Plio-Pleistocene Glacial Cycles and Milankovitch Variability

Abstract

The Plio-Pleistocene glacial cycles have dominated climate during the past ∼2.8My, with alternating warm interglacial and cold glacial periods with ice caps covering large parts of North America and Europe. The early work of Milutin Milankovitch suggests that changes in summer insolation due to variations in the Earth’s orbit could be the main driver of these large cycles in ice volume. According to this theory, the long cycles regulating the tilt of the Earth’s axis, the precession of the equinoxes, and the eccentricity of the Earth’s orbit could have had a significant impact on the high-latitude insolation and climate through time. At times with relatively cool summers, snow and ice could have persisted through the melt season, and combined with a strong snow albedo feedback, would have led to full glacial conditions. With the discovery of long climate records from deep-sea sediment cores it has become clear that the glacial cycles of the Plio-Pleistocene do indeed exhibit periods with the same frequencies as the astronomical forcing of Milankovitch. However, the mechanisms linking this insolation forcing to the large and relatively rapid nonlinear changes in continental ice are still unclear.