New research from the University of Alabama shows that widespread wildfires during the Late Devonian period were a consequence of ocean deoxygenation, not its cause. By analyzing chemical biomarkers in Tennessee shale, the team found that marine anoxia appeared first, followed by a rise in wildfire activity. The sequence challenges earlier assumptions that wildfires drove the marine extinction. The study explains that when ocean life dies and sinks, its carbon gets buried instead of cycling back into the atmosphere. This burial leaves excess oxygen in the air, which makes vegetation more flammable and fuels larger fires. The effect persisted beyond the extinction event itself, suggesting a long-term shift in atmospheric conditions. For modern climate science, the findings highlight how tightly linked ocean chemistry, carbon storage, and fire regimes are. Understanding these ancient feedbacks can help improve predictions of how current warming and carbon cycle changes might amplify wildfire risks.
