The stability of the Amazon rainforest and the ecosystem's resilience to widespread deforestation may be much lower than previously thought. The replacement of stands of trees with grassland changes evapotranspiration rates and atmospheric moisture convergence, which, in turn, reduce regional rainfall. This feedback effect could drive further deforestation. Previous research indicated that a dramatic shift from forest to grassland could overtake the Amazon when the total deforested area hits 40% to 50% of the forest's current size. New research by Pires and Costa, however, found that the deforestation needed to trigger this equilibrium shift is much lower, closer to just 10%.