The recent flash flood in the Chamoli district in Uttarakhand, northern India, killed at least 32 people and trapped workers in underground tunnels. It even washed away some villages and wiped out newly constructed dams and bridges and two power projects in the Tapovan area of the district. The search for missing people is still on.
A team of scientists investigating the incident believe a piece of a Himalayan glacier broke away and fell into water and triggered the huge flood in other words known as Glacial Lake Outburst Flood (GLOF). A glacier is a slowly flowing river of ice, accumulating snow, rock, sediment and often liquid water along the way.
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What is GLOF?
A significant threat posed by Climate Change in the Himalayas is the formation of a large number of Glacial lakes. The lakes consist of vast quantities of glacial melt water held in place by natural dams of stone and rubble. And if these natural rubble dams break, a tsunami of water, mud, ice, and stone is swept down the valleys, destroying everything in its path. Such events can have devastating consequences to infrastructure and local communities; washing away roads, bridges, houses, people, livestock and crops. Some of the largest floods in Earth’s history have been GLOFs, causing large-scale landscape change, and even altering regional climate by releasing huge quantities of freshwater into our oceans.
If GLOF is indeed the cause behind the Chamoli disaster, then it could just be, literally, the tip of the Iceberg. The global warming in the coming decades will amplify the GLOF events with the accelerating retreat of glaciers and formation of many potentially dangerous glacial lakes.
Himalayan glaciers are Water Towers of Asia
The Himalayan glaciers are the Water towers of Asia, and the origin of some of the world's great rivers: The Yangtze, the Ganges, the Indus and the Mekong. Over 500 million people in South Asia, and nearly 450 million in China completely rely on the health of this fragile mountain landscape.
Mapping more than 5,000 glacial lakes on the Indian side of the Himalayan range, a group of scientists have claimed that there are more than 500 glacier lakes in Uttarakhand at risk of a breakout like Chamoli. Unless there is intervention.
Take the instance of Imja Tsho, a high altitude glacial lake near Mount Everest in the Himalayas, formed by the accelerated melt of the Imja Glacier which flows through eastern Nepal, part of a glacier network that ultimately feeds the Ganges River. The continued glacial melt, bad weather, a landslide, avalanche or a seismic event (quite common in the area) could have triggered a violent GLOF. So in 2016, the Nepal army undertook the highest drainage project of its kind, working with Sherpas for nearly six months to construct an outlet to gradually release the water. Nearly four million cubic metres of water was released. This was part of a UN funded project to help Nepal deal with the impact of Climate Change. The UN provided nearly US$ 3m to lower the lake's water levels.
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Indicators of Climate Change
In the largest-ever study of glacial lakes, published in a journal, Nature Climate Change, researchers used 30 years of NASA satellite data to find that the volume of these lakes worldwide has increased by about 50% since 1990 as glaciers melt and retreat due to Climate Change.
According to the United States Environmental Protection Agency, glaciers are important indicators of climate change because physical changes in glaciers - whether they are growing or shrinking, advancing or receding - provide visible evidence of changes in temperature and precipitation. If glaciers lose more ice than they can accumulate through new snowfall, they ultimately add more water to the oceans, leading to a rise in sea level.
Small glaciers tend to respond more quickly to climate change than the giant ice sheets. Altogether, the world’s small glaciers are adding roughly the same amount of water to the oceans per year as the ice sheets of Greenland and Antarctica. During the last two decades, they added more water overall to the oceans than the ice sheets did!
Glacier melt also increases salinity and disrupts ocean currents. According to the US National Snow & Ice Data Center (NSIDC), Glacial ice can range in age from several hundred to several hundreds of thousands years, making it valuable for climate research. Glaciers preserve bits of atmosphere from thousands of years ago in tiny air bubbles deep within its core, trapped within the ice itself.
The World Glacier Monitoring Service (WGMS) tracks changes in more than 100 alpine glaciers worldwide. Forty-two of those glaciers qualify as climate reference glaciers because their records span more than 30 years.
Assessment of Climate Change over the Indian Region, a report of the Ministry of Earth Sciences (MoES), Government of India has projected that even with the Indian government’s commitment to mitigate greenhouse gases by 2030, the Indian Himalayas could warm by 2.6 to 4.6 degrees Celsius by 2100.