Today's Procedings of the (US) Nation Academy of Sciences has a potentially interesting paper.
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The researchers seem to have worked out how to get good numbers for the ch anges in the oceans when the global temperature went up some 5 to 8 degrees Celcius over a couple of thousand years some 56 million years ago - it di dn't warm up quite as rapidly as it is at the moment, but it did go up unu sually rapidly. I may be able to get hold of the full text.