Integrated modelling of climate change impacts in Northeastern Brazil

Societies in semi-arid areas in developing regions are amongst those, most vulnerable to climate variability and potentially most vulnerable to climate change. The vulnerability to climate variability is caused by the strong restrictions that limited water availability poses on the use of natural resources, by the generally low reliability of water availability and, on the other hand, an often appreciable density of population, strongly depending on these resources with little shortterm options to reduce the dependency. Reasonable conditions in the wetter years support the persistence of population in the area; marginal or poor conditions in dryer years and arrears in development hamper significant improvements in the quality of life. Regional tradition and adaptation to local conditions serve as experiences to cope with droughts. This may help to survive emergency situations, but does not really reduce vulnerability, as it does not reduce development deficits. Present-day climate conditions already are marginal to sustain societal demands, therefore climate change poses a serious potential threat. Clearly, the study of climate change impacts in developing semi-arid regions calls for an integrated approach. The climate impacts are not merely an effect of changes in water availability, but emerge from the confrontation of availability and societal demands and the role these demands play in society. Therefore, the study should include not only the physical understanding of climate impacts on the water balance and on crop yields, but should also include the analysis of water use, agricultural economy and societal impacts. In North-eastern Brazil, one of the most marked societal impacts of droughts is the emigration of population from rural areas in the urban centres and to destinations outside the region (Magalhães et al., 1988).