The biggest ever wipeout of life on Earth was indeed the result of the oceans turning acidic according to researchers. They say unearthed rocks provide the first clear evidence to prove a theory behind the mass extinction 252 million years ago.

The Permian-Triassic extinction event, also known simply as the Great Dying, killed off around 96 percent of all marine species and 70 percent of land-based vertebrates. It’s likely the only such event where the majority of biological families were made extinct.

Scientists have previously worked on the theory that acidification of the oceans was the key factor. That theory is looking much more solid now that a team at the University of Edinburgh has analyzed rocks from the United Arab Emirates [pictured] which were on the seabed at the time.

The rocks show the effects of changes in the ocean and allowed the researchers to put together a climate model. They believe volcanic eruptions in Siberia released such large bursts of carbon dioxide that the gas was absorbed by oceans and turned more acidic. That proved fatal for the marine species and likely had a knock-on effect on the ecosystem as a whole.

The research has naturally prompted debate about parallels with climate change concerns today. While volcanic eruptions might sound like a rapid event that’s very different to any factors affecting carbon dioxide levels today, they were only sudden in comparison to the history of the world.

The release and the resulting acidification actually took around 10,000 years. While the actual amount of carbon dioxide released was huge (likely more than the equivalent of all remaining untapped fossil fuels today), the researchers say the rate of release following the eruptions was “similar to modern emissions.”

(Image credit: Donatella Astratti)