The glaciers of the Pyrenees are in a dying phase. The last masses of ice that remain in the mountain range that separates France and Spain continue to retreat rapidly, according to the latest observations.
The sudden partial collapse of the Marmolada glacier, in the Italian Alps (with its aftermath of 11 deaths), is the most dramatic and striking example of the evolution of ice masses. But the waning trend of the perpetual ice in the Pyrenees is equally unstoppable, although more silent.
The 24 remaining glaciers in the Pyrenees (and totaling 229 hectares) have registered an average loss of 23.2% of their surface in the last 9 years (2011-2020), with an average decrease in the glacial area of 2.6% annual; and its thickness has been reduced by an average of 6.3 meters in this period.
Thus, it is indicated by a study published last year in the journal Geophysical Research Letter and which includes the studies of researchers from the Pyrenean Institute of Ecology (IPE-CSIC).
This work shows that "the retreat of the glaciers in the Pyrenees follows the same rhythm as in previous decades", explains Jesús Revuelta, a researcher at the aforementioned institute.
The frozen surface decreases at the same speed as it has been doing since the 1980s. The loss of the glacier area of 2.6% per year in the period 2011-2020 is similar to the rate of loss of 2.93% and of 2.59% registered in the period 2008-2016 and 1984-2008 respectively.
One might think or suppose that in a historical phase in which the glaciers are in clear retreat (and that they only remain in protected areas), these frozen masses “would melt more slowly; but it is not being like that, ”says Revuelta.
Among the large glaciers (more than 10 hectares), the one that has suffered the greatest retreat in these 9 years has been the Ossoue (25.7%), on the French slope, followed by the Aneto (24.4%) and del Maladeta (18.9%), while in the case of Monte Perdido its withdrawal has been less (12.8%).
The retreat of the glaciers is so pronounced that the aforementioned report suggests that these ice masses can be "contained" in marginal locations. And all this decay process "can cause the complete disappearance of most of the glaciers of the Pyrenees in the coming decades."
Since the mid-nineteenth century, the Pyrenees have lost 90% of the surface of its glaciers, which has been reduced to 229 hectares (0.29 km2).
The aforementioned study also indicates that the four large glaciers (Aneto, Maladeta, Monte Perdido and Ossoue) show a very similar, homogeneous and linear behavior; that is to say, in all of them, the more thickness loss occurs, the more shrinkage there is also on their surface; and vice versa.
On the other hand, the rest of the glaciers (those with less than 10 hectares) show a more heterogeneous evolution, since they lose surface and thickness but at variable rates, which suggests that topographical factors that have to do with the areas of shade against solar radiation or very local specific conditions. Some are located in the middle of the circus and others protected by rocks or in less exposed places, adds Revuelta.
In any case, the weather conditions in all of them are equivalent. It is estimated that the temperature has risen in the Pyrenees by 1.5 ºC in the last century, with especially marked rises in summer.
It is not that the glaciers disappear completely; many times small residual icebergs remain, immobile (unlike glaciers, which are dynamic, rivers of ice).
Satellite images, drones and other complementary comparative information have been used to determine the frozen areas.
Hikers and researchers especially highlight this year the rapid disappearance of seasonal snow. They have surprised, for example, the photos of Monte Perdido, previously devoid of snow, a circumstance that in principle should occur at the end of August or beginning of September, when the glacier reaches its minimum extension.
Jesús Revuelta explains that he himself has been able to verify this anomalous situation on an excursion to Aneto three weeks ago. "There was no longer the snow that protects the ice," he recalls.
The evolution of the ice in the Pyrenees is the same as that seen in the Alps. “A similar trend is observed, although those in the Alps are larger. Our thickest glaciers are like the middle glaciers in the Alps, but the trend you see is equivalent,” he says.
Can a deadly event similar to that of Marmolada in the Italian Alps occur in the Pyrenees? Jesús Revuelta says that it is “the million dollar question”; He emphasizes that in Italy there have been very special climatic circumstances, but above all he expresses his surprise at the way in which the column of ice completely detached. “The collapse took all the ice, up to the base of the glacier. It has been like a bite that has almost undermined the rock”, he sentences.
