Ocean Acidification Caused The Largest Mass Extinction Ever

And acidification is on the rise again

252 million years ago, massive volcanic eruptions sent a vast amount of lava flowing out onto the earth, and spewed huge amounts of carbon dioxide into the air, chemically altering the oceans in a series of events that would change life on earth forever.

It sounds like the dramatic plot of a science fiction thriller, but those are the findings of a new study published this week in Science that found that the largest extinction event on earth was caused by ocean acidification.

One of the lead authors, Matthew Clarkson, said in a press release, “Scientists have long suspected that an ocean acidification event occurred during the greatest mass extinction of all time, but direct evidence has been lacking until now. This is a worrying finding, considering that we can already see an increase in ocean acidity today that is the result of human carbon emissions.”

Clarkson and his colleagues looked at rocks in the United Arab Emirates that submerged in the oceans hundreds of millions of years ago. There, they found chemical evidence that the oceans went from alkaline to acidic relatively quickly in geologic terms–over the course of a few thousand years. There was so much CO2 ejected into the atmosphere in a second huge pulse of volcanic eruptions that the oceans quickly acidified, creating horribly inhospitable conditions for the marine life, destroying food chains and causing the collapse of most of the life in the ocean.

The aftermath of the eruptions killed off 90 percent of marine life and over 66 percent of terrestrial life over the course of 60,000 years. Life bounced back eventually, but the animals that emerged from the Great Dying were vastly different from the ones that came before. Among the winners? The ancestors of dinosaurs, whose descendants would be killed in another catastrophic disaster nearly 200 million years later.

Oceans today are rapidly acidifying due to increased CO2 emissions. Already scientists are finding that rising acidity levels in the oceans is affecting shellfish like lobsters, forcing fisheries around the country and world to plan for a future that hopefully won’t resemble the past.