Hysteresis and orbital pacing of the early Cenozoic Antarctic ice sheet

• Main Authors: Van Breedam, Jonas, Huybrechts, Philippe, Crucifix, Michel
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2023
• Subjects: article; Verlagsveröffentlichung; Antarctic; Antarc*; Ice Sheet
• Online Access: https://doi.org/10.5194/egusphere-2023-399; https://noa.gwlb.de/receive/cop_mods_00065495; https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00064016/egusphere-2023-399.pdf; https://egusphere.copernicus.org/preprints/2023/egusphere-2023-399/egusphere-2023-399.pdf

The hysteresis behaviour of ice sheets arises because of the different thresholds for growth and decline of a continental-scale ice sheet depending on the initial conditions. In this study, the hysteresis effect of the early Cenozoic Antarctic ice sheet is investigated with an improved ice sheet-climate coupling method that accurately captures the ice-albedo feedback. It is shown that the hysteresis effect of the early Cenozoic Antarctic ice sheet is about ~180 ppmv or between 3.5 °C and 5.5 °C, depending only weakly on the bedrock elevation dataset. Excluding the solid Earth feedback decreases the hysteresis effect significantly towards ~40 ppmv, because the transition to a glacial state can occur at a higher forcing. The rapid transition from a glacial to a deglacial state and oppositely from deglacial to glacial conditions is strongly enhanced by the ice-albedo feedback, in combination with the elevation – surface mass balance feedback. Variations in the orbital parameters show that extreme values of the orbital parameters are able to exceed the threshold in summer insolation to induce a (de)glaciation. It appears that the long-term eccentricity cycle has a large influence on the ice sheet growth and decline and is able to pace the ice sheet evolution for constant CO2 concentration close to the glaciation threshold.