Climate Change

Himalayan plunder: 3 million Indians live in areas that can be swept by glacial lake floods, says study

Three of the world’s most dangerous glacial basins are situated in Pakistan, Peru and Bolivia

By Susan Chacko
Published: Thursday 09 February 2023
A glacial lake in the Baltoro glacier. The glacier is located in the Karakoram Range in Gilgit-Baltistan, Pakistan-Occupied Kashmir. Photo: iStock

Three million Indians live in areas where a glacial lake outburst flood (GLOF) can happen at any time, the first global assessment of such areas has found. Together with two million Pakistanis, they form a third of the total number of people worldwide facing such a risk.

Globally, 90 million people across 30 countries live in 1,089 basins containing glacial lakes. Of these, 15 million (16.6 per cent) live within 50 kilometres of a glacial lake, said the new study published in Nature Communications February 7, 2023.

The majority of the globally exposed population amounting to 9.3 million (62 per cent) are located in the region of high mountain Asia (HMA).

Just four highly populous countries accounted for more than 50 per cent of the globally exposed population: India, Pakistan, Peru and China.

The population exposed to GLOFs increases with distance from a glacial lake. Almost half (48 per cent) of exposed populations are globally located between 20 km and 35 km downstream of lakes, said the study by a team of scientists led by Caroline Taylor, Newcastle University.

Only two per cent (300,000) of the global population exposed to GLOFs live within five km of one or more glacial lakes, with the majority of these — 66 per cent or 198,000 people found in HMA.

Populations in HMA live, on average, closer to glacial lakes than anywhere else, with “one million people living within 10 km downstream of a glacial lake, where any early warning time is likely to be low, and, uncertainty in GLOF magnitude high”, the study noted.

The researchers grouped basins into four mountain ranges: HMA, European Alps, Andes and Pacific Northwest (PNW). The remaining 131 (12 per cent) basins outside of these ranges were referred to as ‘High Arctic and Outlying Countries’.

Populations across the PNW and High Arctic and Outlying Countries are generally situated further than 35 km downstream from glacial lakes, according to the study.

People and glacial lakes

ICIMOD or the International Centre for Integrated Mountain Development, a regional intergovernmental learning and knowledge sharing centre, defines a GLOF as:

The sudden release of water from a lake fed by glacier melt that has formed at the side, in front, within, beneath, or on the surface of a glacier.

GLOF has the potential to catastrophically threaten people’s lives, livelihoods and regional infrastructure.

The researchers found that it was not the size or number of glacial lakes that determined the risk to people. Instead, it was the number of exposed people that greatly elevated the potential impact of GLOFs globally especially across HMA and the Andes.

For instance, the island of Greenland has the highest number and area of glacial lakes. However, nobody resides in such areas, giving it a danger score of zero.

On the other hand, the most dangerous basins, mainly found across HMA and the Andes do not always host the most, or the largest, glacial lakes. It is the high number of people as well as their reduced capacity to cope with disaster that plays an important role in determining the overall GLOF danger.

The most dangerous of the 1,089 glacial basins analysed are found in Pakistan (Khyber Pakhtunkhwa basin), Peru (Santa basin) and Bolivia (Beni basin) containing 1.2 million, 0.9 million and 0.1 million people respectively who could be exposed to GLOF impacts.

The study also noted that glaciers across the Andes have undergone rapid deglaciation over the last 20 years in response to climate changes.

This has led to the growth of many large glacial lakes and consequently a growth in overall GLOF lake conditions. The number of glacial lakes across the region increased by 93 per cent, compared to just 37 per cent in HMA across the period.

Concurrent with this increase, populations living in close proximity to glacial lakes have grown, increasing the overall exposure to GLOF, the study noted.

Since 1941 the population in Huaraz, Peru, alone has increased by 100,000. At the same time, regional vulnerability remains high as a result of deep-rooted corruption and poor standards of living.

Closer home, innovator and environmentalist Sonam Wangchuk has appealed to Prime Minister Narendra Modi for urgent intervention to protect Ladakh. Climate impact is visible in the Himalayas, with 25 glacial lakes and water bodies witnessing an increase in water spread area since 2009.

Centre for Science and Environment and Down to Earth’s State of India’s Environment 2022: In Figures found that there has been a 40 per cent increase in water spread area in India, China and Nepal, posing a huge threat to seven Indian states and Union Territories.

Of these, six are Himalayan states / UTs:  Jammu and Kashmir, Ladakh, Himachal Pradesh, Sikkim, Assam and Arunachal Pradesh.

The rapid onset and high discharge of GLOFs means there is often insufficient time to effectively warn downstream populations and for effective action to be taken, particularly for populations located within 10-15 km of the source lake.

Improvements are urgently needed in designing early warning systems alongside evacuation drills and other forms of community outreach to enable more rapid warnings and emergency action in these highly exposed areas.

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