Session: Glacial Climates (LGM, Last deglaciation, Ice sheet uncertainties, Glacial-interglacial cycles)
Author: Ilkka Matero / firstname.lastname@example.org / School of Earth and Environment, University of Leeds, Leeds, United Kingdom
Co-author: Lauren J Gregoire, School of Earth and Environment, University of Leeds, Leeds, United Kingdom;
Stephen L Cornford, School of Geographical Sciences, University of Bristol, Bristol, United Kingdom;
At the start of the Holocene, the Laurentide Ice Sheet (LIS) experienced rapid ice loss associated with the disintegration of the ice saddle over Hudson Bay. Constraining the early Holocene rates of ice loss is important as meltwater flux from the LIS has been identified as a likely major forcing of the abrupt 8.2 ka northern hemisphere cooling evenet, the most profound climate change event of the Holocene. Holocene LIS retreat is thought to have been largely driven by surface mass balance processes. However, the influence of Hudson strait ice stream and interactions with ocean and proglacial lakes likely provided an important feedback mechanism for surface mass balance processes in the disintegration of the ice saddle, leading to higher rates of ice loss. Simulating such processes require computationally expensive ´higher order´ ice sheet models scarcely used for past ice sheets. Now the recent BISICLES 3D ice sheet model, thanks to its unique adaptive mesh refinement is capable of accurately and efficiently resolving ice stream dynamics and grounding line migration, allowing us to accurately simulate the demise of the Laurentide Ice Sheet.
We drive BISICLES (offline) with temperature and precipitation forcings from a climate model (FAMOUS) under climatic conditions 9,000 years ago. We investigate the contribution of dynamical ice loss through ice streaming and marine interactions, and combine this with changes driven by surface energy balance. This experiment provides constraints on rates of ice sheet changes and mechanisms of rapid, sub-century ice sheet changes during the early Holocene.