Ice viscosity is more sensitive to stress than commonly assumed

• Main Authors: Millstein, Joanna D, Minchew, Brent M, Pegler, Samuel S
• Other Authors: Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
• Format: Article in Journal/Newspaper
• Language: English
• Published: Springer Science and Business Media LLC 2023
• Subjects: Antarctic; Antarc*; Ice Shelves
• Online Access: https://hdl.handle.net/1721.1/148134

<jats:title>Abstract</jats:title><jats:p>Accurate representation of the viscous flow of ice is fundamental to understanding glacier dynamics and projecting sea-level rise. Ice viscosity is often described by a simple but largely untested and uncalibrated constitutive relation, Glen’s Flow Law, wherein the rate of deformation is proportional to stress raised to the power <jats:italic>n</jats:italic>. The value <jats:italic>n</jats:italic> = 3 is commonly prescribed in ice-flow models, though observations and experiments support a range of values across stresses and temperatures found on Earth. Here, we leverage recent remotely-sensed observations of Antarctic ice shelves to show that Glen’s Flow Law approximates the viscous flow of ice with <jats:italic>n</jats:italic> = 4.1 ± 0.4 in fast-flowing areas. The viscosity and flow rate of ice are therefore more sensitive to changes in stress than most ice-flow models allow. By calibrating the governing equation of ice deformation, our result is a pathway towards improving projections of future glacier change.</jats:p>