Spatiotemporal trends of Cryo-Climatic Parameters in the Chandra Basin, Himachal Pradesh, India

Globally, the cryosphere is very sensitive to Earth’s changing climate. The Himalayan cryosphere is the critical source of water for millions of people downstream. The present study conducted a long-term (1950–2024) spatiotemporal trend analysis of cryo-climatic parameters in the high-altitude Chandra Basin in Himachal Himalaya. The study utilised the ERA5-Land reanalysis high-resolution (0.1° x 0.1°) dataset and analysed five key Cryo-climatic parameters: temperature, total precipitation, rainfall, snowfall, and snow depth trends across monthly, seasonal, and annual timescales at both basin-wide and grid-wise scales. The study has used a multi-method statistical framework, including the Mann-Kendall & Sen’s Slope, Innovative Trend Analysis (ITA), and the Sequential Mann-Kendall (SQMK) test, to detect monotonic and sub-trends. The result shows a significant warming trend (+ 0.15°C/decade), with seasonal warming during the monsoon (+ 0.02°C/year), winter, and pre-monsoon. SQMK shows that an accelerated upward trend started around 1990. The annual total precipitation is declining in the pre- and post-monsoon seasons. Annual rainfall shows a significant upward trend (+ 1.15 mm/year), whereas snowfall declines substantially (-3.0 mm/year), indicating a phase shift in precipitation. The snow fraction (0.121%/year) is declining, and the mean snow depth is decreasing (-42 mm/decade) in the critical pre-monsoon (MAM) season. Spatial analysis shows that the eastern, higher-elevation glacierized areas are experiencing drying trends, while monsoon rainfall has increased in the western, lower-elevation areas. These warming temperatures are driving precipitation phase shifts and subsequent cryospheric degradation, posing significant risks to the regional cryosphere, water security, and downstream agriculture and ecosystem sustainability.