Mountains are warming faster than valleys, threatening water supplies

Mountains around the world are heating up faster than the valleys below. An international team of scientists reached that conclusion in a massive global review that examined four decades of mountain weather data.

The research was focused on elevation-dependent climate change, a pattern where mountain warming and wetness change with altitude, instead of rising evenly everywhere.

The study reveals that this pattern is reshaping water supplies, ecosystems, and hazards for people living in or downstream of mountains.

Mountains show rapid warming

The work was led by Nick Pepin, an associate professor of climate science at the University of Portsmouth (UoP). He studies how temperature, rain, and snow behave differently in high mountain regions compared with nearby lowlands.

The team pulled together records from weather stations, satellites, and global computer grids to see how high country climates had changed since 1980.

On average, mountain air warmed about 0.21 degrees Celsius per century faster than nearby lowlands, while rainfall became less predictable and snowfall declined.

The pattern is not identical everywhere, because mountain climates depend on latitude, slope direction, and how close each range is to oceans or deserts.

The Rockies and the Tibetan Plateau fit the pattern of heightened warming at high elevations, but the Andes and European Alps reveal a more complex, mixed picture.

How mountains shape water

Much of the freshwater people use every day starts high in the cryosphere, the frozen snow and ice that store moisture in mountains.

Experts with the United Nations estimate that over two billion people depend on mountain water for drinking, farming, and power, according to a recent report. 

In Asia, the Himalayas and neighboring ranges feed rivers such as the Ganges, Indus, Mekong, Yangtze, and Yellow that support huge downstream populations.

These rivers supply water for homes, farms, and electricity across South and East Asia, as highlighted by a National Academies study on Himalayan glaciers.

When snow and glaciers shrink, rivers that ran steadily through spring and summer can swing between floods and low flows from year to year.

That volatility makes it harder to plan reservoirs, canals, and hydropower dams, especially in regions that already struggle with droughts and fast growing populations.

Hazardous threats are emerging

As temperatures climb, more winter storms in mountain regions fall as rain instead of snow, which changes how water moves downhill.

Glacial lake outburst floods (GLOF), sudden releases of water from ice dammed lakes, become more likely when meltwater collects behind thinning glaciers.

In August 2025, a sudden cloudburst over Pakistan’s Buner district dumped more than 6 inches of rain in about an hour.

The resulting flash floods tore down valleys, killing hundreds of people and sweeping away villages, according to a news report from the region.

At the same time, many regions see thinner snowpacks that melt earlier in spring, leaving soils and reservoirs drier later in the year.

That combination of sharper floods and longer dry spells puts mountain farming, tourism, and infrastructure under pressures that older climate records did not anticipate.

Factors that drive mountain warming

Plants and animals are already shifting their ranges to higher elevations, seeking familiar seasonal cues.

“As temperatures rise, trees and animals are moving higher up the mountains, chasing cooler conditions,” said Pepin.

This pattern pushes snowlines and treelines upslope, and it can add to landslides, avalanches, and rockfalls, especially where permafrost is thawing.

A 2015 review led by Pepin concluded that snow cover, humidity, and other factors can amplify mountain warming near the freezing point.

One key driver of this extra warming is albedo, the share of sunlight a surface reflects. As snow and glaciers shrink, dark rock, soil, and vegetation absorb more energy and help push temperatures higher at the same elevation.

High elevation monitoring is needed

Tiny aerosols, solid or liquid particles floating in the air, change how sunlight and heat move through mountain air and snow.

Soot that lands on snow can speed up melting, while cleaner air in valleys lets sunshine reach lower slopes and shift warming patterns.

Since installing instruments on remote peaks is difficult and expensive, scientists also rely on satellites and observations from local guides, farmers, and rangers.

The data help reveal which slopes are losing snow fastest, where new lakes are forming, and how frequently extreme storms are striking.

To track all these changes, scientists need more climate models, computer tools that simulate future weather patterns, and better measurements high in remote ranges.

Right now, many weather stations sit in valleys or towns, so important shifts on ridges and glaciers can go unseen for years.

The team argues that better high elevation monitoring and cuts in greenhouse gas pollution will be needed to reduce risks for water and ecosystems.

“We can’t just tackle mountain climate change independently of the broader issue of climate change,” explained Pepin.

The study is published in the journal Nature Reviews Earth & Environment.

—–

Like what you read? Subscribe to our newsletter for engaging articles, exclusive content, and the latest updates. 

Check us out on EarthSnap, a free app brought to you by Eric Ralls and Earth.com.

—–