Simon Beard has a career that most people would consider depressing and terrifying. He is part of a team of researchers trying to figure out if, how, and when climate change could cause the human species to go extinct. The stakes of his research—a potential annihilation of 7.7 billion humans and all the unborn people who come after them—couldn’t be any higher.

The idea that a heating planet will doom humanity is the subject of a lot of public speculation and anxiety, yet there are very few experts studying the existential impacts of climate change with any sort of academic rigor. Beard, who does this work at the Cambridge Center for the Study of Existential Risk, described it as “a field with next to no data” and a lot of unsupported hypotheses. “Under what circumstances could climate change cause a collapse of global civilization?” he said. “When you start asking that question, then your already quite-limited literature gets even more scarce.”

By bringing scientific precision to the doomsday scenario that wipes us off the planet, Beard hopes to convince world leaders to actually do something about it. “That’s really what we’re aiming for at the moment,” he said. “I think this could be genuinely transformative—firstly for the science but also by implication for the policy and the way that these things are discussed in society.”

The starting point for Beard’s research is that humans are incredibly resilient: We have found a way to survive in tropical rainforests, blistering deserts, icy tundra, and even for a brief time on the moon. But that says more about our collective strength than our skills as individuals. Shut down the grocery stores, turn off the taps, disband the government and very few of us, perhaps apart from a small number of rugged survivalists, would be able to stay alive for long.

“And so every one of us as an individual, I think, is very vulnerable, and relies upon these massive global systems that we’ve set up, these massive global institutions, to provide this support and to make us this wonderfully adaptable generalist species,” Beard recalled earlier this year on the Future of Life Institute podcast,

Those systems—the ones that put broccoli and frozen pizzas in our fridges and keep our streets from becoming Mad Max war zones—are themselves way more vulnerable and interconnected than we appreciate. The greenhouse gas emissions that humans are pumping into the atmosphere at record levels are changing the climate in ways that make it harder for us to grow and distribute food. This also increases pressure on our political system—as we saw with drought and crop failures in the lead-up to the Syrian civil war.

At some point—potentially sooner than we think, Beard fears—the stress could become too much. A collapse in one human or natural system could cascade into the others, potentially setting off a “global systems death spiral” that accelerates and amplifies the damage beyond our ability to control it. “That forms a feedback loop,” Beard said. “You basically get food security collapsing, political systems collapsing [and then] rising levels of environmental destruction. With this many people, that could be genuinely devastating for all of humanity.”

But this conceptual model, however terrifying, is crucially incomplete. What is the specific event or series of events capable of setting off this death spiral? Is the spiral enough on its own to end humanity? Are there “death traps or kill mechanisms” along the way that finish us off instead? What would those be? A nuclear war? A disastrous attempt to geoengineer the climate? Is the new stable state at the end of the death spiral habitable? Or is survival there impossible?

Beard and his team believe that they are tantalizingly close to providing answers. They are working on a paper that will attempt to describe in as scientifically robust detail as possible the precise mechanisms—however unlikely they are from actually occurring—that could end our human existence. The paper was supposed to come out at the end of August. He now hopes it will be published by the end of the year. But each time it feels ready they identify another blind spot.

“We do want to get it right, if we just put out a piece of speculation that can easily be rubbished we won’t have achieved our end, and the next time we put forward something then people won’t listen to it that much,” he said. “Professionally this has been one of the hardest judgment calls of my life, and I’m still finding it really stressful.”

Despite all this, Beard won’t let himself become sentimental. The work is too important, and he thinks “people who worry stay in bed.” But there was that time about a year and a half ago when he came home from having heart surgery and started to feel raw and emotional. (The doctors had warned him this could happen.) “I just burst into floods of tears thinking about this kind of existential collapse,” he said on the Future of Life Institute podcast. “And, you know, what it would mean for my kids and how we’d survive it, and it was completely overwhelming.”

Beard doesn’t come to this work from a science background. He did a PhD in philosophy, and prior to joining the Centre for the Study of Existential Risk he worked as a researcher in politics and policy for the U.K. parliament and several think tanks. But he sees the Centre’s mission as part of a long scientific tradition of inquiring into doomsday.

He likens what he’s doing to the pioneering work of Carl Sagan on the impacts of nuclear war. People had feared since the first nuclear bombs were detonated in the 1940s that these weapons could mean the end of humanity. But nobody could come up with a scientifically credible scenario—Would the explosions themselves wipe us all out? Would our extinction be caused by radiation?—for how this might take place. Sagan proposed in the early 1980s that nuclear war could hurl ash into the atmosphere, cooling the entire planet, which would destroy our ability to grow food and lead to mass starvation.

“That really stimulated this overall change in how we perceive the danger from nuclear war,” Beard explained. As Sagan’s initially crude calculations were replicated and refined by other scientists, Cold War adversaries Mikhail Gorbachev and Ronald Reagan warned about the horrors of nuclear winter, changing the terms of the nuclear disarmament debate. Beard and his colleagues are now trying to do something similar on climate change.

Not everyone thinks extinction scenarios are a top priority, though. “While it’s an interesting point to theoretically wonder about, I think it’s not really the most important question to be asking, because we’ll get significant problems well before that,” said Steven Lade, a researcher with the Stockholm Resilience Centre.

This gets at one of the climate extinction field’s biggest challenges: Nobody has put out work that is particularly persuasive. You have sensational scenarios such as the Breakthrough National Centre for Climate Restoration report this summer (covered by VICE) that warns of civilizational collapse potentially being triggered by 2050. But this attracted a significant amount of scientific scrutiny. “While there is plenty of scientific evidence that climate change will pose increasingly existential threats to the most vulnerable individuals in society and to key global ecosystems, even these dire outcomes aren’t equivalent to the ‘annihilation of intelligent life,’ as is claimed in the report,” argued UCLA’s Daniel Swan.

Then there are pieces—such as this one in Vox—which summarize the mainstream scientific consensus that even warming as high as 4 degrees Celsius, while undeniably bad for humanity, is not likely to lead to our extinction. “It’s worthwhile to look into the worst-case scenarios, and even to highlight and emphasize them. But it’s important to accurately represent current climate consensus along the way,” wrote Kelsey Piper. “Climate change won’t kill us all.”

Beard is averse to wild and unsubstantiated hypotheses. But he knows that using the extremely limited scholarly research that’s been done on climate extinction as a guide to the future isn’t necessarily a full picture of the horrors that could await us. That’s because we’re constantly learning how incomplete our conceptual models are for predicting cataclysmic risk.

Collage by Lia Kantrowitz

Consider for example the science around compound weather events, which the world still isn't prepared for. “They are events where a combination of multiple climate drivers or hazards cause potentially large impacts,” explained Jakob Zscheischler, a scientist at the University of Bern in Switzerland. That’s how you get what happened to Russia in 2010, when an unusually long high-pressure system led to record hot temperatures, which when combined with extremely dry soil conditions triggered wildfires that destroyed Russian crops and released deadly air pollution. More than 50,000 people died. “We are currently often underestimating the risk of these types of events,” Zscheischler said. “A lot of events we may not even know about because they only emerge in a warmer climate and we haven’t really thought about them.”

Things like the terrible Russian summer of 2010 may end up being a microcosm of what we experience on a planetary scale: Catastrophes that we previously saw as unrelated begin to amplify and intensify each other.

“At some point when you push the system far enough, it’s quite likely that tipping points will happen where the changes start to be non-linear,” Lade said.

Lade is part of a team of researchers that in 2018 laid out a distressing scenario for the future. At some level of atmospheric warming, perhaps as low as the famous 2 degrees Celsius above baseline target set out in the Paris agreement, which we could hit within the next few decades, we may still have to deal with the melting of all the Arctic sea ice or any number of other thresholds that could accelerate warming, pushing us domino-style past further tipping points and committing us to a “Hothouse Earth” that’s radically different from anything we experience today.

The potential impacts to humans are hard to fathom: the permanent flooding of coastal cities like Miami and Mumbai; the collapse of agriculture in Sub-Saharan Africa; Himalayan glaciers, which supply drinking water to over a billion people, retreating. As horrible as all this sounds, researchers like Lade don’t think it would necessarily wipe us off the planet. “I find it difficult to imagine that happening from climate change alone,” he said. “I imagine humans are resilient enough that some of us will survive somewhere, but of course things are bad far before an existential extinction.”

Beard thinks that the Resilience Centre is producing fascinating and useful research. But he worries that our food, political, and natural systems are more fragile than even those researchers assume. “You might actually not need what looks like a particularly devastating level of environmental change, even what the Hothouse Earth people are worried about, to trigger a downward spiral of these three systems,” he said.

With all the professional and existential stress he has bearing down on him, you might expect Beard to be angry, cynical and depressed. But instead he gives off something resembling hope.

“This isn’t science fiction stories that we’re telling ourselves to feel scared or feel a rush. This is a real problem. And we’re here to solve that problem,” he has argued. “Understanding the risk and responding to it: this is the way that we keep all the good things that our civilization has given us. This is the way that we keep international travel, that we keep our technology, that we keep our food and getting nice things from all around the world.”

We may be vulnerable as individuals, Beard believes, but we are not powerless.

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