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Ice-sheet acceleration driven by melt supply variability
1Department of Earth and Ocean Sciences, University of British Columbia, 6339 Stores Road, Vancouver, British Columbia V6T 1Z4, Canada. cschoof@eos.ubc.ca
Nature
|December 15, 2010
Summary
Increased variability in meltwater, not mean melt, drives Greenland glacier acceleration and sea level rise. Short-term melt spikes, not steady melt, cause faster ice flow by increasing basal water pressure.
Area of Science:
- Glaciology
- Climate Science
- Earth System Science
Background:
- Greenland's ice velocities are rising, contributing to sea level rise.
- Faster ice flow is linked to ice-ocean interactions and surface meltwater.
- A positive feedback loop between melting and dynamic thinning was hypothesized.
Purpose of the Study:
- To investigate the relationship between surface meltwater variability and ice flow dynamics.
- To determine the primary drivers of accelerated ice flow in Greenland.
- To assess the validity of the melt-driven ice loss feedback mechanism.
Main Methods:
- Utilized a model simulating dynamic switching between channel and cavity basal drainage modes.
- Analyzed the impact of water input variability on basal water pressure.
- Correlated meltwater input patterns with observed ice velocity changes.
Main Results:
- Ice flow acceleration is driven by increased water input variability, not mean melt.
- Steady high melt rates can suppress ice flow through channelization.
- Temporary spikes in basal water pressure, from diurnal melt cycles or drainage events, cause acceleration.
Conclusions:
- The hypothesized melt/dynamic thinning feedback is not universally operational.
- Short-term melt variability, particularly diurnal cycles, is a key driver of Greenland ice loss.
- Understanding meltwater drainage dynamics is crucial for predicting future sea level rise.
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