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Global warming led to ancient mass extinction event, scientists say

According to new research, a rise of greenhouse gases 250 million years ago led to the disappearance of most life on Earth. CBS News meteorologist and climate specialist Jeff Berardelli spoke to Brock University geochemist Dr. Uwe Brand to find out why scientists are linking the Great Dying to climate change impacts today.

Video Transcript


JEFF BERARDELLI: In Climate Watch, scientists believe they finally solved a mystery that stumped them for decades. A global extinction event, called the Great Dying, occurred about 250 million years ago, and understanding what happened then could provide some insight into the impacts of climate change. Here is CBS News meteorologist and climate specialist, Jeff Bertelli.

DR. UWE BRAND: We're trying to go back in time 250 million years to piece together what caused this massive catastrophic extinction.

JEFF BERARDELLI: Dr. Uwe Brand is a geochemist from Brock University in Ontario, Canada. He's been investigating an event called the Great Dying when 90% of all ocean life and 70% on land just disappeared. Exactly how it happened has baffled scientists for decades.

DR. UWE BRAND: People over the years have speculated on causes. What caused this disappearance of life? And everything from meteorites, asteroids, you know, extraterrestrial impacts to things happening here on Earth.

JEFF BERARDELLI: Now Brand and other scientists may have the answer. In two papers published recently they analyzed the chemical makeup of ancient rocks in Italy and China. They discovered a rare substance called Coronene, dating back even before the dinosaurs 250 million years ago, which can only be formed when fossil fuels burn at extremely high temperatures. The culprit turned out to be a million years worth of volcanic eruptions in Siberia. Brand says that most of this was a gradual process, but towards the end an escalation of volcanic activity and a spike in greenhouse gases was the nail in the coffin.

DR. UWE BRAND: This was not volcanism in the traditional sense where you simply have volcanoes and they spew out material. They That were more like fissures, cracks in the crust, where the lava flowed either on top of the land or it was squeezed in between sedimentary rocks.

JEFF BERARDELLI: It all happened at the end of the Permian geological period and created lava beds that were massive.

DR. UWE BRAND: The size is equivalent to at least half of the United States and to a thickness of several kilometers.

JEFF BERARDELLI: As the lava squeezed through the cracks and crevices it seared large underground deposits of coal, oil, and gas releasing extraordinary amounts of heat trapping greenhouse gases, like carbon dioxide and methane. In fact, concentrations were much higher than today. Globally, the atmosphere warmed to levels 18 degrees Fahrenheit higher than they are right now, forcing animals and plants to adapt, move, or die. At the same time, carbon dioxide combined with water to produce sulfuric acid and that acidified the oceans. Coral disintegrated and the shells of ocean creatures dissolved.

Now on land, the hotter climate shifted vegetation and ignited fires. That exposed more rocks and erosion went into overdrive. As a result, an overabundance of nutrients flowed into the ocean causing, at first, an explosion of life. Then the inevitable death and decomposition eating up most of the life giving oxygen in the ocean and suffocating life. Existence was getting hit from all angles.

DR. UWE BRAND: These are not individual and separate causes, but they all acted together. They acted in concert. That's why I call it the perfect storm.

JEFF BERARDELLI: As catastrophic as the Great Dying was, scientists are concerned the Earth could now be headed for another disaster. Right now, the planet is warming abruptly to levels not seen in over 100,000 years. Oceans are acidifying, and oxygen dead zones are multiplying. And astonishingly the rate of release of heat trapping greenhouse gases right now is much more radical than it was back then.

DR. UWE BRAND: Our emission is 10, easy, 10 to 20 times higher than what happened during the Permian mass extinction, which was the last, largest, and biggest mass extinction.

JEFF BERARDELLI: But Brandt also says we still have time to turn this around by moving away from the burning of fossil fuels. He says to save ourselves we have to learn from events like the Great Dying.

DR. UWE BRAND: You know what they say, learn from history because if you don't you will repeat it. The way I see it, yes, it's going to happen if we don't stop it.

JEFF BERARDELLI: Jeff Berardelli, CBS News.