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POLARPROG-Polarforskningsprogram

Abrupt Arctic Climate Change

Alternative title: Brå klimaendringer i Arktis

Awarded: NOK 12.1 mill.

Project Number:

325333

Application Type:

Project Period:

2021 - 2026

Funding received from:

Location:

Partner countries:

Dansgaard-Oeschger events, rapid climate shifts between warmer and colder intervals, characterised the last glacial period. While extensively investigated, the mechanism behind these profound climate changes is still debated. The Nordic Seas is by many considered a key area that needs to be understood. During the cold phases, the whole Nordic seas were covered by sea ice. During the warm phases, open water was present in parts of the Nordic Seas. How the sea ice cover changes through these events have a profound impact on the ocean atmosphere heat exchange as well as the ocean circulation. To obtain a better understanding of the role of sea ice and ocean changes we investigate how these changed in the northernmost part of the Nordic Seas, the Fram Strait, at unprecedented detail. Sea ice was present throughout, both during the cold and warm phases. During the cold phases, polynyas occurred repeatedly. During the warm phases, seasonal sea ice formed. The transitions between cold and warm phases see significant changes in productivity of foraminifera, fresh water influence and deposition of ice rafted debris, in addition to maximum sea ice concentrations.

The last glacial was characterized by a series of abrupt climate shifts between cold stadials and warm interstadials (DO-events). A link is documented between sea ice variability in the southern Nordic Seas and air temperature change over Greenland, with sea ice identified as a key determination factor for setting up these large, abrupt climate shifts. However, the spatial extent of the sea ice cover is still unknown and several unanswered questions remain, e.g.: When the sea ice cover broke up in the southern Nordic Seas during the stadial-to-interstadial transitions, how far north did it break up? How different were the timing and duration of the events in the northernmost Nordic Seas relative to the southern Nordic Seas? What were the magnitude and timing of changes in the vertical stability of the ocean? What triggered the abrupt, full basin scale changes? In ABRUPT we will reconstruct the sea ice conditions, hydrography and climate of the Fram Strait, with an unprecedented resolution for this area, over two targeted DO-events. These reconstructions and a regional data synthesis will be used in combination with multi-model output from four state-of-the art GCM glacial simulations, for an integrated analysis of the dynamics of abrupt Arctic climate change during the last glacial. Furthermore, the stadial Nordic Seas bear strong resemblance with the present Arctic Ocean, e.g. the existence of a strong halocline stabilizing the sea ice cover and a subsurface layer of Atlantic Water that bring warm and salty water masses into an interior basin, where it recirculates under the halocline. The rate of change seen for the warming around the Fram Strait over the recent decades, where Atlantic water meets the Arctic sea ice cover, is comparable to the rapidity of the DO-events. ABRUPT will evaluate the relevance of the DO-events for ongoing Arctic climate change to unravel mechanisms important for understanding the risk of similar changes in the future Arctic.

Publications from Cristin

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Funding scheme:

POLARPROG-Polarforskningsprogram