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I was reading this paper called Fungi & Sustainability – the premise was that after an asteroid impact, humans would go extinct and the world would be ruled by mushrooms, which would grow just fine in the dark. I thought… why don’t we just eat the mushrooms and not go extinct?

Dr David Denkenberger

If a nuclear winter or asteroid impact blocked the sun for years, our inability to grow food would result in billions dying of starvation, right? According to Dr David Denkenberger, co-author of Feeding Everyone No Matter What: no. If he’s to be believed, nobody need starve at all.

Even without the sun, David sees the Earth as a bountiful food source. Mushrooms farmed on decaying wood. Bacteria fed with natural gas. Fish and mussels supported by sudden upwelling of ocean nutrients – and many more.

Dr Denkenberger is an Assistant Professor at the University of Alaska Fairbanks, and he’s out to spread the word that while a nuclear winter might be horrible, experts have been mistaken to assume that mass starvation is an inevitability. In fact, he says, the only thing that would prevent us from feeding the world is insufficient preparation.

Not content to just write a book pointing this out, David has gone on to found a growing nonprofit – the Alliance to Feed the Earth in Disasters – to brace the world to feed everyone come what may. He expects that today 10% of people would find enough food to survive a massive disaster. In principle, if we did everything right, nobody need go hungry. But being more realistic about how much we’re likely to invest, David hopes a plan to inform people ahead of time would save 30%, and a decent research and development scheme 80%.

According to David’s published cost-benefit analyses, work on this problem may be able to save lives, in expectation, for under $100 each, making it an incredible investment.

These preparations could also help make humanity more resilient to global catastrophic risks, by forestalling an ‘everyone for themselves’ mentality, which then causes trade and civilization to unravel.

But some worry that David’s cost-effectiveness estimates are exaggerations, so I challenge him on the practicality of his approach, and how much his nonprofit’s work would actually matter in a post-apocalyptic world. In our extensive conversation, we cover:

  • How could the sun end up getting blocked, or agriculture otherwise be decimated?
  • What are all the ways we could we eat nonetheless? What kind of life would this be?
  • Can these methods be scaled up fast?
  • What is his organisation, ALLFED, actually working on?
  • How does he estimate the cost-effectiveness of this work, and what are the biggest weaknesses of the approach?
  • How would more food affect the post-apocalyptic world? Won’t people figure it out at that point anyway?
  • Why not just leave guidebooks with this information in every city?
  • Would these preparations make nuclear war more likely?
  • What kind of people is ALLFED trying to hire?
  • What would ALLFED do with more money? What have been their biggest mistakes?
  • How he ended up doing this work. And his other engineering proposals for improving the world, including how to prevent a supervolcano explosion.

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The 80,000 Hours Podcast is produced by Keiran Harris.

Highlights

I am quite optimistic, because even though some of these solutions might not work out as well as I think they might, we do have quite a bit of redundancy in the system, that is, when I analyzed the food sources individually, many of them could increase up to feeding everyone fairly quickly even in one year.

Now, in reality, they would be competing for energy sources, so it’s not quite as good. And I did write another paper which actually analyzed them including the interactions but still found that we could feed everyone two times over or three times over. That’s what’s technically possible.

The other thing is that there are other things that I just haven’t analyzed yet. One of those is seaweed, but also other things like using energy from fossil fuels to directly synthesize food.

We’ve already done that at the lab scale. So the question is how fast could we ramp it up? I just haven’t done that analysis yet. Or bacteria that run on electricity. We’ve talked about how we have methane-eating bacteria, but what about nuclear energy?

The basic assumption in the book of Feeding Everyone No Matter What, assumes that we continue to cooperate. Which means trade of goods, sharing information, etc.

But I have done some less optimistic scenarios, say, what might be an economic scenario. So you would still have trade, you would not have immigration, seeing just how much trouble we’re having with refugees at this point, that’s probably not gonna be a feasible solution in a disaster. But if you still have trade of goods and sharing of information, and then a world food price, I was able to estimate well, what percent of the population would survive. And if you just have for stored food, it’s only around 10% of the population. I estimate, even now without anymore research and development, if countries just knew about these solutions or were told in time before they resorted to further military action, we could do much better than stored food, maybe 30% or so of people would survive.

But if we actually got prepared, like some of these alternate foods need more research. Some have already been developed commercially, but we’d need to figure out how to scale it up quickly, say retrofitting factories. And we actually have plans for scale up, and plans for how we would continue trading and things like that. Then survival could easily be 60, 70, 80%.

The water issue is particularly interesting, because if the earth cools, you get less evaporation from the ocean, and that ends up in less precipitation on the land, something like only half as much, which sounds really bad. But it turns out, more than half of our water is actually used for growing food. So if we’re not growing food, we could use the water for other things. It turns out the major uses of water are agriculture and cooling power plants, even showers is relatively small, and the actual drinking water is minuscule compared to those other things.

I would say that for the countries directly involved, certainly the nuclear exchange would be terrible and the alternate foods does not mitigate those direct impacts of blast and fire. I highly doubt that the decision to go to nuclear war in the heat of the moment would be influenced by whether there’s a back-up plan. Now, there is evidence that both Gorbachev and Reagan cited the nuclear winter studies as a reason to reduce nuclear stockpiles in the 80s. It is true, we’ve reduced nuclear stockpiles by about a factor of three in the last few decades. Some critics have said it was more a decision of reduced cost in the case of the USSR that they were becoming bankrupt. There’s some uncertainty how much the concern of nuclear winter actually led to disarmament or reduced arsenals. I think there is some possibility that alternative foods, if implemented and actually believed there was a back-up plan, then that could be an excuse to not reduce nuclear arsenals as much as they would have otherwise. I think it’s fairly low chance.

I think overall we would be in a much better position with a back-up plan, but I will point out that in this Guesstimate model for the impact on the far future, I do have a parameter for moral hazard. You can adjust that if you want to play with the model.

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About the show

The 80,000 Hours Podcast features unusually in-depth conversations about the world's most pressing problems and how you can use your career to solve them. We invite guests pursuing a wide range of career paths — from academics and activists to entrepreneurs and policymakers — to analyse the case for and against working on different issues and which approaches are best for solving them.

The 80,000 Hours Podcast is produced and edited by Keiran Harris. Get in touch with feedback or guest suggestions by emailing [email protected].

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