All glaciers in the Pyrenees show major regression, in terms of both surface area and thickness. In 1850 there were an estimated 2,060 hectares of ice, whereas today there are just 170, which means a loss of 92%, and the ice mass continues to decrease. Since 2011, the glaciers have lost more than 63 hectares of ice, equivalent to 19 million tons of water. The Aneto glacier, in particular, is in serious danger of disappearing completely.

According to a recent study led by the Pyrenean Institute of Ecology (IPEC-CSIC) in which representatives of the universities of Extremadura, Vitoria, Valladolid, and Toulouse also participated, the glacier is deteriorating rapidly, and this could lead to its disappearance within 10 years if temperatures continue to rise at the current rate (in the Pyrenees the average temperature has risen 1.6º since 1959, 1.2º of this since the 90s).

This study analyzed the evolution of the Aneto glacier from 1981 to 2022. It shows that over the last 41 years the glacier has lost more than 64% of its surface area, and that the thickness of the ice has decreased by 30.5 m, standing at 11.9 m in 2022.  The average annual loss is 1 m of thickness, but the high temperatures recorded in 2022 tripled that loss and it looks as if the same thing will happen in 2023. Hardly any surface area remains for snow to accumulate in winter.

The glacier has split into two bodies, and the largest part is set to fragment into three, which will further accelerate its disappearance.

Nor does it help that there are an increasing number of rock falls on the glacier produced by the melting of the water accumulated in fissures in the rock cirques, the higher parts of the mountain. This has two other consequences: the decrease of the albedo effect caused by the layer formed by the detached material, which creates a "radiator effect", and the appearance of "black ice".

In August 2023, a group of biologists and geographers climbed the Aneto glacier to study this "black ice", a kind of dark mucus a microcosm of bacteria, archaea, and dust. These black layers accumulate heat that adds to the heat in the air and increases the rate at which the ice is melting. As the IPEC points out, "the glacier is at a point of no return."