Over the past 50 million years (myr), major geological events include the formation of the Alpine mountain belt by plate collision, the oslation of the antarctic continent and the opening of the North Atlantic Ocean by sea floor spreading.
Late Paleogene (40-42 Ma) plate tectonic reorganisation of lithosphere plates and reduced spreading rates were accompanied by the removal of substantial amounts of greenhouse gases from the Earth's atmosphere and the onset of modern oceanic circulation, which led to the development of persistent Antarctic ice sheets.
Neogene (25-ca.3 Ma) uplift along the North Atlantic continental margins and enhanced cooling eventually caused Northern Hemisphere ice sheets to grow.
Over the last ca. 1 myr, weak but regular changes of solar irradiation received by Earth caused short-term, warm interglacial episodes to alternate with long-term, cold glacial periods at intervals of 100 thousand years(kyr) added 41 kyr and c. 23 kyr rhythms of alternating cool and mild climate.
The last ice age (ca. 115-11.7ka) experienced high-frequency millenial-scale climate changes of c. 2-10 kyr long epsodes of slow temperature decline towards cooling followed by rapid warming. In the North Atlantic region, the migration of the Polar Front and the strength of the thermohaline ocean circulation probably caused these rapid climatic oscillations. Climate change occured in close tandenm with the growth and decay of Northern Hemisphere ice sheets, and both together which had a decisive impact on the migration of terrestrial biota.