Risk of glacial lake outburst floods in 'Third Pole' increasing: Study

There has been an increase in the occurrence of glacial lake outburst floods (GLOFs) from an average of 1.5 events annually during 1981–1990 to 2.7 during 2011–2020 in the Third Pole region, a study has found.

The Third Pole, which spans the Tibetan Plateau and the surrounding Himalayas, Hindu Kush, and Tianshan Mountain ranges, is extremely vulnerable to the effects of climate change, the researchers said.

The expansion of glacial lakes and the appearance of new ones will likely lead to an increase in the number of GLOFs per year in the future, underscoring the need for developing better analytical methods and datasets to stay one step ahead of potential disasters, they said.

The findings, published in the journal Nature Communications, are concerning for countries exposed to GLOFs in the region, especially China, Kazakhstan, Nepal, India, and Pakistan.

Warming temperatures and altered rainfall patterns have caused more than 10,000 glaciers in the region to retreat over the past three decades, facilitating the formation of thousands of glacial lakes, the researchers said.

Though they appear harmless, these water bodies have tremendous destructive potential, particularly due to their ability to cause GLOFs. When triggered by events like glacier collapse, snow avalanches, landslides, or the collapse of natural dams, glacial lakes can release vast volumes of water swiftly, leading to destructive GLOFs.

A team led by researchers from the Chinese Academy of Sciences decided to carry out a more detailed analysis of GLOF risks in the Third Pole.

The study underscores the need for urgent action and regional cooperation for the economically disadvantaged and highly vulnerable regions in the Third Pole.

The researchers first obtained satellite images from the Sentinel-2A and Sentinel-2B missions between 2018 and 2022.

They then identified and classified all glacial lakes based on their position and topological characteristics in relation to their source glacier.

This updated inventory of glacial lakes, coupled with earlier datasets, enabled them to analyse the changes in this region over the past decades, revealing a worrisome continuous expansion of glacial lakes.

The researchers analysed changes in GLOF activity by consolidating datasets of GLOF events in the Third Pole, tracing back as far as 1900.

Their findings, in contrast to previous studies, revealed a worrisome trend, indicating an increase in GLOF occurrences from an average of 1.5 events annually during 1981–1990 to 2.7 events during 2011–2020.

Finally, the team analyzed the susceptibility to GLOFs in 5,535 glacial lakes and identified 1,499 of those with a high potential for outburst floods.

The researchers also investigated the "potential disaster volume" based on GLOF simulations of these high-risk lakes.

"Approximately 55,808 buildings, 105 existing or planned hydropower projects, 194 square kilometre (km2) of farmland, 5,005 km of roads, and 4,038 bridges are threatened by the potential GLOFs," said Associate Professor Weicai Wang from the Institute of Tibetan Plateau Research.

"Moreover, by utilising regional population distribution data, we estimated that roughly 190,000 lives are directly exposed within the GLOF paths," he explained.

Going ahead, this work will hopefully lead to better risk management strategies for GLOFs and foster cooperation between countries in the Third Pole, the researchers added.