Climate change played a key role in the “catastrophic” 2023 floods in the Himalayan state of Sikkim in India, a new study says.
The breach of one of the “largest, fastest-growing and most hazardous” glacial lakes in Sikkim, the South Lhonak lake, led to cascading floods that killed 55 people and washed away a 1,200 megawatt (MW) hydropower dam.
The event was identified as a glacial lake outburst flood (GLOF), which is a sudden release of water from a lake fed by glacial melt.
The research, published in Science, explores the many drivers of the GLOF, its extensive impacts and policy implications going forward.
“There are many, many factors that came together here,” the study’s lead author tells Carbon Brief, but the “main driver” was the destabilising effect caused by thawing permafrost.
The research also finds that the South Lhonak lake has been expanding for decades, due to meltwater from the glacier above, with its area growing 12-fold between 1975 and 2023.
The paper concludes that the GLOF highlights the “complex interactions” between climate change, glacier mass loss and human infrastructure in mountainous regions.
It also demonstrates the importance of “robust monitoring systems and proactive measures to minimise devastating consequences and enhance resilience”, the authors add.
Flood cascade
Sikkim is a small Himalayan state in north-east India, bordering China in the north, Bhutan in the east, Nepal in the west and the state of West Bengal in the south.
Part of the eastern Himalaya, Sikkim is host to more than 90 glaciers and Kanchenjunga, the world’s third-highest peak. Sikkim serves as the origin and upper river basin for the Teesta river, one of the largest tributaries of the Brahmaputra river system.
On the night of 3 October 2023, a ridge of frozen rock and other debris on the side of the South Lhonak glacier – called a “lateral moraine” – collapsed into the glacial lake. This set off a tsunami-like wave nearly 20 metres high that breached the front of the lake, sending 50m cubic metres of water – almost half the lake’s volume – downstream.
According to the study, the GLOF’s peak discharge “vastly exceeds” the magnitude of any meteorological flood in the region’s history, equivalent to a “rare” one-in-200-year event.
Dr Ashim Sattar, a glaciologist at the Indian Institute of Technology, Bhubaneswar and the lead author of the study, tells Carbon Brief the sheer scale of impact is not always evident in satellite images. He explains:
“Here, 270m cubic metres of sediment was eroded, enough to fill 108,000 Olympic swimming pools. The South Lhonak Lake itself is 2.2km long. Just walking around it will make you sweat.”
Two hours later, the GLOF and huge volumes of eroded sediment reached the village of Chungthang 35km away, destroying the 1,200MW Teesta-III hydropower project on impact and damaging four other dams downstream.
Exclusive visuals from completely damaged Chungthang Dam in Sikkim
Received from Pokhraj Rai Ji pic.twitter.com/x9gFxs1PC6
— Weatherman Shubham (@shubhamtorres09) October 12, 2023
As the GLOF travelled, it set off 45 secondary landslides, many of them deep-seated and up to 150 metres in depth, with impacts not just in Sikkim, but also in neighbouring West Bengal and Bangladesh.
In all, the flood cascade damaged 25,900 buildings, 31 major bridges and flooded 276km2 of agricultural land. The most heavily inundated zone was in Bangladesh 300km away, where intense cyclonic rainfall – initially attributed as a main GLOF driver – exacerbated flooding.
The figure below, taken from the study, shows before-and-after images and illustrations of the moraine collapse and the flood’s path from Sikkim to Bangladesh, where floodwaters finally discharged into the Brahmaputra river.
Dr Jakob Steiner, a geoscientist at the University of Graz and a member of the Himalayan University Consortium, who was not involved in the study, says the assessment captures the “cascading” impacts of GLOFs and their interaction with other complex, climatic factors in great detail. He tells Carbon Brief:
“Even if the glacial lake is relatively small, it can trigger other movements downstream and that can have far-reaching consequences, even for hydropower plants miles away from any lakes. So the message [of the study] is that you’re not safe anywhere and, hopefully, that’s a message that policymakers will get. Institutionally, however, we are not yet prepared to receive that kind of message.”
What caused the flood?
To study such a complex and multifaceted event, researchers combined satellite imagery, meteorological data, field observations and numerical modeling.
Study lead Sattar tells Carbon Brief that “capturing this entire process into one model is very tricky and complex”.
Throughout the paper, the authors emphasise the “multi-hazard” nature of the disaster, explaining that multiple short- and long-term changes in the climate and terrain converged to create the conditions needed for the event.
However, Sattar tells Carbon Brief that the “main driver” of the GLOF was the long-term impact of rising temperatures on permafrost – the perennially frozen ground that makes up much of the mountain’s slope.
According to the authors, decades of rising temperatures have led to permafrost thaw, which caused “extensive, rapid deformation” of the slope for years preceding the collapse. The paper estimates that permafrost warming has reached a depth of 100 metres below the surface of the soil.
The study also identifies the expansion of the South Lhonak lake as an important driver. The authors find that the South Lhonak glacier, which sits above the lake, has been melting for decades. Meltwater from the glacier flows directly into the lake, which has been gradually filling up.
The charts below show the annual mass balance of the glacier (left) – where a negative number indicates a shrinking glacier – and the increasing area of the lake (right) between 1951 and 2023.
The research finds that the lake has been expanding by 0.32km2 per year over 1975-2023. It notes there has been a “doubling” in the rate of expansion over the past two decades.
The authors suggest that rising temperatures are responsible for the glacier losing mass, as the annual average temperature in the region has been increasing by 0.08C per decade since the 1950s.
The long-term permafrost thaw and growth of the lake means that, by October 2023, the region was in a state of “increased sensitivity” to a multi-hazard cascade, the paper says.
The authors say the final “trigger” was the intense rainfall that hit Sikkim on 3-4 October. Though the rainfall was “typical” for the region and season, the authors say that it “saturated the soil and increased the vulnerability of slopes to failure”.
Dr Stephan Harrison – a researcher from the University of Exeter – tells Carbon Brief that the study is “very significant” and is “written by some of the leading scientists in the field”.
Dr Miriam Jackson is the programme coordinator for the cryosphere initiative at the International Centre for Integrated Mountain Development, and was not involved in the study. She echoes Harrison’s praise, but warns about the “lack of good data” in the region for these sorts of studies. She says:
“We desperately need more data on the status of glaciers and glacial lakes, more meteorology measurements at high elevation and more data on the status of frozen ground in the Hindu Kush Himalaya.”
Harrison and Jackson gave conflicting answers about whether GLOFs are increasing or decreasing globally. However, both pointed to the lack of data on GLOFs, noting that datasets are incomplete or unavailable in many regions and emphasised the need to get better records before definitive answers can be drawn.
Hydropower rush
The Sikkim GLOF event joins a chain of recent disasters in high-mountain Asia that have destroyed hydropower plants. Given the sheer “physical magnitude” of these events and their impacts, the study highlights “potential limits to adaptation” in the Himalaya, warning that “even the most diligent and comprehensive suite of disaster risk reduction strategies [is] unlikely to entirely prevent” loss and damage.
The study draws attention to a “surge” of hydropower development in the Himalayan region near glacial lakes, which it attributes to a rising demand for “stable and renewable energy”.
With more than 650 projects planned or under construction in high-mountain Asia, it warns that many dams are “moving closer to these hazard-prone areas” and this could “exacerbate” GLOF impacts. The Teesta basin, for instance, hosts the highest density of hydropower projects in the Himalayan region, with 47 dams planned, including the reconstruction of the Teesta-III project.
While dams themselves are “susceptible” to a wide array of high-mountain hazards, they also increase the exposure of communities, workers and infrastructure investments to a “greater likelihood” of GLOFs in the future, according to the paper.
Comprehensive risk assessments, stringent building standards, regulating land use and regional cooperation among river-sharing countries are among the measures suggested by the study to reduce GLOF risks.
Sattar says governments “can make a start” by developing “basin-scale” early-warning systems. However, he cautions that structural measures such as draining glacial lakes “are easy to say, but difficult to do” in harsh terrain.
Meanwhile, geoscientist Steiner says it is critical that the key role played by infrastructure development in damage caused by GLOFs is not downplayed – noting that a failure to do so risks “absolv[ing] local institutions of their responsibility”. He concludes:
“As scientists, we find it important to show that climate change is involved, but we have to be aware that the science we create is very, very political… [A] big part of the disaster is not climate change; it’s institutional failures, it’s infrastructural failures.
“If nobody takes the responsibility and everyone just says: ‘it’s my neighbour and not me’, then we are truly in deep shit. Maybe we already are.”
The post ‘Catastrophic’ 2023 lake outburst in India driven by glacial melt and permafrost thaw appeared first on Carbon Brief.
‘Catastrophic’ 2023 lake outburst in India driven by glacial melt and permafrost thaw
The Turkish government and the International Renewable Energy Agency have called for a stronger global push to run vehicles, industry and buildings on electricity rather than fossil fuels, ahead of this year’s COP31 climate talks.
COP31 President Murat Kurum told the Copenhagen Climate Ministerial on Wednesday that governments should be “decarbonising the way we generate electricity, but also expanding electrification into every sphere of life”.
“We must make the technologies of the future accessible at scale – and we must ensure that no one is left behind,” he told the gathering of climate diplomats and ministers from around 40 countries in the Danish capital.
Kurum said that the percentage of final energy consumption which is met by electricity – the key metric of electrification, which is currently around 20% globally – should be increased “as much as we possibly can”.
The head of the International Renewable Energy Agency (IRENA), Francesco La Camera, also addressed the Copenhagen gathering. While his comments to ministers were not public, IRENA released a statement ahead of the talks calling for a goal to increase electricity’s share of final energy consumption to 35% by 2035.
The two officials did not reference the war with Iran and the price hikes in oil and gas as a result of related supply disruptions, but UN and other leaders have used this as an argument in favour of transitioning away from planet-heating fossil fuels towards clean, domestically produced renewables.
35 by 35 goal
“The world must adapt to a new energy reality,” La Camera said in the IRENA statement. “Beyond the goals of tripling renewables and doubling energy efficiency [by 2030] lies the wider challenge of transforming entire energy systems and reducing fossil fuel use across supply and demand. Electrification and fossil fuel phase-out are inseparable and must advance together.”
He said electrification, which can be achieved through technologies like electric heat pumps, vehicles and cookers, will reduce greenhouse gas emissions, enhance energy security and bolster economic competitiveness.
A new “transitioning away from fossil fuels” roadmap released by IRENA says this 35% by 2035 electrification goal is vital if the world is to “remain” on a pathway to limit global warming to 1.5C. Electrification should reach at least 50% by 2050, it adds.
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To enable this goal to be met, the amount of money invested in power grids each year should double from $0.5 trillion in 2025 to around $1 trillion each year until 2035. Significant investment in electricity storage and demand flexibility is also needed, the roadmap says.
Clémence Dubois, campaigns manager for green group 350.org, welcomed Kurum’s remarks but added that electrification and energy justice should be funded through large developed countries taxing the windfall profits of fossil fuel companies.
Collective goal or coalition?
It is not yet clear whether the Turkish government, or the Australian government which is tasked with leading the COP31 negotiations, will attempt to get all countries to agree to an electrification goal at November’s climate summit in Antalya.
If so, such a goal could be collectively endorsed by all nations in a COP decision, as with the COP28 targets to triple renewables capacity and double the rate of growth in energy efficiency, both by 2030. Where there is narrower support, other goals have been voluntarily launched at COPs, backed by coalitions of countries, including pledges to boost nuclear energy, biofuels and grid investment.
A source with knowledge of Türkiye’s priorities confirmed that electrification is important to the COP31 host, alongside energy storage, energy security, clean cooking and resilient and clean energy systems.
The post Electrification emerges as Turkish COP31 priority appeared first on Climate Home News.
Climate Change
Cropped 20 May 2026: Deforestation roadmap | Melanesian Ocean Summit | Returning pet parrots to the wild
We handpick and explain the most important stories at the intersection of climate, land, food and nature over the past fortnight.
This is an online version of Carbon Brief’s fortnightly Cropped email newsletter.
Subscribe for free here.
Key developments
Deforestation talks
COP30 ROADMAP: Brazil’s global roadmap away from deforestation will involve countries producing their own voluntary pathways to halt and reverse forest loss by 2030, according to a first outline covered by Climate Home News. At the COP30 climate talks in Belém last year, some 93 countries called for a deforestation “roadmap” to be part of the summit’s formal outcomes. Despite this, countries failed to agree to one – leading host nation Brazil to promise to bring forward a voluntary roadmap as a compromise.
FOREST FORUM: Speaking at the UN Forum on Forests earlier this month, Juliano Assunção, an advisor to the COP30 presidency on deforestation, presented a first outline of the roadmap, said Climate Home News. According to the publication, Assunção said the roadmap “will not prescribe a single model”, but would instead invite countries to convert their pledges “into forest roadmaps grounded on regional and national diagnosis”. Elsewhere at the forum, Indonesia announced carbon-offsetting plans involving the restoration of 12m hectares of degraded land, said Reuters.
GOALS REPORT: Amid the talks, the UN published its latest assessment on achieving six global forest goals for 2017-30, concluding that “progress is evident, but insufficient”. Down to Earth reported that, according to the report, the world remains off track on two of the “key” targets: ending deforestation and eliminating extreme poverty among forest-dependent populations. Sustainability magazine reported that the goals set a target of increasing global forest area by 3% by 2030, but that, in reality, forest area has declined by more than 40m hectares since 2015.
Melanesian Ocean Summit
SEA SOLIDARITY: The leaders of Papua New Guinea, Fiji and Vanuatu signed a declaration to establish the Melanesian Ocean Corridor of Reserves, reported the Pacific Islands News Association. The corridor will “establish joint border governance, enforcement and marine science frameworks” across five Pacific nations and territories, said the outlet. Vanuatu’s prime minister, Jotham Napat, told the Melanesian Ocean Summit that the corridor “reminds us that our solidarity, not the legacy of colonial rule, determines our future”, according to Vanuatu’s Daily Post.
SEA SOVEREIGNTY: Part of the Melanesian corridor is a new marine protected area the size of the UK, announced by Papua New Guinea at the summit, said Oceanographic magazine. The new MPA will “prohibit all fishing within its boundaries”, reported the outlet. Meanwhile, Tuvalu’s Post Courier reported that the country is “currently developing its first-ever national-security policy, which will place maritime conservation and management at the absolute centre of the country’s strategic architecture”. Prime minister Feleti Teo stated: “The ocean is our sovereignty.”
CONSIDER THE OCEAN: In a comment article in the journal npj Ocean Sustainability, Dr Carlos García-Soto from the Spanish National Research Council wrote that there is a “structural weakness” in UN climate processes. He noted that the final decision text from COP30 “omitted the ocean entirely”, despite the summit “deliver[ing] the strongest ocean-related initiatives ever presented at a UN climate conference”. García-Soto also outlined five key priorities for integrating ocean considerations into climate governance.
News and views
- CANADA OWN GOAL: The Canadian government has no plans to enshrine into law commitments meant to ensure the nation meets its international nature goals, despite hosting the pivotal COP15 biodiversity summit less than four years ago, said CBC News.
- CREDIT CHANGE: Brazil’s national monetary council has postponed a regulation that would have blocked farms involved in deforestation from receiving rural credits, reported Folha de São Paulo. The change occurs “following pressure from agribusiness groups to relax the rules”, said the outlet, and means the requirement will now not take effect until January 2027.
- SAND CRISIS: A growing global appetite for sand is outstripping demand and threatening ecosystems, according to a new UN report covered by Reuters.
- LAOS DAMMED: A natural world heritage site in northern Laos is being put at risk by a $3.5bn dam project, reported Nikkei Asia.
- RAPID RESPONSE: The European Commission released its fertiliser action plan to “provide rapid support to farmers…and prevent rising food prices” amid the conflict in the Middle East, said Agenzia Nova.
- MARSH REVIVAL: Rising water levels are “beginning to revive” southern Iraq’s Cibayish marshes following a years-long drought and “drawing buffalo herders and fishermen back to areas once abandoned”, said Reuters. The country’s water ministry was able to “release growing volumes” of water from reservoirs following heavy winter rains, added the newswire.
Spotlight
Returning pet parrots to the wild
This week, Carbon Brief visits a conservation project working to return former pet parrots to the wild in Colombia.
Beautiful feathers. The playfulness and intellect of a small child. On occasion, the ability to partake in some pleasant conversation.
Parrots have captured the attention of humans for centuries. But their unique qualities have also contributed to their decline in the wild.
Some 16m parrots were moved across borders to be sold as pets over 1975-2016, according to one study, making them the most internationally traded bird in the world.
In Colombia, the world’s most biodiverse country by area, the introduction of tougher laws in 2016 means keeping a wild animal as a pet is now viewed as a “crime against the environment”, punishable with monetary fines.
These stricter rules led to greater numbers of wild parrots being seized by the police and more people giving up their birds voluntarily.
But this clampdown created a new conundrum: What will the Colombian authorities do with their growing population of these, formerly pet, parrots?
A charity called Fundación Loros – “Parrot Foundation” in English – hopes to have the answer.
Parrot rehabilitation
The foundation is based on 33 hectares of tropical dry forest in Bolívar – around a 40-minute car ride from the popular tourist city of Cartagena on Colombia’s Caribbean coast.
The deafening screeches of parrots when entering through the site’s gates were impossible to ignore.
Inside, foundation guide Corina walked Carbon Brief through the various stages of pet parrot rehabilitation.
Former pet parrots that are released directly into the wild are unlikely to survive. This is because they often lack the necessary skills, such as how to find food or stay away from predators, including monkeys and coatis.
Parrots arriving at the foundation follow a seven-stage process.
First, they are checked over by a vet and given a tag, so they can be continuously monitored.
Following this, they are kept in a large enclosure and slowly reintroduced to the types of food they might encounter in the wild, including wild fruits and nuts.
After this, they undergo “flight training” – many of the parrots will have been kept in a small cage and never learned how to travel long distances. This involves workers encouraging the birds to fly greater distances in exchange for rewards.
They also join other birds for “flock cohesion” lessons. In the wild, parrots are highly social animals who rely on their group to survive and raise chicks.
Following these steps, parrots are taken deeper into the foundation’s forest reserve – away from loggers and poachers.
There, they spend some time in an enclosure getting acquainted with their new surroundings.
After this, the door to the cage is opened – allowing them to fly free, but return for shelter and food if they need. Eventually, the birds settle back into the wild.
Waiting list
In addition to their parrot rehabilitation programme, the charity built a series of nest boxes and installed them high in the tree canopy across the reserve.
Their continuous monitoring of the birds has shown that many of the former pets have started raising wild chicks.
The work is hugely rewarding, said Corina, but the charity currently has a waiting list that is “months long”, given the growing number of wild animals needing rehabilitation across Colombia.
Despite helping the authorities with their wild animal problem, the charity largely relies on private donations to continue, she said. The hope is to develop an eco-tourism model to make more revenue in the future, she added.
Watch, read, listen
CARBON CONSULTATIONS: The Diplomat explored whether local residents were properly consulted on a carbon-offsetting programme in Cambodia.
FISH FIGHTS: The Ghanaian Times examined the tensions surrounding marine conservation in the country and how it is unduly burdening small-scale fisherfolk.
DELTA WORK: Mongabay reported on how the world’s “great deltas” are sinking, leading to the loss of a “global food system”.
LITHUANIA PEAT BOGS: The New York Times reported on Lithuanian efforts to restore peat bogs in order to “reinforce the border” and “lock away” carbon.
New science
- Coastal marshes are encroaching on uplands “nearly twice as fast” on agricultural land as they are on forestland, suggesting that agricultural practices are “accelerat[ing] the impacts of saltwater intrusion” | Nature Sustainability
- Fungi that cause diseases in plants will approximately double in abundance around the Antarctic Peninsula by 2100 under a moderate emissions scenario | Global Change Biology
- Conserving Ethiopia’s protected areas currently involves managing “trade-offs between nature and people” that are “central to whether global biodiversity commitments can be delivered” | Nature Ecology and Evolution
In the diary
- 20-22 May: Informal consultations of parties to the UN Fish Stocks Agreement | New York City
- 30 May-6 June: Meeting of the Global Environment Facility Assembly | Samarkand, Uzbekistan
- 31 May: Colombian presidential elections
- 8-18 June:Subsidiary body meetings of the UNFCCC | Bonn, Germany
Cropped is researched and written by Dr Giuliana Viglione, Aruna Chandrasekhar, Daisy Dunne and Orla Dwyer. Please send tips and feedback to cropped@carbonbrief.org
The post Cropped 20 May 2026: Deforestation roadmap | Melanesian Ocean Summit | Returning pet parrots to the wild appeared first on Carbon Brief.
Climate Change
Prescribed Burns and Forest Thinning Averted Millions of Tons of Emissions and Billions in Damages
In addition to preventing an estimated 2.7 million tons of carbon emissions and $2.8 billion in damages, UC Davis researchers determined that fuel treatments prevented nearly 60 premature deaths.
Work to reduce excess flammable vegetation in forests warded off the release of 2.7 million tons of carbon dioxide, averted nearly 60 premature deaths and avoided $2.8 billion in damages in the Western U.S., according to a new study from the University of California, Davis.
Prescribed Burns and Forest Thinning Averted Millions of Tons of Emissions and Billions in Damages
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