How Climate Change Is Making Mountaineering Riskier: Glaciers, Rockfall and Changing Seasons

By Blake Penson · Updated 2026-10-23

Blake Penson has climbed Everest twice and has 20 years in the mountains.

Climate change is making mountaineering more dangerous in several ways. Rising temperatures are shrinking glaciers, which opens more crevasses, exposes loose moraine and makes approaches longer and harder. Thawing permafrost, the frozen ground that holds steep rock faces together, is causing more rockfall, especially in hot summers. Warmer weather also makes seracs and glaciers less stable, as seen in the 2022 Marmolada collapse in Italy, which killed 11 people. Snow and ice routes are deteriorating, classic climbs are becoming more dangerous in mid-summer, and climbing seasons are shifting earlier or later in the year. Climbers can adapt by starting earlier in the day, choosing routes and seasons carefully, following local warnings and guide advice, and accepting that some routes are no longer safe in summer. ExpedReview's regional rankings list guide companies by verified climber reviews; experienced local guides are one of the best ways to manage changing conditions.

Climate change and climbing at a glance

Change	Effect on climbers
Glacier retreat	More crevasses, longer approaches, unstable moraine
Thawing permafrost	More rockfall on steep faces and ridges
Warmer summers	Weaker snow bridges, more serac and ice collapse
Less snow and ice	Deteriorating ice routes, exposed rock and loose ground
Shifting seasons	Best conditions earlier in spring or later in autumn
Extreme weather	More intense storms and heatwaves

Glaciers are shrinking fast

Glaciers around the world are retreating. In the Alps, scientists monitoring Swiss glaciers reported record losses in 2022 and very large losses again in 2023, adding up to roughly a tenth of Switzerland's remaining glacier volume in just two years. Similar trends are seen across the Himalaya, the Andes, Alaska and East Africa, where Kilimanjaro's ice fields have shrunk dramatically over the past century.

For climbers, shrinking glaciers mean:

• More crevasses. Thinner ice and less snow cover leave crevasses open or hidden under weak snow bridges.
• Longer, harder approaches. As glaciers retreat, paths and ladders to huts have to be extended, and climbers must cross loose moraine.
• Unstable ground. Retreating ice leaves steep, loose moraine walls that can collapse.
• Changing routes. Glacier routes that were once straightforward can become complex and dangerous.

Thawing permafrost and rockfall

High in the mountains, much of the rock is held together by permafrost: ice in the cracks and pores of the rock. As temperatures rise, this ice melts, and rock that was frozen in place can break away.

The result is more frequent rockfall, especially in hot summers. Famous examples include:

• The Matterhorn (2003): During the 2003 European heatwave, a large rockfall on the Hörnli Ridge forced the evacuation of dozens of climbers and closed the route for a time.
• Mont Blanc's Goûter route: The Grand Couloir, which climbers must cross on the normal route, is notorious for rockfall. In hot, dry summers, including 2022, local authorities and guide companies have warned climbers away from the route, and some guide companies suspended ascents for periods. See ExpedReview's guide to Mont Blanc routes.

Rockfall is especially dangerous in the afternoon, when the sun has warmed the rock, and after long periods of heat.

Serac and glacier collapse

Warm temperatures can make glaciers and seracs unstable. Meltwater lubricates the base of the ice and weakens its structure.

• Marmolada, Italy (2022): On 3 July 2022, after a period of record heat, a large section of the Marmolada glacier in the Dolomites collapsed, sending ice, water and rock down a popular route. Eleven people died.
• Blatten, Switzerland (2025): In May 2025, a huge collapse of the Birch glacier buried much of the village of Blatten in the Lötschental. Residents had been evacuated in advance after scientists detected signs of instability.

On big Himalayan peaks, serac fall and avalanches are long-standing hazards, such as in the Khumbu Icefall on Everest. Climate change may make some of these hazards less predictable.

Snow and ice routes are deteriorating

Many classic snow and ice routes are changing:

• North faces that were once climbed in summer now have bare rock and loose ground for much of the season.
• Ice couloirs melt out earlier, leaving loose rock.
• Snow bridges across crevasses weaken earlier in the season.
• Ice climbs form later and melt sooner.

As a result, many climbers now attempt classic alpine routes in spring, early summer or autumn, rather than in July and August.

Climbing seasons are shifting

In the Alps, the best conditions on many glaciated routes now often come earlier, in late spring and early summer, while hot mid-summer periods bring rockfall and poor snow. Some routes are best climbed in autumn or winter. In the Himalaya, monsoon timing and weather patterns are changing, and some climbers report more variable weather windows. On Everest, Nepalese officials blamed unusually variable weather, which they linked to climate change, for the deadly 2023 season. See the 2023 Everest season.

More extreme weather

Climate change brings more frequent and intense heatwaves, storms and heavy rain or snow. Heatwaves raise the freezing level, sometimes above the highest summits in the Alps, meaning snow does not refreeze overnight. That makes glacier travel and snow climbing more dangerous, even early in the morning.

Climate change in the Himalaya

The Himalaya are warming, and the effects are visible to climbers and trekkers. Glaciers are thinning and retreating, and many debris-covered glaciers, such as the Khumbu Glacier below Everest, are developing ponds and unstable ice. Sherpas who have worked on Everest for decades describe a more broken Khumbu Icefall and more exposed rock on parts of the route.

One growing danger is glacial lake outburst floods (GLOFs). As glaciers melt, lakes form behind loose moraine dams. If the dam fails, a sudden flood can sweep down the valley. In August 2024, a flood in the Thame valley in the Khumbu, linked to glacial lakes upstream, destroyed homes, a school and other buildings in Thame, a village known as the home of many famous Sherpa climbers. Such events affect local communities as much as climbers.

Changing snowfall can also affect avalanche risk, and some climbers report less predictable weather windows on 8,000 m peaks.

The Andes and Africa

Tropical glaciers are particularly sensitive to warming. In the Andes of Peru, Bolivia and Ecuador, many glaciers are shrinking quickly, which changes climbing routes and affects water supplies for communities below. Some routes on peaks in the Cordillera Blanca and Ecuador's volcanoes have become harder or more dangerous as ice retreats and crevasses open. See Ecuador mountains and the Huayhuash Circuit.

On Kilimanjaro, the famous ice fields near the summit have shrunk dramatically since the early 20th century, and scientists expect them to keep shrinking. Climbers still reach the summit without crossing ice on the main routes, but the glaciers are a striking visual reminder of change.

North America

In North America, glaciers in Alaska, the Cascades and the Rockies are retreating. On peaks such as Mount Rainier and Mount Baker, crevasses often open earlier in the season, and some routes become difficult or impassable in late summer. Guide companies may change routes during the season as conditions change. On Denali, warmer conditions on the lower Kahiltna Glacier can make crevasse travel more dangerous later in the season.

How guides are adapting

Professional guides are on the front line of these changes, and many have changed how they work:

• Earlier starts to finish climbs before the snow softens and rockfall increases.
• Changing routes, avoiding couloirs and faces that have become dangerous in summer.
• Moving seasons, offering more climbs in spring, early summer or autumn.
• Cancelling climbs during heatwaves, sometimes for weeks, when conditions are unsafe.
• Using more fixed equipment or alternative paths where approaches have changed.
• Monitoring conditions closely through hut wardens, rescue services and other guides.

For clients, this means flexibility is important. Book trips with spare days, accept alternative objectives, and choose guides who put safety before summits.

Rescue and insurance

As conditions become less predictable, rescues can become more common and more complex. Make sure your insurance covers mountaineering and helicopter rescue at the altitudes you plan to climb, and check that it covers the specific countries you are visiting. In some countries, rescue is free or partly funded by the state; in others, it can be very expensive.

What this means for climbers

Changing conditions require climbers to be more flexible and careful:

• Start earlier. Leave before dawn to be off snow and below rockfall zones before the day warms.
• Watch the freezing level. Check forecasts for the overnight freezing level. If snow will not refreeze, consider changing plans.
• Follow local advice. Local guides, hut wardens and mountain rescue services know current conditions. Follow warnings and closures.
• Choose the season carefully. Many alpine routes are now better in early summer, autumn or winter.
• Have a plan B. Be ready to switch to a safer objective.
• Upgrade your skills. Crevasse rescue, rockfall awareness and route-finding are more important than ever. See the basics of glacier travel.
• Hire an experienced guide. Guides who climb a route regularly know how it is changing. See who are IFMGA guides.

Reading conditions for yourself

Even with a guide, it helps to understand the warning signs of dangerous conditions:

• No overnight refreeze. If the snow is soft and wet at dawn, snow bridges and slopes will be weak. Consider turning back or choosing a lower, safer objective.
• Frequent rockfall sounds. Rattling stones and the smell of broken rock are signs of an active slope. Move through quickly or avoid it.
• Meltwater on the glacier. Streams on the glacier surface and slushy snow mean the ice is under stress.
• Fresh debris. Ice blocks or rock at the base of a slope show recent activity.
• Exposed ice. Bare, hard ice where there used to be snow makes crampon work harder and falls more serious.
• Hut warnings. Notice boards and wardens often have the latest information on route conditions. Read them and ask questions.

Combine these observations with weather forecasts and freezing level data. In many regions, mountain rescue services and guide offices publish condition reports, and climbing websites share recent route information.

How climbers can reduce their impact

Mountaineers love the mountains, so many want to help protect them:

• Travel thoughtfully. Flights often make up most of a climbing trip's carbon footprint. Consider fewer, longer trips, and climbing closer to home.
• Use public transport to reach trailheads and huts where possible.
• Choose responsible operators. Look for companies that manage waste, support local staff and reduce their environmental impact.
• Leave no trace. Carry out rubbish and human waste where required.
• Support conservation. Many mountain communities and organisations work on glacier monitoring, trail maintenance and climate adaptation.

See ExpedReview's guide to climbing Everest responsibly.

Frequently asked questions

How does climate change affect mountaineering?

It melts glaciers, thaws permafrost, increases rockfall, makes seracs and snow bridges less stable, and shifts the best climbing seasons.

Why is there more rockfall in the Alps?

Thawing permafrost releases rock that was once frozen in place, especially during hot summers.

What happened on the Marmolada glacier?

On 3 July 2022, after record heat, part of the Marmolada glacier in Italy collapsed, killing 11 people.

Is Mont Blanc dangerous because of climate change?

Rockfall on the Goûter route, especially in the Grand Couloir, is a serious hazard and can be worse in hot, dry summers. Authorities have issued warnings during heatwaves.

When is the best time to climb in the Alps now?

For many glaciated routes, late spring and early summer often offer better conditions than mid-summer. Check with local guides.

Are glaciers disappearing?

Glaciers are retreating in most mountain ranges. In the Alps, scientists have recorded record losses in recent years.

Is climbing getting more dangerous?

Some routes and seasons are more dangerous than before, but careful planning, early starts and local advice help manage the risks.

What is a glacial lake outburst flood?

A sudden flood caused when a lake formed by a melting glacier breaks through its natural dam of ice or moraine.

Is Kilimanjaro's ice disappearing?

Kilimanjaro's summit ice fields have shrunk dramatically over the past century and are expected to keep shrinking.

What is the freezing level, and why does it matter?

The freezing level is the altitude at which the air temperature is 0°C. If it stays above the route overnight, snow does not refreeze, so snow bridges, slopes and loose rock are less stable.

Should I still plan an alpine climb in summer?

Yes, but stay flexible. Book with spare days, check conditions and heatwave warnings, start early and be ready to choose a different route.