- For 46 days, a Franco-Italian team of scientists, accompanied by three logisticians and an emergency doctor, ventured far on the Antarctic plateau, the time of a journey of 1.318 km they come from finish.
- The challenge ? Collect data on the accumulation of snow in areas where humans have never been, and thus try to solve one of the great unknowns of climate change: how does the Antarctic continent react to the current warming?
- Back at the Concordia scientific base, the members of this raid shared their first observations via videoconference.
The Franco-Italian Concordia scientific base, on the Antarctic plateau, at 3,100 km above sea level and 1,100 km from the nearest coast. It's hard to find a more hostile environment. For scientists of the EAIIST expedition (for East Antarctic International Ice Sheet Traverse), this was only the starting point. On December 7, they left it to venture even further towards the South Pole, to an area of megadunes never explored by humans.
Six hundred and fifty-nine kilometers in one direction, as much in the other, all under temperatures of - 25 to - 40 ° C as Antarctica knows in summer, and at a snail's pace. Between 10 and 12 km / h. Difficult to go faster for a convoy made up of fifteen maritime containers placed on sleds and pulled by crawler tractors. "The whole thing was 250 tonnes," says Anthony Vendé, logistics manager on this raid, this Thursday morning, during a videoconference organized from the Paris headquarters of the CNRS. In addition to the scientific equipment, we carried a scientific laboratory, a caravan for the life of the group, another dedicated to the storage of the energy necessary for the expedition… ”
Faster than expected!
The raid is complete. After 46 days in total autonomy, the Franco-Italian team - made up of about fifteen scientists, but also three logisticians and an emergency doctor * - is back at the Concordia base. “We even advanced a little faster than expected, says Anthony Vendé. Closer to 12 km / h than the 10 planned. And if we knew some technical glitches - a sled and a broken tractor engine -, they arrived at the end of the route and did not impact the raid too much. "
"Scientific expeditions of this magnitude are rare," recalls Jérôme Chapellaz, director of the French Polar Institute Paul-Emile Victor (Ipev), which coordinates and organizes logistical support for French science in the polar regions. EAIIST is the fourth raid organized in Antarctica since 2011, he slips. The longest and most complex we have had to coordinate. "
The big unknown in climate change?
The stake is worth the candle. Joël Savarino, research director at the Institute of Geosciences (IGE in Grenoble), scientific manager of the raid, refers to the special IPCC report on the oceans and the cryosphere, published on September 24th. "This points to the risk of a rise in sea level which could be + 80 cm by 2100 if we take the most pessimistic trajectory [scenario 8.5] taken into account by the IPCC," explains T it from Concordia station. But on this forecast, there is a large uncertainty of more or less 40 cm. "
What you can contemplate from a tractor of the #EAIST raid on the Antarctic plateau: the blue sky and the ice. pic.twitter.com/B2mFyqro6z
- IGE (@IGE_Grenoble) January 17, 2020One of the big unknowns, precisely, is how the Antarctic continent will react to global warming. "We already observe, on the coasts, an increased melting of the cap, via what is called in glaciology the" velages ", that is to say the production of icebergs by a glacier when masses of glasses are detach from it, ”begins Vincent Favier, physicist at the IGE and another member of the EAIIST expedition. But global warming would also have the effect of transporting warmer air to the Antarctic plateau, and therefore containing more humidity. This is potentially synonymous with more intense precipitation on the plateau. "It may be, then, that the accumulation of snow on the Antarctic continent increases and makes it possible to compensate, in part, for the loss of ice by calving," continues Vincent Favier. Which could moderate the rise of the oceans.
Check snow accumulation on the plateau
This is the main objective of this EAIIST expedition: to test this hypothesis by seeking to know if Antarctica gains or loses snow mass on its plateaus. Impossible to do from space. "The satellites are not precise enough to measure the accumulation of snow and its variations," explains Jérôme Chapellaz. What is more, to know the rate of accumulation in cm of water per year, a density measurement is necessary, possible only from the ground. "
During these 46 days of journeys, the EAIIST scientists collected the equivalent of six tonnes of ice on their journey. "This represents 900 meters of carrots, taken up to 200 meters deep," says Joël Savarino.
GPS, weather station, seismic stations
The mission was not limited to these samples. At the same time, the scientists carried out radar profiles to probe the stacking of snow layers and deploy on-site autonomous instruments, which continue to collect data at this time and will make it possible to obtain a complete seasonal record of the behavior of the ice. and precipitation on the various sites visited. “It is notably a GPS which will allow us to know the displacement of the ice on the surface, explains Joël Savarino. It is also a weather station, which will allow us to learn more about wind speeds or temperature variations. There are still five seismic stations that will record the different sounds of the earth: wave, tide, atmospheric circulation or the cracking of the ice cap, which will determine its thickness.
The data collected is being transferred to the coasts of Antarctica. They will then be transported by boat to France. Joël Savarino does not expect them before May or June. Then a long analysis work will begin. "It will take from six months to a year to have the first information on the rates of snow accumulation on the sites," evaluates the Raid's scientific manager.
A new raid in a year?
We will also have to go back in a year. This is the whole problem of the five seismic stations left behind. "The data they collect cannot be transmitted by satellite," says Joël Savarino. This will not necessarily be the subject of a new land convoy. "On the five sites, we have groomed a runway in order to allow an aircraft to return to the site and collect the data," specifies Anthony Vendé.
It remains to be seen whether these tracks will be practicable in a year… "Not sure", we recognize in the EAIIST team. This is why a new raid is not a track that has been ruled out to date. "This is one of the observations that we can draw from our expedition," says Joël Savarino. On the route taken, the ice is much harder than we imagined, so that it is not as difficult to access as we imagined for our vehicles. "
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* They were permanently ten on the convoy. Six scientists, three logisticians and the emergency doctor.
- science
- Ocean
- Global warming
- Snow
- Antarctic