The man who wants to save humanity from nuclear winter

Seventy thousand years ago, it’s believed that humanity nearly went extinct.

A supervolcanic eruption, called Toba, dropped a thick layer of ash across much of the world and dimmed the sun for six full years. Crops worldwide died, and by most estimates, only a few thousand humans survived — some researchers believe it was as few as 40 “breeding pairs” of survivors.

The possibility of an event like that happening again keeps David Denkenberger up at night. Denkenberger is an assistant professor of mechanical engineering at the University of Alaska Fairbanks, and his thinking about apocalypse scenarios has driven him to a quixotic side project: figuring out how to ensure that no one starves to death in the aftermath of a natural catastrophe like Toba or a manmade one like a nuclear winter.

It may seem like a peculiar fixation, but it’s a real problem that very few people are thinking about. The world does not have much food stored up for the possibility of a large-scale disaster. To be fair to us, those disasters are quite rare. Toba was one. Another was the asteroid believed to have killed the dinosaurs. And there are manmade disasters — risk of a “nuclear winter” in the aftermath of a thermonuclear war, for one.

None of these are likely. But each would be catastrophic if it happened, and Denkenberger argues that if we start acting now, we could make them less catastrophic. He’s started an organization — Alliance to Feed the Earth in Disasters (ALLFED) — aimed at doing just that.

He got the idea in 2011 while reading a paper called “Fungi and Sustainability,” which concluded that if humans drive ourselves extinct, mushrooms would again rule the world. “I thought, why don’t we just eat the mushrooms and not go extinct?” Denkenberger recalls.

For a long time, thinking about catastrophe has been the domain, mostly, of fringe groups and individual survivalists. There’s very limited academic literature looking at things that might wipe humanity out, and how to prevent such disasters or survive them. “There are more academic papers on dung beetles than the fate of H. sapiens,” one researcher into existential risks wrote last year.

But that’s slowly changing. The fate of human civilization is an important subject of research and scientific inquiry — and if we get unlucky enough, it might be a vital one.

ALLFED is an eight-person nonprofit with a simple mission statement: to help increase the preparedness of governments, NGOs, corporations, and international bodies to feed everyone in the world in the aftermath of a catastrophe. The group focuses on both research and communications: figuring out how to produce food without the sun, and disseminating that information to help humanity in the event of a disaster.

When Denkenberger first dove into the existing research on survival in the aftermath of such catastrophes, what he found wasn’t encouraging. Most existing research takes for granted that billions of people will die.

But Denkenberger argues that technology has advanced far enough that there’s no reason for such pessimism. Mushrooms turn out not to be a great solution — too expensive and slow-growing — but there are several alternatives. Insects, for one — they grow fast, they eat things we can’t, and they are edible (though not friendly to American culinary sensibilities).

Seaweed and algae are another. They might grow all right with less sunlight. The sudden cooling from a sunless world would change how currents in the oceans move, and while that’s hard to model, it might actually produce a nutrient-rich ocean suitable for low-light food growth.

Then there are bacteria that turn biological products like leaves and grass, which we can’t eat, into sugars and proteins that we can, and bacteria that do the same thing but are fed on methane from natural gas. (The companies working on this much prefer the term “single-celled proteins,” Denkenberger tells me, and it definitely sounds more appetizing.).

In a book, Feeding Everyone No Matter What, Denkenberger and co-author Joshua M. Pearce explore the state of these options. They don’t sound appetizing — but the critical thing is that they might be possible. If humanity set its sights on producing enough calories without the sun, it looks like we could nearly do it, and additional research might close the remaining gaps.

These aren’t, for the most part, schemes you can set up in your backyard. “Lot of efforts, like the preppers” — a subculture of people who prepare for the collapse of civilization — “have been more focused on individual and family survival,” Denkenberger points out. But today, food production is vastly more efficient for being centralized in factories, and that would still be true in the aftermath of a catastrophe. So the ALLFED team looks at how to convert chemical plants and factories to grow food, more than at how households and individuals could do it.

“Some of these ideas can be used at the household scale,” Denkenberger said, but “it’s sort of a backup plan for if we can’t do the large-scale cooperation required to retrofit a factory”

Feeding the world would also ensure our resilience against a catastrophe in more indirect ways. For example, countries might be less likely to go to war and governments more likely to hold themselves together if there was reliable food access in the middle of a crisis, whereas wars and internal conflict might be more likely in the event of a food shortage.

Worst-case planning might come in handy in situations that aren’t as bad as the worst case, like a bad drought that produces what Denkenberger calls a “10 percent shortfall.” A 10 percent drop in global agricultural production would still leave enough food that it could supply everyone, but in practice, food prices would likely jump and hundreds of thousands would starve. A backup plan could be helpful in those situations too.

ALLFED is a fairly new organization, so at present they’re just investigating the lowest-hanging fruit in a dozen different areas of relevance to feeding the world in a catastrophe. Can ethanol-producing bioreactors be used, instead, to turn biofuels into sugar people can eat? Can single-celled proteins be grown on sheets of plastic? How expensive will retrofitting chemical plants be?

Of course, all this raises the question: Why not pour this effort into preventing these catastrophes, whose casualties would no doubt be enormous even if very few people starved? Denkenberger certainly agrees we should focus on that. But sometimes, it’s worth preparing even for something we’d very much prefer to prevent.

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