Abstract:
The last glacial cycle was punctuated by multiple abrupt climate transitions. These fluctuations, know as Dansgaard-Oeschger (D-O) events, feature rapid warming of up to 15 degrees in a course of a few decades. Why these extreme climate events, recorded in all the Greenland ice core records, occurred, has eluded scientists since their discovery in the 60s.
The prevailing hypothesis for D-O events is that they are caused by abrupt changes in the Atlantic Meridional Overturning Circulation (AMOC). Given the abruptness of the events and the mounting evidence for past rapid changes in sea ice, we present a theory for D-O events based on the interplay between Atlantic water temperature, surface fresh water input and the impact of hydrography on the stability of Nordic Seas sea ice.
Experiments with an idealised geometry, eddy permitting ocean model, as well as a coupled global climate model, illustrate the high sensitivity of Greenland temperature to changes in Nordic Sea sea ice, as well as the potential for abrupt transitions and unforced oscillations in sea ice given relatively small changes in the hydrography.
The question which remains is wether these abrupt changes in Greenland climate are examples of what we have in store for the future.
What is the Joint Oslo Seminar (JOS):
Atmospheric and climate sciences have a stronghold in Oslo among the four institutions University of Oslo, the Meteorological Institute, CICERO and NILU. This joint seminar invites renowned international experts to contribute to an informal series of lectures, meant to create interaction with the Oslo atmospheric and climate science community on recent highlights and analysis in the field. All seminars will be held on Thursdays (Noon -1pm) and lunch (sandwiches) will be served on a “first-come-first-served”-basis.