If deforestation increases by 1%, the rainfall falls by 0.25 mm/month
(sustainabilityenvironment.com) – There is a clear correlation between deforestation and the reduction of precipitation on a local scale. The more a portion of the forest is degraded, the less rainfall it will receive in subsequent years. Thus adding an additional stress factor for an ecosystem already under pressure. This is the first time scientists have identified a link between deforestation and generalizable rain, that is not restricted to a single case study. The credit goes to a research team of the University of Leeds, which published the results in Nature.
Scientists analyzed data on forest loss and rainfall in all tropical regions between 2003 and 2017 using satellite data, local stations and reanalysis to get a clear and complete picture. The result in short is this. A link emerges between more deforestation and sparser rainfall at all the scales analyzed.
“The effect of deforestation on rainfall has increased at greater scales, with satellite data showing that forest loss has caused dramatic reductions in rainfall at scales above 50 km,” the study’s authors explain. “The biggest falls in rainfall occurred at 200 km, the largest scale we explored, for which a percentage point of forest loss reduced rainfall by 0.25 0.1 mm per month”.
Transposed on a larger timescale, these data indicate a rather clear scenario: the main lungs of the planet will tend to become increasingly arid. By the end of the century, scientists calculated, “if the rate of deforestation in the Congo – the second largest tropical rainforest in the world – continues at its current rate, rainfall in the region could fall between 8% and 12%”. This would have a strong impact on biodiversity and agriculture and could even threaten “the vitality of the forests of Congo, which are among the largest carbon deposits in the world”. The Amazon, of course, would also be strongly affected by this dynamic. The South American forest recycles 25-50% of the rainfall in the area thanks to trees.
“Tropical forests play a key role in the hydrological cycle, helping to maintain local and regional rainfall patterns. The reduction in rainfall caused by tropical deforestation will have an impact on populations living nearby, increasing water scarcity and reducing harvests,” Callum Smith said, before signing the study. “The same tropical forests depend on moisture to survive and the remaining forest areas will be affected by a drier climate”.
