This time the planet is warming much, much faster
Most people have heard of climate change, the long-term and rapid changes in weather patterns Earth is experiencing today. But fewer know that the planet has undergone similar climate changes before—with devastating consequences.
The ocean simply became too hot and too oxygen-poor.
Some 252 million years ago, massive volcanic eruptions spewed greenhouse gases into the sky, trapping heat in the Earth’s atmosphere and warming the planet by more than 10 degrees Celsius. This extreme temperature change occurred over only a few thousand years—a very short time in geologic history. It increased ocean temperatures, deprived ocean-dwellers of oxygen, and triggered what geologists call the “Great Dying” the greatest mass extinction in Earth’s history. 90% or more of marine life went extinct, and terrestrial species didn’t fare much better.
Scientists have hypothesized several ways this drastic climactic change might have prompted the Great Dying, including ocean acidification and metals from the eruptions poisoning a variety of species. But a recent study has unveiled the most likely culprit: The ocean simply became too hot and too oxygen-poor.
In the study, researchers simulated ancient Earth’s conditions before the Great Dying. Then they modeled marine species’ simulated responses to extreme warming. Since testing the model with experiments was impossible, the researchers needed another way to verify its accuracy. To do so, they compared their model’s predictions for how many species would disappear with the actual fossil record of extinct species—and the predictions matched.
The events leading up to this ancient die-off share ominous parallels with contemporary climate change
Like all studies, this one isn’t perfect. To run their model, the researchers needed to know different extinct species’ limits for oxygen and heat. Of course, they didn’t have enough data on these species that died of hundreds of millions of years ago. So instead, the authors used data on similar living species. While this isn’t ideal, it’s a clever workaround for several reasons. For one, the climate today is similar to the Permian climate, so species are adapted to similar environments. Secondly, and more importantly, the researchers ran some test runs of their model to show that even if their results are biased, it wouldn’t change the general conclusions.
Their study yielded an interesting but counter-intuitive result: Tropical species were less likely to go extinct than those at higher latitudes. The tropics were already hot before the climate changed, so how did marine life handle even more extreme temperatures after rapid warming? The answer is: they didn’t. When conditions become too extreme, tropical species simply migrated to colder latitudes. But species in polar oceans who got too hot were out of luck—there was nowhere colder for them to go!