Climate response to astronomical parameters, CO2 and ice sheets during past interglacials

• Main Author: Wu, Zhipeng
• Other Authors: UCL - SST/ELI/ELIC - Earth & Climate, UCL - SST/ELI - Earth and Life Institute, UCL - Faculté des Sciences, Yin, Qiuzhen, Guo, Zhengtang, Van Oost, Kristof, Goosse, Hugues, Crucifix, Michel, Yan, Zhao, Qingzhen, Hao, Haibin, Wu
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: 2023
• Subjects: Arctic; Hudson; Hudson Bay; Southern Ocean; Ice Sheet; Sea ice
• Online Access: http://hdl.handle.net/2078.1/276133

Characterized by warm climate, small ice sheets and high sea level, past interglacials are quite relevant for a better understanding of our present-day warm climate and its future evolution. Investigating the response of climate system to different forcing factors, such as astronomical parameters, greenhouse gases (GHG) and ice sheets, could help better constrain the uncertainty of the sensitivity of the climate system and provide a basis for better understanding the internal climate processes and feedbacks. This thesis aims to perform a comprehensive and systematic investigation of the climate response in the two hemispheres to astronomical parameters, CO2 and Northern Hemisphere (NH) ice sheets during the interglacials of the past 800 ka mainly based on snapshot and transient simulations using the LOVECLIM model. The results show that the climate of the two hemispheres responds differently to astronomical parameters, CO2 and NH ice sheets. In terms of the effect of astronomical parameters, precession plays a dominant role on the Arctic sea ice, while obliquity plays a dominant role on the Southern Ocean sea ice. This is mainly related to the different geographical condition of the Arctic and the Southern Ocean and the related atmospheric and oceanic feedbacks. In the low latitudes of both hemispheres, SST shows a strong precession signal. However, in the mid and high latitudes, obliquity plays a dominant role on the Southern Hemisphere (SH) SST whereas precession is more important on the NH SST. This is largely due to the different response to insolation and feedbacks related to the different land-ocean distribution in the two hemispheres. The model results also show that the effect of CO2 on the SST in the mid-high latitudes is larger than in the low latitudes of both hemispheres, and CO2 plays a more important role on the SST at mid-high latitudes and sea ice in the SH than in the NH. The status of the Hudson Bay changed (closed or open) with the advance and retreat of the North American ice sheet. ...