Transition from late Neogene to early Pleistocene environments

The late Neogene was generally warmer than today, but the first signs of cooling of Earth's climate already became evident. Ice sheets, ice caps, glaciers and sea ice expanded in the polar regions of our planet, especially during the late Pliocene in the Northern Hemisphere. The onset and intensification of Northern Hemisphere glaciation are concepts often used when describing this late Neogene glacial expansion, yet there is considerable confusion in the literature about the timing and duration of both. Here we describe what we consider to be the onset and intensification and review the available terrestrial and marine evidence of glaciation. We describe the patterns of cryosphere expansion in the late Pliocene and examine the potential mechanisms (ocean gateways and tectonics, atmospheric CO2, orbital parameters, ocean circulation) behind this climate transition.