mostly by the NAO. The combined indices explained much of the interannual variability in vegetation productivity in the Sahelian zone and southern Africa, implying that both the NAO and ENSO may be useful for monitoring effects of global climate change in sub-Saharan Africa.