The Pyrenees’ three main glaciers—Aneto, Monte Perdido and Ossoue—lost more than two metres of thickness on average during the 2025–2026 measurement period, despite abundant spring snowfall. The losses rank among the largest recorded, exceeded only by those in 2022 and 2023, according to researchers from the CryoPyr group at the Pyrenean Institute of Ecology (IPE-CSIC).

The team attributes the severe melt primarily to exceptionally high temperatures that lasted longer than usual. This summer was the warmest in the Pyrenees since records began, at 3.4 degrees above the 1991–2020 average, said research group leader Nacho López-Moreno. He added that the outcome would have been even worse without the spring snow.

Researchers have monitored the region’s glaciers since 2011, using drone surveys and photographs to estimate changes in thickness. They also report increasingly dark ice, where rocks and debris gather on the surface. The material absorbs more solar heat and contributes to faster melting.

Ossoue, on the Spain-France border, was among the hardest hit, with an average loss of more than three metres and local losses approaching five metres. The glacier has barely moved for several years, raising the possibility that it is becoming a stagnant ice mass, known as an ice patch.

Aneto, the Pyrenees’ largest glacier, lost an average of 2.4 metres, with a maximum recorded loss of 4.8 metres. Its ice has split into four sections, two of which are already considered ice patches. Falling rocks and increasingly steep ice have made the traditional route across the glacier too dangerous for guides to recommend. Researcher Jesús Revuelto said climbers can now reach Aneto’s summit without stepping on ice, something that was not possible four years ago.

Monte Perdido, previously the best-preserved of the group, recorded an average loss of 2.3 metres, with a maximum of six metres. New areas of exposed rock are also contributing to melting, while part of the glacier is showing signs of degrading into a remnant ice patch. The Llardana glacier, below Posets peak, lost an average of 1.5 metres and is increasingly covered by debris.

The researchers say the 2025–2026 results continue a decades-long trend of decline and show how vulnerable the southernmost glaciers in Europe are to prolonged, warmer summers. CryoPyr monitors 14 glaciers in the Pyrenees; López-Moreno said many may no longer remain by next year.

Sources: El País Ciencia.