In recent decades, the Arctic has warmed 3 to 4 times faster than the rest of the world, a phenomenon known as Arctic amplification. The effects of global warming are particularly visible in the melting of sea ice, continental glaciers and permafrost. But many other disturbances are much harder to observe, particularly in the pelagic and benthic ecosystems of the Arctic Ocean. These polar zones, remote and difficult to access, are still very poorly understood, even though they play a key role in climate regulation.
As part of the REFUGE ARCTIC project, led by Mathieu Ardyna (IRL Takuvik, Université Laval, Quebec), an international oceanographic expedition was organised from 08/08 to 03/10/24 in the Canadian Arctic Archipelago. Aboard the research icebreaker CCGS Amundsen, operated by the Canadian Coast Guard with the support of Amundsen Sciences, more than 80 scientists took it in turns for 2 months to sample these little-known ecosystems.
Departing from Iqaluit, the capital of Nunavut, the first leg focused on the fjords, continental glaciers and the Lincoln Sea. After a crew change at the American base in Thule, north of Greenland, the second leg explored the Nares Strait, which links the Baffin Sea to the Lincoln Sea, navigating through ice and icebergs.
Three LSCE teams (GEOTRAC, OCEANIS and PALEOCEAN) were involved in the project and took part in the polar expedition. The work carried out at sea focused on the dynamics of the air-sea interface, the physico-chemical properties of the last multi-year ice sheets, oceanic food webs, the carbon and carbonate cycle and the transfer of contaminants (trace metals, mercury, micro-plastics). The LSCE teams analysed and collected numerous samples of sea water, ice and sediment.
The samples will return to France in December 2024 and we will study them over the next few years. The expected results will enable us to better quantify the level of acidification of Arctic waters, to understand the oceanic carbon cycle with measurements of organic and inorganic (δ13C and ∆14C), dissolved and particulate carbon isotopes, and to identify the different water masses with water isotopes. The study of sedimentary deposits, which bear witness to past changes in these particularly sensitive and vulnerable areas, will provide information on recent upheavals, particularly at the start of the Holocene period, which was warmer than the pre-industrial period.
Photos : LSCE and Science Amundsen