Basal lubrication — the input of melt water to the interface between glaciers or ice sheets and bedrock — is often thought to increase ice velocity. However, recent theoretical work illustrated how the development of efficient subglacial drainage associated with high melt-water input can lead to reductions in ice velocity. Now, satellite observations of ice velocity in Greenland are used to provide empirical support: although initial ice speed-up is similar in all years, warm years with high melt-water input experience a dramatic late summer slowdown, relative to warm years. The findings show that expectations of speed-up from basal lubrication alone cannot be assumed to cause net ice speed-up.
- Aud Venke Sundal
- Andrew Shepherd
- Philippe Huybrechts
