Glaciers in Bhutan are melting at an alarming rate, with significant implications for the country’s water supply, infrastructure, and safety. Recent findings from the National Center for Hydrology and Meteorology (NCHM) reveal a concerning trend: The glaciers in Bhutan have a negative mass balance, meaning they are losing more ice than they are gaining. This has led to visible effects, prompting recommendations for villages to relocate permanently to safer areas. Additionally, there are plans for expeditions to pump out water from glacial lakes to protect critical infrastructure.
Karma, the Chief of Cryosphere Studies, explained that Bhutan’s glaciers are categorized into two types: debris-covered and clean-type glaciers. The debris-covered glaciers, often found in valley regions with large land areas and frontal lakes, have a melting rate of 32 to 35 meters per year. This rate is exacerbated by a natural process called calving, where chunks of ice break off from the glacier, contributing to its rapid retreat.
In contrast, clean-type glaciers, which lack debris cover, melt more uniformly. The retreat rate for these glaciers varies between 12 to 16 meters per year, depending on specific site conditions and external factors.
Phuntsho Wangdi, an NCHM official, said that the organization monitors three benchmark clean-type glaciers annually, located in the Bumthang Chhu, Pho Chhu, and Thim Chhu basins. The findings from these sites are generalized to represent other similar glaciers in the region.
The chief highlighted that the rising temperatures are the primary driver behind the accelerated melting of glaciers. The NCHM’s analysis points to a correlation between increased temperatures and the frequency of glacier lake outburst floods (GLOFs). GLOFs occur when water breaches the natural barriers of glacial lakes, leading to sudden and catastrophic flooding. These events are more common in debris-covered glaciers, which have frontal lakes and are more susceptible to calving.
One of the most critically dangerous glaciers, Thorthomi, has now become a fully formed glacial lake with only a few chunks of ice remaining afloat.
Currently, GLOFs pose a significant risk to downstream communities and infrastructure in Bhutan.
Out of the Seventeen potentially dangerous lakes in Bhutan, Thorthormi and Rapstreng Lakes are critically hazardous. These two lakes are separated by a moraine dam of ice and rock , which has decreased in size from about 45 meters in 2008 to approximately 33 meters in 2019.
Thangza and Toenchoe chiwogs are situated in close proximity to these glaciers, making them particularly vulnerable to GLOF events. The NCHM has recommended relocating residents from these areas to safer locations, such as Damthangkha, Bayza-Gangjuk, and Dungbiteng, due to the limited time available for evacuation during such events.
Despite the recommendations for permanent relocation, challenges remain as people plan to return during the winter and move back during the summer. Lunana Gup Kaka said, “People are more than happy to relocate to a safer location. They have moved with their important belongings, leaving the rest behind and living in temporary huts.”
The Gup noted that although the relocation was intended to be permanent, people plan to return during the winter because the cold weather freezes the water.
The Dzongda of Gasa said, “Currently, people are staying there for their own safety because we have not officially distributed the land yet; we’ve just sent out a survey team. Only 18 households were identified, and all of them wanted to move. They have been practicing this seasonal migration for a while, and some even have structures there.”
The Dzongda added that people plan to stay in the new location during the summer and return in the winter, expressed concerns that constructing new homes takes time.
On the other hand, when asked if this was a wise decision, the chief emphasized that GLOFs are not confined to any particular season, citing the 1993 GLOF that occurred in October.
The threat of GLOF is not only limited to the people, so following a government directive, the National Centre for Hydrology and Meteorology (NCHM) is exploring measures to lower the water level at Thorthormi glacial lake in Lunana.
The chief said, “The reason for planning this expedition is not just to save lives. While enhancing the early warning systems can provide enough lead time to evacuate people, the hydropower projects and the Punakha Dzong cannot be moved. Even if people in the Dzong can escape, the structure itself remains vulnerable. Our goal is to protect these vital infrastructures downstream by exploring innovative methods to lower the hazard. In September, we are planning an expedition to study and identify the most feasible method for pumping water from the lake to minimize the risk of a GLOF.”
The NCHM is exploring innovative solutions to mitigate the risks posed by GLOFs. In September, the organization plans to conduct an expedition to study the feasibility of lowering the water levels in glacial lakes, potentially through pumping methods.
One of the methods being explored is the use of the siphon method to lower the water level of the lake and mitigate the risk of a potential GLOF. This method involves using gravity to transport water from the higher elevation of the lake to a lower elevation, typically the outlet, through pipes. It works similarly to the process of siphoning fuel from a vehicle.
The retreat of Bhutan’s glaciers has broader implications beyond immediate safety concerns. The country’s major river basins, including the Chamkhar Chhu and Mangde Chhu, originate from glacier-fed sources. As these glaciers diminish, water shortages for drinking and irrigation are becoming more common. The NCHM officials highlighted that glacier melt contributes significantly to these shortages, impacting agriculture and daily life.
Recognizing the threat of GLOFs, the Minister of Energy and Natural Resources Gyem Tshering said, “Initially, we were rich in hydropower, but due to global warming, climate change, and glacier melting, we have diversified into solar and wind energy.”
The government plans to generate 12,000 MW of solar energy and 12 MW of wind energy between 2024 and 2034.