The M2 glaciation
A sharp cold snap interrupts the Pliocene warmth, and then the world goes back to being warm.
- When
- —
- Duration
- 36 thousand years
- Known to
- ± 30 thousand years
- Era
- Pliocene, Cenozoic
Around 3.3 million years ago, just before the Mid-Piacenzian warmth, oxygen isotopes record a substantial glacial event — ice volume increases, sea level falls perhaps 60 metres, and carbon dioxide drops. Then it reverses completely. M2 is important because it is a failed transition: the climate system approached the icehouse state, did not stay there, and needed several hundred thousand more years of carbon dioxide decline before glaciation became permanent.