Dehradun: Short-lived weather extremes — ranging from intense heatwaves to sudden heavy snowfall — can significantly affect the health of Himalayan glaciers and alter the pace at which they melt, accentuating the increasing vulnerability of the region’s cryosphere driven by climate change. A recent study by researchers from the Indian Institute of Technology Indore found that although long-term warming remains the primary driver of glacier retreat across the Himalaya, brief but extreme weather events are increasingly influencing glacier behavior from one year to the next.Published in Nature journal, the study has provided fresh evidence of this trend through detailed observations at the Chhota Shigri Glacier, one of the most extensively monitored glaciers in the western Himalaya. Conducted by researchers Himanshu Kaushik, Mohammad Azam and Mohd Arif Hussain, the study examined two sharply contrasting years to show how sensitive glaciers are to seasonal weather extremes.During 2021–22, the glacier experienced its “most negative mass balance on record”, largely driven by severe heatwave conditions that accelerated melting across the region. The researchers found that unusually warm spring temperatures exposed darker glacier ice earlier than usual, increasing heat absorption and intensifying summer melt.However, conditions changed dramatically the following year. In July 2023, an unusual spell of heavy summer snowfall blanketed the glacier with fresh snow. The study noted that more than 300 mm of snow fell between July 8 and 10, sharply increasing the glacier’s surface reflectivity and slowing melt rates. As a result, the glacier recorded a slightly positive annual mass balance in 2022–23 — despite 2023 being the warmest year globally on record.Researchers noted that between July 6 and 24, 2023, the glacier gained nearly 250 mm water equivalent mass. During the same period in 2022, it had lost 532 mm water equivalent. The study also found that melt rates across debris-covered sections of the glacier declined by nearly 45-50% during the snowfall year compared to the extreme heatwave year.Scientists, however, cautioned against viewing such isolated snowfall events as evidence of glacier recovery. “Contrasting years such as 2021-22 and 2022-23 underscore the growing dominance of extreme weather events under continued warming. While positive mass balance years such as 2022-23 represent a blip in the long-term glacier wastage trend, they should not be misinterpreted as a sign against ongoing climate change,” said Kaushik.Long-term observations continue to show the glacier steadily losing mass at an average rate of around –0.47m water equivalent annually, reflecting the broader warming trend affecting Himalayan glaciers.The researchers also warned that future warming could outweigh the temporary benefits of episodic snowfall. Their analysis showed that every 1°C rise in annual temperature would require nearly 80 mm of additional summer snowfall to maintain glacier stability. However, climate projections indicate declining snowfall and increasing rainfall at high altitudes across the Himalaya.“The findings highlight the importance of continuous glacier monitoring as extreme weather events become more frequent and unpredictable in the Himalayan region. The Himalayan cryosphere plays a crucial role in sustaining rivers, water security and ecosystems across northern India, making even short-term changes in glacier behavior significant for millions of people living downstream,” the authors said.
