The Urgent Need to Preserve Glaciers in a Warming World

Introduction

Glaciers—moving masses of ice that are also considered freshwater reservoirs—serve as vital components of Earth's climate and hydrological systems, sustaining ecosystems, agriculture and human populations. However, climate change and other drivers of change have accelerated glacier melt, threatening water security, biodiversity and regional economies. As we observe the World Day for Glaciers (21 March 2025), it is crucial to recognize the environmental, social and economic significance of glaciers and the urgent need for cooperation for their preservation.

The global state of glacier loss

Globally, glaciers are melting at an unprecedented rate, with ice loss accelerating over the recent two decades compared to previous decades.¹ Within just 23 years starting in the year 2000, Earth's more than 215,000 glaciers² have lost an annual average of 273 gigatonnes of ice, with these losses accelerating by 36 per cent between 2012 and 2023 compared to the previous decade. Glaciers are now, in fact, losing more mass than the Greenland or Antarctic ice sheets 2021. This acceleration has significantly contributed to sea-level rise, accounting for 21 per cent of observed sea-level rise.³ Even the most optimistic projections indicate that 25–29 per cent of glacier mass could be lost by 2100, whereas under higher-emission scenarios, the mass loss could range from 46–54 per cent.⁴ This could potentially lead to the disappearance of 49–83 per cent of glaciers under both scenarios, respectively.⁵ In the Hindu Kush Himalaya (HKH), this loss is even more pronounced, with mass loss 65 per cent higher than in previous decades.⁶

Beyond rising sea levels, melting glaciers are also driving the rapid growth of glacial lakes. In just 28 years since 1990, lakes across the globe grew in volume by 48 per cent and saw an increase in their number and area by more than 50 per cent.⁷ This rapid expansion of glacial lakes significantly raises the threat of glacial lake outburst floods (GLOFs); nowhere is this a more perilous risk than in High Mountain Asia, where approximately 1 million people reside within just 10 kilometres of a glacial lake.⁸ Moreover, the projections also indicate that the frequency of such events could increase threefold in the coming decades,⁹ underscoring the urgent need for preparedness and mitigation efforts in this vulnerable region.

The role of glaciers

Glaciers hold around 69 per cent of the world’s freshwater and function as essential water towers that regulate river flows in major mountain regions such as the Himalayas, Andes and Alps.¹⁰ During dry seasons, meltwater from glaciers plays a vital role in maintaining agricultural activities, generating hydroelectric power and offering drinking water supplies for millions of people. These glaciers also provide essential ecosystem services, shape unique habitats and support life in high altitudes regions.¹¹ They also regulate local climates, support biodiversity resilience and hold cultural significance.

After Earth’s two poles, HKH—often referred to as the “Third Pole”—holds the largest concentration of glaciers. In addition to its high density of ice, this region is a place where glaciers, life and livelihoods become closely intertwined. These glaciers feed 10 major rivers, including the Ganga, Indus and Brahmaputra, and support the livelihoods of over 1.5 billion people across South Asia.¹² Glaciers and glacier lakes also host unique microbial communities, while high-altitude microclimates foster endemic plants, animals and specialized ecosystems such as peatlands. At the same time, as ice retreats, new areas for vegetation emerge, potentially increasing primary productivity and species richness due to warmer temperatures.

However, changes and retreating of glaciers also pose serious threats to biodiversity due to habitat loss and degradation, the development of unstable slopes, altered water cycles and invasive species, often leading to a decline in ecosystem services and function.¹³

A call for action to protect glaciers and local communities

While the World Meteorological Organization confirmed that 2024 was the warmest year on record, with the global average surface temperature reaching 1.55 °C, ± 0.13 °C above the 1850-1900 baseline, it is important to note that a year or two of warmer temperatures does not necessarily indicate that we have breached the long-term temperature thresholds set out in the Paris Agreement on climate change. However, from here on, every fraction of a degree in warming matters, especially for the state of the glaciers and the fate of humankind. This is why we need a comprehensive approach that blends adaptation and mitigation; scientific monitoring with community engagement; and localized resilience strategies to preserve these vulnerable ecosystems, water resources and the communities that depend on them.

Key to this approach is strengthening the resilience of high-altitude vulnerable communities by developing early warning systems and investing in climate resilient infrastructure.¹⁴ In addition, integrating sustainable watershed management and establishing protected areas can help mitigate habitat degradation and preserve biodiversity across these vulnerable areas.¹⁵ Further, empowering communities through education and participatory planning, and further strengthening adaptive capacity, are equally important. Together, these actions form the backbone of a holistic and effective response to the accelerating impacts of glacier mass loss in this warming world.

Notes

¹ David R. Rounce and others, “Global glacier change in the 21st century: Every increase in temperature matters”, Science, 379(6627) (2023), pp. 78–83.