According to an international study published in Nature, ice sheets can retreat up to 600 m per day during climate warming. The rate of retreat is 20 times faster than previously measured. The study, led by Newcastle University‘s Dr. Christine Batchelor, mapped more than 7,600 small-scale landforms called “corrugation ridges” across the seafloor to track how quickly an ice sheet that extended from Norway retreated 20,000 years ago. The ridges were formed when the ice sheet’s margin moved with the tides, pushing seafloor sediments into a ridge every low tide. The team was able to calculate the speed of retreat by the number of ridges produced each day.

The study shows that periods of rapid ice-sheet retreat may only last for days to months, far shorter than previously thought. The research suggests that the mechanism behind the rapid retreat is when the ice margin becomes buoyant and ungrounds from the seafloor, retreating near-instantly. This occurs across relatively flat beds where less melting is required to thin the ice to the point where it starts to float.

The seafloor mapping program, MAREANO, collected data to inform the study, emphasizing the value of high-resolution imagery of glaciated landscapes preserved on the seafloor. The findings indicate that current melting rates are sufficient to cause short pulses of rapid retreat across flat-bedded areas of the Antarctic Ice Sheet, including at the Thwaites Glacier. The glacier is the subject of considerable international research due to its potential susceptibility to unstable retreat. The authors suggest that Thwaites Glacier could undergo a pulse of rapid retreat due to its recent retreat close to a flat area of its bed.

The research is vital to inform computer simulations that predict future ice sheet and sea-level change, and the authors suggest that such rapid retreats can be far quicker than observed. Computer simulations must be capable of reproducing this “pulsed” ice-sheet behavior to better understand the mechanisms behind such rapid retreats.

References

• Batchelor, C. L., Christie, F. D. W., Ottesen, D., Montelli, A., Evans, J., Dowdeswell, E. K., Bjarnadóttir, L. R., & Dowdeswell, J. A. (2023). Rapid, buoyancy-driven ice-sheet retreat of hundreds of metres per day. Nature. https://doi.org/10.1038/s41586-023-05876-1
• Newcastle University Press Office. (2023, April 11). Comment: New research shows how rapidly ice sheets retreat. Newcastle University Press Office; Newcastle University. http://www.ncl.ac.uk/press/articles/latest/2023/04/conversationicesheetantarctica/