Diatoms take over the plankton
Glass-shelled algae expand as the oceans cool, and change how the sea handles carbon and silica.
- When
- —
- Duration
- 8 million years
- Known to
- ± 3 million years
- Era
- Eocene, Cenozoic
Diatoms build their cell walls from silica and thrive in cool, turbulent, nutrient-rich water. As the Eocene cools and ocean circulation strengthens, upwelling increases and diatoms expand dramatically, drawing down dissolved silica and dominating high-latitude and coastal productivity. Because they are large and sink fast, they export carbon to the deep ocean far more efficiently than smaller plankton — so their rise both responds to the cooling and reinforces it. Diatoms today account for roughly a fifth of global photosynthesis.