| Summary: | © The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Millstein, J. D., Minchew, B. M., & Pegler, S. S. Ice viscosity is more sensitive to stress than commonly assumed. Communications Earth & Environment, 3(1), (2022): 57, https://doi.org/10.1038/s43247-022-00385-x. 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 n. The value n = 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 n = 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. .D.M. was partially funded through an NSF Graduate Research Fellowship. J.D.M. and B.M.M. where partially funded through NSF-NERC award 1853918. B.M.M. received additional funding through NSF-NERC award 1739031.
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