Widespread deforestation, especially in the northern high latitudes, takes a toll on the monsoon across the northern hemisphere, with rains over India particularly badly affected, according to a new study from researchers at the Indian Institute of Science in Bangalore.
By the 1750s, only about seven per cent of the global land area had been cleared for agriculture and that proportion has since risen to around one-third.
Govindasamy Bala, a professor at the IISc’s Divecha Centre for Climate Change, along with post-doctoral researcher N. Devaraju and a doctoral student, Angshuman Modak, used a climate model to investigate the effects of large-scale deforestation. With the climate model, they could simulate what happened when extensive deforestation took place across the whole globe, just in the northern high latitudes, only in temperate areas as well as when it was restricted to the tropics.
Such deforestation reduced rains in the monsoon regions of the northern hemisphere. India was affected the most, with global deforestation producing an 18 per cent reduction in its summer monsoon rains, the scientists noted in a paper in the Proceedings of the National Academy of Sciences.
On the other hand, the deforestation led to moderately increased rains over South Africa, South America and Australia in the southern hemisphere.
The study showed that when forests in the northern high latitudes were removed, more sunlight was reflected back into space and this region cooled sharply.