When the oceans became acidic

Colossal volcanic eruptions some 250 million years ago have long been linked to the widespread global extinction known as the “Great Dying“, a 60,000-year period that saw 90 percent of all sea creatures and more than two-thirds of all plants and animals on land die off. But new research has for the first time identified the specific cause of the carnage to identify when the oceans became acidic.

 

A team of scientists in the U.K., Germany, and New Zealand analyzed chemical footprints in ancient rocks, revealing a massive spike in oceanic pH levels over the course of the Great Dying. The dramatic increase was the result of huge amounts of carbon dioxide released into the atmosphere by the volcanic eruptions. The majority of that C02 was absorbed into the oceans—the same process occurring today. The scientists warn that this ancient event might foreshadow a future calamity if ocean acidification caused by fossil fuel emissions continues. “I think it might be a massive warning and a worst-case scenario,” says study author Matthew Clarkson. “Diversity didn’t recover for 5 million years.”

 

TED Talk: Rob Dunbar – The threat of ocean acidification

 

According to The Smithsonian, “Scientists formerly didn’t worry about this process because they always assumed that rivers carried enough dissolved chemicals from rocks to the ocean to keep the ocean’s pH stable. However, while the chemistry is predictable, the details of the biological impacts are not. Although scientists have been tracking ocean pH for more than 30 years, biological studies really only started in 2003, when the rapid shift caught their attention and the term ‘ocean acidification’ was first coined. What we do know is that things are going to look different, and we can’t predict in any detail how they will look. Some organisms will survive or even thrive under the more acidic conditions while others will struggle to adapt, and may even go extinct.”

As is the case with many aspects of human-caused climate change, the dangers, if they are in fact inevitable, could be enormous, but are still poorly understood. The future effects are only speculative at best, as adaptation can only be speculative as well.