Glaciers and ice sheets are large masses of ice that form when fallen snow is compressed and recrystallized over the course of decades and centuries. Together, they cover approximately 10 percent of the Earths total land area.
But while we often associate these natural wonders with the polar regions or mountain peaks, glaciers play a wide variety of roles in life across the planet though theyre changing rapidly. Over the past two decades, glacier loss has been escalating, with some regions of the world losing nearly 40 per cent of their ice mass. With current greenhouse gas emissions, the world is on track to lose almost all low-lying and tropical glaciers and much of the cryosphere globally.
This World Day for Glaciers, held annually on 21 March, we look at what the UN Environment Programmes new Mountains in Motion: Global Linkages from Ridge to River report has to say about the various identities of glaciers and what the evolving role of the cryosphere means for people and nature.
All information and charts are taken from the Mountains in Motion report.
Glaciers are protectors of ecosystem memory
While some of todays glaciers are only a couple hundred years old, the majority are remnants from the most recent global Ice Age that ended more than 10,000 years ago. As such, glaciers are not only ice they are also archives holding records of climate, pollution and planetary change. The aerosols, bacteria, biomass and other particles embedded in glaciers are clues of past atmospheres and biospheres, helping scientists understand how natural systems have evolved over time. As glaciers retreat, the world risks losing irreplaceable evidence that can both deepen our understanding of the past and inform climate projections for the future.
Glaciers are crucial sources of freshwater
Its estimated that 70 per cent of the worlds freshwater is held in glaciers, meaning that glaciers help sustain life in major regions of the world. Together with snowmelt and rainfall, glacial meltwater feeds into far-reaching downstream water systems that support drinking water, agriculture, energy production and economies. The report, however, warns that this is changing. Many river basins have already passed peak water, the point at which the amount of glacial meltwater switches from boosting runoff to causing its decline. One third of the worlds largest river basins are projected to see runoff fall by more than 10 per cent by 2100 due to glacier loss.
Glaciers are our silent guardians, says Sonam Tashi, Director of Bhutans Department of Environment and Climate Change. When they melt too fast, it is not only our landscapes that change it is our water security, our food systems, economy and our peoples safety that are put at risk.
Glaciers are landing pads for pollution
Even mountain peaks are not exempt from pollution nowadays. Windborne contaminants from industry, transport and agriculture make their way to remote high-altitude landscapes, where they accumulate in snow and ice. Often black in colour, pollution deposited on glaciers traps heat, accelerating glacier melt and releasing other pollutants long stored in the ice. The report highlights heavy metals, persistent organic pollutants and other contaminants as part of this growing risk, linking glacier loss directly to water quality, ecosystem health and human well-being.
Glaciers are enablers of biodiversity
While glaciers are quite solitary landscapes, life around them flourishes. Their meltwater supports a variety of freshwater systems, while new land exposed from glacier retreat is ripe for colonization by pioneer species. Over time, these uncovered areas can develop into grasslands, forests, wetlands and other ecosystems that support a wide array of biodiversity and ecosystem services. Yet this transition is not always good news: glacier regression is a sign of progressing climate change, and species that have specially adapted to glacier environments risk losing their only habitat once the glaciers go.
Glaciers are governors of risk
Glaciers not only regulate water they also influence hazard patterns in mountain regions. As the cryosphere shrinks, the report warns of rising risks from floods, avalanches and landslides. Glacier melt means increased runoff and raising the likelihood of flooding during some seasons, while shifting patterns can also intensify drought in others. For communities living in mountain regions, glacier loss can come with major consequences for their homes, farms, infrastructure and livelihoods.
Glaciers are climate regulators
Glaciers are not simply bystanders of the climate crisis. They are active parts of the climate system, and their decline can amplify the very changes driving their disappearance. Their bright white surfaces (when pollution is not widely deposited) reflects sunlight back into the atmosphere, helping temper warming in mountain environments something known as albedo. As ice and snow shrink, that reflective shield is reduced, exposing darker surfaces that absorb more heat and can accelerate warming and melt. The report also notes that glaciers play a role in regulating local weather systems as well as global hydrology patterns that are already being altered.
Glaciers are cultural touchstones
Glaciers matter in ways that cannot be measured in square metres or tonnes. The report illustrates the cultural and spiritual identities that have been built around mountains and glaciers, and that their disappearance is already seeing ceremonies, literature, art and public events become focused on their decline. For many Indigenous and local communities, glaciers are woven into their sense of place and collective memory, and such loss represents not only environmental disruption but also cultural grief. Recognizing glaciers and cultural touchstones broadens their story beyond science and risk, reminding us that cryosphere loss is also about belonging, heritage and how societies make sense of profound landscape change.
Glaciers are prompting international action
There are signs that the world is beginning to respond to glacier loss. At the seventh United Nations Environment Assembly (UNEA-7) in December 2025, governments adopted a landmark resolution dedicated to the preservation of glaciers and the broader cryosphere, particularly in mountain regions. The resolution, proposed by Tajikistan and co-sponsored by Bhutan and Peru, calls for stronger cooperation, finance, capacity building and action to help vulnerable countries and communities respond to accelerating glacier loss. It also asks UNEP to strengthen the science-policy interface by identifying gaps and needs, and by supporting knowledge exchange on approaches to protect mountain and post-glacial ecosystems.
The UNEA-7 resolution sends a clear message: the protection of glaciers and the broader cryosphere is a shared global responsibility and a strategic investment in sustainable water resources management, ecological balance, resilience, and human well-being, says Bahodur Sheralizoda, Chairman of Tajikistans Committee for Environmental Protection. We hope it will translate into concrete action, stronger partnerships, and greater investment for present and future generations.
