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India flash flooding death toll climbs after a glacial lake burst that scientists had warned about for years

Melting Himalayan ice may pose serious danger
Melting Himalayan glaciers pose serious dangers to humans, report finds 06:59

New Delhi — The death toll from devastating flash floods unleashed by a glacial lake bursting its banks in India's ecologically sensitive Himalayan region shot up to at least 47 on Saturday after more bodies were recovered, government officials said, with at least 150 people considered missing. The Lhonak Lake in India's mountainous state of Sikkim bust through a dam Wednesday after a cloudburst triggered rains and an avalanche, causing major flooding in the Teesta river.

The floodwater caused massive devastation, washing away or submerging 15 bridges and dozens of roads, cutting off significant sections of the small state in India's far northeast, which is surrounded on three sides by China, Nepal and Bhutan. The only highway connecting the state to the rest of India was damaged, making relief and rescue work challenging.

FILE PHOTO: Trucks buried in mud are seen in an area affected by flood in Sikkim
Trucks buried in mud are seen in an area affected by floods unleashed by a glacial lake burst, in Sikkim state, India, in an image released by the Indian Army on Oct. 5, 2023. India Army/Handout/REUTERS

Police said nearly 4,000 tourists were stranded in two locations, Lachung and Lachen in the northern part of the state, where access was severely restricted as the floods had washed away roads. But the bad weather has made rescue efforts more challenging, with authorities unable to deploy helicopters to assist those stuck in vulnerable areas.

Some 3,900 people were currently in 26 relief camps set up by the state, Chief Minister Prem Singh Tamang said on Saturday. He added that seven out of the 22 Indian army soldiers who were reported missing had died.

Scientists have warned of such disasters for decades

The flooding was one of the worst disasters to date in India's fragile Himalayan region, but it was the latest in a series catastrophes linked to extreme weather events blamed by scientists on climate change.

India Sikkim Floods
Buildings are seen inundated after flash floods triggered by the bursting of a glacial lake after heavy rainfall, in Rangpo, Sikkim state, India, Oct. 6. 2023. Prakash Adhikari/AP

Last year, severe flooding in Sikkim killed at least 24 people and displaced tens of thousands. In 2021, a tragedy similar to Wednesday's in another Indian Himalayan state, Uttarakhand, left dozens dead when a glacial lake burst its banks.

Scientists have warned about the melting of Himalayan glaciers for decades, saying the pace at which they're losing ice is a threat to the whole world, not just Asia.

Alaska home collapses into raging river as melting glacier causes flood 01:11

But experts warned about the possibility of Lhonak Lake bursting specifically in 2021, when a study highlighted the increasing length of the lake and cautioned that it was sensitive to extreme weather events such as cloudbursts.

"It was already predicted in 2021 that this lake would breach and impact the dam," Dr. Farooq Azam, a glaciologist at the Indian Institute of Technology Indore, told CBS News on Friday. "There has been a substantial increase in the number of glacial lakes as the glaciers are melting due to global warming."

In fact, scientists had warned there was a very high probability of a sudden outburst of Lhonak Lake in 2013, and again in 2001.

Earth's average surface temperature has risen about 2 degrees Fahrenheit since pre-industrial times, but the world's high-mountain regions have warmed at twice that pace, climate scientists say.

Trekkers collect water near the Gaumukh, ("cow mouth" in Hindi) at Gangotri glacier, believed to be the source of the Ganges River, in India's Gangotri National Park, Oct. 19, 2022. XAVIER GALIANA/AFP/Getty

Researchers say snow cover, glaciers and permafrost will continue melting in almost all global regions throughout the 21st century. There's also high confidence among scientists that the number of and the area covered by glacial lakes will continue to increase in most regions in the coming decades, with new lakes developing closer to steep, potentially unstable mountains, where landslides can trigger lake outbursts.

"There are more than 54,000 glaciers across the Hindu Kush Himalayan region and very few of them are monitored, which means that such disasters will continue to increase," a climate scientist and lead researcher with the United Nation's Intergovernmental Panel on Climate Change (IPCC), previously told CBS News.

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