Dynamic Antarctic ice sheet during the early to mid-Miocene

Area of Science:

• Paleoclimatology
• Glaciology
• Earth System Science

Background:

• Geological records show significant Antarctic ice sheet volume and extent fluctuations during the early to mid-Miocene.
• Simulating these changes is challenging due to ice sheet hysteresis and limited proxy data for atmospheric CO2 concentrations.

Purpose of the Study:

• To simulate large-scale variability of the early to mid-Miocene Antarctic ice sheet.
• To reconcile discrepancies between climate models and geological data regarding Miocene ice sheet and sea level changes.

Main Methods:

• Employed a novel climate-ice sheet coupling method with a high-resolution atmospheric model to capture ice sheet-climate feedbacks.
• Incorporated ice-cliff failure and ice-shelf hydrofracture mechanisms into the ice sheet model for realistic retreat dynamics.
• Utilized isotope-enabled climate and ice sheet models to account for changes in oxygen isotopic composition.

Main Results:

• Successfully simulated Antarctic ice sheet variability equivalent to a 0.52-0.66‰ seawater oxygen isotope shift.
• Modeled sea level equivalent changes ranged from 30-36 meters.
• Achieved these simulations with atmospheric CO2 concentrations between 280 and 500 ppm under varying astronomical configurations.

Conclusions:

• The advanced modeling approach resolves the conflict between model simulations and geological data for Miocene Antarctic ice sheet and sea level variability.
• This study provides a more accurate representation of past climate dynamics and their impact on global sea levels.