Black Ice
I thought the key element of these studies was that a *fall* in CO2 triggered Antarctic glaciation. Absolute values from so long ago are rough estimates, and misleading in a contextless headline. Conclusions about climatic events in specific geographic locations, like the Antarctic, have to be viewed from the context of the influence of many other changes in its environment also, like latitude changes from continental drift, changes in ocean currents, and changes in local flora and fauna, - all of which can amplify or impede the effects of greenhouse warming and cooling.