Mass extinctions on Earth are more common than you think. 

Most of us know about the asteroid that hit Earth just off the coast of the Yucatan Peninsula 65 million years ago and wiped out the dinosaurs, but that’s not the whole story. Many scientists now believe the 110-mile-wide rock may have been only partially responsible for the mass extinction at the end of the Cretaceous Period, pointing to a volcanic field in modern India that erupted around the same time, flooding the land with hot lava and turning the oceans to acid. One of the few reasons some birds, the last vestiges of the dinosaur age, were able to survive the slaughter was that they were burrowers who rode out the disaster underground.

Mass extinctions on Earth are more common than you think

And that’s only the most recent of Earth’s major life-threatening crises. In his new book, “The Ends of the World: Volcanic Apocalypses, Lethal Oceans, and Our Quest to Understand Earth’s Past Mass Extinctions” (Ecco), science writer Peter Brannen criss-crosses North America to review what we know about the moments when life on our planet was knocked down, only to get back up again. It’s a story that begins 450 million years ago, at the end of the Ordovician Period, which fell victim to a global warming that caused a 100-foot rise in the sea level, flooding the early continents.

‘These mass extinction events can be linked to drastic changes to Earth’s climate, often associated with a massive fluctuation in the carbon cycle, especially when the volcanoes are involved.’

Along the Hudson River, the cliffs of the Palisades show us how, 201 million years ago, at the end of the Triassic Period, the Earth’s wobbly rotation affected the amount of sunlight that hit the northern hemisphere, drastically dropping the planet’s temperature and wiping out nearly three-quarters of life on the planet in just 20,000 years. It was a particularly tough blow, coming only about 50 million years after Earth’s worst mass extinction, the End-Permian, when 90 percent of all life was obliterated.

The End-Permian is a smorgasbord of apocalyptic conditions: Where Russia stands today, a chain of volcanoes buried the land several miles deep in lava—and pumped enough carbon dioxide and other chemicals into the air to tear apart the ozone layer, along with raising the planet’s temperature to the point where the ambient temperature in the ocean was over 100° Fahrenheit. Acid rain destroyed the forests, and, some scientists speculate, conditions were so bad they might even have spawned 500-mile-per-hour mega-hurricanes full of poisonous gases that could rip through entire continents.

These mass extinction events can be linked to drastic changes to Earth’s climate, often associated with a massive fluctuation in the carbon cycle, especially when the volcanoes are involved. The implications for a world where climate change has became a (nearly) globally unifying concern are immediate and obvious. “Our current experiment — quickly injecting huge amounts of carbon dioxide into the atmosphere,” Brannen observes, “has in fact been run many times before in the geological past, and it never ends well.”

Brannen is not, however, a simple alarmist. As one scientist tells him, if we were really in a new mass extinction period, we would know it; in addition to the sorts of large beasts mankind has always hunted down, like tigers and elephants, even basic creatures like rats would be dying off. So, even though we’re adding carbon dioxide to the atmosphere at a rate ten times faster than conditions at the End-Permian, and increased baseline temperatures and rising sea levels now seem inevitable, we might still be able to find a way through the current situation. “You can’t beat [human] culture for resisting all kinds of horrific things,” another scientist tells Brannen, adding that it’s more likely “quality of life is going to go down the tubes” for most people than that we’d actually die out as a species. It’s even possible that, as the northern hemisphere once again begins losing sunlight, we may be raising the earth’s temperature just enough to save ourselves from a long-overdue ice age.

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