Tropical deforestation drives strong dry-season precipitation reductions at large spatial scales

Tropical forests play a critical role in the hydrological cycle and can impact local and regional precipitation. To date, the effects of tropical deforestation on precipitation have largely been assessed based on case studies focused on a specific region, with the broader impacts being poorly constrained. Here, we make the first pan-tropical assessment of how tropical forest loss between 2003 and 2017 impacts precipitation at a range of spatial scales, using satellite, station-based and reanalysis datasets. We find the impact of forest loss on precipitation increases at larger spatial scales, with satellite datasets (n=9) showing robust reductions in precipitation at scales greater than ~50 km. The greatest relative declines in precipitation were observed at ~200 km, where reductions in canopy cover caused a 30% decrease in dry season precipitation (satellite data). Station-based and reanalysis datasets were unable to capture the precipitation response to deforestation shown by satellite datasets, likely due to limited tropical in situ data and poor representation of surface changes in land-surface schemes. Our analysis provides further evidence that tropical deforestation disrupts the forest-rainfall cascade, with consequences for forest ecosystems, human settlements and agriculture downwind that are reliant on moisture propagated inland through recycling over forests.