Preprints
https://doi.org/10.5194/tc-2020-230
https://doi.org/10.5194/tc-2020-230

  28 Aug 2020

28 Aug 2020

Review status: a revised version of this preprint was accepted for the journal TC and is expected to appear here in due course.

Understanding Drivers of Glacier Length Variability Over the Last Millennium

Alan Huston1, Nicholas Siler1, Gerard H. Roe2, Erin Pettit1, and Nathan J. Steiger3,4 Alan Huston et al.
  • 1College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR, USA
  • 2Department of Earth and Space Sciences, University of Washington, Seattle, WA, USA
  • 3Institute of Earth Sciences, Hebrew University, Jerusalem, Israel
  • 4Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY, USA

Abstract. Changes in glacier length reflect the integrated response to local fluctuations in temperature and precipitation resulting from both external forcing (e.g., volcanic eruptions or anthropogenic CO2) and internal climate variability. In order to interpret the climate history reflected in the glacier moraine record, therefore, the influence of both sources of climate variability must be considered. Here we study the last millennium of glacier length variability across the globe using a simple dynamic glacier model, which we force with temperature and precipitation time series from a 13-member ensemble of simulations from a global climate model. The ensemble allows us to quantify the contributions to glacier length variability from external forcing (given by the ensemble mean) and internal variability (given by the ensemble spread). Within this framework, we find that internal variability drives most length changes in mountain glaciers that have a response timescale of less than a few decades. However, for glaciers with longer response timescales (more than a few decades) external forcing has a greater influence than internal variability. We further find that external forcing also dominates when the response of glaciers from widely separated regions is averaged. Single-forcing simulations indicate that most of the forced response over the last millennium, pre-anthropogenic warming, has been driven by global-scale temperature change associated with volcanic aerosols.

Alan Huston et al.

 
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Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement

Alan Huston et al.

Alan Huston et al.

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Short summary
We simulate the past 1000 years of glacier length variability using a simple glacier model and a group of global climate model simulations. Large glaciers are more likely to record global climate changes caused by events like volcanic eruptions and greenhouse gas emissions, while small glaciers are more likely to record natural variability. However, because large glaciers respond more slowly to climate changes, they have only begun to respond to recent warming, implying greater retreat ahead.