A recent study by researchers in Leeds University has established that deforestation means less rainfall in tropical forests.
Typically, tropical forests generate their own rain.
“Forests recycle moisture (rainfall) through the processes of evaporation and transpiration, pumping water back into the atmosphere which ‘feeds’ forests downwind,” Callum Smith, a Ph.D. researcher at the University of Leeds in England and co-author of the study told Timescape Magazine in an interview.
“In the SW Amazon for example, the forest is far from the ocean, and it relies heavily on rainfall that has been recycled by trees upwind of it. Up to 70% of the rain in the SW Amazon comes from water evapotranspired by upwind trees. Crucially, we find that forest loss can disrupt this process and make the remaining forests much less habitable for people and trees,” he explained.
Much of the tree cover both in the Amazon and in the Congo Basin-the two lungs of the earth, is lost to agriculture. Between 2000 and 2010 for instance, over 60 million acres of forest were lost in the Amazone, much of the cleared land used for soy cultivation. In Indonesia, palm oil plantations are the major reason for the decimation of the forests.
In West-Central Africa, it is a combination of illegal logging, the expansion of the palm oil industry as well as deforestation by small scale farmers that has led to the destruction of pristine forests.
The researchers used satellite observations to show that the tropical deforestation that has occurred over the last few decades has caused a reduction in precipitation.
“This means that tropical forests have important benefits for local people through maintaining precipitation patterns,” Smith said.
“Until recently the Congo has experienced relatively little deforestation. This is projected to change with the Congo forecast to experience some of the most rapid deforestation in the next few decades. This rapid deforestation leads to large precipitation reductions of around 8-10%, which will have negative consequences for people living within the region,” Smith told Timescape Magazine.
He said reductions in precipitation from tropical deforestation will impact agricultural yields, which would affect both local farming communities and the wider world which relies on food originating from the tropics.
“Surrounding tropical forests need reliable rainfall to survive, so reduced rainfall will also impact these surrounding forests,” he warned.
“Plenty has been said about the amount of forest lost, but the important thing to know is that forest loss must be substantially decreased if we want to mitigate the negative effects to local and global climate.”
“Overall, our work provides important evidence to support conservation of tropical forests,” he surmised.