Warming in mountains could be 50% faster compared to global average: Study

Warming at high elevations in mountains, including the Himalayas, could be about 50 per cent faster than the global average since 1950, which can have potentially devastating consequences for over a billion people depending on the regions, according to a study.

Globally, compared to lowlands, mountains were estimated to experience an enhanced warming of 0.21 degrees Celsius per century during 1980-2020, an enhanced drying of 11.5 millimetres per century and accelerated melting of snow of 25.6 millimetres per century, findings published in the journal Nature Reviews Earth and Environment show.

An international team of researchers, led by those from the UK's University of Portsmouth, looked at 'elevation-dependent climate change' — a phenomenon where environmental changes can accelerate at higher altitudes. Factors driving it include surface albedo (radiation reflected by a surface compared to what falls on it), specific humidity and aerosol levels in the air.

"Mountains share many characteristics with Arctic regions and are experiencing similarly rapid changes," lead researcher Nick Pepin from the University of Portsmouth's Institute of the Earth and Environment said. "This is because both environments are losing snow and ice rapidly and are seeing profound changes in ecosystems. What's less well known is that as you go higher into the mountains, the rate of climate change can become even more intense," Pepin said.

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.