Research efforts in the Laptev Sea offer clues as to how much new ice is formed each winter. But in order to assess the fate of the Arctic sea ice, the researchers also need to determine how much ice flows back out of the Sea. One of the most important outlets is the Fram Strait – the sea lane between Greenland and Svalbard. Each year, between 500,000 and 800,000 square kilometres of sea ice – an area roughly twice the size of Germany – flow through the strait from the Arctic Ocean to the northern Atlantic.
The motor of this ice transport is the transpolar drift, a major current that pushes ice from the Russian marginal seas of the Arctic Ocean over the North Pole and toward the Fram Strait like a giant conveyor belt. “We are working to better estimate the ice mass balance in the Arctic by examining two factors – how ice is created in the Laptev Sea, and how it is lost again via the Fram Strait – in relation to one another,” says Thomas Krumpen.
As a rule, it is only the sea ice formed in the Laptev Sea in the early winter that survives its first summer. Caught by the transpolar drift, it is transported to the central Arctic. Once there, it can remain two to three years, growing to several-metre-thick pack ice in the process, before passing through the Fram Strait and into the Atlantic, where it melts. In contrast, the ice formed in the late winter usually melts before it can flow out of the Laptev Sea.
Over the past several years, Thomas Krumpen and his colleague Stefan Hendricks have regularly taken part in plane or helicopter flights over the Laptev Sea and the Fram Strait. During these flights they rely on the EM-Bird, a device that can measure differences in electrical conductivity from the air, allowing it to determine how thick the ice is.