The scene of the crime
Around 252 million years ago, the world ended. This cataclysm, known as the Permian-Triassic extinction or "The Great Dying," was the most severe extinction event in Earth's history, wiping out about 96% of marine species and 70% of terrestrial vertebrate species. The main cause is a massive volcanic region in Russia known as the Siberian Traps.
This was not a single volcano, but a Large Igneous Province (LIP), where enormous fissures in the crust bled lava for approximately two million years. The eruptions disgorged an estimated 4 million cubic kilometers of basaltic lava, covering an area of about 7 million square kilometers—larger than western Europe. The source of this immense volcanism is thought to be a mantle plume, a massive upwelling of hot rock from deep within the Earth that melted through the crust. These were not explosive eruptions but flood basalts, where lava poured out and spread across the landscape, creating step-like hills called "traps," from the Swedish word "trappa" for stairs.
The lava itself was not the main killer. The true weapon was the cocktail of gases released into the atmosphere. The magma intruded into and burned through vast underground deposits of coal, carbonate, and other organic matter, releasing astronomical quantities of carbon dioxide, methane, and toxic gases.
The global fallout
The release of volcanic gases triggered a cascade of environmental disasters. Atmospheric carbon dioxide levels may have soared from around 400 parts per million to as high as 10,000. This initiated a runaway greenhouse effect, causing global temperatures to rise dramatically. Equatorial ocean temperatures may have exceeded 40°C (104°F).
This intense warming had devastating effects on the oceans. As the water heated up, it could hold less dissolved oxygen, creating vast anoxic "dead zones." Marine animals, their metabolisms sped up by the heat, essentially suffocated. At the same time, the immense volume of CO2 dissolved into the seawater, causing rapid ocean acidification. This prevented organisms like corals, brachiopods, and mollusks from building their calcium carbonate shells and skeletons, leading to the collapse of entire ecosystems.
On land, the situation was equally dire. Acid rain from sulfur dioxide and other gases would have destroyed forests. The combination of extreme heat and acid rain stripped the land of vegetation, leading to massive soil erosion. The entire food web, on land and in the sea, was systematically dismantled. Famous groups like the trilobites and sea scorpions (eurypterids) vanished completely. It took life on Earth as long as 10 million years to fully recover from the event.