New study warns deforestation could deplete Amazon’s rainfall

Deforestation significantly reduces rainfall in tropical regions, according to a new study by scientists at the University of Leeds.

Amazon Forest, Picture: Anderson Coelho/ Getty Images

Researchers used satellite and meteorological data from pantropical regions to prove a correlation between deforestation and regional precipitation. They found that the more rainforests are cleared in tropical countries, the less local farmers can depend on rain for their crops and pastures. The study also discovered that, at the most enormous measured scale of 200km squared, rainfall was 0.25 percentage points lower each month for every one percentage point loss of forest.

The research adds to concerns that the Amazon rainforest is approaching a tipping point, after which it will no longer be able to generate its rainfall, and the vegetation will dry up. One of the authors of the study, Professor Dominick Spracklen, explained that 25% to 50% of the rain that falls in the Amazon comes from precipitation recycling by trees, stating that although the forest is sometimes described as the “lungs of the world”, it functions far more like a heart that pumps water around the region. Spracklen hopes the study will provide a strong incentive for policy and decision-makers within tropical nations to conserve tropical forests to help maintain a cooler and wetter local climate, benefiting nearby agriculture and people.

The study notes that crop yields could decline by 1.25% for each ten percentage point loss of forest cover. The consequences will likely be felt in cities and farm fields hundreds or thousands of kilometres outside the cleared forest. The authors also looked forward to the possible effects of further deforestation. For the Congo basin, they estimated a rainfall decline of 16mm a month by the century’s end based on forest loss projections.

The research indicates the urgent need to protect forests and other vegetation in the Amazon and Congo basin regions and Southeast Asia. Governments and agricultural companies must invest more in protecting trees to avoid further degradation of these vital ecosystems. The local impact of reduced water recycling is far more apparent and persuasive to governments and corporations in the global south than arguments about carbon sequestration, which is seen as having more benefits to industrial countries in the northern hemisphere.