Snowfall Shift and Precipitation Variability over Sikkim Himalaya Attributed to Elevation-Dependent Warming

Abstract

Sikkim Himalaya hosts critical water resources such as glacial, rain, and snow-fed springs and lakes. Climate change is adversely affecting these resources in various ways, and elevation-dependent warming is prominent among them. This study is a discussion of the elevation-dependent warming (EDW), snowfall shift, and precipitation variability over Sikkim Himalaya using a high-resolution ERA5-land dataset. Furthermore, the findings show that the Sikkim Himalaya region is experiencing a warming trend from south to north. The majority of the Sikkim Himalayan region shows a declining trend in snowfall. A positive advancement in snowfall trend (at a rate of 1 mm per decade) has been noticed above 4500 meters. The S/P ratio indicates a shift in snowfall patterns, moving from lower elevations to much higher regions. This suggests that snowfall has also transitioned from Lachung and Lachen (3600 m) to higher elevated areas. Moreover, the seasonal shifting of snowfall in the recent decade is seen from January-March (JFM) to February-April (FMA). Subsequently, the preceding 21 years are being marked by a significant spatiotemporal change in temperature, precipitation, and snowfall. The potent negative correlation coefficient between temperature and snowfall (–0.9), temperature and S/P ratio (–0.5) suggested the changing nature of snowfall from solid to liquid, which further resulted in increased lower elevation precipitation. The entire Sikkim region is transitioning from a cold-dry to a warm-wet weather pattern. In the climate change scenario, a drop in the S/P ratio with altitude will continue to explain the rise in temperature over mountainous regions.