Modelling the Last Glacial Maximum and Abrupt Climate Changes during the Last Glacial-Interglacial Cycle

• Main Author: Gong, Xun
• Format: Thesis
• Language: unknown
• Published: 2012
• Subjects: Greenland; Ice Sheet; North Atlantic
• Online Access: https://epic.awi.de/id/eprint/31934/; https://epic.awi.de/id/eprint/31934/1/dissertation_xgong_2012.pdf; https://hdl.handle.net/10013/epic.40620; https://hdl.handle.net/10013/epic.40620.d001

The climate during the last glacial-interglacial cycle exhibits distinct climate states and variability in various time scales with different spatial characteristics. These changes occur for natural reasons, but their mechanisms are not well understood. Compared to the research on present-day climate, which involves influences of human activity, the investigation of the climate during the last glacial-interglacial cycle can attribute to discover the underlying process of natural climate change, and assistant us to have a better prediction of future climate. Additionally, in comparison to studies on proxies, climate models provide a simplified numerical representation of dynamical and thermodynamical processes governing different components of the Earth’s climate system, which is not able to be recorded in proxy data. In this dissertation work, our first scientific focus is to clarify the mechanistic effects of a higher Northern Hemisphere ice sheet on large-scale North Atlantic Ocean surface circulation and Atlantic Meridional Overturning Circulation (AMOC) during glacial climate periods. We use the Community Earth System Models (COSMOS) to simulate five representative climate states during the last glacial-interglacial cycle: the Eemian interglacial, Mid Holocene, Pre-industrial (PI), stadial Marine Isotope Stage3 (MIS3), presented by 32 kilo years before present (ka B.P.), and Last Glacial Maximum (LGM). We have examined mean climatological states and variability of major large-scale North Atlantic Ocean surface circulation elements, including the Subtropical Gyre (STG), Subpolar Gyre (SPG), and Gulf Stream. Our results show that the existing Laurentide Ice Sheet and the elevated Greenland Ice Sheet induce increased surface winds over the North Atlantic Ocean during the LGM and MIS3, which subsequently enhance the North Atlantic gyres and the Gulf Stream. In addition, statistical analysis suggests that the correlation between AMOC and surface winds is increased during glacial climate states. The second part of ...