Lorraine Williamson
The high Pyrenees are witnessing a transformation once thought unthinkable. Spain’s last glaciers, fragile remnants of an older climate, are disappearing at a pace that researchers say leaves little time for recovery. New measurements from CryoPyr, the research group at the Pyrenean Ecology Institute (IPE-CSIC), confirm that the 2024–2025 hydrological year ranks among the most damaging in modern records.
The findings come after several seasons of hot summers and winters with little snow. Together, they have pushed the glaciers to the edge. Scientists now warn that all of Spain’s active glaciers could vanish within ten years if these conditions persist.
A devastating year for the ice
CryoPyr’s data shows that Spain’s glaciers lost more than a metre of thickness on average during 2024–2025. In some places, the losses reached four metres. This is one of the worst results since systematic monitoring began. The pattern is becoming familiar. The five most damaging seasons have all occurred in the past decade.
Warm summers speed up melting. Poor snowfall leaves glaciers without the winter protection they once relied upon. When those two forces combine, the balance turns sharply negative. What melts is no longer replaced.
Aneto’s collapse signals the endgame
Nowhere is the shift more visible than at Aneto. Once the pride of the southern European ice landscape, the glacier has broken apart into three disconnected bodies. One no longer moves at all. It has been reclassified as “helero”: stagnant ice that no longer counts as a living glacier.
The scale of retreat is stark. Aneto covered more than 135 hectares in 1981. By 2022, it had shrunk to around 48. It now occupies barely 30 hectares. A section of 3.6 hectares detached completely this year, accelerating its decline and leaving bare rock where continuous ice once stretched across the cirque.
Glaciologists report that the glacier is in its terminal phase. The fractures, thinning, and loss of internal movement show that its long-term survival is no longer viable.
Retreat across the Pyrenees
Other glaciers are following the same path. Ossoue, straddling the French–Spanish border, lost around 3.5 metres in a single year. At Monte Perdido, Posets, and Infiernos, melt rates were even higher. The Infiernos Glacier has now vanished as an active system. Only scattered patches remain, unable to move or accumulate ice.
The region held 52 glaciers in the nineteenth century. By 2025, just 14 are left. Most are in advanced decline. As they fragment, they lose the ability to behave as cohesive bodies of ice, speeding up melt and exposing new surfaces to the sun.
Tracking the final years
CryoPyr monitors the glaciers with drones, laser scanners, and annual field surveys. These techniques provide precise measurements of shrinking ice volumes and shifting glacier boundaries. The 2024–2025 season ranks as the third-worst ever recorded. The two most damaging years also fell within the past five years, showing how rapidly the trend is now accelerating.
Researchers say that even optimistic weather scenarios do not offer a path to stabilisation. Too much ice has already been lost. The remaining bodies are too small, too thin, and too fragmented to recover.
Changing mountains, changing ecosystems
The disappearance of glaciers will reshape the Pyrenean landscape. Glaciers carve valleys, regulate river systems, and act as natural archives of past climates. When they melt away, sediment moves differently, streams warm earlier in the year, and alpine ecosystems shift.
Lake Innominato is a clear example. Formed in 2015 from meltwater held in place by an ice dam at 3,150 metres, it was briefly the highest lake in the Pyrenees. As the ice thinned, the dam collapsed. Today, the lake has almost vanished, leaving a dry hollow that tells the story of rapid loss.
A clear warning from the mountains
Scientists are now blunt. There is no realistic scenario in which Spain’s glaciers can survive. The Pyrenees are warming faster than nearby lowlands, a pattern seen in many mountain regions around the world. Their small glaciers, already fragile, have little resilience left as climate change accelerates.
The final years of Spain’s last glaciers are now being recorded in real time: thinning ice, vanishing lakes, and mountains stripped of the features that defined them for centuries. What happens next will determine not only the look of the landscape, but also the story future generations will tell about the moment the Pyrenees lost their ice.
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