Further food for thought regarding the ocean trends in ESM1.6 …
Figures shared here show some changes in ocean temperature in the new August spinup with respect to the June spinup.
There is little difference in the globally averaged SST between the two spinups (top left, black is June, red August).
However, this obscures regional differences; in particular, cooling around Antarctica and warming in the North Atlantic (bottom left).
There are corresponding increases and decreases in average sea ice cover (of the order of 5%) in the south and north, respectively.
As already noted, the average ocean temperature is cooling quicker in the August spinup (top right).
When checking the change in zonally averaged temperature sections (bottom right), this cooling is predominantly in upper 2000 m of the ocean and there is actually some warming in the deeper ocean.
This distribution corresponds to a decrease in Antarctic Bottom Water formation by ~10% in the August spinup corresponding to the switch to CICE5.
IMHO, there is less certainty about long term ocean temperature trends associated with changes in circulation/overturning than when changing insolation/albedo.
Note, differences to the June spinup are to 30 years of this spinup before branching to the August version.