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By Alice Gibbs
Senior Reporter
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The catastrophic glacier collapse that triggered devastating flooding in Nepal and Tibet this week has highlighted the destructive force of hazards originating high in the world's mountain ranges.
While scientists are still determining exactly how the disaster unfolded, the event has renewed attention on the risks posed by glaciers, glacial lakes and rapidly moving masses of ice and rock. Those threats are often associated with the Himalayas and Andes, but researchers say parts of North America face their own glacier-related flood hazards.
Among them is Juneau, Alaska, where annual floods from Suicide Basin have damaged homes, prompted evacuation planning and turned one glacier-fed lake into one of the continent's most closely watched flood risks.
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Could a Disaster Like Nepal's Happen in North America?
The short answer is yes, though experts say the risks vary greatly from place to place.
North America has experienced glacier-related floods for more than a century, particularly in Alaska and western Canada. Researchers who compiled one of the world's largest databases of glacial lake outburst floods found that northwestern North America accounts for more documented events than any other region in their records.
That does not mean a Nepal-scale disaster is imminent in North America. The deadliest glacier-related floods tend to occur where large numbers of people live downstream of unstable lakes or glaciers. Many North American glacier systems are in remote regions with relatively small populations nearby.
But scientists say glacier retreat is changing mountain landscapes, creating and expanding lakes in some areas and forcing authorities to keep a close watch on locations that could threaten downstream communities. A 2023 study published in Nature estimated that around 15 million people worldwide live in areas that could be affected by glacial lake outburst floods, with the greatest concentrations in parts of Asia and South America.
What Is a Glacier?
A glacier is a large mass of ice that forms when layers of snow build up over many years and become compressed.
Although glaciers can appear still, they slowly move under their own weight. As they advance and retreat, they reshape landscapes, carve valleys and leave behind rock and sediment.
When glaciers shrink, melting water can collect in lakes. Most remain stable, but some can release water suddenly, causing flooding downstream. Those floods are known as glacial lake outburst floods, or GLOFs.
Why Juneau Is Watching Suicide Basin So Closely
If one North American community illustrates how serious these threats can become, it is Juneau.
What distinguishes Juneau from many other glacier hazards across North America is that the threat is both recurring and directly connected to a populated community.
While many glacier-related floods occur in remote mountain regions, Suicide Basin has produced annual releases since 2011 and repeatedly affected homes, roads and infrastructure in the Mendenhall Valley. As a result, researchers and emergency managers often regard Juneau as one of the continent's clearest examples of an active urban glacier-flood threat.
The city's Mendenhall Valley sits downstream from Suicide Basin, a lake system connected to the Mendenhall Glacier. Water builds up in the basin before periodically being released into the Mendenhall River. Those releases have occurred every year since 2011.
The floods were once considered relatively minor, but recent years have brought larger and more damaging events.
In August 2024, floodwaters inundated parts of the Mendenhall Valley, affecting about 290 homes and causing extensive damage. The following year brought another record flood, while the latest release on August 13, 2026, pushed the river into major-flood stage once again.
When conditions suggest a release is underway, forecasters issue flood warnings and residents can use inundation maps showing which neighborhoods may be affected at different river levels. Local emergency planning includes evacuation guidance for areas most exposed to flooding along the Mendenhall River system.
The result is that Juneau is often cited as one of North America's clearest examples of a community learning to live with a recurring glacier-flood threat.
Interest in glaciers has also been fueled by searches for Greenland's Petermann Glacier and Glacier National Park in Montana.
Petermann Glacier is one of Greenland's largest glaciers and is closely monitored by scientists because of its contribution to ice-sheet loss and potential sea level rise. However, it is not currently associated with the kind of recurring flood threat seen at locations such as Juneau's Suicide Basin.
Glacier National Park, meanwhile, has become a focal point in discussions about glacier retreat in the United States. While the park's glaciers have shrunk significantly over time, it is also not known for recurring glacier-flood hazards.
What Causes a Glacier Collapse?
A glacier collapse happens when a large section of ice suddenly breaks away or rapidly moves downhill.
Sometimes the collapse involves ice alone. In other cases, ice mixes with rock, mud and water, creating a fast-moving flow that can travel long distances through mountain valleys.
Scientists believe the Nepal-Tibet disaster involved a major collapse of ice and rock high in the Himalayas, although investigations are continuing. The event generated enough force to register on seismic instruments and sent a destructive surge downstream.
Researchers say warming temperatures can contribute to conditions that increase glacier-related hazards, although no single event can automatically be attributed to climate change. A 2025 study published in Nature found reported glacial lake outburst floods have become more common globally since the 1980s, reflecting changes occurring in mountain regions around the world.
What Other Areas Are Being Monitored?
Researchers are also closely watching parts of British Columbia.
Near Place Glacier, northeast of Pemberton, a glacial lake produced outburst floods in both 2024 and 2025. The events prompted evacuation alerts and increased monitoring as officials sought to determine when future releases might occur. Scientists say similar situations could emerge elsewhere as glaciers continue to change.
Experts caution that predicting exactly where the next major flood will occur remains difficult. Every glacier system is different, and a lake's size alone does not determine how dangerous it may be. The number of people living downstream often matters just as much as the amount of water involved.
Contact Newsweek editors on this story: Rebecca Flood and Emma Lee-Sang
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