How research into existential risk will help safeguard humanity

by | Feb 22, 2024

Florian Jehn combines pragmatism with optimism when considering potential threats to human civilization. 
Portrait of Florian Jehn.

Imagining future disaster scenarios might seem like a grim job to most. But some scientists, like Florian Jehn, see it as an opportunity to help humanity.

As a researcher for the nonprofit organization Alliance to Feed the Earth in Disasters (ALLFED), his job is to find ways to prepare for a sudden shock to the global food system, which might be triggered by a supervolcanic eruption, nuclear war, or pandemic more extreme than Covid-19, for example.

His thought-provoking blog, Existential Crunch, explores various existential risks that threaten human civilization, and how we can learn from past events that shook up the world.

We talked to Jehn over Zoom to gain insight into how he approaches his research, the existential risks he’s worried about, and how we can be more resilient if and when catastrophe strikes.

What did you study in university? Was this what you set out to do early on in your studies?   

Environmental science. I mostly focused on soil science, and in my master’s and Ph.D. programs, it was more in the direction of hydrology, basically trying to understand how rivers work.

[What I do now] was definitely not what I originally planned. But during my Ph.D., I noticed that I wasn’t super happy with the impact of the work that I was doing. Hydrology is fine and interesting, but it felt to me like a field where basically all the big questions are kind of answered.

I came across Effective Thesis, an organization that tries to connect students doing their bachelor’s, master’s, or Ph.D. thesis with [research] supervisors [with whom] they can do more impactful research. They connected me with ALLFED, and I volunteered there a bit. When my first postdoc ended, I applied and started working there.

Do you consider yourself a data scientist? What’s your research process?

In general, I see myself as an environmental scientist with a lot of data science skills by now because this is what I’ve been doing for the last few years. I think the first big task in every research [project] is finding out what I even want to do.

My research in the field of global food security is relatively young. There’s all these open research questions everywhere, and the first difficult task is finding the right one to work on. But once I’ve settled on the question, I think the next big step is, “Okay, I know what I want to understand”. And now I have to find the data and the tools out there that I can use to get me to my answer.

This is also often quite a big part, especially because the data isn’t usually structured in the way you want it to be or the way you need it for your analysis. A lot of my time just goes into preparing the data into the way I need it, and then I need to stitch together all the different tools and the data that I found to do the actual analysis.

Once this is done, then comes the fun part. Then, I can do all the plots because creating the figures for the paper is usually, at least for me, the most fun part because you can actually see what you wanted to see all along and answer your questions.

What do you consider the main existential risks today?

I think it’s really difficult to choose [a] main one. But the biggest group that I’m usually working on and interested in is abrupt sunlight-reduction scenarios, which is basically every big catastrophic event that blocks out the sun. We usually count nuclear war, asteroid impacts, and supervolcanic eruptions.

The other big group that I look into is what we classify as “global catastrophic infrastructure loss”. These are events where you have catastrophic impacts on the way we produce stuff — especially impacts on our electrical grid. And those could be things like, for example, a geomagnetic storm, which can disable large parts of the electrical grid and also smaller electronic appliances. If such a thing would happen today, we would probably have quite a big problem.

Which risk are you most worried about?

It’s difficult [to say] because they would all be pretty bad. But I think the one that comes most often to my mind is nuclear war because it can be more easily and quickly triggered than most of the other catastrophes. We would only realize it the moment the nuclear missiles started exploding.

The basic idea is that when you have a nuclear war and you target cities, you are lighting up the whole city at once. So, you just have one very, very big fire, and this — these extremely big fires — they can build up to so-called “firestorms” that suck in the air from the surrounding environment because they act like giant chimneys and pull all the soot that is created high up in the atmosphere. The soot can then be transported even higher, to above the area where rain is happening.

Once it’s over, the rain basically takes years to fall back down to Earth. And in the meantime, you have all these black soot particles that block out the sunlight, which in turn leads to much lower temperatures globally. If you have a very big nuclear war, for example, between Russia and the US, it would probably take 10ish years to get back to normal. And the worst would be the first two to three years.”

I read the article Science denial and nuclear winter” on your blog, and you mentioned that some people deny the possibility of nuclear winter. What are the arguments against it?

Yeah, that’s true. You kind of have to choose — I don’t know what to call it — the “public disinformation” version of this and the more “academic criticism”. A big part of the public disinformation version comes from earlier disinformation campaigns, where people with special interests argued, for example, “Hey, we had those big fires in Kuwait during the wars, and these didn’t lead to any reduction in global temperatures. So, nuclear war would also not be a problem.” This is wrong, but it’s an argument that is often used.

The more academic criticism, which I take seriously, is the big question of “How burnable are cities?” because, fortunately, we often don’t burn a whole city. We usually don’t have the data on how much burnable material would be there and how much soot would be created. The possible range is quite large from the estimates we have. Depending on where you end up on the estimate of how burnable you think a city is, you either get “nuclear winter is basically impossible” to “nuclear winter is almost a certainty”.

What do you think is the best way to prepare for a possible nuclear winter?

I think, in general, the best way to prepare for this is to try to avoid it in the first place. But if this is impossible, then, the organization I work for, ALLFED, is looking into how we can maintain food production in such cases—food production is very much dependent on the status quo. So, if you want to prepare for such catastrophes, one good way is to say, “Look, ok, if our current agricultural system isn’t able to produce food anymore, how can we prepare to make sure that we still have alternative food resources?”

What exactly is ALLFED doing?

In general, ALLFED is a completely remote, nonprofit research organization. We’re dedicated to reducing catastrophic risks that arise from the disruption of food production in general. To do so, on one hand, we’re doing basic research, and on the other hand, we’re trying to inform policymakers.

The way we do this, we’re looking into so-called “resilient foods”, which are all the foods that would still reliably produce calories after global catastrophes. One example that was just recently published is how we can use seaweed as an alternative food after sun-blocking scenarios. This turned out to be quite promising. But, in general, we don’t have a silver bullet that lets us say “Hey, we just do this, and everything is solved.”

But what our research has shown again and again is that we need a mix of different food sources. What’s also quite important is that we manage to maintain global cooperation and trade because surviving global catastrophes gets much, much harder if every country, for example, would be on its own.

One quite interesting thing that we have been looking at is so-called “single-cell protein”. We have a bioreactor: you put nutrients in, and you have bacteria in the bioreactor that can eat those nutrients and produce protein, which you can then eat. This has the advantage that it doesn’t need sunlight. You just need to have the bioreactor, but, obviously, bioreactors aren’t just lying around, so you have to prepare for this. This isn’t science fiction, we’re already using this [bioreactors] right now, but mostly I think they’re used for producing fish food. There’s also the consideration of how to use this more today because it would also be quite helpful to create a very cheap source of protein for humans.

Where in the world do you think is the best place to be in the event of a major catastrophe, and why?

That’s a tricky question. I also wanted to write about this in the future in my blog, where I try to really disentangle all the different parts. But, in general, you don’t want to stay in big cities because they are very dependent on food coming in and also don’t have very big food reserves.

Country-wise, one thing that we find for most — or even all — the catastrophes that we looked at so far is that Australia is pretty good. It’s in the southern hemisphere, so it will likely be less affected by nuclear war. And it’s also relatively hot and dry now, so, if you have abrupt sunlight-reduction scenarios, where it gets cooler with more precipitation, it’s actually kind of good for some places in Australia. It’s also big enough to have its own industrial base, at least for some of the basic goods. New Zealand is also good, but they often run into the problem that their industrial base is relatively small, and they are more reliant on imports than Australia.

If you have sunlight-reduction scenarios, like nuclear winter, it doesn’t mean that the whole world is pitch black for 10 years. But due to the way the atmosphere works, you’ll have less soot near the equator and more sun rays coming in there. So, in general, the closer to the equator you are, the brighter it is, even in those abrupt sunlight-reduction scenarios. Many parts of Australia are close enough to the equator, so you still have enough light there to grow food outside.

You mentioned the terms “hot science” and “cold science” in one of your blog posts. What’s the difference between the two?

This isn’t my own concept. The general difference is that cold science is a very incremental science that tries to pick the last few puzzle pieces to stitch things together. Hot science, on the other hand, is very explorative and curious. To keep with the metaphor, it’s like trying to find a whole new puzzle to work on and not only fill the puzzle pieces.

Is what you’re doing (existential risk research) hot science?

Not everything, I would say. But definitely a lot of it is because, as I mentioned, the tricky thing is to find interesting research questions. You have to do hot science there because otherwise you are mostly just producing very incremental, not-so-interesting research questions, especially if your whole field is very new. It really makes sense to try to be as curious and explorative as possible.

What’s your take-home message for the general public? Should we all be prepping for doomsday?

One of the big takeaways from my research is that if you have a global catastrophe, then doing preparations on your own doesn’t really make much sense. You need global cooperation. You need to work on big solutions to produce enough food for everyone.

I think if you are a [doomsday] prepper, and global cooperation fails, then you just die a few years later than everybody else. But you don’t really win anything. I’m just doing what I can to help ensure that we don’t end up in a situation where it’s everybody on their own because if we end up there, then everybody’s going to have a bad time, either way.

Is climate change a possible reason for civilizational collapse?

Climate change is definitely a big problem. I read a lot of history papers, and the message is pretty clear that for most of the past societal collapses, you often find—or almost everywhere find—that climate is involved in one way or the other.

One good example is the Bronze Age collapse, where all these civilizations in the Mediterranean that existed for hundreds of years, a very complex civilization, was built on interdependence. Then, within 100 or 200 years, basically all of them—or almost all of them—collapsed. Now, we think this is very strongly linked to so called mega drought, where there was very much reduced rainfall for almost 300 years in the region. So, they couldn’t do their agriculture anymore, and if agriculture doesn’t work anymore, then you have a big problem.

What do you think are the most promising climate-change mitigation strategies?

It’s a bit outside my expertise, but in general, I don’t think we have one good solution that will solve all our climate change problems. Classic ones are just not eating as many animal products. But in general, I think having things like CO2 tax is a good idea because many of the negative effects that we have can be traced back to the way we use energy. If we would be able to reduce this via, for example, CO2 tax, then you would be hitting many sectors at once, and you wouldn’t have to find all the piecemeal solutions.

How can people support ALLFED?

We have a complete volunteer pipeline where people, if they’re interested, can say, “Hey, I’ve got those skills and I would be interested in working for or volunteering for ALLFED.” In general, we prefer people who have more time and also a bit more experience.

Especially helpful are people who want to do their Master’s thesis, for example, because then they also have a very strong incentive to keep on working. In the future, we will likely change our volunteer program a bit, and people could apply for the projects they would be interested in, but we haven’t implemented this yet.

What’s your advice for the general public? Should we all be prepping for doomsday?

My general advice, at least from my perspective, the research I’ve done on my own, and the research I’ve read by others, is that the one big factor that determines if a society makes it through hard times is how good their democracy is. And so, I think the most important thing you can do on your own is to make sure your democracy is intact and that you’re engaged politically, and just be as inclusive and participatory as possible because when you try to consider all the different perspectives a society has to offer, you usually come to much better solutions than if you just have one group pushing their agenda through. Take global catastrophic risks seriously, but don’t lose optimism.

Just for fun, what is your favorite post-apocalyptic movie?

I think enough about the end of the world in my day job [he said laughing].

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