The deep sea dissolves
Carbonate on the seafloor is eaten away, and a third of deep-sea foraminifera go extinct.
- When
- —
- Duration
- 100 thousand years
- Known to
- ± 100 thousand years
- Era
- Eocene, Cenozoic
The carbon released at the PETM enters the ocean and acidifies it, driving the depth below which calcium carbonate dissolves sharply upward — in places by more than two kilometres. Drill cores record the result directly as a clay layer where there should be chalk: the carbonate that was raining down simply dissolved. Benthic foraminifera suffer their largest extinction of the Cenozoic, losing 30 to 50 per cent of species. It is the clearest evidence in the geological record of what a rapid carbon release does to ocean chemistry.