Summer surface melt thins Petermann Gletscher Ice Shelf by enhancing channelized basal melt

• Published in: Journal of Glaciology
• Main Authors: PETER WASHAM, KEITH W. NICHOLLS, ANDREAS MÜNCHOW, LAURIE PADMAN
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press 2019
• Subjects: Environmental sciences; GE1-350; Meteorology. Climatology; QC851-999; Greenland; Petermann Gletscher; Ice Shelf; Ice Shelves; Journal of Glaciology; Petermann gletscher
• Online Access: https://doi.org/10.1017/jog.2019.43; https://doaj.org/article/70c4297d0ae24291ae753950aeedc07d

Increasing ocean and air temperatures have contributed to the removal of floating ice shelves from several Greenland outlet glaciers; however, the specific contribution of these external forcings remains poorly understood. Here we use atmospheric, oceanographic and glaciological time series data from the ice shelf of Petermann Gletscher, NW Greenland to quantify the forcing of the ocean and atmosphere on the ice shelf at a site ~16 km from the grounding line within a large sub-ice-shelf channel. Basal melt rates here indicate a strong seasonality, rising from a winter mean of 2 m a−1 to a maximum of 80 m a−1 during the summer melt season. This increase in basal melt rates confirms the direct link between summer atmospheric warming around Greenland and enhanced ocean-forced melting of its remaining ice shelves. We attribute this enhanced melting to increased discharge of subglacial runoff into the ocean at the grounding line, which strengthens under-ice currents and drives a greater ocean heat flux toward the ice base.