...
2°C above freezing, so that would be....? Is that 0.2°C (assuming saltwater at -1.8°C) or 2°C? The latter is scary, the former, that's not much above the melt point of the freshwater glacier. Basically an order of magnitude less energy to melt the glacier. that 10x difference may become important....
…
Sea water density changes with temperature, salinity and pressure and the freezing point is also a function of pressure & salinity; therefore, it is best to talk specifically about the water under the specific location (the linked reference gives the conditions under the PIIS shortly before 2011).
Stanley S. Jacobs, Adrian Jenkins, Claudia F. Giulivi & Pierre Dutrieux (2011), "Stronger ocean circulation and increased melting under Pine Island Glacier ice shelf", Nature Geoscience, Volume: 4, Pages: 519–523, doi:10.1038/ngeo1188
http://www.nature.com/ngeo/journal/v4/n8/abs/ngeo1188.htmlAbstract: "In 1994, ocean measurements near Antarctica’s Pine Island Glacier showed that the ice shelf buttressing the glacier was melting rapidly. This melting was attributed to the presence of relatively warm, deep water on the Amundsen Sea continental shelf. Heat, salt and ice budgets along with ocean modelling provided steady-state calving and melting rates. Subsequent satellite observations and modelling have indicated large system imbalances, including ice-shelf thinning and more intense melting, glacier acceleration and drainage basin drawdown. Here we combine our earlier data with measurements taken in 2009 to show that the temperature and volume of deep water in Pine Island Bay have increased. Ocean transport and tracer calculations near the ice shelf reveal a rise in meltwater production by about 50% since 1994. The faster melting seems to result mainly from stronger sub-ice-shelf circulation, as thinning ice has increased the gap above an underlying submarine bank on which the glacier was formerly grounded. We conclude that the basal melting has exceeded the increase in ice inflow, leading to the formation and enlargement of an inner cavity under the ice shelf within which sea water nearly 4 °C above freezing can now more readily access the grounding zone."
&
According to:
https://nsidc.org/cryosphere/seaice/index.html as salinity increases the maximum density approaches the freezing point and in sea water with salinity above 24 psu density is highest at freezing temperature (see the first image).
&
The density of sea water has the same pressure and temperature relationships as fresh water but, with the addition of "salt", its mass is increased (see the second image).