- 1University of Bern, Climate and Environmental Physics (CEP), Physics, Switzerland (christian.wirths@unibe.ch)
- 2Oeschger Center for Climate Change Research, University of Bern, Switzerland
- 3Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Germany
A mechanistic understanding of the main drivers of Quaternary climate variability, especially during the mid-Pleistocene transition (MPT; around 1.2–0.8 million years ago) remains a significant challenge in paleoclimate research. Climate changes during that time include a pronounced shift from 41-kyr to 100-kyr periodicity of glacial cycles as imprinted on sea level reconstructions, and the emergence of much larger ice sheets. While several modeling studies have focused on the interplay between the climate system and northern hemispheric ice sheets during the MPT, the role of Antarctica in driving and responding to climate change at that time remains largely unknown.
Here, we use the Parallel Ice Sheet Model (PISM) to simulate the transient evolution of the Antarctic Ice Sheet throughout the last 3 million years. PISM is forced by a climate index approach that is based on snapshots of climatic conditions in the past. Climate snapshots are derived from the Community Earth System Models (COSMOS), a general circulation model that simulates atmosphere, ocean, sea ice and land vegetation in dependence of reconstructions of paleogeography, orbital configuration, and greenhouse gas concentrations. Interpolation in times between snapshots is linear and based on a convolution of the EPICA Dome C record and the Lisiecki-Raymo benthic isotope stack.
Our simulations indicate that between 1.9 Ma and 800 ka BP, several Antarctic drainage basins crossed critical thresholds at different times, for example leading to the formation of a stable marine-based West Antarctic Ice Sheet. We further examine the characteristics of these thresholds and their associated state transitions. Additionally, our findings suggest that these thresholds, and their interplay, amplified eccentricity-driven climate variability both before and during the MPT, providing new insights into the complex interactions between Antarctic ice sheet dynamics and climate during this period.
How to cite: Wirths, C., Hermant, A., Stepanek, C., Stocker, T., and Sutter, J.: Unravelling abrupt transitions of Antarctic Ice Sheet dynamics during the mid-Pleistocene transition, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8670, https://doi.org/10.5194/egusphere-egu25-8670, 2025.
