Joint IPRC-Oceanography Seminar

February 13, 3:00pm - 4:15pm
Mānoa Campus, Marine Sciences Building (MSB) 100 Add to Calendar

Malte Heinemann
Postdoctoral Fellow
Pennsylvania State University
International Pacific Research Center
University of Hawaii

“Simulating the last deglaciation: orbital pacing, CO2 effects, and climate - ice-sheet interactions”

Abstract: One of the most recent massive climate change events in earth’s history was the last glacial termination 19-9 thousand years before present (ka BP). 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 about 4°C. It is still unresolved what exactly caused this reconstructed climate change and ice sheet melting.

To address this question, we conducted numerical experiments with a coupled 3-dimensional ice-sheet–climate model. 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, and does not recover. A possible reason for this lack of recovery is that the opening of the Bering Strait due to sea level rise is not captured in the ocean model.

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Oceanography, Mānoa Campus

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(808) 956-7633

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