Mass extinctions litter the history of life on Earth, with about a dozen known in addition to the five largest ones — the last of which, at the end of the Cretaceous Period 66 million years ago, killed off the dinosaurs and 70% of all life on Earth.
A new study, led by scientists at Dartmouth College in New Hampshire, concludes that most of these mass extinctions had one thing in common: They occurred after mega-eruptions that spewed volcanic lava and toxic gases for hundreds of thousands of years, and some for as long as a million years.
The analysis linking mass extinctions throughout Earth’s history with major eruptions, characterized by lava and gas spilling from perhaps dozens of volcanoes and long fissure vents, confirms what many geologists have suspected for years. The most well-known mass extinction, referred to as the Cretaceous-Paleogene (K-Pg) extinction, was famously tied to a comet or asteroid impact in the Caribbean, but geologists have since found that the impact was preceded by a long period of eruptions in India that left behind flood basalts known today as the Deccan Traps. Massive amounts of sulfur dioxide emitted during the long-term eruption would have cooled the planet and caused the massive die-off seen in the fossil record.