Future Changes in the Aridity of South America from Regional Climate Model Projections

Future changes of the aridity of South America (SA) are investigated. The projected changes of the Budyko and United Nations Environment Programme (UNEP) indices in the mid- and end of the twenty-first century from the ensemble mean RegCM4 simulations using the scenario RCP 8.5 are presented. The RegCM4 model driven by the global models of HadGEM2, MPI, and GFDL for the period 1970-2100 carries out the simulations. For both Budyko and UNEP indices, an aridity increase over SA is projected. Over Brazil, the higher changes were found in the Amazon, North Brazil, and Northeast Brazil (NEB). In the Amazon and North Brazil, an increase of the aridity of 33.8% and 36.9% (for the UNEP index) and 4.6% and 13.9% (for the Budyko index), respectively, are noted at the end of the twenty-first century suggesting an increase of the process of savannization in future climate. In NEB, a rise of 37.3% and 14.1%, respectively, for the UNEP and the Budyko indices, is found, indicating an expansion of areas of the dry land regime.