Tropical deforestation drastically reduces rainfall, scientific study confirms

From the Amazon to the jungles of Africa and Southeast Asia, large-scale deforestation threatens to reduce rainfall in the tropics, according to a study published Wednesday (March 1) in the journal Climate Change. Nature (in English). The document was released in full at a forest summit in Gabon that brought together experts and leaders, including Emmanuel Macron. The Congo Basin, an important carbon sink and refuge for rare species (the second largest on the surface after the Amazon) is at the center of the debate.

It is precisely in this region that the risk of deforestation and reduced rainfall is most severe in the coming years, the study said. Researchers warn that they could be reduced by 10% by the end of the century. “We may get to the point where rainforests can’t regenerate themselves.” said lead author Callum Smith of the University of Leeds.

“Least moisture returned to atmosphere”

Using satellite data collected from 2003 to 2017 in tropical regions of the Amazon, Congo and Southeast Asia, scientists found that large-scale deforestation disrupts the water cycle, leading to significant reductions in rainfall, with the largest losses occurring during the wet season. Seasons. Trees emit water vapor through their leaves, which can cause localized precipitation.

Previous research on small-scale deforestation, however, has suggested that deforestation may increase rainfall in some areas. But by and large, there is “Less moisture is returned to the atmosphere, which reduces precipitation”, confirmed Callum Smith. This calls for increased conservation efforts, as research has shown that restoring large swathes of cleared forest can partially reverse this phenomenon.