Climate Action

Why we need climate action to avert glacial lake outburst floods in Bhutan

Bhutan's Baytsho, Raphstreng and Thorthomi glacial lakes climate change melting

Bhutan’s Thorthomi and Raphstreng glacial lakes are under threat of outburst due to climate change. Image: UNDP

Kanni Wignaraja
Assistant Secretary-General, UN; Regional Director for Asia and the Pacific, United Nations Development Programme (UNDP)
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  • The mountainous Kingdom of Bhutan was the first carbon-negative country in the world but lives under the constant threat of climate change.
  • Its glaciers are melting fast as temperatures rise, raising water levels in the glacial lakes and magnifying the risk of an outburst flood.
  • The world’s major carbon emitters must consider accelerated actions and take responsibility for turning the tide on climate change.

At 4,200 metres above sea level, the remote highland community of Lunana – made up of a cluster of 17 villages – is a place almost untouched by visitors.

Tucked away in a corner of the tiny Kingdom of Bhutan, it takes seven days to trek here from the capital Thimphu. The only other way in, depending on the weather, is a helicopter ride that follows the river bending and weaving between the mountains.

Lunana inherits its allure from its geography. A place ringed by majestic snow-capped mountains, stunning glaciers, and turquoise glacial lakes, a beauty that is captivating but today is potentially lethal.

Glaciologist Karma threat tsunami in the sky glacial lake outburst flood climate change
Glaciologist Karma warns of the threat of a 'tsunami in the sky' causing another glacial lake outburst flood. Image: UNDP

Glaciologist Karma calls that danger ‘a tsunami in the sky’, a threat that is brewing in these mountains that could lead to another glacial lake outburst flood, also known as GLOF.

Lunana is home to four glacial lakes – Lugge, Thorthomi, Rahpstreng and Beytsho. The first three are among Bhutan’s 17 most dangerous glacial lakes. As temperatures get warmer, the glaciers are fast melting, raising water levels in the glacial lakes, and magnifying the risk of an outburst flood.

Bhutan bears the climate consequences of other countries' emissions

Bhutan does not contribute to global warming. In fact, it is the first carbon-negative country in the world, yet it must now bear the consequences of the actions of other countries, both near and far from its borders.

Karma and his team, from the National Center for Hydrology and Meteorology – who spend several months in Lunana every year monitoring the glaciers and lakes – have long warned about a worst-case scenario of a combined explosion of water from the Thorthomi and Raphstreng glacial lakes.

The two lakes are separated by a thin, weak ridge, whose collapse would lead to the convergence of the two lakes, triggering a massive outburst flood, four times more severe than the one in 1994.

This would devastate not only communities in Lunana, but also several others downstream, and it would destroy two of Bhutan’s biggest hydropower projects, the 1200-megawatt Punatsangchhu I and 1020-megawatt Punatsangchhu II. Hydropower is the country’s largest export, irrigates its agricultural base and hence contributes heavily to its economy.

In Lunana, the outburst of 1994 remains a vivid memory. When I visited the area last month, Wangmo, a woman from the village of Tenchoe told me about how she and others in the community ran for their lives when the flood struck.

It was around 9pm, when they heard a fearsome rumbling, and guessed a flood was coming. It was dark as they rushed out of their homes, carrying children and the elderly to higher ground, Wangmo said. Despite their quick response the flood claimed nearly two dozen lives and destroyed homes, farms, infrastructure, and biodiversity, in Lunana as well as downstream communities. It took a long while to build back and they are older now.

So today, even the slightest of sound from the mountains is cause for concern. Villagers are witnessing the changes around them almost in real time. The Thorthormi glacier is retreating at about 30 to 35 metres per year. In case of a lake outburst, the people of Thanza, the closest community to the lakes, have only 20 minutes to move to safer ground.

Collaborative action needed to turn tide on climate change

As we approach another global meeting – COP27 – aimed at reducing greenhouse gas emissions, the UN Development Programme is working with governments to enact policies and programmes, and bring in investments, to reduce emissions, including through renewable energy and energy efficiencies and demonstrating low carbon options in sectors such as agriculture and transport.

Policy changes include reducing subsidies on fossil fuels, introducing carbon taxes, and incentives to use low-emission technologies and supply chains.

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Given the gravity of the situation, some countries are trying to enhance their carbon sinks – forests, marshes, mangroves or water bodies that can capture and store carbon dioxide from the atmosphere – and are implementing initiatives to restore biodiversity.

The private sector is developing and implementing higher energy efficiency technology and standards and is providing much needed financing to support green development. Meanwhile civil society organizations are raising awareness, mobilizing people to act, and highlighting the vulnerability of the most marginalized.

It will take all such interventions and more, with stakeholders working in concert to turn this tide and avert climate change disasters such as glacial lake outbursts, in Bhutan.

Bhutan schoolgirl's climate message to world leaders

Few people outside of Bhutan had heard of Lunana, until the film Lunana: A Yak in the Classroom, was nominated for Best International Feature Film at the 2019 Academy Awards. During my visit, Chimi Yangzom – an eight-year-old girl in grade two at the school featured in the movie – walked an hour to Tenchoe from her village in Tsojong, to meet me.

She wanted me to hand over a message she had written, to world leaders. “My village is in great danger because of global warming,” read the message. “The glaciers are melting and glacial lakes above our village are getting bigger every day. I am sure it will cause a big flood in our village anytime.” Her letter was read out by Bhutan’s Foreign Minister Dr Tandi Dorji at the UN General Assembly.

Chimi future glaciers snow mountains beautiful glacial lakes Lunaps Lunana climate change
Eight-year-old Chimi’s message goes on to say: “In the near future, we may not see glaciers and snow on the mountains, beautiful glacial lakes and Lunaps (residents of Lunana) in this place. Image: UNDP

Her warning is prescient. The latest report from the Intergovernmental Panel on Climate Change (IPCC) warned that the glaciers in the entire Hindu Kush Himalayan region will keep shrinking if the world fails to slash emissions drastically.

The message is simple – we cannot wait. The world’s major carbon emitters must consider accelerated actions and take responsibility for turning the tide on climate change and do so now.


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Chimi’s message goes on to say: “In the near future, we may not see glaciers and snow on the mountains, beautiful glacial lakes and Lunaps (residents of Lunana) in this place. Therefore, I would like to request Your Excellency to kindly convey this small message to the world leaders, and big and small nations, to help and save our tiny village from global warming. I am sure if we all come together, we cannot only save our tiny village but also make our earth safe for all living beings.”

A simple yet powerful message from a little girl from the mountains of Bhutan, that remains etched in my mind. It’s now or never.

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