Carbon dioxide locks into its glacial range
For 800,000 years the atmosphere never goes below 170 or above 300 parts per million.
- When
- —
- Duration
- 645 thousand years
- Known to
- ± 30 thousand years
- Era
- Middle Pleistocene, Quaternary
Antarctic ice cores show carbon dioxide oscillating in a tight band across every glacial cycle: roughly 180 parts per million at glacial maxima, 280 to 300 in interglacials, driven by ocean solubility, circulation and biology. The band is remarkably stable across eight complete cycles. It is the baseline against which the modern rise is measured — atmospheric carbon dioxide passed 300 parts per million around 1910 and is now above 420, far outside anything in the entire ice core record.