Eocene Thermal Maximum 2
A second, smaller carbon release two million years after the PETM shows the system is still unstable.
- When
- —
- Duration
- 150 thousand years
- Known to
- ± 100 thousand years
- Era
- Eocene, Cenozoic
Also called the Elmo horizon, ETM2 at around 54 million years ago repeats the PETM in miniature: a negative carbon isotope excursion roughly half the size, several degrees of warming, and shoaling of the carbonate compensation depth. Several smaller hyperthermals follow it. Their spacing tracks the long eccentricity cycle of Earth's orbit, which is strong evidence that the carbon reservoir being tapped was repeatedly primed and released by orbital forcing rather than by one unrepeatable accident.