CPOM@EGU26 Blog – Modelling past deglaciations to improve our understanding of current and future behaviour of ice sheets
3rd May 2026
This study, led by Dr Lauren Gregoire, uses state-of-the-art coupled model FAMOUS–BISICLES (General Circulation Atmosphere–ice-sheet model) to examine ice sheet changes in the Northern Hemisphere during the two most recent deglaciations (which took place around 21,000 to 7,000 years ago and 140,000 to 128,000 years ago).
The FAMOUS model (Fast Met Office—UK Universities Simulator) produces simulations for atmosphere–ocean, while BISICLES, which was developed in partnership with CPOM scientists, simulates ice sheet dynamics using adaptive mesh refinement for higher resolution in critical areas such as the grounding line of the ice sheet. By bringing these two models together FAMOUS-BISICLES can simulate climate-ice sheet interactions over thousands of years.
Following PMIP4 (Palaeoclimate Model Intercomparison Project 4) protocols, the team used ongoing climate model outputs for sea surface temperatures and sea ice to drive the simulations. They assessed the impact of concentrations of greenhouse gases, variations in the Earth’s orbit and orientation relative to the Sun, and uncertainties in model parameters and sea surface temperature, on the model projections of the patterns of ice retreat.
The study projected that there was an acceleration of ice retreat during the final stages of the last glacial person (referred to as Bølling warming), but results varied dependent on the type of terrain and the abruptness of sea surface temperatures. The study also identified marine-based sections of the ice sheet as particularly sensitive to ocean changes.
Understanding how and why ice sheets retreated during previous deglaciations gives us a longer-term perspective on ice sheet behaviour, extending far beyond the few decades of satellite observations. Coupled models like FAMOUS-BISICLES can be tested against these past events, helping us refine and validate the tools we use to project current and future ice loss.
Find out more by reading the abstract and attending their presentation online or in-person at EGU26.
