Two hundred million years ago, at the end of the Triassic period, a mass extinction, often attributed to major volcanic activity, wiped out half of all marine life on Earth. But new research published in the journal Science suggests that the extinction was more likely to have been caused by the release of at least 12,000 gigatons of methane from the seafloor into the atmosphere.
Volcanic activity occurred over a period of 600,000 years at the end of the Triassic, while the extinction took place over a period of just 10,000 to 20,000 years, said Micha Ruhl, an earth scientist at the University of Copenhagen in Denmark and the study’s lead author.
Dr. Ruhl and his colleagues studied carbon isotopes of sediments from the period and found that the extinction event coincided with the giant release of methane into the atmosphere.
Volcanoes still played in a role in the process, Dr. Ruhl said.
“There was a release of CO2 from volcanic eruptions that warmed up global temperatures and also the ocean,” he said. “Methane is only stable under certain temperatures. If it gets warm, it is released.”
The study could be foreshadowing the effect of climate change on Earth, Dr. Ruhl said. An increase of carbon dioxide in the atmosphere from fossil-fuel use could warm up the planet enough to release methane from the ocean floors, he said.
“Methane is a much stronger greenhouse gas than CO2, so potentially that could result in a strong increase in temperature and climate change,” he said.