Based upon the retreat of glaciers worldwide, and opening of the Arctic ocean, and Greenland's hastened dissolution, global atmospheric warming would seem to be with us. But has there been any global oceanic warming? None yet definitively detectable by thermal expansion of the oceans (i.e. proxy of sea surface rise). http://en.wikipedia.org/wiki/Sea_level_rise The specific heat of water is much greater (4x) than that of the atmosphere. And heat capacity is just specific heat x volume. http://en.wikipedia.org/wiki/Specific_heat_capacity So has the total enthalpy (heat) of coupled oceanic-atmospheric system changed significantly, in a fractional sense? The enormous heat capacity of the oceans would seem to serve as a buffer for increased heating of the planet. If one assumed an extreme scenario of tropical waters to 200 meters for most of planet, what would be the consequences? Has the Paleocene-Eocene Thermal Maximum, about 55 million years ago, already conducted such extreme experiment? http://en.wikipedia.org/wiki/Paleocene%E2%80%93Eocene_Thermal_Maximum NATURE'S PAST EXPERIMENT An experiment of nature on the effect of intense global warming has already occurred in the Eocene 38-55 million yrs. ago; the so-called Paleocene-Eocene Thermal Maximum (PETM).(1) There were no massive extinctions comparative to that of Cretaceous-Tertiary (K-T) period defining Mezozoic/Cenazocic eras at 65Myrs. At the Paleocene-Eocene divide, paleo-stratigraphic results show that there was deep water benthic foraminifera mass extinction associated with the increased temperature and hence dysoxic (less oxygenated) waters.(1) But most marine and terrestrial extinctions occurred with cooling at the end of the Eocene, and into the Oligocene epoch.(1) The consequences of the present warming are unknown in regards to extinctions. However nature already has conducted one experiment in regards to intense global warming, with seemingly not overwhelming catastrophic results. 1. Hallam Tony, Catastrophes and Lesser Calamities Oxford Univ Press, 2004, and references therein. Other sources consulted. 2. Raup David M., Extinction: Bad Genes or bad Luck?, W.W. Norton, 1991, and references therein. 3. Stanley Steven M., Extinction, Scientific American Books, 1987, and references therein.