Amazon savannization and climate change are projected to increase dry season length and heat waves over Brazil

Abstract

Abstract Land use and atmospheric composition drivers of climate change can interact to affect both local and remote precipitation and temperature regimes. In this article, we investigate the impacts of Amazon savannization and climate change in a global coupled ocean-atmosphere model simulation. We find that both Amazon land use change and atmospheric radiative forcing enlarge the dry season and reduce annual rainfall over most of South America; with the land use driver reinforcing the drying effects of global climate change not only over the Amazon, but also the southern Brazil states. The combined effects of land use and climate change resulted in a mean annual rainfall reduction of 44% and dry season length increase of 69%, when averaged over the Amazon basin, relative to the control run. Modulation of inland moisture transport due to Amazon savannization shows the largest signal to explain the rainfall reduction and dry season length increase throughout Brazil. Temperature wise, the combined effects of savannization and global warming resulted in maximum daily temperature anomalies, reaching values of up to 14 °C above the current climatic conditions over the Amazon. Also, as a consequence of both climate drivers, both soil moisture and surface runoff decrease over most of the country, suggesting cascading negative future impacts on both agriculture production and hydroelectricity power plants generation.