Fossil Corals Suggest a Mass Extinction Is on the Way: 'It's Like a Slow-Motion Car Crash'

If those who don't know history are destined to repeat it, then we should pay close attention to the last time that life on Earth almost ended. That's according to a team of scientists who have found compelling evidence that another mass extinction is underway.

At first glance, their work might seem obscure, meant only for other specialists. It involved comparing modern corals to their ancient counterparts. But like an urgent encrypted message from the past, the data revealed eerie parallels between the fate of today's species and those that disappeared with the dinosaurs.

"When we finally put all this together and saw the result, for me it was that moment when the hair on the back of your neck stands up," said marine biologist David Gruber, of The City University of New York. "It was like, Oh my goodness, [the corals] are doing exactly what they did back then."

Coral reefs, which harbor a teeming variety of fish and other sea life, have been devastated by the ocean warming associated with climate change. More than half the world's reefs have perished in the past 30 years. The study, published today in Scientific Reports, reveals that the coral species that are bleaching and dying are hauntingly similar to the ones that vanished in the last mass extinction 66 million years ago.

"It is a very clever study," said James W. Porter, a marine biologist at the University of Georgia who was not involved in the research. "They used the geological past to find clues to predict the future. I think they did a brilliant job."

Corals are ideal for a then-and-now comparison, because their hard skeletons leave a permanent, time-stamped fossil record. Meanwhile, the 839 corals on the "red list" of threatened species, compiled by the International Union for Conservation of Nature, provided the scientists with a modern benchmark for comparison.

The team began by identifying the shared traits of the few coral species that managed to survive the last big extinction. Then they scanned modern corals for those traits.

What they found was not only that the colorful, wavy corals that are most vulnerable today resemble the ones that died out in the past. Just as telling, the modern corals that are still thriving—those that form small colonies, favor deep water and thrive in a variety of locales—are the same ones that "hopped over" the extinction boundary millions of years ago and survived.

"The corals are transitioning toward these disaster traits," said Gruber, who is a National Geographic Explorer. "I think that is a powerful message."

There have been five major extinctions in Earth's history. Over the past 150 years, extinction rates have been steadily accelerating.

A landmark report was released last year by an international consortium, the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services. It found one million plant and animal species were at risk of extinction.

Porter, a member of the consortium, said the planet is already losing species at an alarming rate. And with the recent wildfires in the Amazon and Australia, this rate could now be far worse. "The Anthropocene is a very dangerous time for species on this planet," Porter said.

Stony coral
The stony coral (Oculina patagonica) after being exposed to acidic ocean condition (pH 7.4) after two months and four months. This shows how some coral species are able to adapt to more acidic, extinction-like conditions by transforming from colonial communities (top) to solitary existence. Fine & Tchernov, 2007 Science

But dramatic as the extinction crisis is, on a human time scale it's barely visible. "It's like a slow-motion car crash," Gruber said. The study—the first to compare today's threatened species with those that disappeared with the dinosaurs—provides a window into what many biologists have begun to call the "sixth extinction."

The good news from the study, at least for sentimentally inclined marine biologists, is that some corals are likely to be among the hardy creatures that survive the sixth extinction. Mass extinctions winnow life; they don't annihilate it. "Not everything goes extinct," Gruber said. "It takes a few million years and everything bounces back, but in a very different way."

Whether people will survive is anyone's guess. Some 60 percent of primate species are already threatened with extinction, according to a 2017 study. "That's our cohort," Gruber pointed out wryly. "We are beginning to transition and go through the extinction," he added. "Who comes out the other side is up for grabs."

Some creatures are particularly well suited to withstand harsh conditions. Jellyfish polyps can go into a cyst phase and endure for years without food. Tardigrades can dry out completely, then revive with a drop of water. Humans are not as flexible. "Even though we think we're so strong and resilient, we're actually very delicate compared to other species," Gruber said.

Where people do have the advantage is the ingenuity that our sophisticated brains bring to the problems we want to solve.

"We can put a person on the moon, we can come up with all these amazing technologies. We can reverse this in due time if we have the motivation," Gruber said. "But what the data is showing is that we're not doing that. We're putting our foot further on the pedal, whereas the corals are reacting and changing."

Correction 03/04/2020 3.02 a.m. This story has been corrected to remove erroneous figures about the number of species lost per day.

Editor's pick

Newsweek cover
  • Newsweek magazine delivered to your door
  • Unlimited access to
  • Ad free experience
  • iOS and Android app access
  • All newsletters + podcasts
Newsweek cover
  • Unlimited access to
  • Ad free experience
  • iOS and Android app access
  • All newsletters + podcasts