Glaciers in Asia’s Hindu Kush Himalayas are melting at an unprecedented rate and could lose 75 percent of their volume by the end of the century, scientists say, warning of dangerous floods and water shortages for the 2 billion people who live along the dozens of rivers that originate. In the mountainous region.
A report by the Kathmandu-based International Center for Integrated Mountain Development (ICIMOD) on Tuesday warned that flash floods and avalanches are likely to increase in the coming years, affecting access to clean water for 240 million people. region as well as another 1.65 billion downstream.
“People living in these mountains who have not contributed to global warming are at high risk from climate change,” said Amina Maharjan, a migration expert and one of the report’s authors.
“Current adaptation efforts are grossly inadequate and we are deeply concerned that without greater support, these communities will be unable to cope,” he said.
Various previous reports have found that the cryosphere – the regions of the Earth covered in snow and ice – is the most affected by climate change.
Recent studies have shown that the glaciers of Mount Everest, for example, have lost 2,000 years of ice in the past 30 years.
“We map out for the first time the connections between changes in the cryosphere with water, ecosystems and society in this mountain region,” Maharjan said.
The report found that Himalayan glaciers had disappeared 65 percent faster since 2010 than in the previous decade and said changes to the region’s glaciers, snow and permafrost driven by global warming were “unprecedented and largely irreversible.”
With 1.5 degrees Celsius or 2 degrees Celsius of warming above pre-industrial temperatures, glaciers across the region will lose 30 percent to 50 percent of their volume by 2100, it said.
But where glaciers melt depends on location. At 3 degrees Celsius of warming – roughly what the world is on track for under current climate policy – glaciers in the eastern Himalayas, which include Nepal and Bhutan, will lose up to 75 percent of their ice. At 4 degrees Celsius of warming, that increases to 80 percent.
“We’re losing glaciers, and we’re losing them within 100 years,” said Phillips Wester, an environmental scientist and ICIMOD fellow who was lead author of the report.
The Hindu Kush Himalayas stretch 3,500 km (2,175 mi) across Afghanistan, Bangladesh, Bhutan, China, India, Myanmar, Nepal, and Pakistan.
Scientists have struggled to assess how climate change is affecting the Hindu Kush Himalayas. Unlike the European Alps and North American Rocky Mountains, the region does not have a long historical record of field measurements that reveal whether glaciers are growing or shrinking.
“There’s always been some uncertainty in the Himalayas – are they really melting?”, Wester said.
In 2019, the United States declassified 1970 spy satellite images of the region’s glaciers, providing a new scientific baseline.
Further advances in satellite technology over the past five years, along with step-by-step field research, have improved scientists’ understanding of ongoing changes. The report relies on data up to December 2022.
Compared to the 2019 ICIMOD assessment of the region, “there is now much more confidence in these results”, Wester said.
“We have a better idea of what the damage will be by 2100 at different levels of global warming.”
With this new realization comes serious concern for the people living in the Hindu Kush Himalayas.
The report found that water flows in the region’s 12 river basins, including the Ganges, Indus and Mekong, could peak around mid-century, with consequences for more than 1.65 billion people dependent on these supplies.
“While it may seem like we’ll have more water because the glaciers are melting at an increased rate … very often it will rise as a flood rather than a steady stream,” Wester said.
The study says 200 glacial lakes across the mountains are considered dangerous, and the region could see a significant spike in floods from glacial lake outbursts by the end of the century.
But once the water runs out, the supply will eventually dwindle.
“Once the ice melts in these regions, it’s very difficult to get it back to its frozen form,” said Pam Pearson, director of the International Cryosphere Climate Initiative, who was not involved in the report.
He added: “It’s like a big ship at sea. Once the ice starts moving, it’s very hard to stop. So, with glaciers, especially the big glaciers in the Himalayas, once they start losing mass, it’s going to continue for a really long time before it stabilizes.”
Limiting warming to the 1.5 degrees Celsius agreed at the 2015 Paris climate conference is crucial for Earth’s snow, permafrost and ice, Pearson said.
“I understand that most policymakers don’t take the goal seriously but, in the cryosphere, irreversible changes are already happening,” he said.
The effects of climate change are already felt by Himalayan communities, sometimes acutely.
The Indian hill town of Joshimath began to sink earlier this year and residents had to be evacuated within days.
Governments in the region are trying to prepare for these changes. China is working to increase the country’s water supply. And Pakistan is setting up early warning systems for glacial lake outburst floods.