Mid-Pleistocene Transition

[5] Before the MPT, the glacial cycles were dominated by a 41,000-year periodicity with low-amplitude, thin ice sheets, and a linear relationship to the Milankovitch forcing from axial tilt.

[6] After the MPT there have been strongly asymmetric cycles with long-duration cooling of the climate and build-up of thick ice sheets, followed by a fast change from extreme glacial conditions to a warm interglacial.

Later glaciations were increasingly based on core areas, with thick ice sheets strongly coupled to bare bedrock.

[5] Osmium isotope evidence suggests that a major change in chemical weathering flux into the oceans took place during the MPT, consistent with the regolith hypothesis.

[13] This hypothesis is based on the observational evidence of obliquity damping in climate proxies and sea-level record during the Last 1.2 Ma.

[15] However, a 2020 study concluded that ice age terminations might have been influenced by obliquity since the MPT, which caused stronger summers in the Northern Hemisphere.

[20] In Europe, the MPT was associated with the Epivillafranchian-Galerian transition and may have led to the local extinction of, among other taxa, Puma pardoides, Megantereon whitei, and Xenocyon lycaonoides.

[28] In the middle of the MPT, there was a sudden decrease in denitrification, likely due to increased solubility of oxygen during lengthened glacial periods.

[30] In Central Africa, detectable floral changes corresponding to glacial cycles were absent prior to the MPT.

Following the MPT, a clear cyclicity became evident, with interglacials being characterised by warm and dry conditions while glacials were cool and humid.