“This is the way the world ends, not with a bang but with a whimper.” — T.S. Eliot
When most people hear the phrase mass extinction, they imagine an extra-terrestrial object plummeting towards Earth. Maybe they picture the unfathomable shockwave that rocked the planet 66 million years ago as herds of giants and beasts lost their lives in a matter of seconds. But that isn’t the reality of most mass extinctions. In complex life’s roughly 2.33-billion-year history, Earth has survived at least five of these events. A mass extinction, or extinction event, is defined as a period when 75% of life on Earth is wiped out within a relatively short span of geologic time. The five such events in the known paleontological record are the end-Ordovician, late Devonian, end-Permian, end-Triassic, and end-Cretaceous extinctions. These events feel far-flung and perhaps almost mythical things that happened long before our collective memory and could never happen again. But what if they aren’t?
Since the late 1900s, scientists have speculated that Earth may have entered its sixth mass extinction event. In 2000, Paul Crutzen and Eugene Stoermer argued that the time since the start of the Industrial Revolution should be called the Anthropocene. Since then, some scientists have suggested that the Anthropocene may simply be the beginning of a new mass extinction.
Recently, I read The Ends of the World by Peter Brannen. In this scientific thriller, Brannen walks the reader through all five historic mass extinctions in glorious, almost heartbreaking detail. While reading, his comparisons between the end-Permian extinction, the end-Triassic extinction, and today’s climate crisis were honestly terrifying. As an aspiring vertebrate paleontologist, I understand just how important paleontological comparisons are to understanding our world. But now, more than ever, understanding these ends of the world may be the only way to know what our future may hold. Throughout the book, Brannen shows that there is one major culprit behind most of these extinction events: carbon dioxide. That sounds pretty familiar, doesn’t it? The Permian and Triassic extinctions are two of the best comparison points for our current rapid climate change, so those are the events worth focusing on.
While the asteroid responsible for wiping out the dinosaurs and an estimated 76% of life on Earth (the end-Cretaceous) is the most popular and well-studied extinction event, it was far from the worst. The Permian extinction, also known as The Great Dying, completely blows the Cretaceous extinction out of the water. The Permian period lasted from about 298 to 251 million years ago, and its end marked the close of the Paleozoic Era and paved the way for the rise of dinosaurs. Around 250 million years ago, Earth was left as essentially a barren wasteland, and an estimated 96% of all species were lost within just a relatively short span of Geologic time. It earned it’s gloomy nickname because it was the closest Earth has ever come to losing nearly all of its diversity.
This event was caused by the eruption of the Siberian Traps. Even calling this “volcanic activity” almost undersells what actually happened. For comparison, the Yellowstone supervolcano pales in comparison to the Siberian Traps. Lava from these eruptions covered an area of more than two million square kilometers, in places reaching up to four kilometers thick. Along with the lava came an estimated 52–80 tons of CO₂ per square meter. This massive and rapid increase in greenhouse gases caused intense global warming, ocean acidification, marine anoxia, and worldwide ecosystem collapse.
While the end-Triassic extinction was less grandiose, similar mechanisms were at play. Around 200 million years ago, underwater volcanic activity triggered global warming and chemical changes in the oceans, leading to the extinction of roughly 80% of life on Earth.
In The Ends of the World, Peter Brannen compares our current climate crisis to these two events because today we emit over 35 billion tons of COâ‚‚ each year. As temperatures continue to rise, the similarities are hard to ignore. Our oceans are becoming more acidic, and ocean diversity seems to shrink every year as coral reefs disappear (something that also famously occurred during the Permian and Triassic mass extinctions). On top of that, since the beginning of the Anthropocene, many scientists estimate that extinction rates are now up to 10,000 times higher than natural background rates.
This raises the question: are we in the midst of a sixth mass extinction event? I agree with Brannen’s take that the answer is no, but it may be rapidly approaching. Earth has not yet reached the proverbial event horizon of destruction — the point of no return, where the loss of massive amounts of biodiversity is inevitable. We still have time to prevent our species from becoming the next Siberian Traps, dooming a huge percentage of life on Earth.
The fight against the loss of Earth’s biodiversity is not yet lost. Now, more than ever, this is the moment for change and for a new precedent to be set. We can’t undo the damage humans have already caused, but we can learn from the cold, barren world our distant ancestors inherited, and ensure we never leave our descendants with something similar.
What brings me comfort is the idea that, despite all of these grand extinction events scattered throughout Earth’s history, life itself is resilient. Someday, a mass extinction will bring about the end of all complex life as Earth slowly loses carbon dioxide from its atmosphere. My hope is that this happens long after the traces of humanity have weathered away and disappeared into the sands of time. I sometimes imagine the last animal on an entirely unfamiliar Earth watching the sunrise, just as we do now. I remember that, in cosmic time, we may leave little to no lasting mark at all. As Brannen writes at the end of his book, “all will be well.”