Global call to action: A decade of glacial preservation begins

Kathmandu, Jan. 19: The United Nations has declared 2025 as the International Year of Glacier Preservation. The declaration came after the UN General Assembly adopted a resolution in December 2022 to mark 2025 as the starting point for a decade-long focus on glacier preservation until 2034.

As Nepal is home to thousands of glaciers that are rapidly melting due to rising temperatures, the declaration comes as a positive benchmark to raise awareness among stakeholders and international agencies to address the issue of glacier preservation by reducing CO2 emissions. These glaciers, the primary source of water for downstream communities, have been melting at an alarming rate in recent years, posing a significant threat to the country’s livelihoods, biodiversity and ecosystems.

The opportunity to mark the year for glacier preservation aligns with the announcement of March 21 as the World Day for Glaciers, starting this year. This serves as a platform to raise awareness about the critical role of glaciers, snow and ice in the climate system, as well as their economic, social and environmental impacts, glaciologists said.

Glaciologist Rijan Bhakta Kayastha, Professor at the Department of Environmental Science and Engineering at the School of Science, Kathmandu University, said that the UN's declaration to preserve glaciers does not imply physically covering glaciers, as they cover vast areas. Instead, it stresses the need to reduce global greenhouse gas emissions and temperature rise, as the most significant impacts are being felt in mountainous countries like ours with large glacier masses over 10,000 square kilometres and 20,0000 square kilometres.

“Now, the path has opened for us to conduct more research on glaciers in Nepal seeing international help to understand their current status and predict future changes. The first impact will be seen in hydropower production, as we are already experiencing prolonged dry seasons. These effects will increase over the next 10 to 20 years. Glaciers are shrinking, and glacial lakes are expanding, which also increases the potential threat of glacial lake outbursts,” Kayastha said.

“The only solution is to reduce temperature rise and follow the Paris Agreement determined to keep the global temperature increase below 1.5 degrees Celsius compared to pre-industrial levels,” he added. 

The impact of rising temperatures is already evident. NASA has confirmed that Earth's average surface temperature in 2024 was the hottest on record. The global temperature in 2024 was 1.28 degrees Celsius above the agency’s 20th-century baseline, surpassing the record set in 2023.

In a virtual event titled Reporting on Glaciers in 2025, organised by the World Meteorological Organisation on Thursday, John Pomeroy, Distinguished Professor in the Department of Geography & Planning and Canada Research Chair in Water Resources and Climate Change, floated the question: As glaciers continue to retreat due to climate change, what are some of the most promising solutions we should focus on to highlight both the challenges and potential pathways forward?

He explained that mountain glaciers have long provided a vital ecosystem service by storing water over seasons, years, and decades, releasing meltwater during the hottest and driest periods. However, as glaciers continue to decline, this critical service is being lost.

To adapt, he stressed the need for changes among downstream populations, including adjustments to irrigation practices, increased water conservation efforts, and enhanced water storage in wetlands, groundwater, and sometimes reservoirs. "Water management needs to be more precise and based on improved predictions to facilitate this adaptation," Pomeroy added.

GLOF impact in Nepal

The impact has already begun to be seen. A GLOF in Thame village of the Khumbu region on August 16, 2024, was caused by the sudden break of Thyanbo glacial lake, leading to the destruction of numerous houses and infrastructure.

This recent event highlights the growing risks posed by climate change in the Himalayas, as rising temperatures contribute to the expansion and instability of glacial lakes.

According to Kayastha, Nepal has four main glacier-fed river basins -- Koshi, Gandaki, Karnali and Mahakali, along with 19 other sub-river basins. The catchment areas of these rivers extend across the Himalayas into China. Nepal is home to 3,808 glaciers, 2,070 glacial lakes and significant permafrost areas above 5,000 metres.

A new glacial lake inventory report published by the International Centre for Integrated Mountain Development (ICIMOD) has identified 47 potentially dangerous glacial lakes (PDGLs) within the Koshi (42), Gandaki (3) and Karnali River (2) basins spanning Nepal, China and India. Over the past two years, ICIMOD has been working with the United Nations Development Programme (UNDP) Nepal to identify PDGLs in these three basins using high-resolution satellite imagery. 

These glacial lakes are at risk of breaking, which could result in catastrophic glacial lake outburst floods (GLOFs), experts said. With support from the UNDP, the water level of two high-risk lakes in Nepal was reduced to minimise the threat of GLOFs. The water level of Tsho Rolpa was lowered by more than 3 metres in 2000 and Imja Tsho by 3.4 metres in 2016. 

According to the Department of Hydrology and Meteorology, maximum and minimum air temperatures in Nepal increased by 0.56 degrees Celsius and 0.02 degrees Celsius per decade, respectively, from 1971 to 2014. The warming is more pronounced in the Himalayan region than in other parts of the country.  This indicates that even under the best-case scenario, the Himalayas could lose up to one-third more of their permanent ice by the end of this century, experts said.

Dr. Arun Bhakta Shrestha, Senior Climate Change Specialist, said that glaciers are melting at an alarming rate. While water scarcity may not currently be seen across all areas of the country, the critical message about glacier melting must be communicated at the global level.

“There should be a focus on adaptation and resilience,” he said. “Ecosystems and livelihoods need protection and assistance should be sought from the global community, especially now that the UN has initiated the decade-long glacier preservation campaign.”

Rising temperatures threaten Nepal

A GLOFs modelling of Thulagi and Lower Barun Glacial Lakes conducted by Sunwi Maskey, Rijan Bhakta Kayastha and Rakesh Kayastha in Thulagi and Lower Barun Glacial Lakes revealed that the areas have significantly expanded over the past 30 years based on Landsat images.

Thulagi Glacial Lake, which is fed by the debris-covered Thulagi Glacier (2.7 square kilometres), increased from 0.72 square kilometres in 1988 to 0.94 square kilometres in 2018. 

Lower Barun Glacial Lake, also fed by the debris-covered Lower Barun Glacier (1.4 square kilometres), grew from 0.64 square kilometres in 1989 to 2 square kilometres in 2018, with a rapid 34 per cent increase between 2000 and 2017. It has the highest expansion rate among major proglacial lakes in the region, linked to the glacier's retreat.

ICIMOD's GLOF mitigation efforts

Sher Muhammad, Cryosphere Monitoring Lead at ICIMOD, said that ICIMOD has planned several initiatives aligned with the International Year of Glacier Preservation. An awareness initiative is proposed as ‘Tribute to Yala Glacier’ in Langtang, Nepal. The event showcases the result of glacier melt and underlines the urgent need for its preservation. 

The Yala Glacier, located around 80 km north of Kathmandu, has been used as a benchmark and capacity building of almost 100 HKH experts in field-based glacier monitoring, spotlighting Yala Glacier's status due to the ongoing impact of climate change which has shrunk significantly in recent years, making it no more suitable for long-term monitoring as a benchmark. The idea of the Yala Glacier Tribute is to highlight the impacts of climate change and advocacy for cryosphere preservation, he said.

“Decade of Action for Cryosphere Sciences will provide an excellent opportunity for us to scale up its cryosphere monitoring initiatives. It will also contribute to climate adaptation in glacier-fed river basins, putting much emphasis on the sustainable use of water and agriculture and disaster preparedness for the building of resilience among vulnerable communities.” To bridge science and policy, ICIMOD holds conferences and prepares scientific reports, apart from collaborative projects, to develop workable cryosphere conservation strategies.

According to Kayastha, climate change is now impacting both monsoon dynamics and the condition of snow and glaciers in the Himalayas. “We must remain aware and prepared for the consequences,” he added.

In addition to extreme weather events, the geological structure of watersheds must be considered to conduct detailed risk assessments before undertaking costly projects like the Melamchi water supply or determining the locations of future hydropower plants, bridges and roads, he added.