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RTD info logoMagazine on European Research Special issue - May 2005   
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Title  ACEX: The Arctic coring expedition

In August 2004, an international group of scientists retrieved a 370-metrecore from the seafloor beneath the Arctic ocean, providing them with55 million years of Arctic climate data.

Funded by 16 European countries and supported by the European Union (through an ERA-NET), the United States and Japan, the international Integrated Ocean Drilling Program (IODP) instigated the €9.5 million Arctic Coring Expedition (ACEX) with the aim of better understanding both the climate history of the Arctic region and the role which the Arctic has played and continues to play in the Earth’s ongoing climatic variations.

Located 1 200 metres below the surface and roughly 230 kilometres from the North Pole along the deep Lomonosov Ridge, the Arctic’s first scientific borehole was cored by a fleet of three powerful icebreakers: the Norwegian Vidar Viking for drilling, the Swedish Oden and the Russian Sovetskyi Soyuz for protecting the coring platform from the harsh Arctic environment and drifting sea ice. The Lomonosov Ridge was selected as the best possible drilling site due to its eroded aspect and the absence of more recent, less interesting sediment deposit such as would be found on oceanic valley floors.

According to the expedition’s co-chief investigator, Jan Backman of the University of Stockholm, initial analysis of the microfossils found in the core show evidence of massive fluctuations in the water temperature and general environmental conditions of the Arctic over the past 55 million years. Indeed, the Lomonosov core is the first to show evidence of ice-free, subtropical, shallow seas with water temperatures of 20˚C compared to today’s average temperatures of –1.5˚C. Such a truly massive cooling of the Arctic Ocean, which is thought to be responsible for the mass extinction of sea-bottom-living organisms, suggests that worldwide environmental conditions are much more variable than previously anticipated.

The ACEX coring site on the Lomonosov Ridge crest, at 1124 metres down, is an optimum drilling site as erosion has exposed very old sediments. © Courtesy of IBCAO/IODP
The ACEX coring site on the Lomonosov Ridge crest, at 1124 metres down, is an optimum drilling site as erosion has exposed very old sediments.
© Courtesy of IBCAO/IODP
    
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