Scientists have found the first piece of conclusive evidence that high levels of carbon dioxide killed off Earth's marine life 182 million years ago.

The results of the study do not bode well for the future as atmospheric carbon dioxide levels continue to rise due to industrial emissions.

Volcanoes Sent Carbon Dioxide Levels Spiraling Upward

Sometime during the early Jurassic Period, the Earth's powerful volcanoes sent massive amounts of carbon dioxide into the atmosphere. This depleted the world's oceans of oxygen, suffocating marine life and killing off all underwater creatures. The process is not any different to how modern-day industrial facilities pump plumes of carbon dioxide into the air.

Scientists call this the Toarcian Oceanic Anoxic Event (T-OAE), which took place 174 to 182 million years ago. The T-OAE is characterized by global deoxygenation of oceans followed by the mass extinction of marine flora and fauna.

A team of researchers at the Florida State University have decided to examine the T-OAE to better understand how volcanic activity and carbon dioxide levels are linked to mass extinction events.

"Could this be a precursor to what we're seeing today with oxygen loss in our oceans?" says study coauthor Jeremy Owens of FSU's Department of Earth, Ocean and Atmospheric Science. "Will we experience something as catastrophic as this mass extinction event?"

How Too Much Carbon Dioxide Leads To Mass Extinction

The study, published in the journal Proceedings of the National Academy of Sciences, details how the team came to the conclusion that deoxygenation of ancient oceans began well before the T-OAE.

By examining the thallium isotope composition of ancient rocks gathered from North America and Europe, the team found that excessive carbon dioxide in the atmosphere began draining oxygen from the world's oceans hundreds of thousands of years before T-OAE began.

They believe that even though the timescales are different, the onset of T-OAE could paint an eerie picture of a similar disaster-in-the-making that could be happening today.

"Over the past 50 years, we've seen that a significant amount of oxygen has been lost from our modern oceans," says Theodore Them, lead author and postdoctoral researcher at FSU.

High amounts of carbon dioxide in the atmosphere causes a rise in temperature. This triggers a set of chemical, biological, and hydrological events that diminish the ocean's oxygen levels, which could prove to be devastating for modern species.

Curbing The Carbon Dioxide Problem

Scientists have long suggested the link between low oxygen levels and mass extinction. However, they could find no proof for this hypothesis until now.

Previously, most researchers thought ocean temperatures and acidity were the only factors leading to mass extinctions. They have only recently begun probing the effects of oxygen change in what could prove to be a catastrophe for the world's oceans.

There is hope for humanity, however, if governments push for the preservation of ecosystems that absorb huge amounts of carbon dioxide, such as wetlands and estuaries.

Unfortunately, if the rampant rise of atmospheric carbon dioxide levels is not curbed, the future could be bleak for the world's oceans and for all humanity that depends on them.

Photo: Andiseño Estudio | Flickr

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