Deforestation is causing reduced rainfall across large parts of the tropics, according to new research. Although it has been long suspected, until now, scientists have not been able to identify a clear link between the loss of tree cover and a decline in rainfall.
A team of researchers at the University of Leeds combined satellite data of deforestation and rainfall to show that the loss of tree cover in the tropics over the last 14 years was associated with reductions in rainfall.
Callum Smith, the lead author of the study, said the investigation provides “compelling evidence” to protect forests from uncontrolled clearing.
He said, “Tropical forests play a critical role in the hydrological cycle through helping to maintain local and regional rainfall patterns. The reduction in rainfall caused by tropical deforestation will impact people living nearby through increased water scarcity and depressed crop yields. Tropical forests themselves rely on moisture to survive and remaining areas of forest will be impacted by a drier climate.”
The study showed that tropical forest loss caused reductions in rainfall throughout the year, including in the dry season when any further drying will have the greatest ramifications on plant and animal ecosystems. The biggest absolute decline in precipitation was seen in the wet season with up to a 0.6 mm a month reduction in rainfall for every percentage point loss of forest cover.
It is understood that the loss of tree cover disrupts the process where moisture from leaves-through a mechanism called evapotranspiration-is returned to the atmosphere where it eventually forms rain clouds.
As well as harming natural ecosystems, a reduction in rainfall would be detrimental to agriculture and hydropower plants. The researchers say, on average, crop yields declined by 0.5% for every 1% reduction in rainfall.
The team warns that a decline in rainfall has a negative impact on biodiversity, increases the rist of forest fires and reduces carbon sequestration, where nature removes carbon from the atmosphere and stores it.
https://phys.org/news/2023-03-deforestation-tropics-linked-reduction-rainfall.html