EVENT
The Permian-Triassic Extinction
The worst mass extinction in Earth's history — 252 million years ago — in which roughly 96 percent of marine species and 70 percent of terrestrial vertebrates perished, driven by a cascade of positive feedback loops that overwhelmed the biosphere's regulatory capacity.
The Permian-Triassic extinction is the worst documented failure of Gaian regulation. Beginning approximately 252 million years ago, a cascade of
positive feedback loops produced by massive volcanism in what is now Siberia overwhelmed the biosphere's capacity to maintain habitable conditions. Volcanic eruptions released vast quantities of CO₂. CO₂ warmed the climate. Warming destabilized methane hydrates in ocean sediments, releasing additional greenhouse gases. Further warming acidified the oceans. Ocean acidification killed marine organisms whose calcium carbonate shells had been sequestering carbon. The death of those organisms released more carbon, intensifying the warming further. Each step amplified the next. The
negative feedback mechanisms that had maintained Gaian
homeostasis for hundreds of millions of years were not absent — they were overwhelmed. The perturbation was faster than the regulatory response. Approximately 96 percent of marine species and 70 percent of terrestrial vertebrate species perished. The biosphere recovered, but the recovery took roughly 10 million years, and