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Polar Seminar: Johan Nilsson (Stockholm University), "Was the glacial Arctic Ocean covered by kilometer thick floating ice shelves?"

03/05/2019 - 2:00pm
IGPP 4301—Revelle Conference Room
Event Description: 
Recent geological and geophysical data suggest that a 1 km thick ice shelf extended over the glacial Arctic Ocean during Marine Isotope Stage 6, about 140 000 years ago. Here, we analyse the development and equilibrium features of such an ice shelf in the light of inter-glacial-to-glacial changes of the Arctic Ocean. We argue that the dynamically most consistent glacial scenario is an ice shelf with a nearly uniform thickness that covers the entire Arctic Ocean. Further, the ice shelf has two regions with distinctly different dynamics: a vast interior region covering the central Arctic Ocean and an exit region towards the Fram Strait. In the interior region, which is effectively dammed by the Fram Strait constriction, there are strong back stresses and the mean ice-shelf thickness is controlled primarily by the horizontally integrated mass balance. If the surface accumulation and mass flow from the continental ice are sufficiently large, the ice-shelf thickness grows to the point where the ice shelf grounds on the Lomonosov Ridge about 1 km below the present sea level. Using an analytical ice-dynamic model, the stability of equilibrium ice-shelf configurations without and with grounding on the Lomonosov Ridge are examined. Finally, we discuss possible ocean-circulation regimes in the ice-shelf cavity and the role of Arctic Ocean ice shelves for some glacial puzzles.
For more information on this event, contact: 
Maya Becker
Event Calendar: 
Polar Seminar