Holocene sea ice dynamics in Petermann Fjord - implications for the stability of Petermann ice tongue

Marine-terminating outlet glaciers play a fundamental role in the mass loss of the Greenland ice sheet due to non-linear behavior promoted by ice-ocean interactions. Petermann Glacier in northwestern Greenland terminates as a floating ice tongue, draining about 4% of the Greenland ice sheet into Nares Strait, the connection between the Arctic Ocean and the western North Atlantic. Mass loss at Petermann Glacier occurs primarily through submarine melting, but large-scale calving events have been observed in 2010 and 2012, reducing the extent of the floating ice tongue by almost 40%.

Recent modelling studies suggest that the seasonal sea ice cycle in Nares Strait has important implications for the water mass structure in Petermann Fjord and basal melt rates of the ice tongue. While enhanced sea ice results in advection of colder near-surface waters into the fjord, reduced sea ice leads to increased Ekman transport of warm and salty Atlantic-sourced waters into Petermann Fjord promoting basal melting of the ice tongue. Thus, long-term changes in the regional sea ice dynamics could fundamentally alter the oceanic heat transport into Petermann Fjord, influencing the stability of the floating ice tongue.

The Petermann 2015 Expedition targeted several locations in Petermann Fjord and Hall Basin to investigate the dynamic behavior of Petermann Glacier in response to oceanographic and climatic changes across the Holocene. Here we use a suite of sea ice related biomarkers to explore sea ice dynamics in Petermann Fjord across the last 7 ka. This provides important insights into the role of sea ice for the stability of the Petermann ice tongue across the Holocene.