Amazonian deforestation significantly impacts regional and global climate. Using a coupled atmosphere-biosphere model, researchers found that replacing tropical forests with degraded pasture in the Amazon leads to a 2.5°C increase in surface temperature, a 30% reduction in evapotranspiration, and a 25% decrease in precipitation. These effects are most pronounced during the dry season, with larger diurnal temperature fluctuations and vapor pressure deficits. The reduction in precipitation exceeds the decrease in evapotranspiration, indicating reduced moisture convergence. The dry season lengthens in southern Amazonia, threatening forest regeneration. An empirical bioclimatic model showed savanna-forest boundaries shift in response to climate changes. Deforestation could alter regional climate, affecting biodiversity and atmospheric chemistry. Observations suggest Amazonian rainforests efficiently recycle water, but degraded pasture cannot maintain such high evapotranspiration. The study highlights the sensitivity of the Amazonian climate to forest presence, with deforestation reducing precipitation more than evapotranspiration, leading to lower runoff. The model simulations show that deforestation reduces surface temperatures and increases sensible heat flux, with larger impacts during the dry season. The results suggest that deforestation could significantly alter Amazonian climate, with implications for regional and global climate systems.Amazonian deforestation significantly impacts regional and global climate. Using a coupled atmosphere-biosphere model, researchers found that replacing tropical forests with degraded pasture in the Amazon leads to a 2.5°C increase in surface temperature, a 30% reduction in evapotranspiration, and a 25% decrease in precipitation. These effects are most pronounced during the dry season, with larger diurnal temperature fluctuations and vapor pressure deficits. The reduction in precipitation exceeds the decrease in evapotranspiration, indicating reduced moisture convergence. The dry season lengthens in southern Amazonia, threatening forest regeneration. An empirical bioclimatic model showed savanna-forest boundaries shift in response to climate changes. Deforestation could alter regional climate, affecting biodiversity and atmospheric chemistry. Observations suggest Amazonian rainforests efficiently recycle water, but degraded pasture cannot maintain such high evapotranspiration. The study highlights the sensitivity of the Amazonian climate to forest presence, with deforestation reducing precipitation more than evapotranspiration, leading to lower runoff. The model simulations show that deforestation reduces surface temperatures and increases sensible heat flux, with larger impacts during the dry season. The results suggest that deforestation could significantly alter Amazonian climate, with implications for regional and global climate systems.