Sea ice in the central Arctic hasn’t melted quite as much as expected this summer. Instead, there was an unusually large amount of snow on the sea ice in August and September, said Marcel Nicolaus, sea ice physicist at the Alfred Wegener Institute in Bremerhaven.

Nicolaus and a research team led by AWI director Antje Boetius spent two months on the icebreaker “Polarstern” to the North Pole to measure the properties of the sea ice. The ship is expected back in Bremerhaven on Saturday.

“The Arctic sea ice is actually characterized by the fact that there is no snow on it in summer and it is covered with ponds,” Nicolaus said at an online press conference broadcast from ship. One explanation for the phenomenon is the unusually stable low pressure area in summer, which caused cold polar air in the Arctic.

Hardly any ice algae on the underside of the sea ice

In view of the global record summer of 2023 and the rapid melting in May and June, the researchers actually expected there to be particularly little sea ice in the Central Arctic. Instead, the ice thickness was around 1.2 meters – more than in the particularly bad years of 2020 and 2012.

“That was extraordinary,” said Nicolaus. “The snow saved the ice.” The snow ensured that the ice was protected from surface melting.

At the same time, unlike usual, hardly any ice algae formed on the underside of the sea ice. “The ice looked completely different than in previous years, it was dead, so to speak,” said Antje Boetius. In the past, entire algae forests would have hung under the ice, which served as a source of nutrients for the underwater ecosystem.