Alaskan River Reaches Record High From Melting Glacier. An overflowing glacial lake caused a surge in the Mendenhall River on Wednesday, prompting flood alerts and evacuations in Juneau.

 

A timelapse view from cameras monitored by the U.S.G.S. of the Suicide Basin before the glacial lake outburst flooding from the Mendenhall Glacier, in Juneau, Alaska, covering a period from July 21 to Aug. 13.CreditCredit...U.S.G.S.

 

By Raymond Zhong

 

An overflowing glacial lake north of Juneau, Alaska, caused the Mendenhall River to surge to a record height on Wednesday, flooding homes and streets in parts of the state capital, which has a population of more than 30,000.

Such floods have been a recurring problem in Juneau since 2011, but recent years have seen record-setting surges as rising temperatures cause glaciers in the area to melt more rapidly. Alaska has warmed faster than the global average, and the fastest of any state, according to the Environmental Protection Agency.

Flooding last August from the same glacial lake inundated several hundred homes in Juneau with four to six feet of water, although no deaths or injuries were reported. The city put up a temporary levee along the river in response. Residents this week were urged to evacuate ahead of the latest round of high water.

Here’s what to know about these floods.

What’s a glacial lake outburst flood, or GLOF?

As glaciers melt, they tend to retreat uphill, leaving an empty bowl at the bottom of the valley where the ice once sat. Meltwater from the glacier starts pooling in this bowl, and over time a lake forms.

 But the sides of the lake are fragile. They might be formed of loose dirt and rock or ice. If one day an avalanche or a landslide occurs, or a piece of a nearby cliff plunges into the water, the disturbance can cause the sides of the lake to collapse. In a flash, most of the lake’s water might cascade down the valley, threatening towns and cities below.

 

Glacial lake outburst floods can be catastrophic because, by the time the water reaches downstream settlements, it has picked up huge amounts of sediment and boulders along the way, turning it into a thick slurry that can knock down buildings.

In 2023, a GLOF in northern India killed at least 55 people and destroyed a hydropower dam. All in all, 15 million people around the world live within 50 kilometers, or 31 miles, of a glacial lake and less than a kilometer from the potential path of a GLOF, scientists estimated in a 2023 study.

How common are they in Alaska?

The glacial lake that is overflowing this week in Alaska sits at the foot of the Suicide Glacier, an ice mass north of Juneau. Decades ago, the Suicide Glacier flowed into a much larger river of ice, the Mendenhall Glacier. But as the Suicide melts and shrinks, a steep gap has opened up between it and the Mendenhall. This gap is now called Suicide Basin.

(Experts have proposed renaming Suicide Basin to Kʼóox Ḵaadí Basin, which in the Tlingit language translates to “Marten’s Slide Basin.” A marten is a lithe, weasel-like animal found in the area.)

Snowmelt and rain accumulate in the basin, and when the water is high enough, it starts draining through cracks in the Mendenhall Glacier before flooding the Mendenhall River.

The first time this happened was in July 2011, and it took downstream communities by surprise. The basin has since filled and drained at least 39 times, according to the National Weather Service. Early Wednesday, as the basin drained once more, the Mendenhall River peaked at a height of 16.65 feet, exceeding a record set last year.

The glaciers in this region are part of the Juneau Ice Field, a sprawling area of interconnected ice that is melting twice as quickly as it did before 2010, scientists reported last year. More of the area’s glaciers are detaching from one another, the researchers also found, which can lead to the formation of lakes like Suicide Basin.

Accelerated melting is producing more water to fill these lakes and hence more water that eventually floods neighborhoods downstream, said Bob McNabb, a glaciologist at Ulster University who has studied the Juneau Ice Field. “As you get more and more melting coming down, that will fill up the basin a bit more each time,” Dr. McNabb said.

How is climate change affecting GLOFs?

The world’s high mountains are warming more quickly than Earth as a whole. That is causing thousands of glaciers to shrink and new lakes to form beneath them. Since 1990, the number, area and volume of glacial lakes around the world have all grown by roughly 50 percent, scientists estimated in a 2020 study.

But bigger lakes don’t directly translate into greater GLOF hazards. Each glacial lake and valley has distinct features that influence how likely it is to burst, and what the consequences would be if it did. So predicting future flood risks is “very complex,” Dr. McNabb said.

In the Mendenhall Valley, for instance, rising temperatures are the reason the Suicide Glacier has withered away and Suicide Basin has formed. But as the planet warms further, the Mendenhall Glacier might melt by so much that the flood threat actually decreases. The reason? There would no longer be enough ice at the side of Suicide Basin to trap large amounts of meltwater. Instead, the water would just empty into the valley gradually.

Scientists in Alaska have predicted that this could come to pass within the next decade or two. Until then, the people of Juneau will continue to live with the dangers from the warming landscape just a few miles to their north.

Melting glaciers threaten to wipe out European villages - is the steep cost to protect them worth it ?

 

In a small village in Switzerland's beautiful Loetschental valley, Matthias Bellwald walks down the main street and is greeted every few steps by locals who smile or offer a handshake or friendly word.

  by Imogen Foulkes Geneva correspondent

 

Mr Bellwald is a mayor, but this isn't his village. Two months ago his home, three miles away in Blatten, was wiped off the map when part of the mountain and glacier collapsed into the valley.

The village's 300 residents had been evacuated days earlier, after geologists warned that the mountain was increasingly unstable. But they lost their homes, their church, their hotels and their farms.

Lukas Kalbermatten also lost the hotel that had been in his family for three generations."The feeling of the village, all the small alleys through the houses, the church, the memories you had when you played there as a child… all this is gone."

Blatten's residents were evacuated days before the disaster

Today, he is living in borrowed accommodation in the village of Wiler. Mr Bellwald has a temporary office there too, where he is supervising the massive clean-up operation - and the rebuild.

The good news is, he believes the site can be cleared by 2028, with the first new houses ready by 2029. But it comes with a hefty pricetag.

Rebuilding Blatten is estimated to cost hundreds of millions of dollars, perhaps as much as $1 million (USD) per resident.

Voluntary contributions from the public quickly raised millions of Swiss francs to help those who had lost their homes. The federal government and the canton promised financial support too. But some in Switzerland are asking: is it worth it?

 Houses were destroyed after a large part of Blatten was buried under masses of ice, mud, and rock

 

Though the disaster shocked Switzerland, some two thirds of the country is mountainous, and climate scientists warn that the glaciers and the permafrost – the glue that holds the mountains together – are thawing as the global temperature increases, making landslides more likely. Protecting areas will be costly.

Switzerland spends almost $500m a year on protective structures, but a report carried out in 2007 for the Swiss parliament suggested real protection against natural hazards could cost six times that.

Is that a worthwhile investment? Or should the country - and residents - really consider the painful option of abandoning some of their villages?

The day the earth shook

The Alps are an integral part of Swiss identity. Each valley, like the Loetschental, has its own culture.

Mr Kalbermatten used to take pride in showing hotel guests the ancient wooden houses in Blatten. Sometimes he taught them a few words of Leetschär, the local dialect.

Losing Blatten, and the prospect of losing others like it, has made many Swiss ask themselves how many of those alpine traditions could disappear.

'I'll never forget it. The earth shook.' Fernando Lehner recalls the day of the landslide

Today, Blatten lies under millions of cubic metres of rock, mud, and ice. Above it, the mountain remains unstable.

When they were first evacuated, Blatten's residents, knowing their houses had stood there for centuries, believed it was a purely precautionary measure. They would be home again soon, they thought.

Fernando Lehner, a retired businessman, says no one expected the scale of the disaster. "We knew there would be a landslide that day… But it was just unbelievable. I would never have imagined that it would come down so quickly.

"And that explosion, when the glacier and landslide came down into the valley, I'll never forget it. The earth shook."

Landslides are 'more unpredictable'

The people of Blatten, keen to get their homes back as soon as possible, don't want to talk about climate change. They point out that the Alps are always dangerous, and describe the disaster as a once in a millennium event.

But climate scientists say global warming is making alpine life more risky.

Matthias Huss, a glaciologist with Zurich's Federal Institute of Technology, as well as glacier monitoring group Glamos, argues that climate change was a factor in the Blatten disaster.

"The thawing of permafrost at very high elevation led to the collapse of the summit," he explains.

Glaciologist Matthias Huss argues that climate change was a factor in the Blatten disaster

"This mountain summit crashed down onto the glacier… and also the glacier retreat led to the fact that the glacier stabilised the mountain less efficiently than before. So climate change was involved at every angle."

Geological changes unrelated to climate change also played a role, he concedes - but he points out that glaciers and permafrost are key stabilising factors across the alps.

His team at Glamos has monitored a record shrinkage of the glaciers over the past few years. And average alpine temperatures are increasing.

In the days before the mountain crashed down, Switzerland's zero-degree threshold – the altitude at which the temperature reaches freezing point – rose above 5,000 metres, higher than any mountain in the country.

"It is not the very first time that we're seeing big landslides in the Alps," says Mr Huss. "I think what should be worrying us is that these events are becoming more frequent, but also more unpredictable."

Blatten's residents lost their homes, church and farms: living below a mountain, as many Swiss do, looks increasingly precarious

A study from November 2024 by the Swiss Federal Research Institute, which reviewed three decades of literature, concurred that climate change was "rapidly altering high mountain environments, including changing the frequency, dynamic behavior, location, and magnitude of alpine mass movements", although quantifying the exact impact of climate change was "difficult".

More villages, more evacuations

Graubünden is the largest holiday region in Switzerland, and is popular with skiers and hikers for its untouched nature, alpine views and pretty villages.

The Winter Olympics was hosted here twice - in the upmarket resort of St Moritz - while the town of Davos hosts world leaders for the World Economic Forum each year.

One village in Graubünden has a different story to tell.

Brienz was evacuated more than two years ago because of signs of dangerous instability in the mountain above.

Its residents have still not been able to return, and in July heavy rain across Switzerland led geologists to warn a landslide appeared imminent.

Average alpine temperatures are increasing, say scientists. Meanwhile glaciers are shrinking

Elsewhere in Switzerland, above the resort of Kandersteg, in the Bernese Oberland region, a rockface has become unstable, threatening the village. Now residents have an evacuation plan.

There too, heavy rain this summer raised the alarm, and some hiking trails up to Oeschinen Lake, a popular tourist attraction, were closed.

Some disasters have claimed lives. In 2017, a massive rockslide came down close to the village of Bondo, killing eight hikers.

Bondo has since been rebuilt, and refortified, at a cost of $64 million. As far back as 2003, the village of Pontresina spent millions on a protective dam to shore up the thawing permafrost in the mountain above.

Not every alpine village is at risk, but the apparent unpredictability is causing huge concern.

The debate around relocation

Blatten, like all Swiss mountain villages, was risk mapped and monitored; that's why its 300 residents were evacuated. Now, questions are being asked about the future of other villages too.

In the aftermath of the disaster, there was a huge outpouring of sympathy. But the possible price tag of rebuilding it also came with doubts.

An editorial in the influential Neue Zürcher Zeitung questioned Switzerland's traditional - and constitutional - wealth distribution model, which takes tax revenue from urban centres like Zurich to support remote mountain communities.

The article described Swiss politicians as being "caught in an empathy trap", adding that "because such incidents are becoming more frequent due to climate change, they are shaking people's willingness to pay for the myth of the Alps, which shapes the nation's identity."

It suggested people living in risky areas of the Alps should consider relocation.

 

Preserving the alpine villages is expensive. And Neue Zürcher Zeitung was not the first to question the cost of saving every alpine community, but its tone angered some.

While three quarters of Swiss live in urban areas, many have strong family connections to the mountains. Switzerland may be a wealthy, highly developed, high-tech country now, but its history is rural, marked by poverty and harsh living conditions. Famine in the 19th century caused waves of emigration.

Mr Kalbermatten explains that the word "heimat" is hugely important in Switzerland. "Heimat is when you close your eyes and you think about what you did as a child, the place you lived as a child.

"It's a much bigger word than home."

Ask a Swiss person living for decades in Zurich or Geneva, or even New York, where their heimat is, and for many, the answer will be the village they were born in.

For Mr Kalbermatten and his sister and brothers, who live in cities, heimat is the valley where people speak Leetschär, the dialect they all still dream in.

 

The fear is that if these valleys become depopulated, other aspects of unique mountain culture could be lost too - like the Tschäggättä, traditional wooden masks, unique to the Loetschental valley.

Their origins are mysterious, possibly pagan. Every February, local young men wear them, along with animal skins, and run through the streets.

Mr Kalbermatten points to the example of some areas of northern Italy where this loss of culture has happened. "[Now] there are only abandoned villages, empty houses, and wolves.

"Do we want that?"

Lukas Kalbermatten believes the site can be cleared by 2028, with Blatten's first new houses ready by 2029.

For many, the answer is no: An opinion poll from research institute, Sotomo, asked 2,790 people what they most cherished about their country. The most common answer? Our beautiful alpine landscape, and our stability.

But the poll did not ask what price they were prepared to pay.

Trying to tame a mountain

Boris Previsic, the director of the University of Lucerne's Institute for the Culture of the Alps, says that many Swiss, at least in the cities, had begun to believe they had tamed the alpine environment.

Switzerland's railways, tunnels, cable cars and high alpine passes are masterpieces of engineering, connecting alpine communities. But now, in part because of climate change, he suggests, that confidence is gone.

"The human induced geology is too strong compared to human beings," he argues.

"In Switzerland, we thought we could do everything with infrastructure. Now I think we are at ground zero concerning infrastructure."

Boris Previsic says that many Swiss, at least in the cities, had begun to believe they had tamed the alpine environment

The village of Blatten had stood for centuries. "When you are in a village which has existed already for 800 years, you should feel safe. That is what is so shocking."

In his view, it is time to fight against these villages dying out. "To fight means we have to be more prepared," he explains. "But we have to be more flexible. We have always also to consider evacuation."

At the end of the day, he adds, "you cannot hold back the whole mountain".

In the village of Wiler, Mr Previsic's point is greeted with a weary smile. "The mountain always decides," agrees Mr Bellwald.

"We know that they are dangerous. We love the mountains, we don't hate them because of that. Our grandfathers lived with them. Our fathers lived with them. And our children will also live with them."

Helicopters carry debris from the disaster site at Blatten. Even the military is involved in the operation.

At lunchtime in the local restaurant in Wiler, the tables are filled with clean-up teams, engineers and helicopter crew. The Blatten recovery operation is in full swing.

At one table, a man from one of Switzerland's biggest insurance companies sits alone. Every half hour, he is joined by someone, an elderly couple, a middle aged man, a young woman. He buys each a drink, and carefully notes down the details of their lost homes.

Outside, along the valley's winding roads, lorries and bulldozers trundle up to the disaster site. Overhead, helicopters carry large chunks of debris. Even the military is involved.

Sebastian Neuhaus commands the Swiss army's disaster relief readiness battalion, and says they must press on despite the scale of the task. "We have to," he says. "There are 300 life histories buried down there."

The abiding feeling is one of stubborn determination to carry on. "If we see someone from Blatten, we hug each other," says Mr Kalbermatten.

"Sometimes we say, 'it's nice, you're still here.' And that's the most important thing, we are all still here."

Lead image: The village of Blatten after the disaster. Credit: EPA / Shutterstock