Bhubaneswar: A study by researchers from the Indian Institute of Technology Bhubaneswar (IIT Bhubaneswar) has documented significant changes in snowmelt timing and vegetation greenness across the Hindu Kush-Karakoram-Himalaya (HKKH) mountain system.
Researchers Subhransu Sekhar Gouda and Saket Dubey from the School of Infrastructure, IIT Bhubaneswar, examined nearly three decades of satellite observations to understand how changing snow conditions are influencing high-altitude ecosystems.
Their findings have been published in the journal npj Climate and Atmospheric Science under the title “Contrasting trends of greening in the waning snowfields of the Hindu-Kush Karakoram Himalaya.”
The study compares the periods 1994–2005 and 2013–2024, focusing on seasonal snow-covered areas above the treeline across six mountain systems: Hindu-Kush, Karakoram, Western Himalaya, Central Himalaya, Eastern Himalaya and Hengduan-Shan.
The research found that the regional average timing of snow disappearance shifted 4.37 days earlier, with a standard deviation of 3.67 days, across the study region.
However, the change was not uniform. About 65.2% of the analysed pixels showed an earlier snowmelt, while 32.74% showed delayed snowmelt and 2.06% showed no detectable shift.
In areas where snowmelt occurred earlier, the shift was considerably larger, at about 11.03 days on average.
The study found that approximately 80.77% of waning snowfields across the HKKH showed positive changes in maximum NDVI, a satellite-based indicator of vegetation greenness.
The study suggests that earlier snowmelt can extend the period during which high-altitude surfaces remain snow-free. This provides vegetation with greater exposure to warmer conditions during the growing season.
The researchers measured this effect using Growing Degree Days (GDD), which represents accumulated heat available for vegetation growth after snow disappears.
For areas where snow historically persisted longer, GDD increased by more than 50% in the Hindu-Kush and Karakoram, while increases exceeded 70% in the Western Himalaya, Central Himalaya, Eastern Himalaya and Hengduan-Shan.
The findings highlight the importance of considering snow dynamics alongside temperature and vegetation changes when studying the future of high-altitude Himalayan ecosystems. The researchers argue that snow-cover dynamics should be incorporated into climate adaptation strategies for mountain environments.
Source: Research paper: Contrasting trends of greening in the waning snowfields of the Hindu-Kush Karakoram Himalaya, npj Climate and Atmospheric Science, by Subhransu Sekhar Gouda and Saket Dubey.
