Antarctica freezes
Ice sheets spread across a continent that had carried forest, and the world enters its current icehouse.
- When
- —
- Duration
- 500 thousand years
- Known to
- ± 200 thousand years
- Era
- Eocene, Cenozoic
At the Eocene-Oligocene transition, cooling that had been gradual becomes a step change. The EOT-1 cooling at about 34 million years ago is followed by the Oi-1 glaciation at roughly 33.7, when a continental-scale East Antarctic Ice Sheet appears in a geological instant. Oxygen isotopes jump, sea level falls, and the carbonate compensation depth plunges more than a kilometre. Declining carbon dioxide is the leading cause, with Southern Ocean gateway opening as a contributing factor. Earth has had permanent polar ice ever since — we are still living in the icehouse that starts here.