Understanding the regional anthropogenic signature in weakening of the south Asian Summer Monsoon

Abstract:

The evidence from observation shows that South Asia underwent a widespread drying from the last five to six decades during the summer. The underlying reasons are unclear, whether this trend is due to natural or anthropogenic activities. Using a state-of-the-art global variable resolution climate model with high-resolution zooming over South-Asia, we decomposed the regional factors responsible for the weakening of monsoon circulation and rainfall. To address this issue we conducted several long simulations from 1886 to 2095, with and without anthropogenic forcing. The simulation provides key information about the regional responses to changes in south Asian summer monsoon, which leads to the decline in mean monsoon, and enhancement in the occurrence of localized extreme precipitation events in a warming climate. Further the 21^st century climate projection using the same high-resolution model indicates persistent decrease of monsoonal rains due to land-atmosphere feedbacks in a warming environment. This would have severe impacts on agriculture, water resources and ecosystem over South Asia.