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Researchers found that 40% of glacial area has been lost and that mass loss in recent decades has been 10 times faster than loss since the Little Ice Age.
Loss of glacial mass in the Himalayas has been “exceptional” when compared to all other regions in the world, a new paper has shown. The authors mapped 14,798 Himalayan glaciers during the last period of glacial advance, the Little Ice Age, around 400–700 years ago. They analyzed around 2,300 kilometers of the mountains, ranging from India to Bhutan.
Researchers found that 40% of the glacier area has been lost and that mass loss in recent decades has been 10 times faster than loss since the Little Ice Age. The eastern Himalayas experienced the greatest glacial mass loss, with Nepal and Bhutan experiencing the fastest declines.
Tracking Glacial Loss Over Centuries
The study is the first assessment of changes in Himalayan glaciers over a centennial timescale.
Many studies have quantifiably assessed the rate of glacial mass change across the Himalayas for recent decades. But “these are still within the time period of anthropogenic climate change and make no comparison with glacier mass loss before their study time period,” said Ethan Lee, a researcher at Newcastle University and lead author of the paper. Studies that have been concerned with glacial mass loss since the Little Ice Age “have either been limited to small regions or watersheds or singular glaciers and cannot be extrapolated to across the Himalaya,” he added.
To expand the field of study and get a more holistic evaluation of glacial retreat, the authors aimed to create a data set of glaciers at their Little Ice Age extents and perform glacial ice surface reconstruction to identify the overall mass loss from the Little Ice Age to present.
As for what exactly is driving the exceptional acceleration in glacier mass loss across the Himalayas, Jonathan Carrivick, a senior lecturer in physical geography at the University of Leeds and a coauthor of the study, identified climate change as the “root cause.”
“The rapidly melting glaciers will increase flood risk from the breach of glacial lakes since such lakes will increase in size and number from the fast-melting glaciers.”
Rijan Bhakta Kayastha, the coordinator of the Himalayan Cryosphere, Climate and Disaster Research Center at Kathmandu University who was not involved in the new study, agreed. He pointed to a 2017 study by Nepal’s Department of Hydrology and Meteorology that found that throughout the country, temperatures increased by 0.056℃ per year. Another reason for the region’s rapid glacial retreat is a lack of corresponding increase in precipitation, Kayastha said. “If temperature and precipitation increase, there could be some balance because of new ice formation. But this is not happening,” he explained.
Elaborating on what glacial mass loss means for the people in the region, Kavita Upadhyay, an independent water policy researcher based in the Indian Himalayas, said, “The rapidly melting glaciers will increase flood risk from the breach of glacial lakes since such lakes will increase in size and number from the fast-melting glaciers.”
Upadhyay noted that development activities in the Himalayas (like the construction of roads alongside rivers and massive hydropower projects) compound disaster risks. Upadhyay is one of the authors of a June 2021 paper that evidenced how hydropower infrastructure contributed to a disaster in the Himalayan state of Uttarakhand that claimed more than 200 lives.
Loss of glaciers also contributes to “water insecurity in the long term,” Upadhyay said, as glaciers feed rivers throughout the Himalaya.
Need for Collaboration
In India, there is “no institutional structure for constant dialogue and collaboration” between policymakers and researchers working on glaciers, said Anil V. Kulkarni, a visiting scientist at the Divecha Centre for Climate Change, Indian Institute of Science.
Speaking of what researchers could do to bridge the gap, Lee said they could better communicate actionable recommendations and make their research more easily accessible so that policymakers could make informed decisions.
Piyoosh Rautela, executive director of the Uttarakhand Disaster Mitigation and Management Center, expressed similar concerns. Policymakers can only work on glacial research that addresses societal implications, he said, but many research papers “focus on hard science and not on actionable inputs.” He also added that the lack of open access to some journals is “a serious constraint” to both policymakers and researchers working in small institutions. As a path ahead, Rautela suggested early-stage collaboration between researchers and policymakers and not mere communication after the research is published.
More broadly and importantly, glaciology is a “multidisciplinary research topic,” Kulkarni said. Consistent and structured collaboration at institutional levels is needed, he explained, as opposed to “sporadic efforts by individuals.”
Pointing to one area of collaboration, Kayastha said that there is a need for governmental focus on and funding of glacial monitoring at high altitudes across South Asia.
—Rishika Pardikar (@rishpardikar), Science Writer