On Wednesday morning, part of a glacier and the mountainside beneath it collapsed on the north side of Langtang Lirung, a 23,734-foot peak near Nepal’s border with Tibet, setting off a 60-mile flood of water, mud and debris.

By Friday, Nepal’s National Disaster Risk Reduction and Management Authority said that 579 people had been killed. Many, many more are still missing.

More than 4,000 miles west, victims of another disaster in the region were being mourned. That morning, in Dorset, England, family and friends gathered to commemorate Nirmal Purja, the celebrated Nepali mountaineer known as Nimsdai. Among them was Mingma Gyalje Sherpa, one of Nepal’s leading climbers and the founder of the expedition company Imagine Nepal. After an avalanche on Broad Peak in Pakistan’s Karakoram range killed Mr. Purja and nine other climbers on July 30, Mr. Mingma Sherpa led the expedition that recovered Mr. Purja’s body.

The two disasters occurred within a month of each other on the mountainous region that extends from Pakistan through Nepal, where scientists, climbers and trekkers have witnessed accelerating losses of snow and ice.

For Nepal, the consequences extend far beyond the mountains. Tourism represents 6.1 percent of the country’s economy and supported about 1.2 million jobs in 2023, roughly 15 percent of all employment, according to the World Bank.

Of the more than 1.16 million international visitors who went to Nepal in 2025, 165,056 listed trekking and mountaineering as their primary reason for visiting. The industry that has grown around them includes more than 3,000 trekking agencies and tens of thousands of registered guides, as well as expedition companies, porters, cooks, teahouses, hotels, airlines, helicopter operators and drivers.

At the lucrative extreme is high-altitude climbing. This spring, 1,195 climbers obtained permits for 31 mountains, generating about $9 million in government royalties alone. Nearly 500 received permits for Mount Everest, where the spring permit for a foreign climber now costs $15,000.

Over seven years working on expeditions, Mr. Purja had become one of the world’s best-known climbers and the owner of an international expedition company, Elite Exped, with his own sports clothing line. Mr. Mingma Sherpa is part of the same generation. His company runs expeditions on Everest and other Himalayan peaks. “It’s one of the best jobs in Nepal,” he said, speaking after the Langtang Lirung flood. A successful high-altitude guide, he estimated, can make “10 times” an ordinary Nepali salary.

But many believe that this livelihood is threatened by global warming. Arbindra Khadka, 35, a glaciologist and research scientist at Tribhuvan University in Kathmandu, noted that Himalayan glaciers are losing about a meter (nearly 3.3 feet) of ice a year. “It’s not just Everest” that is in trouble, he said. “The entire Himalayas are melting.”

Disappearing Snow and Ice

Increasingly, those in the trekking business depend on mountains that are changing beneath climbers’ feet. Tul Singh Gurung, president of the Nepal National Mountain Guide Association, believes the Broad Peak avalanche may have begun when a serac, a tower of glacial ice, collapsed and triggered the slab avalanche below. What troubled him was where it happened. Climbers generally regarded the slope between Camps II and III as one of Broad Peak’s more stable sections at that time of year.

“The mountains are getting black,” Mr. Gurung said, describing the disappearing snow and ice across the Himalayas and Karakoram. “Every mountain has a rockfall problem.”

Dave Watson, a 50-year-old American mountaineer who has summited Mount Everest seven times since 2004, has witnessed the change. “Some of this hazard has always been there, but in a lower volume,” Mr. Watson said.

The changes are visible not just at the extreme elevations reached by Everest climbers but also on mountains visited by the trekkers and climbers vital to Nepal’s economy.

Dr. Khadka cautioned that it was too early to say precisely what triggered the Langtang disaster. But he theorized that a relatively small cornice collapse high on the ridges of Langtang Lirung had started an avalanche of loose rock and moraine across slippery, thawing ground during the wet mid-monsoon season.

For Dr. Khadka, the latest disaster is personal. Speaking from Nepal, he was waiting for news of missing relatives and friends.

Mr. Gurung said guides were already encountering places where traditional climbing and trekking routes had become difficult to recognize as snow and ice disappear and bare rock emerges. One of the most closely watched is the Khumbu Icefall, which begins the climbing route up Everest from Nepal. Dr. Khadka expects it to keep changing. Some sections may become easier to cross, he said, while hanging ice and exposed slopes create new dangers.

Mr. Mingma Sherpa has watched the transformation firsthand. When he first crossed the Icefall in 2004, he remembers negotiating numerous crevasses on aluminum ladders. This year, he said, climbers needed ladders in only two places.

Mr. Watson knew the region devastated by the latest flood. He passed through the Nepal-Tibet border area twice in 2024 and remembered how dramatically it had developed since his early expeditions two decades ago. On journeys to the north side of Everest, crossing the border used to require an overnight stop while climbers waited for immigration formalities and transferred equipment between trucks. In recent years, roads, restaurants, hotels and residences have been built to cater to increasing traffic between the two countries.

Mr. Watson saw the aftermath of another Himalayan catastrophe. An earthquake in 2015 shook loose rock and ice in Langtang, where an avalanche buried much of the village and killed hundreds. “The thousand-year flood is happening every few years now,” he said.

Yet Nepal’s younger climbers show little sign of abandoning the profession. Mr. Mingma Sherpa said young people continued to be drawn by the pay and the work, although their backgrounds are changing. Increasingly, Sherpa families live in Kathmandu and other lower-altitude cities. “We were used to playing at higher altitude,” he said. “Now Sherpas are born in the city.”

Drones, Transceivers and Lighter Equipment

Dipan Gurung, 25, is part of the new generation of guides. He comes from the Makalu region and a family of farmers rather than the Khumbu communities traditionally associated with Himalayan guiding. He began as a trekking porter in 2019. Many young men from his region traditionally went into the army, he said; now growing numbers are seeking professional climbing and rescue training.

Mr. Gurung has watched glaciers melt into ponds. “We are facing a future of rockfalls and floods,” he said. Yet he does not believe that makes his career prohibitively dangerous. While the mountains are becoming less predictable, equipment and tools are more accurate and advanced. His generation has detailed weather forecasts, GPS devices, avalanche transceivers, lighter equipment and training in reading snowpacks. They also use drones, which provide information on conditions and carry supplies.

Some of those tools are already changing the way Everest is climbed, particularly for the Sherpas and other Nepali high-altitude workers who have long borne much of the danger of commercial expeditions. While foreign clients may cross the Khumbu Icefall a handful of times during an expedition, Nepali workers traditionally make repeated trips through it, carrying tents, oxygen, food and equipment to higher camps. On April 18, 2014, that disparity in risk became starkly apparent when a mass of ice collapsed above the route, killing 16 Nepali climbing workers in the icefall.

Drones now offer a way to reduce some of that exposure. “We are trying to reduce people going through the icefall by moving loads up by drones,” Mr. Gurung said, describing machines capable of carrying roughly 88 pounds. Mr. Watson expects drones to increasingly scout for danger as well. “Drones will be a huge part of safety plans in the future,” he said.

Helicopters offer another way around dangerous terrain, although Mr. Gurung and Mr. Watson are wary of treating them as a solution because high-altitude flying depends on visibility, wind and landing conditions.

On Wednesday, while Mr. Purja’s family and friends gathered in England, Mr. Gurung was back at work in Nepal, helping coordinate rescue teams in the disaster zone. With roads severed and some areas accessible only by helicopter, his association was sending trained guides into steep terrain and confined spaces difficult for conventional rescue teams to reach.

Soon, if conditions allow, climbers and trekkers will return to the mountains. The autumn trekking season is approaching. Expeditions are booked, and guides, porters, teahouses and lodges are depending on them.

For Mr. Watson, perhaps the starkest evidence of how much those mountains have changed is at the very top of the world.

“If the summit of Everest has that much less ice,” Mr. Watson said, “then there is no place on Earth that is untouched.”

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