If handled appropriately, the Himalayan region's glaciers are nature's regenerative reservoir of fresh water that serves hundreds of millions of people downstream. However, due to rapid global warming and the ensuing long-term loss of natural freshwater storage, glaciers in the area are retreating. Lakes begin to emerge behind recently exposed terminal moraine as glaciers retreat. The unstable "dams" behind which these lakes are constructed may suddenly burst due to the rapid accumulation of water in them. Glacial Lake Outburst Floods, or GLOFs, are the consequent massive flows of water and debris that frequently have catastrophic results.
The damage to roads, bridges, trekking trails, settlements, and agricultural lands, along with the loss of human life and other infrastructure, are all significant effects of a GLOF occurrence downstream. The sociological effects can be immediate when people die or indirect when the hamlet must be relocated and the agricultural grounds become debris-filled. A GLOF has occurred in Nepal on average once every three to ten years, with different degrees of socioeconomic impact, according to records of previous GLOF incidents.
Time series satellite photos show that the glaciers are retreating, increasing the number and extent of glacial lakes to the point of probable GLOF. In order to lessen the physical vulnerability in the watersheds of the Himalayan region, thorough monitoring of potential GLOF and early warning systems should be created. If possible, the most suitable mitigation measures should be employed.
IMPACTS OF CLIMATE CHANGE ON GLACIERS
The Himalayan highlands are warming between 0.3 and 0.7°C faster than the world average, which is resulting in receding snowlines, melting glaciers, and a higher risk of flooding from bursting glacial lakes.
Glaciers and glacial lakes will unavoidably shift in response to these climate changes. Results indicate that rising temperatures have caused a recession rate increase. Up to one-fourth of the world's alpine glacier mass was predicted to vanish. The net retreat of glaciers and the growth in size and quantity of glacial lakes as a result of climate change have increased the frequency of GLOFs in recent years. The lives and possessions of mountain people will ultimately be impacted by these climate changes.
The unstable moraine ridges behind Kanjiroba suddenly disintegrated due to the exceptionally high rain that replaced the snow, sending the debris flow rushing down to the village below. The water supply project in Kathmandu, which is the most expensive infrastructure project in Nepal, was destroyed by a similar flood on the Melamchi River in June. A record-breaking amount of rain fell in Manang, a trans-Himalayan valley to the north of the Annapurnas, causing devastating floods.
One of the main indicators of climate change is the glacier. Since climate statistics have been tracked and reported since 1861, there have been numerous warm years in the Northern Hemisphere following 1990, which is consistent with the anticipated rise in global mean temperatures. Depending on the climate model and greenhouse gas emission scenario the amount in 2100 might range from 1.4 to 5.8°C. The volume of glaciers has shrunk by 5.5 per cent over the past 30 years in China, and comparable outcomes have been observed in Nepal, India, and Bhutan. Smaller glaciers and valley glaciers are receding more quickly. It is known that the majority of the glacier lakes in the Himalayas originated during the previous 50 years.
The quantity and size of glacial lakes are growing as a result of global warming. GLOF incidents are afterwards noted in the area at least once every three to ten years. Numerous lives have been lost as a result of these GLOF episodes, which also resulted in the destruction of homes, bridges, fields, woods, hydropower plants, highways, and other structures. In areas that could experience GLOF, regular monitoring of glaciers and glacial lakes is necessary, as are adaptation strategies like early warning systems and mitigation measures. It is crucial to connect policy, planning, and community to this scientific knowledge of potential GLOF threats.
It could be dangerous to make too many assumptions about which of the various future climate scenarios for the Himalayan region will be the most accurate. Although it is difficult to predict how much, it is evident that temperatures will rise.