Volcanic Activity and Declining Ocean Oxygen caused Mass Extinction

Volcanic Activity and Declining Ocean Oxygen caused Mass Extinction

Artist conception of the Jurassic Extinction. Credit: NewScientists.com

Marine Organisms could go extinct in the coming years if industrial emissions of Carbon Dioxide are not controlled on an emergency basis.

Climate change is inflicting disastrous effects on Earth in several ways. One of the most dangerous among them is the rapid increment in the levels of Carbon Dioxide in our atmosphere. As a result, Oxygen is being sucked away from oceans at an alarming rate and what makes it worse is that the scientists are unaware of the response that our planet will have to do that. As the last resort, they were forced to look for a similar instance in the past and the findings are not promising by any stretch of the imagination.

An international team of researchers, which was led by Theodore Them, investigated the Toarcian Oceanic Anoxic Event (T-OAE). It is a phase of ‘Global Oceanic Deoxygenation’ which occurred in the Early Jurassic Period and it led to a mass extinction of marine organisms. Scientists discovered that Oxygen was sucked out from the oceans as volcanoes filled our atmosphere with Carbon Dioxide, millions of years ago. This was the root cause of the mass extinction that followed. Them, a Postdoctoral Researcher at the Florida State University (FSU) explained the reason for studying that interval of time and the results of their study in the following words:

We wanted to reconstruct Early Jurassic ocean oxygen levels to better understand the mass extinction and the T-OAE. We used to think of ocean temperature and acidification as a one-two punch, but more recently we’ve learned this third variable, oxygen change, is equally important.

The huge episodes of Volcanic Activity which caused large-scale deoxygenation can be compared with the industrial emissions we experience these days. According to Them, the levels of Oxygen in our oceans have gone down considerably in the last 5 decades. He believes that despite the fact that both the timescales are millions of years apart, volcanism of that time can be compared with current Carbon Dioxide emissions. He told the world that this was the reason which forced them to study such an old volcanic activity. A co-author of the study, Jeremy Owens who is an Assistant Professor at the Department of Earth in FSU, stressed that point further as he said,

We want to understand how volcanism, which can be related to modern anthropogenic carbon dioxide release, manifests itself in ocean chemistry and extinction events. Could this be a precursor to what we’re seeing today with oxygen loss in our oceans? Will we experience something as catastrophic as this mass extinction event?

The team also analyzed the composition of the Thallium isotope found inside ancient rocks in North America and Europe. It showed the researchers that oceanic Oxygen started to deplete well before the time that is generally linked with T-OAE. This exaggerated the fear that a repeat of that catastrophic event could be on the cards given the recent observations.

When the concentration of Carbon Dioxide becomes too much in the atmosphere, temperatures tend to increase globally. This generally initiates a series of chemical, biological, and hydrological events that suck oxygen away from the oceans. The marine organisms that rely on Oxygen are deprived of this compulsory commodity and consequently, a massive-scale extinctions happen. The scientists conducting this research found evidence that hundreds of thousands of years before the T-OAE, the atmosphere of our planet was filled with Carbon Dioxide by Volcanoes.

This triggered that sequence of events which ultimately wiped away a lot of species from the surface of this planet. This study holds special significance as scientists suggested a link between volcanism, loss of oxygen, and mass extinction many years ago but there was no scientific proof to back these claims. Following this research, humanity has the first conclusive data to work with. Them acknowledged that by saying,

As a community, we’ve suggested that sediments deposited during the T-OAE were indicative of widespread oxygen loss in the oceans, but we’ve never had the data until now.

The team of researches mentioned that whenever the levels of Carbon Dioxide have increased beyond a certain limit, we have had a major incident of destruction. Them warned the world about the calamity as he indicated that if the rate of deoxygenation continues to follow its current trend, future marine organisms have a pretty bleak chance of surviving. He said,

If you’re an oxygen-consuming organism, you don’t want to see major changes in marine oxygen levels. You either adapt or go extinct.

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