A new study involving scientists from the University of Cambridge has developed innovative methods to build a better picture of how ice sheets and glaciers move.
Published in the journal Nature Geoscience, the University of Otago – Ōtākou Whakaihu Waka-led study used previously collected lab data to refine knowledge of how ice sheets deform as they slide into the ocean. Details of ice flow behaviour are crucial for getting accurate predictions about ice loss and sea-level rise in response to climate change.
As oceans warm, floating ice shelves thin and lose their ability to buttress inland ice, leading to faster flow of ice sheets into the sea and increased melting. Meltwater from the Greenland and Antarctic ice sheets has been responsible for about a third of global sea level rise since 1993.
Lead author of the study Dr Sheng Fan, formerly a postdoc at Cambridge Earth Sciences and now at the University of Otago, said being able to estimate sea level rise is important to protect communities from flooding and plan for coastal erosion. “One of the key parts of how scientists do this is based on a model called flow law, a mathematical equation that describes the physics of how ice flows,” Fan said.
There are currently two commonly used flow laws, but they do not capture the full complexity of ice behaviours. “We need a more precise flow law so we can reduce prediction errors, especially with the way climate change is progressing.”
The researchers gathered 70 years’ worth of data from lab experiments on ice and performed a statistical analysis which can overcome the shortages of other flow laws and can make future predictions more accurate.
Dr David Wallis from Cambridge Earth Sciences said their new analysis fills key gaps in scientists’ understanding. “We can now define ice flow behaviour within a few degrees of its melting point, which is particularly relevant to understanding how ice moves at the base of the ice sheets, at the contact with bedrock.”
Wallis usually works on the deformation of rocks, “ice is a crystalline material and is basically just a rock that is close to its melting temperature (albeit one with an unusual composition), so all the microscale physical processes by which ice flows are the same as those that operate in conventional rocks. That means we can share knowledge in studying ice and rocks.” Fan was a postdoc in Wallis’ lab, where he worked on the flow of ice, in addition to rocks from Earth’s mantle.
Professor David Prior, of the University of Otago, said the study is significant. “There are lots of things that contribute to sea level rise and the future of the ice sheet is probably the biggest uncertainty.”
“This study illustrates that we need to describe the behaviour of the ice much more precisely, particularly if we want to use ice sheet modelling as a predicting tool. If we want our predictions of ice movement over the next few decades to be robust, we need to get the physics right.”
Reference: Fan, S., Wang, T., Prior, D.J., Breithaupt, T., Hager, T.F. and Wallis, D., 2025. Flow laws for ice constrained by 70 years of laboratory experiments. Nature Geoscience, pp.1-9.
Feature image: A glacier in Priestley Glacier, Terra Nova Bay, Antarctica, featuring debris which has fallen from higher in the mountains. The surface of the glacier is fractured by the middle of the glacier moving much faster than the edge of the glacier. Photograph: David Prior
Adapted from an original press release by the University of Otago.