Y'know, in terms of sea level rise, there are variations in the surface of the oceans which dwarf the actual rise due to expansion, increasing runoff/melt, etc.
I was amazed to learn that, much as water swirling in a bowl will rise up higher around the edges (centrifugal force?),the polar currents create a similar effect. Unbroken ice-cover attenuates the effect, but as ice is breaking up more and retreating, the Arctic Ocean is getting more "bowl shaped." Hence the dramatic problems up there already.
I think the currents actually speed up as ice cover is reduced, which then contributes to redistribution of the overall ice cover, hence the increase of sea ice in some areas?
It occurs to me that ENSO similarily raises and lowers the actual height of the ocean surface over wide areas of the Pacific. Local or regional currents changing direction, speed, and or temperature would also produce noticable effects that are larger than global changes.
I can think of a slight parallel with glaciers here, but let's save that canary for another post.
So, would changing ocean currents qualify as a canary?
~SA
