Tropical forests enhance regional rainfall but a robust analysis of this benefit is lacking. Consequently, the rainfall generating services of tropical forests are rarely accounted for in policymaking. We synthesised observational and model-based values of the reduction in rainfall due to tropical deforestation to quantify rainfall generation. Across these studies, we estimate that each meter squared of forest contributes 240 ± 60 L each year to regional rainfall. The Amazon forest has an even stronger rainfall benefit, with each meter squared of forest contributing 300 ± 110 L each year. Using a simple approach that assumes a constant water unit price, we estimate that Amazon forest rainfall generation is worth US$59.40 per hectare annually and the Brazilian Legal Amazon delivers rainfall generation worth US$20 ± 7 billion annually. Recognizing the economic value of tropical forests’ rainfall provision will unlock crucial investment and transform policy discussions on payments for forest protection.
