The relative contribution of orbital forcing and greenhouse gases to the North American deglaciation

Understanding what drove Northern Hemisphere ice sheet melt during the last deglaciation (21–7 ka) can help constrain how sensitive contemporary ice sheets are to greenhouse gas (GHGs) changes. The roles of orbital forcing and GHGs in the deglaciation have previously been modeled but not yet quantif...

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Bibliographic Details
Published in:Geophysical Research Letters
Main Authors: Gregoire, Lauren J, Valdes, Paul J, Payne, A J
Format: Article in Journal/Newspaper
Language:English
Published: 2015
Subjects:
Ice sheets
Modeling
Milankovitch theory
Greenhouse gases
Insolation forcing
deglaciation
North America
orbit
Milankovic
Ice Sheet
Online Access:https://hdl.handle.net/1983/4cc21787-e6c7-4260-828e-3834cd660c2d
https://research-information.bris.ac.uk/en/publications/4cc21787-e6c7-4260-828e-3834cd660c2d
https://doi.org/10.1002/2015GL066005
https://research-information.bris.ac.uk/ws/files/79052144/Gregoire_et_al_2015_Geophysical_Research_Letters.pdf
Description
Summary:Understanding what drove Northern Hemisphere ice sheet melt during the last deglaciation (21–7 ka) can help constrain how sensitive contemporary ice sheets are to greenhouse gas (GHGs) changes. The roles of orbital forcing and GHGs in the deglaciation have previously been modeled but not yet quantified. Here for the first time we calculate the relative effect of these forcings on the North American deglaciation by driving a dynamical ice sheet model (GLIMMER-CISM) with a set of unaccelerated transient deglacial simulations with a full primitive equation-based ocean-atmosphere general circulation model (FAMOUS). We find that by 9 ka, orbital forcing has caused 50% of the deglaciation, GHG 30%, and the interaction between the two 20%. Orbital forcing starts affecting the ice volume at 19 ka, 2000 years before CO2 starts increasing in our experiments, a delay which partly controls their relative effect.

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