Glacier Retreat Projections to 2100
Projecting how glaciers will respond to future climate is one of the most consequential tasks in applied glaciology. The results of these projections have moved steadily from academic journals into policy documents, infrastructure planning, and national adaptation strategies, because the downstream implications — for river flow, sea level, and freshwater availability — affect populations far removed from any glacier. The projections are not speculative: they are grounded in decades of measured mass balance data, well-tested ice-flow models, and the same physics-based climate models used for weather forecasting.
The short answer is that virtually all mountain glaciers outside Antarctica and Greenland are projected to lose substantial volume by 2100, with losses ranging from roughly 30 percent to more than 80 percent of present-day ice mass depending on emission trajectories and regional conditions. Explore the current distribution of the world's glaciers on the map and consider how radically that map may look by the end of this century.
The Basis of Glacier Projections
Glacier projections combine two model types: global climate models that forecast temperature and precipitation changes, and glacier-specific models that translate those climate forcings into ice volume change. The most widely used glacier models in large-scale studies include the Open Global Glacier Model (OGGM), GloFAS, and several regional variants tuned to specific mountain ranges. These models are initialised with observed glacier outlines from the Randolph Glacier Inventory, which documents approximately 220,000 individual glaciers worldwide.
Uncertainty in projections comes from two main sources. The first is the emissions scenario — future greenhouse gas concentrations depend on human decisions that cannot be predicted with certainty. The Intergovernmental Panel on Climate Change uses a range of shared socioeconomic pathways, from aggressive decarbonisation to high-fossil-fuel scenarios. The second source of uncertainty is internal glacier dynamics, particularly for marine-terminating glaciers where ice-ocean interactions are poorly constrained.
Alps, Pyrenees, and European Mountain Glaciers
European mountain glaciers have among the most thoroughly documented retreat records and face some of the most severe projected losses. Under a high-emission scenario, the Alps are projected to lose between 80 and 95 percent of present ice volume by 2100. Even under optimistic low-emission pathways, losses of 50 percent or more are projected because of the warming already committed by historical emissions.
The Grosser Aletsch Glacier in Switzerland — the largest glacier in the Alps — currently spans approximately 23 kilometres in length. Models project that under high emissions, the Aletsch could retreat by more than 10 kilometres and lose the majority of its lower tongue entirely. The Mer de Glace in the French Alps has already retreated several kilometres over the twentieth century; projections suggest this retreat will accelerate through the mid-century regardless of emission pathway.
High Mountain Asia
The glaciers of High Mountain Asia — encompassing the Himalaya, Karakoram, Hindu Kush, Tien Shan, Pamir, and Tibetan Plateau — are frequently described as the Third Pole, a reference to the enormous volume of freshwater ice stored outside the polar regions. A landmark multi-model study published in 2019 in Science projected that one-third of these glaciers would be lost even under a low-emission scenario, and two-thirds under high emissions.
The regional diversity within High Mountain Asia is significant. The Karakoram range in northern Pakistan and China has shown anomalous stability or slight growth in some glaciers over recent decades, linked to specific regional atmospheric circulation patterns bringing enhanced winter snowfall. However, most models project that even the Karakoram Anomaly will give way to net mass loss under continued warming, particularly as summer temperature increases override the modest precipitation gains.
Alaska and the Canadian Rockies
Alaskan glaciers represent some of the largest non-polar ice masses outside the ice sheets and are currently among the fastest-retreating glaciers by volume on Earth. The Columbia Glacier in Prince William Sound retreated more than 20 kilometres between 1980 and 2020 and continues to thin rapidly. The Juneau Icefield, which straddles the Alaska-Canada border, feeds dozens of outlet glaciers including the Mendenhall and Taku glaciers. The Taku had a positive mass balance for much of the twentieth century but shifted to negative balance around 2013 and has retreated since.
Projections for Alaska under high-emission scenarios suggest ice volume losses of 70 percent or more by 2100, with the remaining ice concentrated in higher-elevation accumulation zones. The loss of tidewater glaciers has particular implications for proglacial fjord ecology and Alaska's fisheries, as glacial meltwater influences water temperature and nutrient supply in productive coastal waters.
Patagonia
The Southern Patagonian Ice Field is the largest contiguous mass of ice in the Southern Hemisphere outside Antarctica. It feeds major outlet glaciers including Perito Moreno, Upsala, and Viedma. While Perito Moreno famously shows periodic advance-retreat cycles due to its geometry at Lago Argentino, the broader Southern Patagonian Ice Field is losing mass rapidly. Studies using GRACE satellite data show it to be one of the largest contributors to sea level rise among all mid-latitude glacier systems.
Projections for Patagonia are complicated by limited high-altitude climate data and uncertainty in regional precipitation trends. However, the overall direction is clear: continued warming will drive losses across the ice field, with the smaller northern component particularly vulnerable.
Greenland and Antarctica Ice Sheets
The Greenland and Antarctic ice sheets are governed by dynamics quite different from mountain glaciers. Their size means that the committed warming already in the climate system will drive centuries of mass loss even if emissions were halted today. Ice sheet projections typically extend beyond 2100 and involve large uncertainty ranges, particularly for West Antarctica where marine ice sheet instability could drive non-linear retreat.
For the twentieth-century period to 2100, the IPCC Sixth Assessment Report projected Greenland mass loss equivalent to 3 to 23 centimetres of sea level rise, and Antarctic mass loss of 3 to 28 centimetres, with upper-bound scenarios dependent on poorly understood ice cliff instability mechanisms.
The Implications of Projected Loss
The practical consequences of glacier retreat by 2100 are unevenly distributed. For communities in the Andes, Central Asia, and Hindu Kush-Himalayan region that depend on glacier-fed rivers for irrigation water in the dry season, near-term increases in runoff from melting ice will eventually give way to sharp declines as ice volumes exhaust. This transition — from temporary abundance to water stress — is projected to occur in many basins between 2040 and 2080, depending on glacier size and warming rate.
For coastal populations globally, the cumulative sea level contribution from all glacier sources through 2100 is projected at roughly 20 to 60 centimetres under varying emission pathways, added to thermal expansion of the ocean. The total rise will fundamentally alter the exposure of low-lying coastal areas to storm surge and regular tidal flooding.
What Emission Pathways Change
The most important message from glacier projection research is that emission pathway choices made over the next one to two decades will determine outcomes across the entire century. The difference between a high-emission trajectory and a low-emission trajectory corresponds to hundreds of millimetres of sea level rise and the survival or disappearance of entire glaciated mountain ranges. Glaciers that exist in 2100 under ambitious decarbonisation scenarios simply cease to exist under business-as-usual scenarios. That distinction is the direct, physical consequence of choices being made now.