Scientists warn mountain climate change is accelerating faster than predicted, putting billions of people at risk

• Temperature, rainfall, and snowfall patterns are shifting at an accelerated rate in mountain regions 

• Over one billion people worldwide depend on mountain snow and glaciers for water, including the populations of China and India 

• As temperatures rise, more snow is changing to rain, decreasing mountain snowfall 

Mountains worldwide are experiencing climate change more intensely than lowland areas, with potentially devastating consequences for billions of people who live in and/or depend on these regions, according to a major global review. 

The international study, published in Nature Reviews Earth & Environment, examines what scientists call "elevation-dependent climate change" (EDCC) - the phenomenon where environmental changes can accelerate at higher altitudes.  

It represents the most thorough analysis to date of how temperature, rainfall, and snowfall patterns are shifting across the world's mountain ranges. 

Led by Associate Professor Dr Nick Pepin from the University of Portsmouth, the research team analysed data from multiple sources including global gridded datasets, alongside detailed case studies from specific mountain ranges including the Rocky Mountains, the Alps, the Andes, and the Tibetan Plateau. 

The findings reveal alarming trends between 1980 and 2020: 

• Temperature: Mountain regions on average are warming 0.21°C per century faster than surrounding lowlands 

• Precipitation and snow: Mountains are experiencing more unpredictable rainfall and a significant change from snow to rain 

“Mountains share many characteristics with Arctic regions and are experiencing similarly rapid changes,” said Dr Pepin from the University of Portsmouth’s Institute of the Earth and Environment. “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.” 

The implications extend far beyond mountain communities. Over one billion people worldwide depend on mountain snow and glaciers for water, including in China and India - the world's two largest countries by population - who receive water from the Himalayas. 

Dr Pepin added: “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.” 

"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.” 

Recent events highlight the urgency. Dr Pepin points to this summer in Pakistan, which experienced some of its deadliest monsoon weather in years, with cloudbursts and extreme mountain rainfall killing over 1,000 people. 

This latest review builds on the research team’s 2015 paper in Nature Climate Change, which was the first to provide comprehensive evidence that mountain regions were warming more rapidly higher up in comparison to lower down. That study identified key drivers including the loss of snow and ice, increased atmospheric moisture, and aerosol pollutants. 

Ten years on, scientists have made progress understanding the controls of such change and the consequences, but the fundamental problem remains. “The issue of climate change has not gone away,” explained Dr Pepin. “We can't just tackle mountain climate change independently of the broader issue of climate change.” 

A major obstacle remains the scarcity of weather observations in mountains. “Mountains are harsh environments, remote, and hard to get to,” said Dr Nadine Salzmann from the WSL Institute for Snow and Avalanche Research SLF in Davos, Switzerland. “Therefore, maintaining weather and climate stations in these environments remains challenging.” 

This data gap means scientists may be underestimating how quickly temperatures are changing and how fast snow will disappear. The review also calls for better computer models with higher spatial resolution - typically most current models can only track changes every few kilometres, but conditions can vary dramatically between slopes just metres apart. 

Dr Emily Potter from the University of Sheffield added: “The good news is that computer models are improving. But better technology alone isn't enough - we need urgent action on climate commitments and significantly improved monitoring infrastructure in these vulnerable mountain regions.”