A new global study has revealed a startling twist in the climate crisis narrative: while most glaciers worldwide are shrinking at unprecedented rates, a small but powerful fraction is suddenly surging forward. Scientists warn that these dramatic advances are not signs of recovery, but signals of instability that could intensify flood risks, disrupt infrastructure and endanger vulnerable mountain communities.
From the Arctic to High Mountain Asia, researchers have identified more than 3,000 glaciers that have experienced sudden bursts of acceleration. Though they represent only about one percent of the world’s glaciers, these massive bodies of ice account for roughly 16 percent of global glacier area making their behaviour highly significant in understanding future climate risks.
The Science Behind the Sudden Surge
Unlike typical glaciers that steadily retreat as temperatures rise, surge-type glaciers alternate between long periods of slow movement and short phases of rapid acceleration. During these surges, ice flow can jump from a few metres per year to tens of metres per day. In extreme cases, glaciers have moved more than 60 metres daily, reshaping entire landscapes within months.
The trigger lies beneath the ice. Meltwater becomes trapped at the glacier’s base instead of draining away efficiently. This trapped water reduces friction between the glacier and the ground, effectively lubricating the ice and allowing it to slide forward at high speed. When the water eventually drains, the glacier slows again sometimes abruptly.
One dramatic example was observed at Nathorstbreen in the Arctic archipelago of Svalbard, where the glacier advanced more than 15 kilometres over roughly a decade beginning in 2008. The surge transformed the surrounding terrain and highlighted how quickly frozen landscapes can change.
Surging glaciers are concentrated in specific regions, including the Arctic, the Himalayas, other high mountains of Asia and parts of the Andes. They are largely absent in regions that are too warm, such as the European Alps, or too cold and dry, such as much of Antarctica’s interior.
Growing Risks for Downstream Communities
Despite appearing to contradict the broader trend of glacier retreat, scientists stress that surging glaciers can actually accelerate long-term ice loss and make glaciers more vulnerable to warming. More immediately, they pose serious hazards to people living downstream.
Advancing ice can overrun farmland and infrastructure or block rivers, forming unstable lakes. When these natural ice dams fail, they can unleash devastating floods. In the Karakoram mountain range, repeated drainage of a lake formed by the surge of Shisper Glacier between 2019 and 2022 caused extensive damage to the strategically important Karakoram Highway linking Pakistan and China.
Surges also create deep crevasses, complicating travel in regions such as Svalbard, where glaciers serve as natural highways between isolated settlements. Tourism, mountaineering and maritime activities can be disrupted as well. When surging glaciers reach the sea, they can release large numbers of icebergs in short periods, posing navigation risks.
Climate warming is now reshaping how and when glaciers surge. In some regions, surges are becoming more frequent; in others, they are declining as thinning glaciers lose the mass required to build toward a surge. Extreme weather events, including intense rainfall and heavy melt periods, have also been linked to earlier-than-expected surges trends likely to intensify in a warming world.
Scientists warn that glacier behaviour is becoming increasingly unpredictable. Regions that have never recorded surges before could begin to see them, adding new layers of risk in already climate-stressed areas.
As the planet continues to warm, surging glaciers serve as a reminder that ice does not respond to climate change in simple or uniform ways. Understanding these dramatic exceptions and preparing for the hazards they bring will be essential in managing risk in an era of accelerating environmental change.