Deforestation weakening India’s monsoon: Study

MUMBAI: Conversion of forests into agricultural land is weakening India’s monsoon, especially in August and September, reveals a study published in Scientific Reports by Nature Publishing Group on Wednesday.

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Forests are a source of evapotranspiration (ET), or recycled precipitation, which adds to rainfall. Trees channel moisture from the soil into the air through a process called transpiration. This contributes to around 25% of total precipitation in the later stages of the monsoon. Deforestation, however, replaces deep-rooted plants with shallow-rooted vegetation that cannot do the same job, the study says.

“Due to the large scale deforestation, there is a significant reduction in the recycled precipitation and hence in total precipitation,” said professor Subimal Ghosh, Interdisciplinary Program in Climate Studies, IIT-B.

“Impacts of deforestation are quite prominent in those areas due to reduction in ET and recycled precipitation,” said Supantha Paul, IIT-B.

Using satellite data, the present study found a significant decrease in leaf area index - a measure of green cover - when the team compared two-time periods to anaylse the impact of land use land cover change in rainfall across India.

The study is significant as the Indian summer-monsoon rainfall between June and September contributes to 80% of the annual rainfall in the country, vital for agriculture and economy. Ghosh said the findings have significant implication in terms of generating rainfall projections for future to be used for climate change adaptation.