It is summer and the air temperature is just below freezing. Fog has crept in, blurring the outline of Polarstern, the German icebreaker moored to a kilometre-long ice floe at 85 deg N latitude. Next to a hole we have just drilled through 1.4 metres of ice, Morten Iversen, who studies the flow of carbon around the ocean, has attached several plastic containers to a rope secured by ice screws. They will be left hanging in the water under the ice for a day to catch marine snow – clumps of dead algae and zooplankton faeces that sink from the upper ocean to the deep sea.
A few metres away, a team of biologists perforate the ice floe with a core drill. They are looking for algae that grow at the bottom of sea ice, which play an important role in the Arctic Ocean food web. Metre-long ice cores are pulled up, packed in plastic sleeves and stacked on a sledge to be processed in the ship’s laboratories.
