Secas no nordeste brasileiro diante de um cenário de mudanças climáticas

Abstract

Northeast Brazil (NEB) is located in a region where a regular rainfall distribution should be expected. However, it has a semi-arid climate, characterized by a pronounced time and space variability in precipitation distribution. The “Drought Polygon”, region that covers eighty per cent of NEB’s total area (~1.5 million km2), has annual evaporation from 2400 to 3000mm and mean annual precipitation below 800mm, which is narrowly concentrated in few months. The result of these climatic adverse conditions are recurrent droughts (Secas) with serious social and economical effects: most of population of rural area are completely dependent upon agriculture and very sensitive to the phenomena; droughts in Nordeste regularly lead to famine and mass exodus. Nowadays, the world scientific community discuss climatic changes and greenhouse effect; in the scenario of global warming, an increase of evaporation should be certainly expected; in the same way, an expansion in precipitation must occur. What can happen to this Region, regarding to droughts, under a scenario of higher evaporation? How much should the precipitation increase to counterbalance it? That is the question that this paper will try to answer.