Claim: The climate changed rapidly alongside sea ice decline in the north

by University of Copenhagen, Dec 6, 2020 in WUWT

Researchers from the Niels Bohr Institute, University of Copenhagen have, in collaboration with Norwegian researchers in the ERC Synergy project, ICE2ICE, shown that abrupt climate change occurred as a result of widespread decrease of sea ice. This scientific breakthrough concludes a long-lasting debate on the mechanisms causing abrupt climate change during the glacial period. It also documents that the cause of the swiftness and extent of sudden climate change must be found in the oceans.

Scientific evidence for abrupt climate change in the past finally achieved

During the last glacial period, app. 10,000 – 110,000 years ago the northern hemisphere was covered in glacial ice and extensive sea ice, covering the Nordic seas. The cold glacial climate was interrupted by periods of fast warmup of up to 16.5 degrees Celsius over the Greenland ice sheet, the so called Dansgaard Oeschger events (D-O).

These rapid glacial climate fluctuations were discovered in the Greenland ice core drillings decades ago, but the cause of them have been hotly contested. D-O events are of particular significance today as the rate of warming seems to be very much like what can be observed in large parts of the Arctic nowadays. The new results show that the abrupt climate change in the past was closely linked to the quick and extensive decline in sea ice cover in the Nordic seas. Very important knowledge as sea ice is presently decreasing each year.

“Our, up until now, most extensive and detailed reconstruction of sea ice documents the importance of the rapid decrease of sea ice cover and the connected feedback mechanisms causing abrupt climate change”, says Henrik Sadatzki, first author of the study.

Sediment core and ice core data were combined in order to achieve the result