Glacial floods threaten millions of people worldwide

Millions of people use the summer meltwater from glaciers to irrigate crops, provide for livestock and people, and to generate hydroelectricity. However, as the atmosphere and oceans warm, this glacial water may turn out to be a danger rather than a blessing. When glaciers retreat, meltwater collects in front of them and forms a lake, which can suddenly burst and overflow if the volume becomes too large. 

When a glacial lake bursts, it may give rise to a fast-flowing Glacial Lake Outburst Flood (GLOF) that can spread over a large distance – more than 120 km from the original site in some cases – and threaten human lives, property, infrastructure and agricultural land that lies in its path. GLOFs can be highly destructive and lead to significant loss of life. The number of glacial lakes has grown rapidly since 1990 as a result of climate change and, at the same time, the number of people living in these catchments has also increased significantly.  

An international team of scientists led by Newcastle University has now produced the first global assessment of areas at greatest risk of Glacial Lake Outburst Floods and quantified the number of people who could be impacted by such floods. Their findings are published in the journal Nature Communications.

The research team looked at 1,089 glacial lake basins worldwide and the number of people living within 50 kilometers of each one, as well as the level of development in those areas and other societal indicators as markers of vulnerability to GLOFs. They then used this information to quantify and rank the potential for damage from GLOFs at a global scale and assess communities’ ability to respond effectively to a flood.   

The results show that 15 million people currently live within 50 km of a glacial lake and that High Mountain Asia (which encompasses the Tibetan Plateau, from Kyrgyzstan to China), has the highest risk of damage from GLOFs, with 9.3 million people living within the area of potential impact. India and Pakistan have around 5 million exposed people – about one third of the global total combined.

“This work highlights that it’s not the areas with the largest number or most rapidly growing lakes that are most dangerous. Instead, it is the number of people, their proximity to a glacial lake and importantly, their ability to cope with a flood, that determines the potential danger from a GLOF event,” said study lead author Caroline Taylor.

The research also highlights Peru as one of the four countries, along with India, Pakistan and China, that are home to more than half of the number of people worldwide exposed to potential danger from glacial lake flooding. The experts point to the relative lack of research on the danger from glacial lakes in the Andes and say that further research is urgently needed to better understand the potential GLOF danger on a local level in this area due to the large number of people living in proximity to glacial lakes here, and their reduced capacity to cope with the impact of a GLOF.

“Understanding which areas face the greatest danger from glacial flooding will allow for more targeted and effective risk management actions which, in turn, will help minimize loss of life and damage to infrastructure downstream as a result of this significant natural hazard,” said study co-author Dr. Rachel Carr.

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By Alison Bosman, Earth.com Staff Writer

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