[A look back at the outcomes of Tara's scientific expeditions] - Thanks to Tara, its legendary schooner and an exceptional oceanographic vessel, Tara Ocean Foundation has been carrying out ambitious expeditions across the global Ocean for the past 21 years. In 2006, it embarks on its first transpolar drift, yielding crucial results on the situation of Arctic ice. Then in 2009, it sets out to explore microorganisms, also called plankton, the invisible Ocean’s peoples. In 2016, coral reefs are at the heart of the expedition. Plastic and the effects on the environment of this chemical pollution are the focus of expeditions between 2014 and 2019. Discover the main scientific outcomes of these expeditions in this series of articles. This month : Tara Arctic
Interviews conducted in Lorient, France, on October 5, 2024.
Tara on the Arctic pack ice @ Grant Revers – Tara Ocean Foundation
20 years of expedition at the service of fundamental research
For over 20 years, the Tara Ocean Foundation has been taking international scientists on board the Tara schooner. The aim is to gain a better understanding of the ocean through time and expeditions. Few oceanographic missions, like Tara, take an interest in a specific ecosystem over several months, or even several years on a global scale, using the same standardised protocols.
For each expedition, a collective of interdisciplinary scientists is put in place, with around thirty laboratories from a dozen countries involved. All the data collected during the expeditions and analysed mainly in France are made available to the international scientific community in open source format so that all research teams can make use of this wealth of information. Research conducted with this data leads to new knowledge and contributes to improving the governance of the Ocean.
Tara meets the North Pole: the transpolar drift
In 2005, the European Commission’s research programme proposed to fund a study programme on the extreme climatic phenomena that could affect Europe in the future. The Damocles Project, proposed by 55 laboratories, won the tender, proposing to study the future influence of the Arctic on the European climate.
Jean-Claude Gascard, Director of Research at the French National Centre for Scientific Research (CNRS) is the project director and backer. Exchanges between him and Etienne Bourgois from the Tara Ocean Foundation led to the launch of the Tara Arctic expedition. This will be followed by a 500-day transpolar drift during which Tara, the schooner, will follow the same trajectory as her only predecessor, Fridtjof Nansen’s FRAM in 1893.
Tara achieved this drift more than a century after FRAM’s first Arctic transpolar drift, but it was four times faster due to the change in Arctic conditions encountered!
Jean-Claude Gascard, scientific director of Tara Arctic Damocles
Around the schooner drifting with the sea ice, a scientific camp is quickly set up to deploy a series of instruments and sensors such as :
A weather station
An atmospheric balloon (to measure temperature)
Autonomous beacons, radiometers (to measure the albedo)
A seismometer
Instruments and sensors deployed around the drifting schooner @Tara Ocean Foundation
Major retreat of summer ice at the North Pole
Shortly after the expedition, initial results showed that the surface of the ice pack in the summer of 2007 had shrunk significantly (from 8 km2 to 4 km2). This is a real record, which will be confirmed in 2012, so if this trajectory had continued, there would already be no ice pack in the Arctic at the end of summer.
Before 2007, the volume of Arctic ice pack oscillated between 15,000 km3 and 30,000 km3 due to seasonal fluctuations. But researchers found that between 2007 and 2012, the volume of pack ice only fluctuated between 5,000 km3 and 25,000 km3.
Based on this finding, the forecasts predicted a very sharp fall in ice levels in the following years, but in the end, ice levels seem to have stabilised since 2012. The forecasts made in 2007 have therefore proved to be inaccurate.
The degradation process has slowed and stabilised the melting of Arctic sea ice over the last 12 years (since 2012). The causes and consequences of this phenomenon are still being studied: “The models have not yet provided clear answers, and various hypotheses are still being tested” says Jean-Claude Gascard.
The Arctic paradox
Despite the obvious loss of ice, scientists have noted that the surface of seasonal ice (young ice) has increased while that of old ice has decreased. This paradox can be explained by the change in the seasonal cycle of Arctic sea ice, i.e. a large amplitude of seasonal ice that now covers an area of 10 million km2 (that is 4 million km2 more).
Nearly 10,000 gigatonnes of ‘old ice’ disappeared (net loss) in the Arctic during the transition from the 20th to the 21st century. This young ice is thinner and more mobile. “It is important to ensure the continuity of observations over the long term, which is why we are looking forward with great interest to the implementation of Tara Polar Station“, concludes Jean-Claude Gascard.
It is important to continue scientific monitoring at the North Pole to be able to anticipate future changes. The Arctic is essential to the equilibirum of our planet, and especially that of our Northern Hemisphere, which is why the Foundation is launching, in the framework of France’s Polar Strategy, a new kind of oceanographic vessel dedicated to polar drift research. It will set sail on its first expedition in the summer of 2026.
