Overview

Work carried out by Andrew Shepherd and colleagues at Leeds University, Pete Nienow in Edinburgh Geosciences and collaborators from the University of Sheffield and the Vrije Universiteit Brussels studying the dynamics of the Greenland Ice Sheet have revealed a close link between summer ice melt and ice movement. In summer, surface meltwaters drain to the bed of the ice sheet, lubricating the ice-bed interface and enabling the ice sheet to slide more easily - at times, more than twice as fast in summer compared with winter. The extent of the summer velocity enhancement is not only dependent on the amount of summer melt but also on the rate at which hydraulically efficient subglacial drainage channels become established at the glacier bed each summer. These observations demonstrate that assessments of the impact of melt-induced acceleration on Greenland's flow must account for the seasonal development of the subglacial drainage system.

The observed behaviour, which is similar to that found in Alpine glaciers, provides a better understanding of how the ice sheet responds dynamically to changes in air temperature. The results, when incorporated into numerical ice sheet models, should help improve projections of sea level rise in response to climate change

For further coverage, see:

• ' Melt-induced speed-up of Greenland ice sheet offset by efficient subglacial drainage'
  Nature 469 | 521-524 | (27 January 2011) | doi:10.1038/nature09740
• or contact:
  Dr Peter Nienow
  School of Geosciences
  tel: 0131-650-9139
  e-mail: pnienow@geo.ed.ac.uk