Saturday, September 18

The glaciers of the Pyrenees have lost up to a fifth of their surface since 2011

A study led by researchers from the Pyrenean Institute of Ecology (IPE-CSIC) carried out between 2011 and last year in 17 of the 24 glaciers that exist in the Pyrenees reveals that they have lost more than six meters in thickness and up to a fifth of their surface , 23.3%.

Attention, ‘spoiler’: the disappearance of the Pyrenean glaciers already has a date

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In some, the thickness of the ice has decreased by an average of 10 meters, exceeding 20 meters in some points, and the reduction of ice in all of them has maintained a similar rate since the 1980s, according to this work in which different centers have participated. of research from Spain and France, whose main conclusions have been published in the journal “Geophysical Research Letters”.

As reported by the IPE, dependent on the Higher Council for Scientific Research (CSIC), researchers Ixeia Vidaller and Jesús Revuelta have led the publication of this international study in which the changes in area and thickness registered in the last decade have been analyzed.

As an example of these changes, they point to those observed in the Aneto glacier, whose losses are estimated at 24.3% in terms of its area and an average of 8.5 meters in thickness, registering decreases of up to 21 meters in some areas.

Among the most affected ice masses are the Ossoue glacier, in the Vignemale massif, which has suffered a 25.7% decrease in area and average thickness losses of 10 meters; or the Taillón glacier, which on average has lost 11.6 meters, exceeding 23 meters in its central area.

Although the climatic conditions do not vary much between the areas where the glaciers are located, since the climate has varied in a similar way throughout the Pyrenees, according to the scientists, the evolution of the ice “has been heterogeneous during this period.”

Thus, the smallest Pyrenean glaciers, with an area of ​​less than 10 hectares, such as Barrancs in the Maladeta massif, or Llardana in the Posets massif, are strongly controlled by the local topography. This is deduced from the contrast between their losses in area and those in thickness.

However, the largest glaciers are predominantly influenced by the climatic conditions of this mountainous region, so that the larger masses, such as those of Aneto, Maladeta, Ossoue and Monte Perdido, evolve in a similar way with losses in area and thickness. equivalents.

In this regard, the authors of the study emphasize the importance of having maps that show in detail the observed losses in order to monitor and understand the reasons why glaciers are becoming progressively more confined to protected areas, with less solar radiation and greater accumulation of snow.

In these areas, -as they predict- the glaciers may have a slower degradation, but in all cases they will be doomed to a progressive disappearance of the dynamics that characterize them.

The Pyrenean glaciers are the largest in southern Europe and their survival is threatened by climate change, so the results obtained in this work are a preview of what can happen in other mountain ranges of more northern Europe, such as the Alps. in which the glaciers also show a clear retreat.

The variations in the area of ​​the glaciers have been calculated with high-resolution images captured by different satellites with optical sensors, while the changes in thickness have been determined by comparing the 3D surfaces generated with drone flights (year 2020) and those obtained with a Airborne LiDAR sensor (year 2011).

According to the IPE, the use of this methodology has enormous potential, but its application is complex given the characteristics of the monitored areas, both at the flight and access level.

The authors of the study assess that the combination of flight techniques with drones and LiDAR has made it possible to quantify the variations in the surface of glaciers with an uncertainty of less than 0.4 meters.

Researchers from the University of the Basque Country, CESBIO and LEGOS of Toulouse, the MORAINE glaciology association, the University of Zaragoza and the University of Valladolid.

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