The oceans turn acid
Carbon dioxide dissolves into the sea faster than it can be buffered, and shells stop forming.
- When
- Known to
- ± 500 thousand years
- Era
- Permian, Paleozoic
Boron isotope records show a rapid acidification pulse within the extinction interval, as volcanic carbon dioxide entered the ocean too quickly for rock weathering to neutralise it. Organisms that build calcium carbonate skeletons — corals, brachiopods, molluscs — were hit hardest, precisely the pattern acidification predicts. It is the clearest deep-time analogue for what fossil fuel emissions are doing to the oceans now.