How an outburst flood could wash out vulnerable American communities

Daily Mail​

16-07-2025

As the US continues to deal with a summer full of devastating flash floods, scientists warn that something even worse could soon wash out vulnerable American communities. Flooded subway tunnels in New York City and deadly overflowing rivers in the Texas Hill Country were powerful examples of how destructive water can quickly become during extreme weather events.
But scientists say an 'outburst flood' could deliver more destruction than 90 of the most powerful nuclear bombs in history. Officially known as glacial lake outburst floods (GLOFs), they're becoming increasingly common due to climate change , and millions of people, including thousands in the US, are in harm's way. GLOFs are not new, but the scale and frequency are rising fast.
At the end of the last Ice Age, roughly 15,000 years ago, the Missoula Floods swept across the American Northwest, triggered by massive glacial lakes bursting through ice dams. This catastrophic event all started with a remote glacial lake quietly growing in size, swelling more than twelvefold as melting ice relentlessly fed it. However, after several decades, the water became too much. With immense pressure building behind a ridge, the lake exploded, unleashing a wall of water up to 60ft that roared down a valley, obliterating everything in its path.
Each of the 400 individual floods during this event unleashed the energy of 4,500 megatons of TNT, nearly 100 times the force of the largest nuclear weapon ever detonated, Soviet Russia's 'Tsar Bomba.' Water roared at speeds of 65 miles per hour, carrying boulders the size of cars, reshaping the landscape and carving vast canyons that are still visible today. In 2023, India's Sikkim region suffered the deadliest GLOF in recent memory, when a glacial lake burst following years of steady melt, killing dozens and leaving hundreds homeless.
Now, attention is turning to the US, where three states - Alaska, Washington and Wyoming - are facing growing threats. One Alaskan lake, ominously named [Death] Basin, has burst two years in a row, releasing a staggering 14.6billion gallons of water in each event. That's the equivalent of 22,000 Olympic swimming pools flooding downtown Juneau, turning streets into rivers and forcing residents to flee with pets in carriers.
Floods beneath the basin have been recorded since 2011, but researchers are now alarmed at the rapid acceleration. A recent study found 106 out of 120 glacier-dammed lakes in Alaska have drained at least once since 1985, and new lakes are forming as the glaciers retreat. 'The danger is growing,' scientists warned. 'As ice-free basins fill with water, they eventually reach a breaking point. 'Pressure builds until the glacier can't hold, and the result is a sudden, violent flood downstream.'
These floods, they say, are often unpredictable and have already caused significant loss of life and infrastructure worldwide. Washington State was once the site of the legendary Missoula Floods, and experts say history could repeat itself. All 47 glaciers currently monitored in the state are retreating, creating new lakes in unstable terrain.
Back in 1947, a combination of rain and glacial melt triggered a GLOF from the Kautz Glacier, sending 1.4 billion tons of mud and debris surging six miles and carving a canyon 300 feet deep. Now, the northeastern region of the state is considered a GLOF hotspot, and scientists have called for more urgent monitoring. In 2025, a panel of glaciologists urged the installation of seismic sensors and real-time weather stations to detect potential bursts before they happen.
Despite advances in modeling and hazard mapping, the team wrote in the science journal called Nature, 'These events continue to cause large-scale destruction due to weak policy enforcement, inadequate warning systems and poor community preparedness.' While not as high-risk as Alaska, Wyoming's Wind River Range and Absaroka Mountains have experienced multiple GLOFs, and the state remains on alert. In 2003, the Grasshopper Glacier released 3.2 million cubic meters of water, damaging nearby infrastructure.
A study using NASA Landsat satellite data found 13 separate GLOFs between 1994 and 2007, and local records have identified at least 15 total outbursts around Mammoth Glacier alone. That's the highest concentration of GLOFs documented in the Rockies since the Ice Age-era Missoula Floods. 'Glacial retreat is exposing new terrain where meltwater can accumulate,' scientists wrote. 'Eventually, these lakes become unstable, and when they go, they go fast.'