As this occurred during an ice age, presumably there would have been rather more (i.e. thicker) ice on the surface than we’re used to. Assuming that the warmth probably originated, then as now, from undersea volcanoes, could it just be basically a case of better ‘insulation’ preventing it from escaping?
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vukcevic says:
This finding is particularly surprising because it occurred during the last major ice age.
Inflow of warm heavier salty water from the N. Atlantic’s currents would circulate at some depth below lighter fresh water, while totally frozen surface would prevent any mixing due to tides or storms above; thermo-haline circulation had ideal conditions.
