Localized positive snow water equivalent anomalies in the Hindu Kush Himalaya under 1.5–5.0 °C warming levels

The Hindu Kush Himalaya (HKH) region is one of the regions in the global cryosphere characterized by localized positive anomalies, where the mass and extent of some glaciers have increased rather than declined. To explore whether the snow cover in this region exhibits localized positive snow water equivalent (SWE) anomalies and whether such anomalies may persist under global warming, ERA5-derived reanalysis data (1979–2024) were integrated with a random forest model that incorporates key climatic variables, including temperature, downward shortwave radiation, wind speed, relative humidity, and precipitation-derived snowfall. In addition, multi-scenario simulations from five CMIP6 climate models were used to investigate the spatiotemporal changes and future trends in SWE in the HKH region under 1.5–5.0 °C global warming levels. The results show that a localized SWE-positive anomalous area, identified by combining positive SWE trends with a Local Moran’s I spatial correlation constraint, covered approximately 5.5 × 10 4 km 2 in the northeastern Western Himalayas, the northern Eastern Himalayas, and parts of the Karakoram, where annual SWE increased weakly, in contrast to the significant decline ( p < 0.05) observed in the whole region. The annual positive SWE signal was mainly associated with persistently lower mean temperature (nearly 10 °C colder than the non-anomalous area), abundant snowfall, and reduced downward shortwave radiation. Under 1.5–5.0 °C global warming, these positive SWE anomalies are projected to persist in high-elevation areas, with mean SWE remaining generally below the baseline (1995–2014) and showing only slight future variation, while the mean elevation of areas retaining positive SWE anomalies shifts slightly upward to about 5030–5040 m. These results highlight the persistence of localized SWE-positive anomalies within the HKH cryosphere.