MUSTANG, Nepal — On a crisp morning after a night of rain, the breeze diffuses the smell of wet earth in the village of Kagbeni in Mustang, Nepal’s trans-Himalayan frontier. The perennial Kali Gandaki River, rejuvenated by the rain, roars with its silt-laden water as scores of pilgrims carry packages of grain, flowers, saffron powder and sesame seeds to offer to their ancestors.

The narrow alley leading to the riverbanks is soon converted into a parking lot for idling motorcycles, buses and SUVs waiting for the pilgrims to finish their prayers, take a dip in the river, and hand over the offerings to the sacred river — believed to carry these to their ancestors — before heading to the Muktinath temple upstream.

As if the river slices time into two, one of the banks reflects the present and the other tells a tale from a distant past. On the far side lies a fragile slope, constantly eroded by the river’s flow and the powerful winds that have shaped the sedimentary rocks ever since the Himalayas began rising and the ancient Tethys Sea disappeared during the Cenozoic Era. On the near side, on the other hand, stands a row of concrete lodges, hotels and tea houses that are symbols of the rapid transformation as climate change and mass tourism converge in the region.

One of those new buildings belongs to 33-year-old Tashi Gurung. He grew up in Kagbeni but left for Kathmandu years ago. “After the road came, more tourists arrived. I thought it was a good time to come back and start something,” he says, standing behind the reception desk of his two-story hotel.

That road — an all-weather link between Upper Mustang (north of Kagbeni which remains a restricted, high-value trekking destination) via the more accessible ‘lower’ Mustang (home to Kagbeni, Jomsom and Muktinath) and the rest of Nepal completed eight years ago — marked the beginning of a profound shift. Travel time was cut from days to mere hours, opening Mustang to all forms of tourism: adventure, spiritual and leisure. In the past, Kagbeni, like much of Mustang, saw mainly dedicated foreign trekkers on the Annapurna Circuit, with only occasional Nepali devotees visiting to pay homage to their forefathers. “Before, lodges didn’t want Nepali guests because they spent less than foreigners,” Gurung recalls. “Now, things are different.”

Domestic tourists now arrive in droves, drawn to the desert-like landscapes rarely seen elsewhere in Nepal. The flow intensified after Indian Prime Minister Narendra Modi visited the Vaishnav temple of Muktinath; since then, Indian pilgrims, many in large groups, have begun arriving year-round. The results are striking: According to the district police office, Mustang welcomed 678,536 visitors between mid-July 2024 and mid-June 2025 — a 49% jump from the 454,326 recorded the previous year. Domestic arrivals rose by 52%, reaching 539,872, while foreign arrivals grew by nearly 40%, totaling 138,664 visitors from 72 countries.

To accommodate this surge, hotels, guest houses and tea houses have sprung up from Jomsom to Kagbeni and beyond, often perched on fragile riverbanks and alluvial fans. As zoning laws are weakly enforced, construction has expanded into flood-prone areas once serving as natural buffers for the Kali Gandaki and its tributaries.

Alongside the physical footprint, the demands of tourism weigh heavily: Hotels require showers, flush toilets and laundry facilities. When Mongabay visited Kagbeni, sewage treatment was found to be inadequate, leaving waste to flow into the river.

“People invest in hotels because tourists bring quick money,” says Sonam. “Farming is harder as the weather is unpredictable, and water is not always enough.”

Yet, the pressures on Mustang are not just human-made. Climate change is reshaping the region’s geology and hydrology in ways locals and researchers are only beginning to understand. A stark warning came on Aug. 13, 2023, when heavy rains triggered a flash flood in Kagbeni that swept away homes, hotels, a police post, bridges, vehicles and electricity poles.

Such an event was unexpected in a region long thought to be in the rain shadow of the Annapurna and Dhaulagiri ranges. Until recently, clouds entering Nepal from the Bay of Bengal were believed unable to breach that mountain wall. But new research suggests that warming in the Arabian Sea is pushing the northern edge of monsoon clouds farther north, strengthening winds and carrying moist air deeper into Mustang.

The shift is evident: Places that were once dry are now seeing heavier summer rains. “We also see an increase in the intensity of rainfall that wash away sediments and destabilize slopes, triggering massive landslides and endangering settlements,” explains researcher Apechhya Aryal, who recently studied precipitation changes in the region.

Horticulturist Padma Atreya, who was stationed at the government-run apple farm in Marfa, Mustang, says he has seen this first-hand. His office sits below a towering mound of sedimentary rocks. “Every time there’s rain, we are afraid that the mound may fall on us,” he tells Mongabay.

The warming trend is also affecting the Third Pole, the Himalayas’ high mountains. Melting permafrost and shrinking glaciers threaten the Kali Gandaki River, Mustang’s lifeline, which supplies drinking water, irrigation for crops and hydropower. “When the permafrost is gone, the river could face periods of extreme low flow,” Aryal warns.

Geologist Shree Kamal Dwivedi expands on this: “As permafrost thaws, the loose soil beneath is exposed. With precipitation shifting from snow to rain, erosion increases and sediments are washed into rivers, triggering sediment-laden floods. This could explain the recent flood. We’ve seen the same phenomenon in other Himalayan rivers as well.” He adds that melting glaciers also risk glacial lake outburst floods (GLOFs) when meltwater pools behind weak natural dams of ice and rock, only to eventually burst with devastating force.

Looking ahead, further development could further amplify risks. The proposed construction of the world’s longest cable car in Mustang has raised alarm among environmentalists. They warn it could fragment habitats, push visitor numbers beyond carrying capacity, and heighten disaster risks in a landscape already vulnerable to the impact of climate change.

Others, however, remain more optimistic about the tourism. Ram Chandra Sedhai, CEO of the Trekking Agencies’ Association of Nepal (TAAN), argues that “tourism has brought more positive impacts than negative ones to Mustang. Major concerns of tourism are related to energy use and landscape changes.”

He notes that energy largely comes from hydropower and solar rather than deforestation, and claims the landscape itself “hasn’t altered much due to tourism.” Communities once reliant on forests and agriculture now benefit from tourism, he says, stressing that climate change is a global issue beyond local control: “Their emissions are small and insignificant. The hotels are not blocking the river, they are the ones at risk of floods.”

Aryal argues that regardless of the impact of tourism, it is time for urgent action. “The first step is to gather more data and research to understand what is happening and then take steps to mitigate the risks,” Aryal emphasizes. “Suggested measures include relocating people from high-risk zones and establishing early warning systems,” she adds.

Such efforts, however, aren’t underway. The work of the National Trust for Nature Conservation, which manages ACAP, has been limited to providing warnings to tourists to avoid disaster prone areas, says Rabin Kadariya, the project’s head.

The local municipalities in the area are attempting to draw the attention of the whole country to Mustang’s climate challenges. “Gharapjhong Rural Municipality is organizing a meeting of all mayors and their deputies from around Nepal in Mustang to talk about climate change on September 16 this year,” Mohan Singh Lalchan, president of Gharapjhong Rural Municipality, tells Mongabay.

Back in Kagbeni, Sonam watches trekkers walk past his hotel from the hotel window. The morning sun has dried up the trail washed by last night’s rain, but the memory of last year’s flood lingers. “I want to welcome guests,” he says. “Tourism gives us life here. But I also want my village to be safe.”

Banner image: Prayer flags in Mustang. Image by Abhaya Raj Joshi/Mongabay.

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Citation:

Zhang, J., Hu, R., Ma, Q., & Niu, M. (2022). The warming of the Arabian Sea induced a northward summer monsoon over the Tibetan Plateau. Journal of Climate, 35(23), 7541–7554. doi:10.1175/JCLI-D-22-0273.1