salinity levels have been changing in the atlantic so perhaps it is occuring in the pacific ocean too.
The volume ratio of the Atlantic to Arctic is significantly smaller then the Pacific to Arctic. Would suspect the Atlantic to be more sensitive to salinity exchanges with the Arctic. The Northern Pacific also needs to be analyzed distinctive of the Southern Pacific. Land forms significantly affect the water exchange with the Arctic. In the Southern Hemisphere, the most Southern Cold Ocean surrounding Antarctica is freely mixing. Probably best to think about all these effects in globular terms.