Accelerated Greenland Ice Sheet melt influences South Asian precipitation

Abstract Greenland Ice Sheet (GrIS) melt has accelerated in the recent decades, particularly during the boreal summer (June–August). Using satellite observations and experiments with the Indian Institute of Tropical Meteorology (IITM) Earth System Model, the drivers of enhanced GrIS melt and its teleconnections with the tropics, especially the South Asian summer monsoon rainfall is studied. We examine the inter-annual variability of GrIS melt and its interactions with atmosphere and ocean. Results reveal that amplified Arctic warming and frequent atmospheric blocking over Greenland modulated by large-scale climate modes including the Arctic oscillation (AO), Arctic dipole (AD), and North Atlantic Oscillation emerge as key contributors to intensified surface melting. Concurrent negative phases of these modes weaken the subpolar gyre, promoting intrusion of warm and saline Atlantic water into south of Greenland. This Atlantification enhances ocean heat content near marine-terminating glaciers, further accelerating GrIS loss. In addition, GrIS melt events during boreal summer are generally preceded by El Niño in the previous winter. Excess GrIS melt freshens the North Atlantic, weakens and shifts the midlatitude westerlies equatorward, and produces warming in the north tropical Atlantic (NTA). The resulting NTA warming promotes a transition from pre-existing El Niño to a La Niña-like state in the following summer, influencing the tropical precipitation, especially the South Asian summer monsoon rainfall. Sensitivity experiments using IITM-ESM with and without GrIS melt confirm this mechanism. The model simulated response to the interannual variability of GrIS melt shows a La Niña-like response in the eastern Pacific and intensification of South Asian summer monsoon precipitation. Our results show that GrIS melt, and associated interannual climate variability, modulate large-scale circulation, linking Arctic change to tropical climate and monsoon variability with profound societal implications.