Why is the Permian-Triassic extinction considered the largest mass extinction in Earth’s history?

The Permian-Triassic extinction is considered the most severe mass extinction in Earth’s history due to the staggering scale of biological loss it caused. During this event, approximately 90 percent of all species on Earth were eliminated. This included the loss of more than 95 percent of marine species and 70 percent of terrestrial species, alongside the disappearance of more than half of all taxonomic families present at the time.12

This catastrophic decline is attributed to a combination of severe environmental stressors, most notably intense volcanic activity associated with the Siberian traps. These eruptions released massive quantities of carbon dioxide and volcanic ash, which likely triggered extreme global warming, disrupted photosynthesis, and contributed to widespread oceanic anoxia (a lack of dissolved oxygen). These conditions created a hostile environment that decimated both marine and terrestrial ecosystems. While other major extinction episodes have occurred throughout geologic time, the Permian-Triassic event remains the most devastating in terms of both species and family-level diversity loss.32415