Risk of flooding from melted glaciers to increase as climate warms, study says

Scientists are racing to determine what will happen as a result of melting glaciers before the repercussions of climate change on communities become a reality.

Researchers are especially worried about the increased risk of flood outbursts from glacial lakes, which can pose threats to residents who live downstream, according to a new study published Thursday in Nature Climate Change.

PHOTO: Ice and debris is seen in the tongue of Glacier 1, at the base of Mount Gongga, known in Tibetan as Minya Konka, on Nov. 13, 2015, in Hailuogou, Garze Tibetan Autonomous Prefecture, Sichuan province, China.

A glacial lake is a body of water that forms when a glacier erodes into land and then its water melts into the depression that forms. An outburst flood occurs when one of the naturally occurring dams break, sending a tidal wave of water out of the depression.

The risk is especially profound in the Third Pole, the region that encompasses the Hindu Kush Himalayan mountain range, the Tibetan Plateau and surrounding areas. It has the largest number of glaciers outside of the polar regions, according to the study.

PHOTO: Mountains are reflected in water where the Nubra river flows into the Shyok river as part of the Indus River system, that separates the Ladakh and Karakaoram ranges in Nubra, Jamma and Kashmir, India, Nov. 14, 2019.

The Third Pole has distinctly higher warming rates than the Northern Hemisphere, and warming in the region is leading to rapid loss of ice and the formation and expansion of glacial lakes, which then pose a severe threat to communities that reside downstream, scientists said.

“Particularly, when water is suddenly released, glacial lake outburst floods can devastate lives and livelihoods up to hundreds of kilometers downstream of their source,” the study states.

PHOTO: People walk where glacial outburst flooding from Myrdalsjokull, Iceland, swept away a bridge over the Mulakvisi river, July 9, 2011.

The highest risk is in the eastern Himalayas, and the overall risk in the region is expected to triple as a consequence of more lakes developing, according to the study. The outbursts can be triggered by a number of mechanisms, including intense precipitation and snow or, most commonly, from the impact of ice or rock avalanches into a lake.

Glaciers across the Himalayas have experienced significant ice loss over the past 40 years, with the average rate of ice loss doubling in the 21st century compared to the end of the 20th century, according to a study published in Science Advances in 2019.

PHOTO: A bloated Mendenhall Lake submerges walking trails and beach areas popular with tourists in summer on July 11, 2014, in Juneau, Alaska, after glacial outburst flood warnings.

A glacial lake outburst flood was initially blamed for the “water monster” of rushing water and sediment that plunged down a steep flank in the Himalayas and into a hydroplant in northern India in February, killing dozens of people and leaving more than 100 missing.

The results of the study highlight the need for urgent, “forward-thinking” and collaborative approaches to mitigate future impacts of climate change, the researchers said.

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