The Ends of the World: Volcanic Apocalypses, Lethal Oceans, and Our Quest to Understand Earth's Past Mass Extinctions

by Peter Brannen

in 1896 Swedish scientist Svante Arrhenius predicted that doubling CO2 in the atmosphere would warm the planet by about 4 degrees Celsius, a prediction that’s roughly in line with those of our most powerful modern supercomputers. Needless to say, discussion of this basic science by actors with baldly political motivations can be depressing beyond words.

The idea that life could be wiped out in an eyeblink was a disreputable one—one that reeked of Old Testament destruction. The field had spent almost two centuries trying to shake off the specter of Genesis-inspired flood “geology” of the sort that now enjoys a nauseating revival in some parts of the United States.

One gas in particular stands out as the primary killer in what would become the greatest mass death in earth history. Researchers don’t study the worst catastrophe ever purely out of academic, or even morbid, curiosity. The End-Permian mass extinction is the absolute end-member—the worst-case scenario—for what happens when you jam too much carbon dioxide into the atmosphere.

Ward’s talks—a mix of technical exposition and gallows humor—introduced me to the idea that carbon dioxide–driven global warming is not just being simulated in climate models on government supercomputers, but is an experiment that the earth has already run many times in the deep past. More shocking to me was that global warming might have been implicated in the most extreme die-off ever in the fossil record.

It was later discovered that buckyballs can’t trap helium-3 for more than a million years anyway before it leaks out.

Given how outrageous some of these End-Permian scenarios were, I asked Kump whether comparisons to the modern day are really appropriate. “Well, the rate at which we’re injecting CO2 into the atmosphere today, according to our best estimates, is ten times faster than it was during the End-Permian. And rates matter. So today we’re creating a very difficult environment for life to adapt, and we’re imposing that change maybe ten times faster than the worst events in Earth’s history.” “That’s the take-home message.” He chuckled again. “Not to be a gloom-and-doom guy.”

At the end of the Cretaceous, the largest asteroid known to have hit any planet in the solar system in a half-billion years hit Earth . . . At virtually the same time that one of the largest volcanic eruptions ever smothered parts of India in lava more than 2 miles deep.

While the Texas oil economy relies on the truth of geology, many of its inhabitants remain stubbornly resistant to its charms.

The invention of the written word allowed this information about manipulating the physical world—that now resides and mutates outside the genome, in books, magazines, newspapers, science journals, and, most recently, the Internet—to be dispersed ever more widely. There is a straight line of cultural evolution—a cultural clade—from spears to nuclear weapons. Culture has allowed us to cast off the shackles of evolutionary time. Today these tens of thousands of years of cultural evolution have given us a world where we have gained such mastery over the physical environment that we hold the knobs of the entire earth system—and are twisting them violently.

human civilization is now propped up by a continuous explosion of energy, a global mega-metabolism, with hundreds of millions of years’ worth of sunlight being released all at once in combustion engines and power plants. Carbon dioxide is a by-product of this new civilizational metabolism, and we now emit 100 times more CO2 each year than volcanoes. This far outstrips the ability of the earth’s thermostat to keep up through rock weathering and ocean circulation, operating as those processes do on 1,000- to 100,000-year timescales.

“The headlines are not just inaccurate,” writes futurist Stewart Brand on the premature obituary for the planet that has become de rigueur in some circles. “As they accumulate, they frame our whole relationship with nature as one of unremitting tragedy. The core of tragedy is that it cannot be fixed, and that is a formula for hopelessness and inaction. Lazy romanticism about impending doom becomes the default view.”

I had written to Erwin to get his take on the now-fashionable idea that there is currently a sixth mass extinction under way on our planet on par with the Big Five. Many popular science articles take this as a given, and indeed, there’s something emotionally satisfying about the idea that humans’ hubris and shortsightedness are so profound that we’re bringing down the whole planet with us. Erwin thinks it’s junk science. “Many of those making facile comparisons between the current situation and past mass extinctions don’t have a clue about the difference in the nature of the data, much less how truly awful the mass extinctions recorded in the marine fossil record actually were,” he wrote me in an email. “I am not claiming that humans haven’t done great damage to marine and terrestrial extinctions, nor that many extinctions have not occurred and more will certainly occur in the near future. But I do think that as scientists we have a responsibility to be accurate about such comparisons.”

When mass extinctions hit, they don’t just take out big charismatic megafauna, like elephants, or niche ecosystems, like cloud forests. They take out hardy and ubiquitous organisms as well—things like clams and plants and insects. This is incredibly hard to do. But once you go over the edge and flip into mass extinction mode, nothing is safe. Mass extinctions kill almost everything on the planet.

Many of us share some dim apprehension that the world is flying out of control, that the center cannot hold. Raging wildfires, once-in-1,000-year storms, and lethal heat waves have become fixtures of the evening news—and all this after the planet has warmed by less than 1 degree Celsius above preindustrial temperatures. But here’s where it gets really scary. If humanity burns through all its fossil fuel reserves, there is the potential to warm the planet by as much as 18 degrees Celsius and raise sea levels by hundreds of feet.

According to Huber and Sherwood’s modeling, 7 degrees Celsius of warming would begin to render large parts of the globe lethally hot to mammals. Continue warming past that, and truly huge swaths of the planet currently inhabited by humans would exceed 35 degrees Celsius wet-bulb temperatures and would have to be abandoned. Otherwise, the people who live there would be literally cooked to death. “People are always like, ‘Oh, well, can’t we adapt?’ and you can, to a point,” he said. “It’s just after that point that I’m talking about.”

The uncommonly pleasant climate window of the past 10,000 years has been among the most equable and stable in the past million years. It’s within this unusual interval that all of recorded history has occurred. Viewed in time-lapse, the earth would pulsate with glaciers over the past 2.6 million years as it dipped in and out of the ice ages. Then, in the last frame—in the most recent of countless glacial retreats—agriculture, the division of labor, writing, all of ancient history, messianic cults with global appeal, architecture, coastal cities, peer-reviewed science, and the Choco Taco would appear. But this temporary climatic arrangement should be appreciated for what it is—exceedingly fortunate and rare.

In 2015, all the countries of the world met in Paris to negotiate a plan to prevent the planet from warming by 2 degrees by 2100. Despite the rosy assessment of many editorial writers, they failed catastrophically. There are no binding commitments, and countries’ adherence to the agreement is voluntary. Though the signatory countries announced their intent to aim for 1.5 degrees of warming, the agreement itself sheepishly acknowledges that if every country met their optimistic emissions pledges, the planet would still easily sail past 2 degrees.

Still, this 2-degree goal is, in fact, extremely ambitious. To reach it—as the world population continues to add billions of souls—fossil fuel use will need to fall to near zero by midcentury at the same time that the world will have to scrape together nearly 30 terawatts of new carbon-free energy, a preposterous amount equivalent to more than double what the world currently consumes, most of which is from fossil fuels. It’s why Columbia economist Scott Barrett wrote about the Paris agreement: “The only way the voluntary contributions pledged thus far could achieve the collective 2-degree goal is if a miracle occurs around 2030, some technological breakthrough forcing global emissions to plummet. Even then, the chances of staying within the 2-degree goal are no better than 50-50.”

Underlying certain segments of the environmentalist movement is a sort of existential misanthropy, the idea—even hope—that humans will get what they deserve. That getting spat out by Gaia is just recompense for trashing the planet. These sentiments pop up both in unenlightened online comment sections and in the understandably resigned fatalism of working scientists, many of whom will tell you after a few beers, “We’re fucked.”