Deforestation is going to play a major rule in decreased precipitation over India marking a whopping 18 per cent decline in rainfall in the country, a new study from Indian Institute of Science, Bangalore published in Proceedings of National Academy of Sciences (PNAS) reveals. Carried out by Govindasamy Bala, N. Devaraju and Angshuman Modak from […]
Deforestation is going to play a major rule in decreased precipitation over India marking a whopping 18 per cent decline in rainfall in the country, a new study from Indian Institute of Science, Bangalore published in Proceedings of National Academy of Sciences (PNAS) reveals.
Carried out by Govindasamy Bala, N. Devaraju and Angshuman Modak from the Divecha Center for Climate Change at the Indian Institute of Science, Bangalore, the study makes used a three-dimensional climate model to perform three different experiments related to deforestation in the tropical, temperate and high-latitude areas.
It has been well established that deforestation results in higher emission of carbon dioxide and other greenhouse gases (GHGs), but there are other problems according to researchers.
“When a climate effect of deforestation is estimated, only the amount of carbon dioxide released to the atmosphere, a biogeochemical effect, and its warming potential is calculated,” said Bala, one of the authors, in a statement. “The changes to surface characteristics such as reflectivity and plant transpiration (biogeophysical changes) and their effect on climate are not accounted.”
Researchers say that deforestation in temperate and high latitudes is causing changes in atmospheric circulation resulting in a southward shift in the monsoon rains. This, researchers say, would translate into a significant fall in precipitation in the northern hemisphere monsoon regions of East Asia, North America, North Africa and South Asia, and moderate increases in rainfall in the southern hemisphere monsoon regions of South Africa, South America and Australia.
“Our study is showing that remote deforestation in mid- and high-latitudes can have a much larger effect on tropical rainfall than local tropical deforestation,” the statement said.
Devaraju, the lead author of the paper, added that large scale deforestation leads to a decrease in global mean surface air temperature in the global, boreal, temperate, and tropical deforestation simulations which results into decrease in precipitation by 3.21%, 1.70%, 1.01%, and 0.50%, respectively.
“This study has huge implications for evaluating the climate benefits of afforestation and reforestation programmes that are promoted by Kyoto Protocol for reducing climate warming. Our study shows that just estimating carbon sequestration benefits of these programmes is not sufficient,” said Bala.
“We need to also account for the biophysical effects like temperature and rainfall as well since they also have large effects. The need for integrated assessment is more pronounced now to tackle the climate impacts of deforestation,” he added.
The study noted that land used for crops and pastures has increased globally from 620 million hectares in the 1700s – or about 7% of the global land surface – to 4,690 million hectares in 2000, about a third of the world’s land surface.