Climate Matters•January 29, 2025
Year of the Glacier
KEY CONCEPTS
2025 marks the International Year of Glaciers' Preservation, a United Nations-led initiative to raise awareness about the critical role of glaciers and the urgent need for their protection.
Human-caused climate change is causing glaciers to melt at an alarming rate, contributing to sea-level rise and jeopardizing the very existence of these vital natural resources. Seven of the ten years with the most significant glacier mass loss have occurred since 2010, highlighting the accelerating pace of glacial retreat in recent decades.
Referred to as “water towers of the world,” glaciers provide freshwater for billions of people, support diverse ecosystems, contribute to clean energy production, and serve as invaluable archives of past and present climate conditions.
Glacial loss poses significant risks to communities, including disrupting tourism economies, eroding cultural heritage and increasing vulnerability to hazards such as landslides, avalanches, tsunamis and glacial lake outburst floods (GLOFs).
Glaciers exist on every continent except Australia and are most abundant in polar regions. In North America, regions such as the U.S. Pacific Northwest, Alaska, and British Columbia, Canada, face elevated risk from glacial hazards, including GLOFs.
2025: A Year for Glacier Preservation
UNESCO and the World Meteorological Organization (WMO) launched the International Year of Glaciers' Preservation on January 21st. This global initiative highlights the critical role of glaciers in providing freshwater to billions of people worldwide, while emphasizing the urgent threat posed by climate change to their very existence.
Covering nearly 10% of Earth's surface, glaciers and ice sheets are integral to the Earth's climate system, storing 70% of the planet’s freshwater, and glacier-fed lakes are home to a third of all terrestrial species diversity.
Glaciers serve as Earth's archives, preserving crucial data about our past climate within their ancient ice. Their disappearance threatens not only water security and unique ecosystems, but also the cultural heritage of many Indigenous communities who consider glaciers sacred spaces.
Moreover, glaciers attract millions of tourists annually, contributing significantly to local economies. For example, in 2023, nearly three million visitors to Montana’s Glacier National Park contributed over $554 million to the local economy.
However, these vital natural resources are rapidly receding due to rising global temperatures associated with human-caused carbon pollution, with potentially devastating consequences for water security, biodiversity, and human livelihoods.
The Melting of Ancient Icons and Outburst Floods
A recent report found that over 18,000 glaciers within 50 UNESCO World Heritage sites are experiencing rapid melting — losing an average of 58 billion tonnes of ice annually.
Rising global air and ocean temperatures are contributing to rapid glacial loss.
This alarming trend threatens the very existence of these iconic geological features. In the next 25 years, a third of these glaciers are projected to vanish entirely, impacting renowned tourist destinations such as Los Glaciares National Park in Argentina, and Vatnajökull National Park in Iceland.
Glacial retreat amplifies the risk of cascading hazards, including landslides, debris flows, avalanches, tsunamis and glacial lake outburst floods (GLOFs). GLOFs, sudden and catastrophic releases of meltwater from glacial lakes, pose a grave threat to downstream communities. These events can devastate property, infrastructure, and agriculture. GLOFs can lead to significant loss of life, causing more than 12,500 fatalities since 1900.
Today, more than 15 million people globally are highly vulnerable to the impacts of GLOFs, with India, Pakistan, Peru, and China facing the greatest risk. Over the last three decades, climate change-driven glacial melt has contributed a dramatic increase in the number and size of glacial lakes worldwide thereby enhancing the risk of outburst floods. A GLOF from India's South Lhonak Lake in October 2023, compounded by dam failure, caused 46 fatalities and displaced nearly 90,000 people across Sikkim, West Bengal, and northern Bangladesh. The flood destroyed critical infrastructure, including bridges and highways, leaving many communities isolated and without essential services.
Some mountainous regions of the U.S. also reside in the GLOF danger zone, particularly in Washington State and Alaska. In August 2023, a major outburst flood from Mendenhall Glacier caused significant flooding in Juneau, Alaska. This event, unprecedented in its scale, would not have been possible without the influence of climate change.
Depleting Earth’s Natural Water Towers
Glaciers, often referred to as “water towers of the world,” are essential for the billions of people who rely on their meltwater to feed and recharge local rivers, lakes and groundwater supplies to support ecosystems, agriculture, hydropower and drinking water.
Formed over centuries or millennia from compacted snow, glaciers exist in a delicate balance between accumulation (snowfall) and ablation (melting and calving). This balance determines the glacier's mass and whether its ice advances or retreats.
In the face of human-caused rising global air and ocean temperatures, glacial loss has dramatically outpaced glacial gain over the past two decades. Excluding the Greenland and Antarctic ice sheets, the annual rate of glacial thinning nearly doubled between 2000 and 2019. The 2010s witnessed the most significant glacier mass loss on record, with some disappearing altogether, adding to a growing list of global glacier casualties. Glacial meltwater accounts for 21% of the total observed global sea-level rise during this period. The IPCC’s Sixth Assessment Report warns that continued glacier degradation is inevitable under all projected emissions scenarios.
LOCAL STORY ANGLES
Historic ice and snow records
The National Snow and Ice Data Center (NSIDC) manages a comprehensive archive of scientific data on snow, ice, glaciers, frozen ground, and related climate dynamics.
Visualizing glacier changes
Learn how Copernicus Sentinel-2 satellite imagery is providing valuable insights into glacier change. Watch this video to see how advancements in remote sensing improve our ability to monitor these fragile landforms.
FIND EXPERTS
Submit a request to SciLine from the American Association for the Advancement of Science or to the Climate Data Concierge from Columbia University. These free services rapidly connect journalists to relevant scientific experts.
Browse maps of climate experts and services at regional NOAA, USDA, and Department of the Interior offices.
Explore databases such as 500 Women Scientists, BIPOC Climate and Energy Justice PhDs, and Diverse Sources to find and amplify diverse expert voices.
Reach out to your State Climate Office or the nearest Land-Grant University to connect with scientists, educators, and extension staff in your local area.
METHODOLOGY
The global annual mass balance of glaciers (mass gain + mass loss) during hydrological years 1949/50 - 2022/23 were obtained from the World Glacier Monitoring Service. Annual average values were calculated for 19 mountainous regions around the world using data from reference glaciers (those with more than 30 years of ongoing glaciological measurements).