- 1NORCE Norwegian Research Centre AS, Climate & Environment, 5007 Bergen, Norway
- 2Department of Earth Science, University of Bergen, Bjerknes Centre for Climate Research, 5007 Bergen, Norway
- 3Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, 27568 Bremerhaven, Germany
- 4Faculty of Geosciences (FB5), University of Bremen, 28359 Bremen, Germany
- 5Key Laboratory of Marine Chemistry Theory and Technology, Ocean University of China, 266100 Qingdao, China
To better understand processes in the Nordic Seas and their connections to large-scale climate variability during Dansgaard-Oeschger (D-O) events, we reconstructed sea ice conditions and subsurface temperatures in the eastern Fram Strait for the period between 40 and 33.5 ka b2k. By integrating our new results with comparable sea ice records from the southeastern Nordic Seas and a published reconstruction of Atlantic Meridional Overturning Circulation (AMOC) strength, we find that AMOC strength cause both expected and unexpected changes in sea ice extent in the Nordic Seas during the study period that spans multiple D-O events.
Under strong AMOC states during Greenland Interstadials, the eastern Nordic Seas were ice-free, likely driven by substantial ocean heat transport via the consistent inflow of warm Atlantic Water. A similarly strong AMOC states was, however, related to an extensive sea ice cover in the eastern Fram Strait despite ice-free conditions in the southeastern Nordic Seas during Greenland Stadials. Despite a comparable strength of AMOC, less heat reached the eastern Fram Strait during Greenland Stadials than during Interstadials.
When the AMOC strengthened, sea ice extent steadily increased in the eastern Fram Strait, while the southeastern Nordic Seas showed a pronounced decreasing trend. This suggests enhanced oceanic heat release in the south before it was transported to the north.
During a somewhat weakened AMOC state, sea ice occupied all of the eastern Nordic Seas independent of whether it was a Greenland Stadial or Interstadial, suggesting an enhanced heat release in the North Atlantic and a deepening of the Atlantic Water layer in the Nordic Seas.
When the AMOC was weak, the southeastern Nordic Seas were largely frozen, while the eastern Fram Strait experienced seasonal ice-free conditions, regardless of whether it was during Greenland Stadials or Interstadials. This pattern suggests that the heat which accumulated beneath the halocline and sea ice cover in the eastern Nordic Seas eventually upwelled, when the submerged Atlantic Water encountered the continental slope in the eastern Fram Strait.
How to cite: Wong, W., Risebrobakken, B., Ödalen, M., Tisserand, A. A., Fahl, K., Stein, R., and Jansen, E.: Ocean control on glacial sea ice in the Nordic Seas, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19343, https://doi.org/10.5194/egusphere-egu25-19343, 2025.
