eocene oligocene glaciation

PALEOCLIMATE: ON TRANSIENT GLACIATION: "there was little global cooling associated with the late Eocene glaciations, suggesting that, as in the earliest Oligocene event[5], most of the shift in delta-18O was due to an increase in ice volume and that cooling may have been limited to high latitudes (or that ice-sheet accumulation there was limited by moisture rather than temperature). As in the earliest Oligocene, the isotopic data seem to require the presence of ice sheets on Antarctica at least as thick as those today, and substantial ice sheets in North America (most likely Greenland). This latter result runs contrary to conventional wisdom, which holds that the Northern Hemisphere glaciation began tens of millions of years later."