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How might changes in carbon dioxide levels have contributed to the Permian extinction?

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Line graph showing the number of marine animal families from the Precambrian era to the present, with illustrations of key groups such as trilobites, ammonoids, marine reptiles, and diatoms. The graph highlights major extinction events and a rise to 1,900 living families today. — Permian extinction The diversity of marine animal families since late Precambrian time. The data for the curve comprise only those families that are reliably preserved in the fossil record; the 1,900 value for living families also includes those families rarely preserved as fossils. The several pronounced dips in the curve correspond to major mass-extinction events. The most catastrophic extinction took place at the end of the Permian Period.

Changes in carbon dioxide levels are considered a primary driver of the Permian extinction, largely linked to the massive, prolonged eruptions of the Siberian flood basalts, known as the Siberian Traps.123

These volcanic events contributed to rising atmospheric carbon dioxide in several ways:
* Direct Emission: The venting of volcanic gases directly injected large quantities of carbon dioxide into the atmosphere.12
* Combustion: Rising magma likely ignited large coal seams and forests, releasing additional carbon dioxide and coal fly ash.123
* Reduced Sequestration: Volcanic ash clouds likely restricted sunlight, inhibiting photosynthesis and reducing the rate at which plants could extract carbon dioxide from the atmosphere.123

Furthermore, the warming and drying of terrestrial environments may have reduced the burial of organic matter, altering the carbon cycle and increasing the amount of carbon dioxide recycled through the atmosphere. These elevated levels of carbon dioxide are associated with widespread oceanic anoxia and ocean acidification, both of which severely disrupted marine ecosystems and contributed to the mass extinction.124