Quantifying tropical forest rainfall generation

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. The Brazilian Legal Amazon region delivers rainfall generation worth US$20 ± 7 billion annually, with each meter squared of forest contributing 300 L of water per year, according to analyses of observational and model-based data.