Floods of the melting glacier in Juneau, Alaska, rapid evacuations and the concern of residents

The flood explosion floods – caused when natural ice or sediment dams collapse and send a rush to downstream flood waters – are also a problem in Europe, Central Asia and South America, where they have historically been more fatal.

The flood explosion floods have killed more than 12,000 people worldwideAccording to estimates by the journal Global and Planetary changes. Most of these deaths took place in two events – floods in Huaraz, Peru, 1941 and Kedarnath, India, in 2013.

A study published in Nature Communications in 2023 revealed that 90 million people in 30 countries lived in areas with glacial lakes. Of these, The study estimated, around 15 million were exposed to the potential impacts of explosions, mainly in India, China and Pakistan.

Another 2023 Study in nature communications Identified at least 120 lakes suspended from the glacier in Alaska. Among these lakes, 106 had been drained since 1985. Most are in remote areas.

To mitigate the risks this year, the city of Juneau has aligned miles of barriers along the river, which prevented water from infiltrating many districts, Even if flood waters are higher. The barriers were partly paid by the residents of Juneau in the flood zone.

“We always assess the obstacles, but we are convinced that they have helped to prevent material damage to the 2024 event,” said Nahaku McFadden, Public Affairs Head of the US Army Corps of Engineers, who helped the city design the barrier system.

How do glacial explosions occur?

Glaciers are slow ice rivers that on mountain slopes. During the cold months, these ice bodies accumulate the mass as the snowfall is compacted. In summer, they shrink as the cast iron waters or if the glacier becomes unstable and loses the ice.

The water flowing from the glaciers flows first in the rivers then ends up going out towards the sea.

But sometimes the flow of cast iron water is blocked by a stopper of ice cream. As the water accumulates, it tunors under the glacier and can destabilize this button of ice.

“Once you get a substantial amount of water behind this ice cap, it can possibly float this ice cream and make it under.

“Once triggered, they can become catastrophic and cause floods of several orders of magnitude beyond the largest floods ever measured by rain and melting snow,” he added.

In Alaska, the floods of the ice explosion are common in August, because it is at this point that runoff peaks, but they are possible at any time of the year.

Often, after the water flows, the slow descent of the glacier collapses from the ice and branches the system again, restarting the cycle. Capps said it was common to have an explosion every year.

In Alaska, there are hundreds of lakes with Monte Glacier who could generate lighting floods, said Capps. But most of them are distant, minimizing implications for downstream people or infrastructure.

“In key places like Suicide basin (Upstream of Juneau), we actually have associated infrastructures downstream, so that’s where you get the problem, “he said.

Ice lighting floods are also possible if the water submerges the natural dams created by moraines, rock and debris left on behalf while a glacier moves or withdraws.

“As a rule – not always – moraic lakes will have a failure and the sediments are swept away and it is done,” said Capps.

What role does climate change play here?

The glaciers retreat worldwide. As a rule, some glaciers grow in the seasons with abundant snowfall or fresh time, and others shrink in the sun or if there is a snow session. But overall, the The world’s glaciers are on a long -term tendency of the decline.

The global glacier surveillance service collects data from 60 “reference” glaciers which each have more than 30 years of mass assessment measures.

“The losses are important and consistent around the world,” said Pelto, who measures changes in the mass of glaciers each year in the northern Washington waterfalls. “2023 was the first year when the 60 lost the mass balance of the same year. This happened in 2024. ”

In Alaska, research suggests that glacial explosions have decreased in volume since 1985, because glaciers stored less water behind ice dams which gradually become shorter and thinner. THE The frequency of these events has been roughly the same over time.

As the glaciers retrace, certain areas subject to floods for explosions could stop producing them.

“I think for Alaska, the risk will drop,” said Pelto. “While glaciers decrease and withdraw, we will have fewer opportunities for a robust ride to develop.”

However, researchers fear that glacial dams at a higher altitude and that in colder places become less stable because the world continues to warm up, forming new lakes and areas at risk of explosions.

On Juneau on Wednesday, the barriers were erected after last year’s disaster. The Startz family home had a little spice in the front courtyard and a small layer of ice silt on the lawn.

The owners of the flood zone pay more than $ 600 per year for this protection.

“If these obstacles work, great! I don’t mind paying this supplement,” Startz said on Tuesday. “We cannot repair the glacier.”