Ecology

Fewer trees mean less rain for the Amazon basin

Tree loss makes distant forests more vulnerable.

By the middle of the century, deforestation in the Amazon could reduce rainfall by up to 20%, even in areas far from those that have lost trees.

Tropical forests release huge volumes of water to the atmosphere, where it moves around and is recycled as rainfall — but pasture and farmland do not. Delphine Zemp at Humboldt University in Berlin and her colleagues modelled how the loss of forests could affect rainfall across South America. They calculate that if deforestation continues at roughly its current rate, dry-season rainfall will decrease by 8% across the Amazon basin by 2050, with localized hotspots losing up to 20% of their rain.

The greatest reductions in rainfall were seen in the southwestern part of the Amazon, and could make the region more vulnerable to disturbances such as extreme drought and fire. Rainfall loss from deforestation could therefore lead to further environmental degradation.