Retreat of Glaciers Makes Some Climbs Tougher

Nowadays, during a hot summer, “you’ll find virtually no snow and ice on its face — none,” he said. “It’s a huge change over the last 20 to 30 years.”

Like Mr. Fowler, mountaineers around the world find themselves forced to adjust to a warming world. Routes that were icy or glaciated in the middle part of the past century, when the world’s highest peaks were being conquered for the first time, are turning into unstable and unappetizing rock.

“Almost every area and route in every range have been affected,” said Jeff Jackson, editor of Rock and Ice , a climbing magazine.

The main issue, scientists and climbers say, is that as permafrost, ice and glaciers melt, they leave areas of teetering rock. Some rock formations high in the mountains have essentially been held together by ice, which “acts as a glue,” said Christian Schlüchter, a professor at the University of Bern’s Institute of Geological Sciences . When the glue disappears — something he has seen happening over the past 15 years in the Alps — the formations can collapse, especially if they are initially weak.

Retreating glaciers are a problem because they leave rocks and other sediments that are poorly compacted and of different sizes, which can make footing treacherous and lead to rockfalls, said John H. Shaw, chairman of the Earth and Planetary Sciences Department at Harvard University.

Mr. Shaw said that as meltwater runs to the foot of a shrinking glacier, it “can make fissures and crevices more common” — and indeed some climbers have noticed more dangerous crevasses.

Glaciers are retreating in many high ranges, including the Himalayas and the Alps (though the Alps are having an unusually snowy year so far), and scientists with the Intergovernmental Panel on Climate Change say they expect the trend to accelerate this century. Recent reports from the International Center for Integrated Mountain Development, which is based in Katmandu, Nepal, indicate that glaciers in the country have shrunk considerably in recent decades and are also fragmenting.

The speed of the changes has amazed — and dismayed — many climbers. Mostly, routes are becoming harder, according to Michael Kennedy, the editor-in-chief of Alpinist magazine. Among regions that he said climbers were especially worried about are the Alps, the Canadian Rockies and the Peruvian mountains, as well as many Himalayan areas.

Some professional climbers are also concerned that amateurs may attempt routes that have become unacceptably dangerous because they are not up-to-date on the changes.

David Breashears, who has climbed Mount Everest five times since 1983 and heads GlacierWorks , a nonprofit climate-change awareness group, said significant changes had occurred on the icefall just above the Everest base camp.

Sherpas and other guides have reported that it is “getting much harder to maintain the ladders and the ice screws and the fixed ropes in the icefall,” Mr. Breashears said. The ice screws, which help anchor things in place, now melt out earlier in May, he said.

Some mountaineers say that a changing climate affects not only the climbs themselves, but also climbers’ ability to reach remote sites in the first place. Mr. Fowler, who is president of the Alpine Club in London , said that during a trip to the Himalayas, his party had been delayed for three days because of rock slides that the locals said were unprecedented. Because the horses could not carry their burdens over the slides, the men had to unload them, carry the supplies across themselves and then reload the horses.

The slides were set off by an extreme monsoon season this summer, Mr. Fowler said, and since the group had only 30 days in Nepal, further delays could have prevented them from reaching the mountain they had come to climb.

“If the landslide problems had continued all the way to base camp, we would never have made it,” Mr. Fowler said.

Climate change is sparing the highest altitudes to some extent, some climbers say.

“In my experience, the higher you go, the less evidence you see of climate change simply because it gets much colder,” said Steve House , a top American climber. “The transition zones, where the ice is newly melting, is where the most danger exists.”

Whereas at 5,500 meters, or 18,000 feet, in the Himalayas the retreating glaciers are leaving slopes of unstable rock, “once you get about 23,000 feet you’re in a land of eternal winter,” Mr. House said.

The International Center for Integrated Mountain Development has also found that glacial retreat is less significant at higher elevations, said David J. Molden, the institute’s director general.

Even so, Mr. Breashears of GlacierWorks said he had noticed changes on the traverse leading to the Hillary Step not far below the Everest summit. And in May 2004, when he was about 8,000 meters up Everest, he saw an unexpected sight — running water.

“It was astonishing to see running water that high,” he said.

In the Alps, recent rockfalls have rendered some historic routes inaccessible. On Le Petit Dru, a peak in the French Alps that was first climbed in 1879, the collapse of the west face in recent years has obliterated the challenging American Direct Route, first established in 1962, as well as another route established 10 years earlier, Mr. House said.

This autumn, a group including Mr. House climbed the mountain’s north face for a film project.

While driving down the valley after the climb, “we heard a huge noise, looked up and saw a massive cloud of dust pouring off the face,” Mr. House said. A pile of rocks had plunged off the peak.

Had the rockfall happened a day earlier, “It was clear that we all would have been killed,” said Mr. House, who links the problems at Le Petit Dru to global warming. Scientists like Mr. Schlüchter cautioned that not every rockfall could be attributed to the climate.

But a changing climate may make some of the world’s highest mountains fractionally more accessible. Because of warmer temperatures, barometric pressure at the top has increased slightly over the past 60-plus years, and that leads to more oxygen, said Peter H. Hackett, who directs the Institute for Altitude Medicine in Colorado and climbed Everest in 1981.

“At extreme altitude, the increasing temperature is making Everest a tiny bit easier to climb,” Mr. Hackett said.