Regional differences in aridity/drought conditions over Northeast Brazil: present state and future projections

Abstract

The focus of this study is to investigate the risk of aridification in the semiarid lands of Northeast Brazil, using a variety of observational information and climate change projections for the future, by means of aridity indices. We use the Budyko and United Nations aridity indices to assess the extent of areas with semi-arid and arid conditions in the present, and for the future out to 2100. Climate projections are derived from the downscaling of the HadCM3 model for the A1B scenario using the Eta regional model with horizontal resolution of 40 km. Consistent with global climate model projections from IPCC AR5, regional climate change projections suggest an increase in dryness in the region, with rainfall reductions, temperature increases and water deficits and longer dry spells, leading to drought and arid conditions expected to prevail by the second half of the 21th century. The area with arid conditions is projected to grow to cover areas currently with dry sub humid conditions, and become larger by 2100. This increase in aridity, combined with land degradation may increase the risk of desertification.