Climate: Deforestation may reduce rainfall in tropical forests

Deforested regions across the topics show reductions in precipitation, an analysis published in Nature demonstrates. The findings indicate that in 2100 projected rates of deforestation in the Congo could reduce local precipitation by 8–10%.

Tropical forests have an important role in regulating climate due to their influence on energy, water and carbon cycles. They also influence local and regional precipitation patterns; evapotranspiration, for example, is a strong driver of regional rainfall accounting for 41% of basin mean rainfall in the Amazon and nearly 50% in the Congo. The role of deforestation and its impact on precipitation is uncertain due to the range of processes happening and the different scales. In the Amazon, small-scale deforestation has been linked to an increase in precipitation but in Indonesia it has been linked to a decrease in rainfall and exacerbation of El Niño impacts.

To explore the role of forest loss on precipitation, Callum Smith and colleagues analysed a satellite dataset of forest cover change from 2003 to 2017 with a focus on the Amazon, Congo and Southeast Asia to identify areas of forest loss. They combined this information with 18 different precipitation datasets. The authors found that the impact of deforestation on precipitation increased at larger scales; robust reductions in precipitation owing to forest loss occurred at spatial scales greater than 50 km, with the greatest reductions observed at 200 km. Absolute changes in precipitation as a result of forest loss were greatest in the wet season. The authors suggest that projected rates of deforestation could lead to a reduction in local precipitation of around 8–10% in the Congo by 2100.

The authors conclude that their findings demonstrate the need for tropical forest conservation to support climate resilience.