([9] and references therein) observed that land-use changes may reduce cloudiness, increasing insolation, and enhance land surface reflectance. Such activities also lead to changes in atmospheric aerosol loading, selleck chem MEK162 from an originally extremely clean atmosphere to a smoky/dusty one, particularly during the dry season: such particulates can in turn further modify rainfall patterns. Savannas are just as important for the hydrological cycle. Both forests and savannas are major CO2 sinks, and human-induced modifications can reduce this highly relevant environmental service.In order to model and assess regional climatic consequences of land-use changes, given their local/regional spatial characteristics, it is necessary to work with a much higher-resolution than that provided by global circulation models (GCMs).

Local/regional climate issues are better addressed, in the current state-of-the-art modeling, with higher resolution (~20�C50km) Regional Climate Models (RMCs) such as RegCM (ICTP, Italy) or PRECIS (Hadley Centre, UK), to name a few.For South America, most local/regional studies have addressed the Amazonian deforestation/land-use change processes, in particular through a number of major field studies such as the Anglo-Brazilian Amazonian Climate Observation Study, ABRACOS [10], and the Large-Scale Biosphere-Atmosphere Experiment in Amazonia, LBA [11]. A number of recent studies including [12�C14] have used RCMs to evaluate various aspects of climate processes occurring within Amazonia. More recently, Medvigy et al.

[15] carried out a study with the sophisticated variable resolution OLAM general circulation climate model, running it in mesoscale resolution over central South America. Note that OLAM is not an RCM since it is a full-scale GCM which is run in mesoscale resolution over a selected area.However, few have focused in extending the analysis of deforestation/land-use changes in the continent to include similar processes occurring within the Gran Chaco and the Selva Paranaense/Mata Atlantica regions. Thus, the aim of this work is to specifically assess the response to deforestation/land-use change taking place both in Amazonia, to the south of the Amazon River, and in the ecosystems within the Rio de la Plata Basin in RCM runs and, as a corollary, assess the potential consequences of such processes to Central South America’s climate. RCM AV-951 PRECIS, developed at the Hadley Centre, UK, is used here, driven by ERA-40 reanalysis and AGCM ECHAM4 model outputs. This first study specifically explores PRECIS’s mean climate response in 40-year runs to three deforestation/land-use change scenarios (Figure 1) during the baseline period 1961�C2000.