Blue specks in the white north

Written by Ellen Viste, communication adviser, Bjerknes Centre for the Climate Research.

– Sometimes when we look out of the window, we wonder if we are in the open sea, says Stijn De Schepper.

The research leader at NORCE and the Bjerknes Centre writes by email from the research vessel Kronprins Haakon, an icebreaker, on a cruise in the Arctic Ocean. He describes a journey through surprisingly navigable sea ice.

This week Kronprins Haakon reached the North Pole – the first time without needing assistance to get through the ice.

Paradoxically, the lack of sea ice makes it easier for the research team onboard to complete their mission: to explore what happens as the Arctic Ocean turns from white to blue.

By the middle of the century the Arctic Ocean may be open water during summer, even with moderate CO₂ emissions. For the first time in history, ice melt in large regions is caused by human activity.

Periods with little ice occurred before. About three million years ago the Arctic Ocean was ice-free in summer. Summers might also have been ice-free during the last interglacial.

Conditions differed largely from today, also between these periods, but as a common denominator, Arctic temperatures were higher. The researchers onboard Kronprins Haakon exploit this past climate parallel to the future.

Together with Jochen Knies from the University of Tromsø, Stijn De Schepper, affiliated with the University of Bergen and NORCE as well as the Bjerknes Centre, leads the European Research Council Synergy Grant Project "Into the Blue".

Their aim is to find out how the ice in the Arctic will evolve in a warmer climate, and how these changes will affect nature and society. Samples from the seafloor will provide the required data.

To find out what happened in the past, the scientists collect sediments. Long tubes are pressed into the seafloor. When pulled up, the tubes are filled with sediments – meters of mud and fossile remains of plants and animals, deposited layer by layer over the years.

Fossiles, pollen, spores, DNA and other substances in the sediments can provide information about the climate at the time when the plankton, animals or plants they came from, were alive.

From various locations in the Arctic, samples have previously been taken up to 8 meters into the sea floor. In addition to such short sediment cores, the researchers on Kronprins Haakon extract cores of 22 meters.

Twenty-two meters is considered long in this context. No one has retrieved sediment cores that long from the Arctic Ocean before, and both ice ages and interglacial periods have passed since the deepest layer of mud was deposited.

"We often discuss how old the sediments we have cored, could be," says Stijn De Schepper. "They will give information about the climate of the last 400 000 years, possibly even a million years."

Such long data series from the Arctic Ocean do not yet exist.

A few decades ago, having to break through three to four meters of ice to reach the North Pole, was common. Arctic warming makes it easier to get there now.

– I do not think we have seen sea ice thicker than two meters, says Stijn De Schepper.

– The Arctic Ocean is still white, but it has large, blue specks

Go along on the journey through the Arctic Ocean! Here you will find the scientists' own cruise blog.