Nepal's glacier time bomb

In August, a glacier collapse in Nepal triggered a catastrophic flood, and the danger still isn't over. Fragile new lakes have formed from the debris, and authorities are warning that another flood could burst through at any moment, putting rescuers still working in the area at risk. It's called a Glacier Lake Outburst Flood, and unlike most disasters, it doesn't really have an aftermath… the same lake can collapse again and again for years. These floods are becoming more common as the climate warms. But there's also a rare bit of good news: a decade ago, Nepal's own army successfully defused a similar lake, flying equipment up a mountain to build a permanent drain. Alaska's capital Juneau has the same problem and the same fix on the table. It just hasn't built it. Follow If You're Listening on the ABC Listen app https://radio.abc.net.au/help/apps. Check out our series on YouTube: https://www.youtube.com/playlist?list=PLDTPrMoGHssAfgMMS3L5LpLNFMNp1U_Nq

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  This podcast was produced on the lands of the Uwabikal and Gadigal people.

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  There's a word you often hear in the days following a natural disaster.

• 0:46Speaker 17

  The aftermath of what was Jamaica's strongest storm on record.

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  The word is aftermath. The quake's aftermath, now a race against time. Rescue workers trying to find survivors and listening for voices under the rubble.

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  The aftermath still being felt right across the territory.

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  Most natural disasters have an aftermath, a period of time after the initial threat is gone, where rescue and recovery operations can begin. The thing about glacier collapses, like the one that's happened in Nepal in August, is there isn't really a clear aftermath. The threat doesn't actually go away. And that's because when a glacier collapse happens, the initial disastrous flood can create the conditions for floods to happen again and again.

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  Fragile Barrier Lake has formed at the border of Tibet and Nepal, which holds millions of cubic metres of water.

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  The debris from the initial flood creates fragile dams, which then fill and breach.

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  That can be very, very dangerous because they can easily be breached and then release massive amounts of debris, water and rocks down valley.

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  In the days after the disaster, Chinese and Nepali rescuers walked through the scoured valley floor, banging on rocks and shouting into the mud in search of survivors.

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  Their shouting, is anybody here?

• 2:23Speaker 03

  But these rescuers are still in terrible danger. Authorities are warning a second flood could be imminent. In satellite pictures taken in the days after the initial catastrophic landslide, you can see several new lakes being formed. One has already collapsed, triggering a secondary flood. And it will just keep going, potentially for months. It's unclear when the aftermath of this disaster will actually start.

• 2:54Speaker 03

  As climate change causes glaciers to recede, melt and collapse, there's not much that people living in the Himalayas and other glacier-adjacent areas can do about the catastrophic landslides like the one we saw in August. But those landslides are comparatively rare. The lakes that are formed by the glacier movements are actually the more pervasive threat. These lakes that glaciers and landslides leave behind are killing people and destroying property every single year. And the thing is, there is actually a solution to that problem.

• 3:41Speaker 03

  Engineers know how to deal with the threat of these lakes. They have done it before. And yet, every year, the flooding continues. Today, a real thing that we can really do to mitigate the catastrophic effects of climate change, and the story of why that is still being made unnecessarily complicated. I'm Matt Bevan, and this is If You're Listening.

• 4:12Speaker 03

  Okay, let's talk about how a glacier works.

• 4:16Speaker 07

  A glacier consists of ice and snow that has been packed and frozen for thousands of years, concealing uncharted mountains, valleys and lakes.

• 4:29Speaker 03

  The reason I've gone into like, school educational video mode here is because I'm Australian, and here in Australia, we really don't know anything about glaciers.

• 4:40Speaker 07

  Glaciers are found on every continent of the world except Australia. See, no glaciers here.

• 4:46Speaker 03

  Ask me about sharks and bushfires, though.

• 4:48Speaker 07

  The glacier relentlessly grinds away as a mighty river of ice down the mountain, creeping forward only a few feet a day.

• 4:56Speaker 03

  Many glaciers are hundreds of metres deep and stretch on for kilometres before they reach a natural end point. The ones in polar regions tend to terminate at the ocean, where big chunks of ice break off and those ice chunks become icebergs, which then float off to terrorise overconfident ocean liners. And then there are the ones located in mountain regions closer to the equator. Those terminate wherever they reach a point that's warm enough to start melting. And this is where things can get dangerous, particularly during warmer months.

• 5:30Speaker 07

  During the summer, much of the ice melts and water trickles down to the lake, causing the water level to rise each day.

• 5:38Speaker 03

  Yes, the lake. The thing is, as glaciers push down valleys, they carry with them lots of debris, changing the shape of landscape as they go. Sometimes, as the glacier melts, the debris they've pushed in front of them creates a natural dam wall, which then traps the water melting off the glacier into a lake. Other times, the glacier itself curls around and creates an ice dam of its own.

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  Forming an ice bridge across the valley, holding back the water like a dam.

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  Essentially, glaciers are so big and powerful that they literally reshape the landscape in front of them, randomly creating dams which create lakes.

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  As temperatures rise, high in the mountains, giant lakes are forming and expanding in the glaciers, like a bowl of ice filled with water.

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  But these glacier lakes are not stable, so they don't stick around for very long. They fill quickly during warmer months, up and up and up.

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  When the front of that bowl weakens and collapses, a huge torrent of water cascades down the valley, sweeping everything away in its path.

• 6:53Speaker 03

  And this kind of flood has a special name, a glacier lake outburst flood, or glough for short. Once upon a time, gloughs were very rare. People used to travel from far and wide to Knyck Glacier in Alaska to watch its annual glough.

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  This is the only glacier in the world that has a seasonal cycle, freezing and melting every year.

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  But in 1967, that cycle stopped. They didn't know it at the time, but climate change meant that the glacier wasn't refreezing as much during winter. As a result, the Knyck Glacier receded up the mountain so far that the dam just didn't form that year, or any year after that. The world's most famous annual glough just stopped happening.

• 7:46Speaker 03

  As the climate started warming more, gloughs in other parts of the world started happening instead, like in the Himalayan country of Bhutan.

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  In the 80s and 90s, Bhutan's glacier dams started to burst with increasing frequency.

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  Bhutan was first alerted to the threat in 1994, when a huge glacial lake burst its banks. The ice binding the moraine-like cement had simply melted away.

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  The equivalent of 7,000 Olympic pools' worth of water surged down the valley, travelling 100 kilometres in five hours. The flooding devastated several small villages and killed 20 people. See, in the steep, rocky valleys of the Himalayas, there's nowhere for floodwater to disperse. They're like giant, concrete stormwater drains. As we've seen with the horrifying videos from the floods in Nepal this year, it's not like a slow-rising flood. The water arrives as a wall and blasts through anything in its way. That flood in Bhutan in 1994 was no different, and the people in the area immediately became

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  worried that worse was yet to come.

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  Within weeks, it became clear that another lake was close to bursting point, and in sub-zero temperatures, locals literally used their bare hands to bail out the water.

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  They didn't have the capacity to release these dams on a large scale, so locals literally used buckets and baskets to scoop the water out and tip it down the valley before it could break the dam wall. By 2005, it was clear that the threat was far bigger than anyone expected.

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  Satellite and computer simulations have revealed the extent of this new and frightening problem. Over the last decade or so, an estimated 2,500 glacial lakes have been forming in Bhutan.

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  Bhutanese Cabinet Minister Jigmei Thinley told the BBC that there was nothing they could do to prevent the disasters.

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  To tamper with the walls, the fragile walls, the natural walls of these lakes would be too risky. So we are simply waiting for the possibility of a great devastation that could take place.

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  Basically, if you tamper with the dam walls too much, they can break. So they just didn't touch them and hoped for the best. But that's obviously not sustainable. Climate change isn't reversing, at least not in the short term, and every year it gets warmer, more lakes will emerge. In the Himalayas alone, there are now thousands of them. All of those lakes will just get bigger and bigger until they burst. It's inevitable. It's just a matter of when.

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  Finally, in 2016, the UN decided to try and do something about it.

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  Here we are in the heart of the Himalayas. This is India Valley, and I'm looking... Working at Imja Lake, which we are working together triumphantly for the next GLOF event.

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  The lake they chose to do this on was Imja Lake, which did not exist until the 1970s. It began as a puddle, but as the glacier above it melted and retreated up the mountain, it grew in size until it was about one and a half kilometres square.

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  This is a lake, one of many. There are 18 in Nepal that are at high risk of bursting its banks.

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  Imja Lake was not only getting bigger, it was also getting bigger faster. By 2016, the volume was estimated at the equivalent of 32,000 Olympic pools, nearly five times the size of that lake that had flooded in Bhutan in 1994. A catastrophic GLOF felt inevitable.

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  And this not just causes significant ecological destruction, it takes a lot of lives and devastates livelihoods for the communities who live downstream.

• 11:55Speaker 03

  What the Nepalese had to do wasn't complex on paper. They were going to basically fortify the natural dam wall, make it less likely to break, and then build a channel for the lake to slowly drain through. A very simple idea, but very difficult to achieve in practice. There are no roads up to Imja Lake. It's also 5,000 metres above sea level, at the bottom of a valley with incredibly high walls. Walking in is difficult, but driving in is impossible, which is less than ideal because large-scale infrastructure projects generally involve large-scale machinery. The only way to carry anything into the valley is via helicopter or yak.

• 12:39Speaker 03

  The thin air at that altitude means that neither of those options have much lifting capacity. Even a helicopter can only carry a tonne of payload at a time. If you need a bobcat or an excavator, you have to carry it up there in small parts and assemble them on-site. Workers could only work for a few hours a day or they'd get altitude sickness, and all food supplies would need to be delivered by yak. When the government put the job out to tender with private contractors, nobody bid for it. In the end, they gave the job to the Nepali Army. This is a unique kind of project.

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  With this, I think, if we can do this successfully, we can do this kind of project anywhere.

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  The project cost $7 million and took six months of incredibly hard work by the Army and Sherpas to complete the job. Since 2016, the system has held up. The Nepali Army managed to prevent catastrophic flooding in the valley below. And they're not the only ones who are doing something proactively to mitigate the risk of these climate-related disasters. So let me take you back to Alaska.

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  Nestled in the mighty mountains of south-eastern Alaska are glaciers that make the largest ones in Europe look small.

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  South-eastern Alaska is a deeply strange bit of geography. It's a narrow strip of American mainland on the edge of the Canadian province of British Columbia, and there's a series of islands just off the coast. The waterways between the islands and the mainland are called the Inside Passage.

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  Along the Inside Passage are Alaska's first cities. This is Juneau, the capital city with about 6,000 inhabitants, and the chief source of employment is one of the world's greatest engineering projects, the famous Alaska-Juno gold mine.

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  Juneau was initially built next to the gold mine on a very narrow bit of flat land between Mount Juneau and the waters of the Inside Passage. As the city began to grow, it spread north into the Mendenhall Valley, which might have been a slight tactical error, because above that valley sits one of Alaska's biggest glaciers.

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  Of all the attractions, the Mendenhall Glacier is the most awe-inspiring. Flowing 12 miles out of the coast mountains, the Mendenhall terminates in a freshwater lake just 13 miles from downtown.

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  In this tourism video from 1989, it was clear that even as the city was expanding into the shadow of this glacier, something was up with it.

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  This glacier is currently in recession, melting about 100 feet per year. The silty water flows from Mendenhall Lake to Gastonau Channel. Local tour operators run raft trips along the river for those not afraid to get a little wet.

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  The Mendenhall Glacier doesn't slide cleanly down the valley, though. It's got a weird little side bit, a blob about the size of a racecourse, which is known as Suicide Basin. Sounds like a really fun place. Anyway, at some point around two decades ago, Suicide Basin stopped being a weird frozen appendix on the side of the glacier and started to become a pool of melted water. For a while, that wasn't a problem. The water was trapped between the mountain and the still-frozen glacier. But in the summer of 2011, the water in the basin broke through its frozen dam and spilled down into the valley.

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  So this is all of the water, this is all of the slide.

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  The trouble is, it wasn't an isolated incident. The flooding happened again next year, and then the year after that, and then every year.

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  Roads and properties in the suburbs of Juneau downstream would be flooded over and over again.

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  My name is Karen Morgan. I moved to Juneau, Alaska in 1969 as a nine-year-old, and I've never seen flooding like this. This is beyond anything I've ever seen.

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  The US government set up a time-lapse camera inside Suicide Basin and recorded the extraordinary cycle that had started occurring every summer. A sudden massive jump in water level inside the basin as the glacier melts, followed by an even more sudden drop. In 2023, the flood broke all previous records. So much water washed down that mountain that homes weren't just inundated but washed away entirely. 2024 was worse, and 2025 worse again. That year, authorities managed to avoid catastrophic damage by spending $8 million on a temporary

• 17:38Speaker 03

  wall of sandbags. This year, the sandbag wall cost nearly $50 million. They are assuming that the wall will cost even more in 2027. And the temporary fix will only work for so long because the flood is getting worse every year.

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  A worst-case flood would submerge most of the Mendenhall Valley if there isn't a way to stop the water.

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  Fortunately for the good people of Juneau, there is a simple solution that doesn't involve hauling around infinite sandbags every summer for the rest of their lives. Remember a few minutes ago when I said that the Nepali Army managed to solve this problem by building a valve in a glacier lake in the middle of the Himalayas? Well, after years of consultation between federal and local government, the US Army decided to do just that.

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  This is KTLO. I'm Yvonne Crumory. Thank you for listening. The US Army Corps of Engineers has landed on a solution to put an end to glacial opus floods that have grown more destructive in Juneau's Mendenhall Valley neighbourhoods over the past few summers.

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  The Army and the local council announced that they would build a tunnel through the mountain to drain the basin.

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  I just think about Suicide Basin as a proverbial bathtub, and what the lake tap is, is just leaving the drain open.

• 19:00Speaker 03

  The Army Corps of Engineers has done this kind of thing several times before. It's not rocket science, it's a tunnel. So they went away to write up the plans. Two months later, a potential price tag of $613 million was floated, which seems like a lot, but it's also around the cost of 12 years' worth of sandbag walls to fix a growing crisis permanently, so it seems like it might be a worthy investment. Plus, the new head of the Army Corps of Engineers, Adam Tell, had just had this exchange with Alaska Senator Dan Sullivan about a new executive order issued by President Trump.

• 19:37Speaker 22

  The Assistant Secretary of Army for Civil Works, that's you, shall immediately review, revise, or rescind any agency action that may in any way hinder, slow, or otherwise delay any critical project in the state of Alaska. That's from the President. So will you commit to abide by that very expansive provision to get things done in my great state after, you know, four years of being crushed by the previous administration?

• 20:08Speaker 08

  Senator Sullivan, absolutely. And when I visited your office, I Tattooed the executive order that the president issued on Alaska on my heart.

• 20:18Speaker 03

  Get critical projects done in Alaska. He had it tattooed on his heart. So it really did sound like things were all set to go. The locals and the council wanted the tap and the military had been greenlit to get everything going, but it didn't happen.

• 20:35Speaker 10

  The US Army Corps of Engineers has backed out of studying a lake tap solution to the glacial outburst floods that have ravaged Juno's Mendenhall Valley neighborhoods in recent years.

• 20:45Speaker 03

  The local council, which was very much behind this project, said the army's decision came as a shock.

• 20:52Speaker 09

  We don't know, we don't understand why this changed. They rescinded all of the direction that they'd previously given and basically said that they would continue to support flood fighting in the area for an undetermined amount of time.

• 21:07Speaker 03

  Hmm, okay. So the suggestion was to stick with the expensive temporary sandbag solution, continuing to pay millions of dollars a year for temporary flood mitigation instead of spending 600 million to fix the problem permanently. It doesn't really seem like a logical solution. And didn't Senator Sullivan and Secretary Tell just agree to get things

• 21:33Speaker 22

  done in Alaska? Oh, wait, hang on. What was that executive order actually called? Day one executive order called unleashing Alaska's extraordinary resource potential.

• 21:43Speaker 03

  Ah, so get things done means green lighting, infrastructure to help mining projects. The core under Adam Tell's guidance was hard at work upgrading a port in the Alaskan town of Nome. But building this lake tap, well, Sullivan and Tell told a Juno town meeting that it was going to take too long and be too expensive.

• 22:04Speaker 22

  We got to get a solution moving that's not 10 years and $10 billion. It's fast

• 22:12Speaker 08

  and it's innovative. We're taking the most creative approach as we possibly can to do exactly what you're saying, which is to reduce risk to Alaskans in a way that's not 10 or 20 years and it's not one or $2 billion to federal taxpayers.

• 22:26Speaker 03

  Hang on, 10 billion? 1 billion? 2 billion? I mean, I don't know how much a lake tap costs to drill, but that's quite a spread, especially considering the initial estimate was $600 million. Secretary Tell said that rather than have the army do the work, he was excited to get to work talking to private sector stakeholders to find a solution.

• 22:50Speaker 08

  Let them tell us the very best way to do this for the, in the best way, the cheapest price. And we're very excited about that. This is all possible under President Trump's leadership. He commands us as his administration's appointees to get creative and solve problems and don't be government as usual. And we're doing this at Trump's speed.

• 23:11Speaker 03

  Don't worry, folks, they're going to solve this problem at Trump's speed.

• 23:17Speaker 03

  Now, scientists estimate that in about 25 years, these glofs won't be a problem anymore because the Mendenhall Glacier will have receded so far that Suicide Basin will no longer fill up. But until then, it means Juno, a state capital in the world's richest country, is sitting there downstream of a time bomb that will go off every year like clockwork for a quarter century. But despite that, the government isn't diffusing the bomb because it's too expensive. To make matters worse, every year this bomb isn't diffused, the government has to spend millions of dollars on sandbags. So that's the thing about climate

• 23:57Speaker 03

  mitigation. Every year you don't do something, it costs more money. And every year you don't act, the situation gets worse. Every degree of warming creates thousands of new bombs. The global number of glacier lake floods is increasing dramatically each year. In Nepal, for example, where the drain on Imja Lake in the Himalayas was successfully installed 10 years ago, there are hundreds of dangerous glacier lakes, the majority of which don't have drains installed. So hundreds of glaciers are filling hundreds of lakes, which are

• 24:36Speaker 03

  all waiting to be broken. About 10 new lakes are being found in Nepal every year. But the unusual thing about this particular threat from climate change is that we can at least see it. If we were determined, we could drain the most dangerous lakes and save a lot of property and lives. So, I mean, he's hoping we start doing that soon and at Trump's speed, too.

• 25:13Speaker 03

  If You're Listening is written by me, Matt Peppin. Supervising producer is Cara Jensen-McKinnon. Audio production this week is by Anna John. I'll catch you on Tuesday.