Tropical Forests Worth Millions in Rainfall Value Each Year, Study Finds

Each stretch of tropical forest does more than provide habitat—it also helps create rainfall on a vast scale, according to new research. Scientists at University of Leeds estimate that a single hectare of tropical forest generates roughly 634,000 gallons of rain each year—about the volume of an Olympic-size swimming pool, reports Phys.org. By combining satellite observations with climate modeling, the team calculated the economic value of that moisture: about $20 billion annually in rainfall that supports agriculture in the Brazilian Amazon alone.

The figure far exceeds the financial incentives currently available to conserve or restore the region’s forests, the authors note. Their study, published in Communications Earth & Environment, connects forest-driven rainfall to major crops. For example, it finds that maintaining cotton and soybean production can depend on larger areas of forest to supply rainfall than the cropland itself covers.

Deforestation in the Amazon—about 80 million hectares cleared in recent decades—may already have eliminated nearly $5 billion per year in rainfall-related benefits. The losses ripple outward, affecting food production, drinking water supplies, and hydropower. The researchers argue that because laws and economic policies rarely account for forest-generated rainfall, governments are undervaluing one of the clearest reasons to keep forests intact and agriculture viable. The Natural History Museum offers further explanation of the science behind how forests help produce rain.