Preprints
https://doi.org/10.5194/egusphere-2023-1618
https://doi.org/10.5194/egusphere-2023-1618
15 Aug 2023
 | 15 Aug 2023

Investigating similarities and differences of the penultimate and last glacial terminations with a coupled ice sheet – climate model

Aurélien Quiquet and Didier M. Roche

Abstract. Glacial terminations are marked by a re-organisation of the different components of the climate system. In particular, rapid ice sheet disintegration leads to multiple complex feedback loops that are still poorly understood. To further investigate this aspect, we use here a fully coupled Northern Hemisphere ice sheet – climate model to perform numerical experiments of the last two glacial terminations. We show that even if the first-order climate trajectory is similar for the two terminations, the difference in terms of solar insolation leads to important changes for the ice sheet – climate system. Warmer temperatures during the penultimate termination are compatible with higher sea level during the last interglacial period with respect to the Holocene. We simulate a last interglacial Greenland contribution to sea level rise of about 2 m of sea level equivalent. We also simulate warmer subsurface Southern Ocean, compatible with an additional contribution from the Antarctic ice sheet. In addition, even without considering freshwater flux to the ocean resulting from ice sheet melting, the two terminations display different Atlantic overturning circulation sensitivity, this circulation being more prone to collapses during the penultimate termination. Finally, with additional sensitivity experiments we show that, for the two terminations, the Northern Hemisphere insolation is the main driver for the ice sheet retreat even if vegetation changes have also to be taken into account to simulate the full deglaciation. Conversely, even though it impacts the temperature, greenhouse gas concentration change alone does not explain the amplitude of ice sheet retreat and only modulate its timing.

Aurélien Quiquet and Didier M. Roche

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-1618', Anonymous Referee #1, 17 Sep 2023
  • RC2: 'Comment on egusphere-2023-1618', Anonymous Referee #2, 23 Sep 2023
Aurélien Quiquet and Didier M. Roche
Aurélien Quiquet and Didier M. Roche

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Short summary
In this work, we use the same experimental protocol to simulate the last two glacial terminations with a coupled ice sheet – climate model. Major differences among the two terminations is that the ice sheets retreat earlier and the Atlantic oceanic circulation is more prone to collapse during the penultimate termination. However, for both terminations the pattern of ice retreat is similar and this retreat is primarily explained by orbital forcing changes, greenhouse gas concentration changes.