In particular, that one-time excess solar heat absorbed by water, previously covered by white reflecting ice, that was directly over ocean downwellings, would conduct that heat to continental shelves or farther into ocean depths, directly adding to AGW, until that heat would be eventually returned to the surface of the ocean.

Thus, that one-time solar heat is added to, by other one-time solar absorption events, creating entire new chains of AGW heat retaining mechanisms. Plus other primary & secondary AGW feedback chains are also created.