I spent a few months in 2019 researching civilizational collapse scenarios, and came to some tentative conclusions. One question that drove my research was: “How difficult would it be to launch a project that significantly improved the resilience capacity of civilization?” and “How likely is it that such a project could improve the long term prospects for humanity?”

For context, I also gave a talk about reducing the uncertainty in collapse scenarios, which you can watch here.

My conclusion after investigating potential collapse scenarios. (I originally wrote this as an EA Forum comment.)

1. There are a number of plausible (>1% probability) scenarios in the next hundred years that would result in a "civilizational collapse", where an unprecedented number of people die and key technologies are (temporarily) lost.
2. Most of these collapse scenarios would be temporary, with complete recovery likely on the scale of decades to a couple hundred years.
3. The highest leverage point for intervention in a potential post-collapse environment would be at the state level. Individuals, even wealthy individuals, lack the infrastructure and human resources at the scale necessary to rebuild effectively. There are some decent mitigations possible in the space of information archival, such as seed banks and internet archives, but these are far less likely to have long term impacts compared to state efforts.

Based on these conclusions, I decided to focus my efforts on other global risk analysis areas, because I felt I didn't have the relevant skills or resources to embark on a state-level project. If I did have those skills & resources, I believe (low to medium confidence) it would be worthwhile project, and if I found a person or group who did possess those skills / resources, I would strongly consider offering my assistance.

Collapse Q&A

In reviewing a grant proposal related to the project above, Oliver Habryka noted he had a number of cruxes about collapse scenarios & mitigations. I thought these were good questions, so recently wrote out my responses.

• Is there a high chance that human population completely collapses as a result of less than 90% of the population being wiped out in a global catastrophe?

I think the answer in the short term is no, if "completely collapses" means something like "is unable to get back to at least 1950's level technology in 500 years". I think think there are a number of things that could reduce humanity's "technological carrying capacity". I'm currently working on explicating some of these factors, but some examples would be drastic climate change, long-lived radionuclides, increase in persistent pathogens.

• Can we build any reasonable models about what our bottlenecks will be for recovery after a significant global catastrophe? (This is likely dependent on an analysis of what specific catastrophes are most likely and what state they leave humanity in)

I think we can. I'm not sure we can get very confident about exactly which potential bottlenecks will prove most significant, but I think we can narrow the search space and put forth some good hypotheses, both by reasoning from the best reference class examples we have and by thinking through the economics of potential scenarios.

• Are there major risks that have a chance to wipe out more than 90% of the population, but not all of it? My models of biorisk suggests it's quite hard to get to 90% mortality, I think most nuclear winter scenarios also have less than a 90% food reduction impact

I'm not sure about this one. I can think of some scenarios that would wipe out 90%+ of the population but none of them seem very likely. Engineered pandemics seem like one candidate (I agree with Denkenberger here), and the worst-case nuclear winter scenarios might also do it, though I haven't read the nuclear winter papers in a while, and there has been several new papers and comments in the last year, including real disagreement in the field (yay, finally!)

• Are there non-population-level dependent ways in which modern civilization is fragile that might cause widespread collapse and the end of scientific progress? If so, are there any ways to prepare for them?

Population seems like one important variable in our technological carrying capacity, but I expect some of the others are as important. The one I mentioned in my other post is basically I think a huge one is state planning & coordination capacity. I think post-WWII Germany and Japan illustrate this quite well. However, I don't have a very good sense of what might cause most states to fail without also destroying a large part of the population at the same time. But what I'm saying is that the population factor might not be the most important one in those scenarios.

• Are there strong reasons to expect the existential risk profile of a recovered civilization to be significantly better than for our current civilization? (E.g. maybe a bad experience with nuclear weapons would make the world much more aware of the dangers of technology)

I'm very uncertain about this. I do think there is a good case for interventions aimed at improving the existential risk profile of post-disaster civilization being competitive with interventions aimed at improving the existential risk profile of our current civilization. The gist is that there is far less competition for the former interventions. Of course, given the huge uncertainties about both the circumstances of global catastrophes and the potential intervention points, it's hard to say whether it would possible to actually alter the post-disaster civilization's profile at all. However, it's also hard to say whether we can alter the current civilization's profile at all, and it's not obvious to me that this latter task is easier.