A decade of ocean changes impacting the ice shelf of Petermann Gletscher, Greenland

• Published in: Journal of Physical Oceanography
• Main Authors: Washam, P., Münchow, A., Nicholls, Keith W.
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Meteorological Society 2018
• Subjects: Greenland; Petermann Gletscher; glacier; Ice Shelf; Petermann gletscher
• Online Access: http://nora.nerc.ac.uk/id/eprint/521018/; https://nora.nerc.ac.uk/id/eprint/521018/1/jpo-d-17-0181.1.pdf; https://doi.org/10.1175/JPO-D-17-0181.1

Hydrographic data collected during five summer surveys between 2002 and 2015 reveal that the subsurface ocean near Petermann Gletscher, Greenland warmed by 0.015 ± 0.013°C yr-1. New 2015 - 2016 mooring data from beneath Petermann Gletscher’s ice shelf imply a continued warming of 0.025 ± 0.013°C yr-1 with a modest seasonal signal. In 2015 we measured ocean temperatures of 0.28°C near the grounding line of Petermann Gletscher’s ice shelf, which drove submarine melting along the base of the glacier. The resultant meltwater contributed to ocean stratification, which forced a stronger geostrophic circulation at the ice shelf terminus compared with previous years. This increased both the freshwater flux away from the sub-ice shelf cavity and the heat flux into it. Net summertime geostrophic heat flux estimates into the sub-ice shelf cavity exceed the requirement for steady-state melting of Petermann Gletscher’s ice shelf. Likewise, freshwater fluxes away from the glacier exceed the expected steady-state meltwater discharge. These results suggest that the warmer, more active ocean surrounding Petermann Gletscher forces “non steady-state” melting of its ice shelf. When sustained, such melting thins the ice shelf.