ON 4 AUGUST 1985, Dig Tsho – a lake situated high in the Himalayas in eastern Nepal – burst its natural dam above the small town of Thame and sent 5 million cubic metres of water crashing down through the valleys below.
Houses, bridges and a newly constructed $3 million (€2.66 million) dam were all destroyed by the burst. There were reports that three people were killed as well as livestock and many hectares of valuable land were lost to the flood.
The burst of the natural dam (called a moraine) came after a huge ice avalanche fell into the lake, triggering a wave reaction.
The event – where a glacial lake bursts its moraine and carries huge amounts of water and debris downstream – is known as a glacial lake outburst flood (GLOF).
Scientists and mountain researchers fear that as a result of warming temperatures caused by global, human-made climate change, glaciers are melting faster and GLOF events are becoming more common.
For communities in the mountains of Nepal the effects could be devastating.
Glacial Lakes
Today, the village of Thame is a small tourist stopover in Sagarmatha National Park in the Solukhumbu region of north east Nepal. Trekkers coming down the long way from the Everest Base Camp trek usually stay in one of its lodges for the night.
Nepal contains eight of the world’s 14 highest peaks, including Mount Everest which is located in Sagarmatha NP. The park is Unesco World Heritage Site and stretches across over 1,150 km squared, encompassing pristine forests, breathtaking valleys and the towering, icy Himalayas.
In normal times it is a magnet for adventurous trekkers and hikers.
With the outbreak of the Covid-19 pandemic earlier this year, Nepal, along with most of the world’s countries, closed its borders to the world in March and cancelled all treks to the Everest region.
Before all this, TheJournal.ie visited the region to investigate the risks of GLOFs and the effects a warming climate was having on the glaciers and if local people were worried about the risks.
In mid-February, Thame was mostly empty as the tourist season hadn’t kicked off yet. At the time there were concerns of coronavirus having some impact on the season, but the trails were still open.
The Himalayan peaks and valleys loomed over the terrain, which was mostly still covered in ice from the winter.
On the way towards Dingboche, a small village on the route towards Everest Base Camp, a local guide Saban Rai pointed towards a nearby hill, which was mostly dark and free of ice.
“This black mountain, in the past this was all ice but now it’s just rock,” he said.
Saban spoke of an older guide who had been arranging treks in the area for decades.
“This guide, he said before the 1980s there was a lot of ice here and people used to go there for ice training before climbing Everest.
“But now there’s no ice anymore.”
The Himalayas
The Himalayan mountain range cuts across the top of Nepal. The range itself is about 2,400 km in length and spans the countries of India, Pakistan, Afghanistan, China, Bhutan and Nepal.
The area is known as the “Third Pole” because of the large amount of glaciers there. The glaciers themselves are a vital source of water for 250 million people in the mountains as well as for 1.65 billion people in the areas below and are the source of 10 of the world’s important river systems.
As temperatures rise across the world as a result of human made climate change, the Himalayan glaciers are melting at an increased pace. A recent major report by the International Centre for Integrated Mountain Development (ICIMOD) in Nepal found that since the 1970s the glaciers have thinned and retreated.
The Hindu Kush Himalaya Assessment found that if global greenhouse gas emissions continue unabated, two-thirds of the glaciers could melt by the end of the century.
Even if global temperature increases are kept to 1.5 degrees Celsius (the ambitious goal of the 2015 Paris Agreement), the assessment found that one-third of the glaciers would be lost.
This would dramatically change the livelihoods of billions of people who rely on the glaciers for food, water, energy and clean air. More immediately, the melting glaciers are causing glacial lakes to expand increasing the risk that they will burst and flood downstream.
“When we were kids in winter seasons – especially in December, January, February – it snowed a lot,” said Dawa Sherpa, a businessman and owner of the highest Irish Pub in the world at Namche Bazaar.
Dawa grew up in Namche and has noticed significant changes to the weather and landscape since he was a child.
“Now it hardly snows twice in the winter. That is [an indication] and the glaciers are melting, the lakes are getting bigger, [Lake] Imja is already in danger, so the signs are all there.”
Glacial lakes in Nepal
The Himalayan glaciers are giant structures of ice and packed snow that dominate the mountainous landscape. As they grow they accumulate debris – like rocks and stones – at the edges.
When temperatures increase and the glacier melts and recedes the rocks and debris become the natural dam (moraine) at the edge of the newly formed glacial lake. The lake grows from the melting glacier and risks bursting the moraine and causing a GLOF event.
The bursting of Dig Tsho in 1985 sparked a flurry of research into glacial lakes and the dangers posed by GLOFs and how to prevent them. Using satellite data, researchers found that certain lakes were growing at an alarming rate and posed significant risks.
“We use remote sensing to map and monitor glacier and glacial lakes. To see how glacial lakes have been increasing over the decades. Using this data we are able to publish the changes [across decades],” said Finu Shrestha, a research associate with ICIMOD mapping glaciers and the expansion of glacial lakes.
By using the same data we can see and have an accurate analysis of the glacier and [how it has] changed. In that time glacial lakes attached to glaciers have shown large expansions in the size.”
There are over 1,500 glacial lakes in Nepal. Research by ICIMOD has found 21 glacial lakes to be potentially dangerous and six to be in critical need of attention.
Imja Lake
After you leave the bustling town of Namche at 3,440m – where trekkers can pick up their last supplies and stay in relative comfort – you make your way through the small village of Tengboche with its Tibetan Buddhist Monastery, through the old Sherpa village of Pangboche and onto the tiny village of Dingboche at 4,410m altitude.
The only way through these villages is by foot. All goods are carried up by porters or yaks and the land is mostly barren in the winter.
At Dingboche, most trekkers veer off north west on the way to Everest Base Camp, but continuing north east you make your way to the tiny collection of lodges that make up the village of Chukhung. A few more hours heading east and you’ll reach Imja Lake.
In February the lake was entirely frozen over, its surface unbroken and pure white stretching towards the foot of the shrinking Imja glacier which feeds it. At just over 5,000m the air is thin and the temperature in February drops to -15 C or below at night. The hills and mountains span off in every direction, uninhabited and covered in snow.
Imja lake – which is about 2km in length with a maximum depth of 90m – didn’t exist 60 years ago. Since then, it has grown as the glacier feeding it has receded. The lake is one of the most dangerous of Nepal’s glacial lakes and poses risks to Chukhung, Dingboche and even Namche Bazaar downstream.
The work by ICIMOD categorises glacial lakes by how dangerous they are and presents reports which governments can then act upon. Because of its size and rapid pace of expansion, Imja is a Category 1 – or one the most dangerous lakes.
Following the devastation of the 2015 earthquake, the Nepalese Department of Hydrology and Meteorology, along with the United Nations Development Project, undertook an operation to drain the lake to make it safe.
After six months of work at a difficult altitude, an outlet was constructed and close to 4 million cubic metres of water was drained from the lake, with water levels lowering by 3.4 metres.
An early warning monitoring system was also installed, which should warn ahead of time if the lake expands to dangerous levels.
The operation was carried out in order to prevent a GLOF event, with officials stating at the time that the process would be repeated with other dangerous lakes.
However, modelling studies have suggested that the lake must be lowered by at least 10m to prevent major damage and by 20m to completely eliminate the chance of a downstream GLOF.
In the years since the operation the lake has continued to grow, but researchers believe the risk has been mitigated for the time being.
“It will fill again but if the flow is contained I don’t think it will be a problem unless and until an avalanche into the lake itself happens,” said Finu Shrestha.
For Shrestha, other lakes are now in need of attention in order to avert potential disasters down the line. GLOF events are usually small events, some that occur in isolated areas with no communities nearby even go unnoticed.
But as the 1985 bursting of Dig Tsho shows they can be potentially catastrophic.
Living with the risk
For the people living and working in the area around the growing glacial lakes, the dangers seem present but at the same time far away.
In February, the main worry people had was the lack of tourists passing through, which posed a much more immediate challenge then the risks associated with melting glaciers.
“People are more worried about immediate problems,” said Saban Rai, the guide.
“Before, the Imja lake was nearly full, it very nearly burst… but now it is gone down.”
Ram Bahadur Tamang – a lodge owner in Dingboche who lived there during the season for 30 years – was concerned with the lack of tourists, but said that the melting glaciers were also an issue.
“Every year you can see a change in glacier, every year because [it gets] warmer… After 10 years if it continues like this there will be a problem,” he said.
Tamang said however that Imja was safer for now because of the operation to lower it.
Dawa Sherpa – the Irish pub owner – said there are many awareness raising campaigns in the mountain regions around climate change and protecting the environment, but that more focus needed to be put on the bigger emitters of planet warming gases.
“It’s not because of the mountain people that the climate is changing. Lots and lots of people come to the mountains and they put their agendas and their climate change campaigns in Everest Base Camp, or on [the] mountains,” he said.
I don’t think it’s a good idea to do it there. It’s not because of the people in the mountain region or the region itself. It’s because of these mega cities and the factories and everything that are creating the issue.
“Glaciers are melting not because of the locals here. It’s because of the urban areas that the glaciers are melting. So we should be more… the news and everything should be more spread in urban areas than the mountains, that’s what I think.”
For Dawa, like all business owners in the region, the immediate worry is the shutdown and steep drop in tourism.
“Things are in complete lockdown and it doesn’t look like bouncing back any time soon,” he said when contacted last week.
According to the Nepali Department of Tourism, over half a million people working in tourism in Nepal have had their livelihoods directly impacted by the lockdown,
The future of the mountains
Across the world, greenhouse gas emissions dropped significantly in the first half of the year as flights were grounded, borders were closed and industries shut down.
In Kathmandu – Nepal’s capital city – air pollution dropped to such an extent that Mount Everest 200 km away was visible from the city for the first time in many years.
A study published in Nature Climate Change last month found that at the peak of lockdown measures daily greenhouse gas emissions dropped by 17% around the world.
“This is a really big fall, but at the same time, 83% of global emissions are left, which shows how difficult it is to reduce emissions with changes in behaviour,” Corinne Le Quéré, a professor of climate change at the University of East Anglia, and the lead author of the study, told The Guardian.
But any reductions were likely to be temporary, and Le Quéré said that “structural changes” to the economy and to industry were needed to halt global warming and its negative effects.
“But if we take this opportunity to put structural changes in place, we have now seen what it is possible to achieve,” she said.
If carbon emissions return to normal levels and temperatures continue to rise, the effects on Nepal’s glaciers and the lives of those near them, as well as those who rely on them for water and their livelihoods will be huge.
In the immediate sense in Nepal, Finu Shrestha said that work needs to be done to mitigate the danger from expanding glacial lakes in a similar fashion to what was carried out at Imja.
“I’m worried that if a GLOF happens in a big lake… then of course there’s very much a risk to communities and infrastructure, but I can’t tell you when the GLOF will happen, at what time, and in which lake and of what magnitude. It’s very difficult to predict all of this,” she said.
For Dawa Sherpa, mountain dwellers are doing their part to avert disaster, and others need to do the same.
“People from those regions really can’t do anything. We’re doing our part anyway. We’re not cutting down the trees, we’re not burning plastic, we’re controlling the pollution,” he said.
“The locals are already aware of it. But it is not because of the mountain people that climate change is happening.”
This article is the second in a series focusing on the impact of climate change on people in Nepal. It is supported by the Simon Cumbers Media Fund.
To embed this post, copy the code below on your site
have your say