Earth has seen five mass extinction events in the past 540 million years, which might seem like ancient history until you realize that insane carbon levels mean we could be in for another one in less than a hundred years.
At least geophysicist Daniel Rothman thinks so. When Rothman compiled a database of fossil records that go up to half a billion years back in time, he found there were scary carbon isotope levels at the same time many species were forever turned into fossils. This is evidence that our planet’s carbon cycle was seriously abnormal—and it’s happening again.
Carbon dioxide emissions have been creeping upward since the smoke of high-carbon fossil fuels first cast a shadow over the industrial revolution. Humans haven’t really been doing much to reverse that trend either, which is what makes Rothman believe that such instability in the environment could eventually explode into a sixth mass extinction. An anomaly in carbon levels that ended up skyrocketing in the last century is difficult to compare to those that developed in thousands and even millions of years. With oceans expected to absorb another 300 billion tons of carbon, scientists are getting nervous.
“It’s not that the date 2100 is a magic date,” said Rothman, who recently published his findings in the journal Science Advances. “The projection of the amount of carbon that will have been added by anthropogenic means — fossil fuel burning — for the most part suggest that 300 gigaton limit will have been surpassed by end of the century. But it may happen sooner. The question in the end is: What happens next?”
Rothman believes that crossing this threshold could end up in catastrophe. Even if we don’t go the way of the dinosaurs by the year 2100, the planet could see an onslaught of environmental change in the next 10,000 years, which is nothing in cosmological terms. Some scientists think he’s giving us too much time. They are convinced that this sixth mass extinction is already looming, and most of us are oblivious to it.
The most devastating extinction event in Earth’s history was the end-Permian extinction, when over 95% of marine species were obliterated. It is no surprise to Rothman that a massive jolt of carbon shocked the Earth during this disaster. While his study doesn’t point at CO2 as the cause for the past five mass extinctions, the eerie coincidence between these anomalies and so many species being wiped out should have us concerned.
“When [processes] start to go in a direction that is amounting to a disturbance, one disturbance begets another, begets another one,” he said.
Meaning, we should really watch our impact on the environment if we don’t want to end up like those dinosaur fossils grinning back at us.