A global analysis of surge-type glaciers was recently published in Nature Reviews Earth & Environment (https://www.nature.com/articles/s43017-025-00757-9)revealing the hazards they cause, and how climate change is making their behaviour increasingly difficult to predict. Ívar Örn Benediktsson, research professor at the Institute of Earth Sciences, is one of the co-authors of this study.
- Over 3100 surging glaciers are identified globally, concentrated in dense clusters across the Arctic, High Mountain Asia, and the Andes. They represent 1% of all glaciers worldwide, but affect almost 20% of global glacier area.
- Glacier surges can have catastrophic impacts on infrastructure and people.
- 81 glaciers are shown to pose the greatest danger when they surge, with the majority in the Karakoram Mountains where they threaten populated valleys.
- Climate change is making surge behaviour increasingly unpredictable, such as extreme weather events triggering earlier-than-expected surges
While most of the world's glaciers are retreating as the climate warms, a small but significant population behaves very differently - and the consequences can be severe.
A team of international scientists has carried out the first comprehensive global analysis of surging glaciers, examining the hazards they cause and how climate change is fundamentally altering when and where these dramatic events occur.
Glacier surges - when a glacier suddenly moves much faster than normal - rapidly transport ice to the glacier front and often cause advances. These events typically last for several months to years, with many glaciers experiencing repeated surges separated by decades or centuries of relative inactivity. Rather than being scattered globally, these glaciers cluster in dense groupings across the Arctic, High Mountain Asia, and the Andes.
The study includes the key features and basic processes controlling glacier surges, characterises the wide range of surging behaviours, and maps the global locations of surge-type glaciers and the climate conditions that cause them to cluster in specific areas.
Contrary to what you might expect, the researchers found surging makes glaciers more vulnerable to climate change. When they surge, these glaciers are responsible for a large proportion of ice mass loss in some regions.
Six major hazards identified
The research identified six main types of hazards caused by glacier surges that affect communities in high mountain regions, which can result in damage to infrastructure and in some cases loss of life:
- Glacier advance - ice overruns buildings, roads and farmland.
- River blockages - surging glaciers dam rivers, creating lakes that can release devastating floods.
- Meltwater outbursts from beneath the glacier - these also release potentially devastating floods.
- Sudden detachments of steep glaciers - cause large ice and rock avalanches.
- Widespread crevassing - high ice velocities fracture glacier surfaces, making travel extremely hazardous in regions where glaciers serve as highways between settlements and are used for tourism activities, and affecting climbing routes where glaciers provide access to mountain peaks.
- Iceberg hazards - when glaciers surge into the sea, they release numerous icebergs in a short time, creating risks for shipping and marine tourism.
Climate change is making surges increasingly unpredictable
Perhaps most concerning is the growing evidence that climate warming is fundamentally changing how glacier surges behave - making them harder to predict just when better forecasting is most needed for hazard management. A growing body of evidence shows how climate change is affecting glacier surges, including where and how often they happen. This includes instances of extreme weather such as heavy rainfall events or very warm summers triggering earlier than expected surges, suggesting an increasing unpredictability in their behaviour.
Some glaciers are now surging more frequently than they did several decades ago, while in other regions surge activity is declining. There is evidence that some glaciers have thinned so much they can no longer build sufficient ice to surge in the future. Surge behaviour may also shift to new regions entirely. It is known that 98% of all surging glaciers are currently concentrated in the Arctic and sub-Arctic and High Mountain Asia, where specific climate conditions make surges more likely. But ongoing climate warming may change this distribution.
Surges might largely stop in places like Iceland, where glaciers are shrinking rapidly and struggling to accumulate enough ice. Meanwhile, they could become more frequent in parts of High Mountain Asia and in the Canadian and Russian Arctic due to warmer temperatures and increased meltwater. It is even possible that glaciers might begin surging in the Antarctic Peninsula and other areas where surge-type glaciers are not currently known to exist.
