Five million years of glacial cycles are shown, based on oxygen isotope ratio believed to be a good proxy of global ice volume. The MPT is the transition between the periodicities shown in green.
The Mid-Pleistocene Transition (MPT), also known as the Mid-Pleistocene Revolution (MPR),[1] is a fundamental change in the behaviour of glacial cycles during the Quaternary glaciations.[2][3] The transition lasted around 550,000 years,[4] from 1.25 million years ago until 0.7 million years ago approximately, in the Pleistocene epoch.[5]