Deforestation of the Amazon is about to reach a threshold beyond which the region’s tropical rainforest may undergo irreversible changes that transform the landscape into degraded savanna with sparse, shrubby plant cover and low biodiversity. This warning derives from an editorial published in the journal Science Advances co-authored by Thomas Lovejoy, a professor at George Mason University in the United States, and Carlos Nobre, chair of Brazil’s National Institute of Science & Technology (INCT) for Climate Change.