Projected shifts in dry–wet extremes and possible associated drivers over the Hindu Kush Himalaya

The Hindu Kush Himalaya (HKH) region is characterized by its mountainous terrain and diverse regional climate patterns. This study investigates how future hydroclimate extremes across four regions of the HKH may be influenced by various Shared Socioeconomic Pathways (SSPs) scenarios, using a CMIP6-based Multi-Model Ensemble (MME). Our results show that the frequency of dry days is projected to increase, with a notable shift in more extreme spells over the extended parts of the northwest Himalaya and Karakoram regions (Zone 1) under high emissions. The eastern HKH (Zone 4) is projected to experience substantially increased precipitation with standardized precipitation index (SPI) values of 1.5–3, indicating moderately wet to extremely wet conditions that are likely to intensify flood risk. In consonance with the drier near-future climate over HKH (Zone 3), we find that the mean local Hadley cell shows a widening signature (expanding to 33.5° latitude). However, the Hadley cell shows an equatorward shift and narrowing signatures during mid (25.6° latitude) and far future (27.7° latitude) under low-to-high emissions scenarios, thus exemplifying the wet conditions over HKH (Zone 3). This work highlights the pressing need to understand the spatial heterogeneity of future global warming impacts over HKH.