Joint Seminar: Deglacial ice-sheet meltdown: orbital pacemaking, CO2 effects, and ocean response

One of the most recent massive climate change events in earth’s history was the last deglaciation about 20-10 thousand years ago. Northern Hemisphere ice-sheets receded quickly, causing global sea level to rise by more than 100 m, meltwater was injected into the North Atlantic halting its deepwater formation, atmospheric CO2 concentrations rose by almost 100 ppmv, and the global surface warmed by more than 3°C.  It is still unresolved what exactly the causes and feedbacks were that led to the reconstructed climate change and ice sheet melting.

To address this question, we conducted numerical experiments with a coupled 3-D ice-sheet–climate model (IcIES-LOVECLIM). I will present this model, and discuss a set of transient simulations of the last deglaciation, which support some elements of the astronomical theory of ice ages. Orbital changes have the potential to, and do in fact initiate the deglaciation in our model. However, without the deglacial CO2 increase, wide areas of North America and Scandinavia would still be covered by land ice today.

To realistically simulate deglacial ocean circulation changes – let alone their possible role for the aforementioned deglacial CO2 rise – is difficult. In our model, the North Atlantic deepwater formation shuts down abruptly in response to increasing meltwater fluxes. We find that the opening of the Bering Strait may have played an important role for the recovery of the deepwater formation.




11:30 h


Bundesstr. 53, room 022/023
Seminar Room 022/023, Ground Floor, Bundesstrasse 53, 20146 Hamburg, Hamburg


Malte Heinemann, IPRC, University of Hawaii


Daniela Matei

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