Lava from Kilauea volcano in Hawaii erupts on July 14, 2018. Scientists say mercury in ancient rocks indicates that volcanic activity was responsible for Earth's greatest mass extinction some 250 million years ago.

(U.S. Geological Survey via AP, File)

At a Glance

Researchers analyzed mercury in ancient rocks to track volcanic activity. The Permian Extinction, or the "Great Dying," was Earth's largest extinction event. Scientists say the research could predict future dire effects of global warming.

Mercury buried in ancient rocks provides the strongest evidence to date that volcanic eruptions caused Earth’s most-deadly mass extinction. That event happened some 250 million years ago and was so catastrophic scientists call it the “Great Dying.”

In a research paper published this month in the journal Nature Communications, paleontologists from China University of Geosciences and the University of Cincinnati in 391 marine sedimentary samples taken from 10 sites around the globe. The samples date back to what is known as the Permian-Triassic boundary, the time period in which scientists say the Great Dying took place.

The samples showed higher than normal levels of mercury, supporting the theory that volcanic eruptions caused the event formally known as the Permian Triassic extinction, which scientists believe happened over the course of hundreds of thousands of years.

"Volcanic activities, including emissions of and combustion of organic matter, released abundant mercury to the surface of the Earth," lead author Jun Shen, an associate professor at the China University of Geosciences said, according to an article from the University of Cincinnati.

The Great Dying is believed to have killed off 95 percent of the life on the planet and happened before dinosaurs even roamed the earth. It’s one of documented in Earth's history.

Scientists had already determined occurred in a volcanic system called the Siberian Traps in what is now central Russia. The violent eruptions happened over hundreds of thousands of years and released vast amounts of mercury into the air that later rained down into marine sediment, according to the University of Cincinnati report.

Those volcanic activities, in turn, led to global warming that increased the Earth’s average temperature by as much as 50 degrees Fahrenheit, said Thomas Algeo, a professor of geology at the University of Cincinnati and a coauthor of the study.

Algeo said the increasing temperatures, combined with acid rain from the eruptions, are the most likely culprits of the mass extinction.

"We're often left scratching our heads about what exactly was most harmful,” the University of Cincinnati article quoted Algeo as saying. “Creatures adapted to colder environments would have been out of luck. So my guess is temperature change would be the No. 1 killer. Effects would be exacerbated by acidification and other toxins in the environment."

Shen said in the report that the Permian Triassic extinction may be a dire warning sign of the impacts of today’s global warming.

"The release of carbon into the atmosphere by human beings is similar to the situation in the Late Permian, where abundant carbon was released by the Siberian eruptions," he said.

Algeo add his concern.

"A majority of biologists believe we're at the cusp of another mass extinction - the sixth big one. I share that view, too," he said. "What we should learn is this will be serious business that will harm human interests so we should work to minimize the damage."