Typical temperature reconstructions for the late Pliocene however [see one at the top of this story - 3.3 - 3.0 Ma] already show an Earth in which a warmer climatic state is indeed [through for
instance ice albedo feedbacks] relatively strong around the poles, and (on average) weaker around the equator, exactly the pattern that is monitored under the current climate warming.
For
instance, the effect of soot making snow and sea
ice darker has a higher efficacy than an equivalent change in CO2 with the same forcing, mainly because there is a more important
ice -
albedo feedback in the soot case.