Scientists believe they may have found the cause of the greatest extinction event in earth’s history: Global warming caused by massive volcanic eruptions between 256 and 252 million years ago in what is now the east coast of Australia.
Scientists were already aware that the extinction event was caused by the planet’s warming, but they were unsure what caused it. The prevailing theory was volcanic eruptions in what is now Siberia, but there is evidence that the earth had already warmed 6 - 8C by the time the Siberian volcanoes began spewing out magma over two million years.
Evidence has been uncovered in the New England region of New South Wales, Australia, that a massive supervolcano, similar to those found in Yellowstone Park in the United States and Taupo, New Zealand, shot 150,000 km3 into the atmosphere, filling it with greenhouse gasses and covering the entire east coast of Australia with ash that would have measured meters thick in some places.
To put that in perspective, the 79AD Mt. Vesuvius eruption that destroyed the Roman city of Pompeii and preserved it in ash only emitted 3 - 4 km3 of volcanic material. For a more modern example, the Mt. St. Helens 1980 eruption killed 57 people and is the deadliest eruption in the United States history, only emitted 1 km3 of volcanic material.
The scientists, who published their findings in Nature, believe that the Siberian volcanoes that followed exacerbated the disaster that the volcanoes in Australia already started.
It is worth noting that at this time, the Earth was a far different place. Nearly every landmass was connected, including what is now Australia and Siberia, in a supercontinent known as Pangaea.
While the extinction event that killed off the dinosaurs at the end of the Jurassic period 65 million years ago is the most famous, this extinction event, known as the Great Permian Extinction was far worse and nearly ended life on the planet entirely.
After both the Australian and Siberian volcanic events, the earth’s temperatures continued to rise, up to 10C on land and 8C on the ocean’s surface. This led to the death of nearly all of the earth’s trees and killed 95% of marine life and 70% of land species. Just about the only non-microbiological kingdom that did well was fungi, which thrived off of the dead organic material left behind from the plants and animals dying in massive numbers.
Some scientists believe we are living through a sixth mass extinction event right now, called the Holocene extinction. It began 10,000 years ago but it is believed human activity is accelerating it greatly through pollution and habitat destruction.