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Understanding the onset of the Last Interglacial: A Modelling Perspective
Paul Gierz
AWI Bremerhaven
Jeudi 26/03/2020, 11:00-12:30
Bât. 714, P. 1129, LSCE Orme des Merisiers

The Last Interglacial (LIG) denotes the youngest period (130-115 ka BP) in Earth’s history where sea level was markedly above present day levels. As such, gaining an understanding of the climate dynamics active during this period may prove to be useful when examining potential future climate states. While the LIG was predominantly forced by variations in the Earth’s orbit, it nevertheless gives an interesting testing ground to understand how our planets climate operates under warmer-than-present conditions. To date, climate models have had difficulty in simulating the early Last Interglacial, and have often required idealised freshwater experiments to properly reproduce the proxy-based reconstructions of temperature and oxygen isotopes which provide a indication of the North Atlantic climate during this time period. Here, we present novel model results and a new proxy reconstruction for the early LIG (130 ka BP). Our model not only simulates the physical characteristics of the prevailing climate, but additionally incorporates a representation of stable oxygen isotopes, allowing for a direct comparison to the proxy reconstructions. We find that correctly representing the initial state for Termination II is a key to simulating the early Last Interglacial, and compare this to various freshwater hosing experiments. Beyond this, we provide an outlook of potential model improvements which may be beneficial to simulating Glacial/Interglacial transitions; showing first results from the AWI-ESM (ECHAM6/FESOM/PISM) for the PMIP4 time slices. Our new model includes not only atmosphere and ocean simulations, but also interaction with a dynamic, bi-directionally coupled ice sheet model. With this new Earth System Model, we provide a new tool to tackle scientific questions about Earth’s climate history during the Quaternary. 

Contact : Aline Govin
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