Article from new Tara’s 10th journal
Like a whale in migration, the polar schooner Tara returned to service in the ice sheets in 2015: destination Greenland. Designed for the icy polar seas, she spent last summer in the element she knows best.
Sea ice, or how the Tara went back to fundamentals. Already back in 2004 our favourite polar sailing boat, under her then new owners Étienne Bourgois and Agnès Troublé (agnès b.), undertook an initial research expedition to Greenland in partnership with the Arctic ecology research group GREA. Étienne Bourgois, Jean Collet and ornithologists Olivier Gilg and Brigitte Sabard took part in this first voyage. In early July 2015 they decided to renew acquaintance with the east coast of the great white island in order to study its fauna and collect information which could then be compared with the data of eleven years ago.
Tara Arctic: A First Since the Drift of the Fram in 1893
Nearly ten years ago the Tara’s first polar mission, known as Tara Arctic (2006–2008), was directed by Jean-Claude Gascard, oceanographer at the Pierre and Marie Curie University, CNRS research director, and coordinator of the European scientific programme DAMOCLES (2005-2010). It was a massive expedition which involved the ship drifting with the polar sea ice in order to study the effects of global warming around the North Pole, a feat last attempted in 1893 by the Norwegian explorer Fridtjof Nansen and his sailing ship the Fram.
Climate prediction is one of the most important issues of our day. We know that data for climate predictions can be found in the ocean and, consequently, sea ice.
After fifteen months locked in the ice pack, the Tara finally broke free and was able to head home with a scientific treasure trove of data collected from the atmosphere up to a height of 1,500 metres and from the freezing Arctic Ocean down to a depth of 4,000 metres. Air and water temperature, pressure, salinity, wind force and the ice sheet were all closely monitored in real time.
In 2013, in association with CNRS research director Éric Karsenti at the European Molecular Biology Laboratory (EMBL), Tara Expeditions concluded the extraordinary adventure that was Tara Oceans with a tour of the Northern Ocean to study its plankton. Today the data collected during the Tara Oceans expedition (2009–2013) constitutes an undreamed of resource for the scientific community, providing as it does a catalogue of several million new genes extracted from the world of plankton. In short, Tara Oceans has changed the way we study the oceans and assess climate change.
With sound knowledge of polar regions in mutation and ever-increasing scientific expertise, which has met with a positive response from the world’s research community, Tara Expeditions intends to establish itself as an international voice on environmental issues. For Étienne Bourgois, the founder of Tara Expeditions, and Romain Troublé, the organization’s general secretary, the aim is to raise awareness not only of the ocean but also of sea ice.
“While the ocean is covered with ice it is isolated
from the atmosphere but once the lid comes off,
the ocean finds itself once again in contact with the atmosphere
and this can lead to intense exchanges of heat and humidity.”
Marie-Noëlle Houssais, specialist in polar oceanography and sea ice at the Oceanography and Climate Laboratory (LOCEAN) of Pierre and Marie Curie University (Paris), shares this aim. She studies interactions between sea ice and the polar oceans. Satellite observations of the cryosphere over the last thirty-five years show a large decrease in the summer range of Arctic sea ice. In 2012, which saw a record minimum for the period, ice cover was estimated to be diminishing at a rate of fourteen per cent per decade. “Over the last ten years we’ve talked a lot about the reduction in ice volumes, which became apparent from ice thickness data collected in the late 1990s,” explains the CNRS research director. “Even though the quantity of perennial ice seems to have stabilized in the last two or three years, we cannot yet say if the trend has been reversed or not because we lack perspective. In recent winters the reduction in ice cover has been much less significant despite sectors such as the Barents Sea seeing ice range retreat at a rapid rate.”
Looking to the Ocean and Ice for Climate Predictions
The stakes are high in this Atlantic sector of the Arctic Ocean where fishing interests and all kinds of prospecting activities exert immense influence. In summer it’s the atmosphere which contributes to the thaw of surface ice, while in winter the ocean is instrumental in subglacial thaw.
“The climate is first and foremost the atmosphere,” confirms Marie-Noëlle Houssais. “While the ocean is covered with ice, it is isolated from the atmosphere but once the lid comes off, the ocean finds itself once again in contact with the atmosphere and this can lead to intense exchanges of heat and humidity. Thus ice cover in late summer or late autumn has the potential to precondition the climate in the few months that follow. This means that it has an impact on winter climate in Arctic regions, as well as on temperate zones through large-scale interactions.” Climate prediction is one of the most important issues of our day. We know that data for climate predictions can be found in the ocean and, consequently, sea ice. “We are beginning to be able to predict ice cover in terms of a season but the challenge is to extend our forecasts beyond a period of twelve months.” And then there’s the ocean in its entirety. “Sea ice is nothing more than a frozen ocean at the surface,” adds Marie-Noëlle Houssais. “In the deep ocean, the influence of the climate is much more ‘long term’ because the phenomena are much slower. In this instance, we can expect to produce forecasts on the scale of a decade and beyond.”
Fluctuations in the surface temperature of the North Atlantic affect the Arctic and the global climate over many decades. On the other hand, the Arctic also influences water circulation in the Atlantic, both at the surface and at depth. This potentially hinders the descent of dense, cold water from the Arctic and its subsequent rise to the surface in equatorial regions.
A Second Arctic Drift Planned for 2019–2021
Tara Expeditions’ policy recommendations, which call for the ocean to be recognized as a key factor in the climate system, draw their inspiration from the expertise of scientists. This sound basis allows the organization to position itself as a consultative body for international institutions. After launching the High Seas initiative and being granted UN observer status, Tara Expeditions can now expect to be accepted as an observer to the Arctic Council.
In the meantime the Tara has been preparing her return to the polar ice pack. A second Arctic drift, following on from the one which began in 2006, is already scheduled for 2019–2021.
Dino Di Meo
Tara’s Journal is available for free at Tara’s “Ocean & Climate” Pavilion