Increased Glacial Melting in the Hindu Kush Himalaya Region Threatens to Bring More Glacial Floods
Background
Recent research has suggested that black carbon (also known as soot) and dust play a major role in melting Tibetan Plateau glaciers. Black carbon and dust are light-absorbing particles, meaning that their dark colour absorbs more energy from the sun than lighter-coloured materials. As a result, when the particles settle on a glacier, they warm the surrounding area, leading to faster glacial melting. The burning of fossil fuels is a major source of black carbon, as is the burning of biofuels, such as wood. Urban activities, such as industrial pollution and car exhaust fumes, also contribute to the spread of black carbon. The presence of black carbon and dust has worsened an already alarming level of glacial melting and threatens to increase environmental disasters across Asia.
Comment
There has been a significant amount of warming across the Hindu Kush Himalaya region (HKH) and even if global warming is limited to 1.5⁰C, this region will be at least 0.3⁰C warmer than the global average. The Himalayan region has lost significant amounts of ice in recent years and the rate of loss has accelerated rapidly over the last decade – a recent study warned that ice loss between 2006 and 2016 was twice the amount lost between 1975 and 2000. Similar rates of melting are underway across other mountain ranges in the region. As a result, surrounding communities are now vulnerable to the environmental disasters that come with increasing glacial runoff.
Glacial melting has already started to have major impacts on the lives and livelihoods of communities in the HKH. As runoff from glaciers has increased, there has been a significant increase in the number of glacial lakes across the region. Those lakes are prone to flooding, especially during the monsoon season and, although they are usually located in remote areas, they pose a major risk to downstream communities.
According to the Hindu Kush Himalaya Report, which was published in February, Glacial Lake Outburst Floods (GLOFs) are increasing across the HKH and rising global temperatures are expected to continue to increase the frequency of GLOFs. While floods generally cause fewer deaths than other natural disasters, such as storms or earthquakes, they are more deadly than drought or extreme temperatures. Floods also cause greater economic losses than any other kind of natural disaster.
In July, a GLOF spread through several villages in the Chitral district of Pakistan, demonstrating the potentially devastating potential of this phenomenon. Thanks to disaster preparedness efforts, no lives appear to have been lost, but the economic impact of the floods has been severe for the affected communities. The flood destroyed roads and bridges as well as homes, irrigation canals, crops and livestock. Water pipes have also been washed away, which along with a loss of roads has made it difficult for residents to access water.
Elsewhere, Bhutan’s largest glacial lake, the Thorthormi Tsho, has risen by close to two metres, after a sustained heatwave. If the lake breaches the rocky dam wall that separates it from the nearby Raphstreng Lake, it would combine the lakes and release more than 53 million cubic metres of water. Such an event would be three times bigger than Bhutan’s last GLOF in 1994, which killed 20 people. As the region’s climate continues to warm, it is increasingly likely that devastating flood events will become more common.
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