Arctic sea-ice decline causes intense summer monsoon precipitation events over South Asia under greenhouse warming

Abstract

Arctic sea-ice decline has been accelerating under greenhouse warming. In this study, we investigate the tropical precipitation response to declining Arctic sea-ice using observations and climate model simulations. Observational evidence and idealized model experiments in which the Arctic becomes seasonally ice free under greenhouse warming reveal association between the Arctic sea-ice decline and intense precipitation events (IPEs) over South Asia. The enhanced Arctic sea-ice melt increases the mid-latitude waviness and intensifies the circumglobal teleconnection-like pattern and strengthens the subtropical high over East Asia. This, together with a La-Nina like response in the Pacific enhances mean summer monsoon precipitation over South Asia. Additionally, the enhanced energy in the tropics and the anomalous mid-latitude intrusions due to the Arctic sea-ice melt provide a conducive environment for moisture convergence and intense summer monsoon precipitation events over South Asia. Our findings reveal that, in a future warming scenario, Arctic sea-ice melt is likely a contributing factor for the amplified mean and IPEs over the South Asian region.

Keywords

• Arctic amplification
• intense precipitation events
• extreme precipitation
• South Asian monsoon