A new study warns that warming in high mountain regions, including the Himalayas, may be about 50 per cent faster than the global average since 1950, raising concerns for more than a billion people dependent on these ecosystems.
Findings published in Nature Reviews Earth and Environment estimate enhanced mountain warming of 0.21°C per century between 1980 and 2020, greater drying and faster snowmelt.
The international research team, led by the University of Portsmouth, examined “elevation-dependent climate change,” influenced by factors such as albedo, humidity and aerosols. “Mountains share many characteristics with Arctic regions and are experiencing similarly rapid changes,” said lead researcher Nick Pepin.
However, it is not as simple as the highest mountains being the most sensitive to elevation-dependent climate change, "because although on average climate change is accelerating at higher elevations, there is lots of regional variation," the lead researcher said in an email, responding to PTI's question about which mountain range might be the most vulnerable.
"In lots of cases, loss of snow is an important driving factor so it is those intermediate elevations where the snow has receded (imagine the snowline is going up) that are changing most quickly," he said.
Aerosols released from lowland areas — for example, in India and China — which can make their way up onto the snow and ice and cause accelerated melt and loss, is another important factor influencing climate change in mountain regions, he added.
The team, which also included researchers from India's Uttaranchal and Jawaharlal Nehru universities, analysed data from global datasets and reviewed evidence from case studies from mountain ranges such as the Alps, Tibetan Plateau and High-Mountains Asia.
"On a global scale, differences between mountain and lowland trends for temperature, precipitation and snowfall are 0.21 degrees Celsius per century (enhanced mountain warming), (minus) 11.5 millimetres per century (enhanced mountain drying) and (minus) 25.6 millimetres per century (enhanced mountain snow loss), respectively, for 1980-2020," the authors wrote.
"Such positive elevation-dependent warming (EDW) is evident at historical and longer timescales, and despite much variation according to time of day, season and location, the mean warming at high elevations is nearly 50 per cent faster than the global mean since 1950," the team said.
Most models were also found to predict a continued warming of 0.13 degrees Celsius per century in mountain regions throughout the twenty-first century, "but precipitation changes are less certain", they said.
Implications extend far beyond mountain communities. Over one billion people worldwide depend on mountain snow and glaciers for water, including in China and India, which receive water from the Himalayas, the researchers said.
"The Himalayan ice is decreasing more rapidly than we thought. When you transition from snowfall to rain because it has become warmer, you're more likely to get devastating floods. Hazardous events also become more extreme," Pepin said.
"As temperatures rise, trees and animals are moving higher up the mountains, chasing cooler conditions. But eventually, in some cases, they'll run out of mountain and be pushed off the top. With nowhere left to go, species may be lost and ecosystems fundamentally changed," the lead researcher said.