Ice behavior is controlled by the geometry of channels underneath the ice cover, hiding the signals of retreat, according to scientists from Durham, Sheffield and Cambridge University, together with the British Antarctic Survey.
The study, funded by The Natural Environment Research Council, UK, is based on a simulation of 10,00 years of Antarctic ice-sheet retreat and collapse. The publication in the journal Nature Geoscience uncovers unknown facts about ice stability, which can assist the prediction of possible sea-level rise and ice cover.
Modeling the interactions between climate, sea level and evolving ice sheets presents the biggest challenge when it comes to predicting sea-level rise, according to The International Panel on Climate Change (IPCC), although a great number of models have been developed over the years in order to create scenarios of future climate.
Dr. Stewart Jamieson, a geologist at Durham University and lead author of the study, states that based on their findings, it is now possible to determine the speed of ice retreat and sea-level rise, by looking at the physical shapes of the channels. Their study shows that stability of an ice stream during a phase of retreat might be a temporary case. The team suggests that in order to improve the uncertainty associated with prediction of future climate change, the landscape underneath the ice cover should be understood.
Ice-sheet retreat is very difficult to predict. The reason for this is the large size of the ice channels where marine-based ice streams flow and move with thousands of meters in a year. If the speed of this flow is increased, then sea level is expected to rise as well. The key point that the team of scientists make is that it is still questionable what can influence the speed of streams’ flow.
Based on temporal analysis of satellite imagery from the past 20 years, scientists have gained understanding of ice sheet stability and have demonstrated how because of higher atmospheric and ocean temperatures, ice streams are retreating and becoming thinner.
In this study, the team analyzed the landscape of the sea floor in Marguerite Bay, in the Antarctic Peninsula. Applying their methodology, they discovered that 13,000 years ago during a rapid phase of recession, retreat paused numerously. They used a model suited for such rapidly changing situations they were able to simulate and reproduce the same patterns.
Dr Vieli from Durham University explains that combining the results from their simulations, with new maps of the ocean floor, it is possible to observe the bottlenecks that occur at the same locations where there was a pause or a slowdown in ice retreat. He suggests that beds under Greenland and Antarctica should be observed as well, so that predictions of the ice retreat can be made.
Moreover, Dr Claus- Dieter Hillenbrand, from the British Antarctic Survey warns that huge parts of the West Antarctic and Greenland ice sheets are losing mass and causing sea-level rise. Therefore, it is essential that factors, which influence stability and retreat and understood.