EAPS DLS Department Highlight Series: Brent Minchew

Speaker: 
Brent Minchew
Date: 
Wednesday, November 3, 2021 - 4:00pm to 5:00pm
Location: 
54-915

How does glacier ice flow and deform?

The dynamics of glaciers and ice sheets influence rates of sea-level rise, freshwater supplies, and landscape evolution. Decades of research has highlighted key processes and connections between terrestrial ice, climate, and the solid earth, but limited observations of glaciated regions have allowed fundamental questions in glaciers dynamics to remain open. In this talk, we will explore a fundamental question in glaciology: What is the viscosity of glacier ice? More specifically, we will discuss recent work aimed at understanding the mechanisms that allow for viscous flow of ice and how best to represent those mechanisms through a constitutive relation in ice-flow models. Traditionally, the deformation of ice has been modeled using a constitutive relation known as Glen’s Flow Law, wherein the rate of deformation is proportional to stress raised to the power n, where n=3 is assumed in virtually all models. We will discuss new evidence collected in large regions of Antarctica and models of ice recrystallization that both suggest a higher value for the stress exponent n, indicating different physical mechanisms at work than previously assumed. We will build upon these efforts with a discussion of new methods being developed to better test the applicability of Glen’s Law to natural glacier ice and to calibrate the rheological parameters using a suite of satellite observations. We will conclude with a discussion of potential implications of this work for projections of sea-level rise and the evolution of ice sheets. 

About this Series

The Department Lecture Series at EAPS at MIT is a series of Weekly talks given by leading thinkers in the areas of geology, geophysics, geobiology, geochemistry, atmospheric science, oceanography, climatology, and planetary science. For more information please contact: Maggie Cedarstrom, maggie84@mit.edu.