The Early Eocene Climatic Optimum
The warmest sustained climate of the last 65 million years — palms in Alaska, no ice on the planet.
- When
- —
- Duration
- 6.6 million years
- Known to
- ± 1 million years
- Era
- Eocene, Cenozoic
For several million years around 53 to 47 million years ago the Earth reaches its Cenozoic thermal peak. Deep ocean temperatures run about 12 degrees Celsius, roughly 10 above today; there is no permanent ice at either pole; and tropical-type vegetation extends far into the high latitudes. Carbon dioxide is estimated in the range of 1,000 to 2,000 parts per million. The EECO is the reference case for a genuinely hot Earth, and much of what is known about how climate systems behave at high carbon dioxide is calibrated against it.