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Arcouzan, a dangerously melting glacier and an emerging bag

By 9 October 2023No Comments

Is the Arcouzan glacier the end of the story?

From 28 to 30 September, a multi-disciplinary team made up mainly of skilled surveyors, specialists from the National Park and supported by TERIA and TOPCON, the experts in GNSS technology, headed into the Ariege Pyrenees on a large-scale scientific and geodetic mission with alarming conclusions.

A human mission requiring a multidisciplinary team.

This September, a team made up of several participants from all over France joined forces for a common 3-day mission.

The team included members of TERIA, co-organiser and co-funder of the expedition, several surveyors and representatives of TOPCON, supplier of GNSS equipment and co-financer. The expedition was also accompanied by a number of students, including topography students from the Lycée Caousou (Toulouse) and the Ecole Supérieure d’Ingénieurs des Géomètres et Topographes (ESGT – Le Mans). Last but not least, the management of the Ariege Pyrenees Regional Nature Park was present, as were a number of qualified guests…

A glacier like no other

Since 2011, TERIA and Géomètres-Experts/ Expert Surveyors have been leading an expedition to the Arcouzan glacier, which is in a unique location.

The Arcouzan glacier is the most isolated glacier in the Ariège Pyrenees. It is located at an altitude of almost 2,500 metres. Nestling at the foot of the north face of Mont Valier, which peaks at 2838m, this glacier is relatively sheltered from the wind and rarely gets any sunlight. Tucked away in the mountains, it also benefits from the snowfall from Mont Valier, which allows it to replenish itself.
For these reasons, until 2016, the glacier remained relatively unaffected by the ravages of global warming, and its surface area was even increasing.

However, since the measurement carried out in 2016, a downward trend has been observed.
In 2021, a particularly remarkable occurrence took place. A tunnel fed by currents of warm air was observed to have formed and sunk into the very heart of the glacier.

Experience the climb again on video

Cutting-edge technology for an alarming conclusion.

The melting of the Arcouzan glacier is a major source of concern. The observations made during this expedition revealed a reduction of several metres. This reduction confirms the downward trend of recent years.
This reduction is not surprising. It is largely attributable to two consecutive years of drought, which have not allowed the glacier to replenish its ice reserves. We have seen the same phenomenon on the summit of Mont Blanc, where the altitude and volume of the ice cap have decreased.

The judicious use of high technology such as TERIA’s PYX and TOPCON has enabled us to take centimetre-accurate readings, giving us a precise picture of the evolution and extent of this worrying melting.

For these reference measurements, the team used high-tech equipment: TERIA’s PYX receivers, HiPer VR GNSS receivers equipped with radio and the FC 5000 TOPCON data collector for use as a mobile base, and finally the GLS 200 scanner for modelling the glacier. All the equipment was connected in real time to the TERIA and TERIAsat services.
Sequences of satellite data were also recorded for subsequent post-processing calculations.

In parallel with the expedition on the glacier, a team also went to measure the highest point on the summit of Mont Valier (different from the official point used by the IGN), using the PYX and the TERIAsat service.

Here is the history of the latest measurements of the glacier’s surface area:


Year  Surface Area(m2)
2011 18600
2012 19700
2013 25200
2014 28100
2016 24800
2018 26000
2021 17800

 Mont Valier rises to 2839,02m.
At the symbolic summit cross

The altitude of the official confirmed IGN point is 2838,06m.

Surprising discovery of a 40-year-old backpack

One of the most surprising discoveries of this expedition was the discovery of a backpack trapped in the ice. After analysing the expiry dates of the items found inside the bag, it was determined that it had been buried in the ice since 1986. It is plausible that the French-branded bag slipped into a crevasse or fell from the summit of Mont Vallier. It is a poignant illustration of the vertiginous upheavals that have affected the glacier over the decades.

This unusual discovery is causing concern because it highlights the considerable melting of the glacier. According to the expedition’s regulars, the glacier has never been so threatened since the first measurements were taken. Although similar periods of drought have been recorded around the world in the past, it is undeniable that current global warming is a contributing factor.

Sac a dos vieux de 40 ans emprisonnédans la glace

TERIA is involved in a number of topographical and scientific expeditions.
Find out more about our other missions.

TERIA, as a partner in expeditions such as the measurement of Mont Blanc, which has been decreasing for 2 measurements (4805.59 m), and Manaslu (8164 m), and the monitoring of endangered species, particularly in Antarctica is joining forces with the scientific community to raise public awareness of the importance of taking action to combat global warming. The results of this expedition confirm the need for collective action on a global scale to preserve our planet’s glaciers and fragile ecosystems.

Want to find out more about our other campaigns?

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