Climate change predictions tied to Amazon deforestation scenarios are increasingly being used by government and non-government organisations for near-future planning applications. Despite incorporating a wide range of biophysical variables, these models neglect future scenarios of land use for adjoining regions, such as the Central Brazil Cerrado, which has been deforested by more than 50%. In this study, we investigate the impact of different Amazon and Central Brazil deforestation scenarios on the rainfall regime of the 'arc-of-deforestation' in Amazonia. We demonstrate that both Amazon and Cerrado deforestation contribute to an increase of the duration of the dry season in this region. Combining the effects of both scenarios, the dry season may increase from 5 months to 6 months, which may change the biosphere-atmosphere equilibrium in this region. This study demonstrates that the assessment of future Cerrado land use scenarios is also necessary to understand the future climate and ecosystem health of Amazonia.

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Deforestation on Amazonia and central Brazil Cerrado could change regional climate, possibly shifting forest equilibrium into a bioclimatic envelope typical of savannas. Although impacts of climate change induced by deforestation are likely to vary subregionally, the potential geographic variation of these effects and the thresholds of rainforest and Cerrado removal that will affect Amazonian bioclimatic equilibrium remain unknown. We evaluate the effects of deforestation scenarios of increasing severity on the bioclimatic equilibrium of Amazon subregions. Results indicate that subregional precipitation responds in three distinct ways to progressive deforestation: a near‐constant rate of reduction, a rapid drop for low deforestation levels, and a decrease after intermediate deforestation levels. Additionally, while inner forest regions remain inside rainforest bioclimatic envelope, outer forest regions may cross forest‐savanna bioclimatic threshold even at low deforestation levels. We argue that at least 90% of Amazonia and 40% of Cerrado should be sustained to avoid subregional bioclimatic savannization.

In southern Amazonia, more than half of all cropland is devoted to the production of two rainfed crops per year, an agricultural practice known as “double cropping” (DC). Climate change, including feedbacks between changes in land use and the local climate, is shortening the extent of the historical rainy season in southern Amazonia, increasing the risk of future detrimental environmental conditions, and posing a threat to the intensive DC agriculture that is currently practiced in that region, with potential negative consequences at regional, national, and even global scales. We argue that the conservation of undeveloped forests and savannas in southern Amazonia is supported by socioeconomic justifications and is in the best interests of agribusiness, local governments, and the public.