Sea ice formation processes occur on sub-grid scales and the detailed
physics describing the processes are therefore not generally represented
in climate models. One likely consequence of this is the premature
closing of areas of open water in model simulations, which may result in
a misrepresentation of heat and gas exchange between the ocean and
atmosphere. This work demonstrates the implementation of a more
realistic model of sea ice formation, introducing grease ice as a wind-
and oceanic- stress-dependant intermediary state between water and new
sea ice. We use the fully coupled land-atmosphere-ocean- sea ice model,
HadGEM3-GC3.1 and perform a three member ensemble with the new grease
ice scheme from 1964 to 2014. Comparing our sea ice results with the
existing ensemble without grease ice formation shows an increase in sea
ice thickness and volume in the Arctic. In the Antarctic, including
grease ice processes results in large local changes to both simulated
sea ice concentration and thickness, but no change to the total area or
volume.