Aneto is the highest mountain in the Pyrenees and in Aragon, reaching a height of 3,404 m a.s.l. It stands in the Spanish province of Huesca, within the Posets-Maladeta Natural Park, just 6 km south of the French border. It forms the southernmost part of the Maladeta massif, which accounts for more than half of all glaciers in Spain, all located in the Pyrenees.
Its northern side holds the largest glacier in the Pyrenees, covering <0.5 km2 in 2022. The Aneto glacier is shrinking rapidly due to rising summer temperatures and reduced winter precipitations over the 20th century: it covered 1.067 km2 in 1981 and 0.79 km2 in 2005. It is estimated that it has lost more than half its surface area in the last 100 years, and that it may disappear around 2050.
Glacier surface loss in the Pyrenees is remarkable: there were 52 glaciers in 1850 and only 21 in 2020, corresponding to an area of 20.6 km2 and 2.3 km2 respectively, representing a loss of nearly 90% of the glaciated area.