Thanks for this detailed post on an underdiscussed topic! I agree with the broad conclusion that extinction via partial population collapse and infrastructure loss, rather than by the mechanism of catastrophe being potent enough to leave no or almost no survivors (or indirectly enabling some later extinction level event) has very low probability. Some comments:
Regarding case 1, with a pandemic leaving 50% of the population dead but no major infrastructure damage, I think you can make much stronger claims about there not being ‘civilization collapse’ meaning near-total failure of industrial food, water, and power systems. Indeed, collapse so defined from that stimulus seems nonsensical to me for rich quantitative reasons.
There is no WMD war here, otherwise there would be major infrastructure damage.
If half of people are dead, that cuts the need for food and water by half (doubling per capita stockpiles), while already planted calorie-rich crops can easily be harvested with a half-size workforce.
Today agriculture makes up closer to 5% than 10% of the world economy, and most of that effort is expended on luxuries such as animal agriculture, expensive fruits, avoidable food waste, and other things that aren’t efficient ways to produce nutrition. Adding all energy (again, most of which is not needed for basic survival as opposed to luxuries) brings the total to ~15%, and perhaps 5% on necessities (2.5% for half production for half population). That leaves a vast surplus workforce.
The catastrophe doubles resources of easily accessible fossil fuels and high quality agricultural land per surviving person, so just continuing to run the best 50% of farmland and the best 50% of oil wells means an increase in food and fossil fuels per person.
Likewise, there is a surplus of agricultural equipment, power plants, water treatment plants, and operating the better half of them with the surviving half of the population could improve per capita availability. These plants are parallel and independent enough that running half of them would not collapse productivity, which we can confirm by looking back to when there were half as many, etc.
Average hours worked per capita is already at historical lows, leaving plenty of room for trained survivors to work longer shifts while people switch over from other fields and retrain
Historical plagues such as the Black Death or smallpox in the Americas did not cause a breakdown of food production per capita for the survivors.
Historical wartime production changes show enormous and adequate flexibility in production.
Re the likelihood of survival without industrial agriculture systems, the benchmark should be something closer to preindustrial European agriculture, not hunter-gatherers. You discuss this but it would be helpful to put more specific credences on those alternatives.
The productivity of organic agriculture is still enormously high relative to hunting and gathering.
Basic knowledge about crop rotation, access to improved and global crop varieties such as potatoes, ploughs, etc permitted very high population density before industrial agriculture, with very localized supply chains. One can see this in colonial agricultural communities which could be largely self-sustaining (mines for metal tools being one of the worst supply constraints, but fine in a world where so much metal has already been mined and is just sitting around for reuse).
By the same token, talking about ‘at least 10%’ of 1-2 billion subsistence farmers continuing agriculture is a very low figure. I assume it is a fairly extreme lower bound, but it would be helpful to put credences on lower bounds and to help distinguish them from more likely possibilities.
Re food stockpiles:
“I’m ignoring animal agriculture and cannibalism, in part because without a functioning agriculture system, it’s not clear to me whether enough people would be able to consume living beings.”
Existing herds of farmed animals would likely be killed and eaten/preserved.
If transport networks are crippled, then this could be for local consumption, but that would increase food inequality and likelihood of survival in dire situations
There are about 1 billion cattle alone, with several hundred kg of edible mass each, plus about a billion sheep, ~700 million pigs, and 450 million goats.
In combination these could account for hundreds of billions of human-days of nutritional requirements (I think these make up a large share of ‘global food stocks’ in your table of supplies)
Already planted crops ready to harvest constitute a huge stockpile for the scenarios without infrastructure damage.
Particularly for severe population declines, fishing is limited by fish supplies, and existing fishing boats capture and kill vast quantities of fishes in days when short fishing seasons open. If the oceans are not damaged, this provides immense food resources to any survivors with modern fishing knowledge and some surviving fishing equipment.
“But if it did, I expect that the ~4 billion survivors would shrink to a group of 10–100 million survivors during a period of violent competition for surviving goods in grocery stores/distribution centers, food stocks, and fresh water sources.”
“So what, concretely, do I think would happen in the event of a catastrophe like a “moderate” pandemic — one that killed 50% of people, but didn’t cause infrastructure damage or climate change? My best guess is that civilization wouldn’t actually collapse everywhere. But if it did, I expect that the ~4 billion survivors would shrink to a group of 10–100 million survivors during a period of violent competition for surviving goods in grocery stores/distribution centers, food stocks, and fresh water sources.”
For the reasons discussed above I strongly disagree with the claim after “I expect.”
“All this in mind, I think it is very likely that the survivors would be able to learn enough during the grace period to be able to feed and shelter themselves ~indefinitely.”
I would say the probability should be higher here.
Regarding radioactive fallout, an additional factor not discussed is the decline of fallout danger over time: lethal areas are quite different over the first week vs the first year, etc.
Re Scenario 2: “Given all of this, my subjective judgment is that it’s very unlikely that this scenario would more or less directly lead to human extinction” I would again say this is even less likely.
In general I think extinction probability from WMD war is going to be concentrated in the plausible future case of greatly increased/deadlier arsenals: millions of nuclear weapons rather than thousands, enormous and varied bioweapons arsenals, and billions of anti-population hunter-killer robotic drones slaughtering survivors including those in bunkers, all released in the same conflict.
“Given this, I think it’s fairly likely, though far from guaranteed, that a catastrophe that caused 99.99% population loss, infrastructure damage, and climate change (e.g. a megacatastrohe, like a global war where biological weapons and nuclear weapons were used) would more or less directly cause human extinction.”
This seems like a sign error, differing from your earlier and later conclusions?
“I think it’s fairly unlikely that humanity would go extinct as a direct result of a catastrophe that caused the deaths of 99.99% of people (leaving 800 thousand survivors), extensive infrastructure damage, and temporary climate change (e.g. a more severe nuclear winter/asteroid impact, plus the use of biological weapons).”
Regarding case 1, with a pandemic leaving 50% of the population dead but no major infrastructure damage, I think you can make much stronger claims about there not being ‘civilization collapse’ meaning near-total failure of industrial food, water, and power systems. Indeed, collapse so defined from that stimulus seems nonsensical to me for rich quantitative reasons.
If there were a pandemic heading toward 50% population fatality, I think that it is likely that workers would not show up to critical industries and there would be a collapse of industrial civilization. I looked into whether the military could replace those workers, and it did not look feasible. Whether there would be further collapse of large-scale cooperation is less certain. If that cooperation is maintained, I agree it would be possible to have agricultural productivity similar to preindustrial Europe. However, it would mean a very rapid scale up of hand/animal farming equipment, and hand powered wells, carts that could be drawn by animals, etc (which ALLFED is planning on investigating). Some people say that modern crop varieties would actually do worse than traditional crop varieties if there were no artificial fertilizers and pesticides. If that were true or if scaling of tools were difficult, then we could have much worse agricultural productivity than preindustrial Europe.
Loss of rapid communication would likely imply fragmentation of large countries, if it is true that empires can only be maintained with I think a ~14 day communication radius. Furthermore, it is possible that cooperation outside of 100 person groups is lost, particularly because of fear of the disease. In this case, I think it is likely with current preparation to only be able to do hunting and gathering. In addition, the hunting and gathering population density could be much less than historic, because the overshoot in population density could mean that plants and animals that are good to eat could be driven to extinction by desperate humans.
Though it is possible that current food storage could be protected well, it is not clear to me that there would be a strong defense advantage. The desperate attackers would have weapons as well. If we go significantly above the carrying capacity and food is distributed fairly equally, then everyone would starve.
I would like to see these sorts of bio-catastrophes discussed in more detail. On my naive understanding, the threat of engineered pandemics seems likely to usher in an age of disruption and surveillance and to completely undermine current liberal democratic norms
My thought would be that getting the level of international coordination required would be extremely hard. (I am speaking from a position of ignorance here)
Maybe there could be groups of countries that agree to coordinate on this, and isolate themselves physically from countries outside their own groups?
I guess there might be ways to deliver disease through the air or wild (wild animals), or just sneaking into a country. The solution to that is domes. :P
Thanks for this detailed post on an underdiscussed topic! I agree with the broad conclusion that extinction via partial population collapse and infrastructure loss, rather than by the mechanism of catastrophe being potent enough to leave no or almost no survivors (or indirectly enabling some later extinction level event) has very low probability. Some comments:
Regarding case 1, with a pandemic leaving 50% of the population dead but no major infrastructure damage, I think you can make much stronger claims about there not being ‘civilization collapse’ meaning near-total failure of industrial food, water, and power systems. Indeed, collapse so defined from that stimulus seems nonsensical to me for rich quantitative reasons.
There is no WMD war here, otherwise there would be major infrastructure damage.
If half of people are dead, that cuts the need for food and water by half (doubling per capita stockpiles), while already planted calorie-rich crops can easily be harvested with a half-size workforce.
Today agriculture makes up closer to 5% than 10% of the world economy, and most of that effort is expended on luxuries such as animal agriculture, expensive fruits, avoidable food waste, and other things that aren’t efficient ways to produce nutrition. Adding all energy (again, most of which is not needed for basic survival as opposed to luxuries) brings the total to ~15%, and perhaps 5% on necessities (2.5% for half production for half population). That leaves a vast surplus workforce.
The catastrophe doubles resources of easily accessible fossil fuels and high quality agricultural land per surviving person, so just continuing to run the best 50% of farmland and the best 50% of oil wells means an increase in food and fossil fuels per person.
Likewise, there is a surplus of agricultural equipment, power plants, water treatment plants, and operating the better half of them with the surviving half of the population could improve per capita availability. These plants are parallel and independent enough that running half of them would not collapse productivity, which we can confirm by looking back to when there were half as many, etc.
Average hours worked per capita is already at historical lows, leaving plenty of room for trained survivors to work longer shifts while people switch over from other fields and retrain
Historical plagues such as the Black Death or smallpox in the Americas did not cause a breakdown of food production per capita for the survivors.
Historical wartime production changes show enormous and adequate flexibility in production.
Re the likelihood of survival without industrial agriculture systems, the benchmark should be something closer to preindustrial European agriculture, not hunter-gatherers. You discuss this but it would be helpful to put more specific credences on those alternatives.
The productivity of organic agriculture is still enormously high relative to hunting and gathering.
Basic knowledge about crop rotation, access to improved and global crop varieties such as potatoes, ploughs, etc permitted very high population density before industrial agriculture, with very localized supply chains. One can see this in colonial agricultural communities which could be largely self-sustaining (mines for metal tools being one of the worst supply constraints, but fine in a world where so much metal has already been mined and is just sitting around for reuse).
By the same token, talking about ‘at least 10%’ of 1-2 billion subsistence farmers continuing agriculture is a very low figure. I assume it is a fairly extreme lower bound, but it would be helpful to put credences on lower bounds and to help distinguish them from more likely possibilities.
Re food stockpiles:
“I’m ignoring animal agriculture and cannibalism, in part because without a functioning agriculture system, it’s not clear to me whether enough people would be able to consume living beings.”
Existing herds of farmed animals would likely be killed and eaten/preserved.
If transport networks are crippled, then this could be for local consumption, but that would increase food inequality and likelihood of survival in dire situations
There are about 1 billion cattle alone, with several hundred kg of edible mass each, plus about a billion sheep, ~700 million pigs, and 450 million goats.
In combination these could account for hundreds of billions of human-days of nutritional requirements (I think these make up a large share of ‘global food stocks’ in your table of supplies)
Already planted crops ready to harvest constitute a huge stockpile for the scenarios without infrastructure damage.
Particularly for severe population declines, fishing is limited by fish supplies, and existing fishing boats capture and kill vast quantities of fishes in days when short fishing seasons open. If the oceans are not damaged, this provides immense food resources to any survivors with modern fishing knowledge and some surviving fishing equipment.
“But if it did, I expect that the ~4 billion survivors would shrink to a group of 10–100 million survivors during a period of violent competition for surviving goods in grocery stores/distribution centers, food stocks, and fresh water sources.”
“So what, concretely, do I think would happen in the event of a catastrophe like a “moderate” pandemic — one that killed 50% of people, but didn’t cause infrastructure damage or climate change? My best guess is that civilization wouldn’t actually collapse everywhere. But if it did, I expect that the ~4 billion survivors would shrink to a group of 10–100 million survivors during a period of violent competition for surviving goods in grocery stores/distribution centers, food stocks, and fresh water sources.”
For the reasons discussed above I strongly disagree with the claim after “I expect.”
“All this in mind, I think it is very likely that the survivors would be able to learn enough during the grace period to be able to feed and shelter themselves ~indefinitely.”
I would say the probability should be higher here.
Regarding radioactive fallout, an additional factor not discussed is the decline of fallout danger over time: lethal areas are quite different over the first week vs the first year, etc.
Re Scenario 2: “Given all of this, my subjective judgment is that it’s very unlikely that this scenario would more or less directly lead to human extinction” I would again say this is even less likely.
In general I think extinction probability from WMD war is going to be concentrated in the plausible future case of greatly increased/deadlier arsenals: millions of nuclear weapons rather than thousands, enormous and varied bioweapons arsenals, and billions of anti-population hunter-killer robotic drones slaughtering survivors including those in bunkers, all released in the same conflict.
“Given this, I think it’s fairly likely, though far from guaranteed, that a catastrophe that caused 99.99% population loss, infrastructure damage, and climate change (e.g. a megacatastrohe, like a global war where biological weapons and nuclear weapons were used) would more or less directly cause human extinction.”
This seems like a sign error, differing from your earlier and later conclusions?
“I think it’s fairly unlikely that humanity would go extinct as a direct result of a catastrophe that caused the deaths of 99.99% of people (leaving 800 thousand survivors), extensive infrastructure damage, and temporary climate change (e.g. a more severe nuclear winter/asteroid impact, plus the use of biological weapons).”
If there were a pandemic heading toward 50% population fatality, I think that it is likely that workers would not show up to critical industries and there would be a collapse of industrial civilization. I looked into whether the military could replace those workers, and it did not look feasible. Whether there would be further collapse of large-scale cooperation is less certain. If that cooperation is maintained, I agree it would be possible to have agricultural productivity similar to preindustrial Europe. However, it would mean a very rapid scale up of hand/animal farming equipment, and hand powered wells, carts that could be drawn by animals, etc (which ALLFED is planning on investigating). Some people say that modern crop varieties would actually do worse than traditional crop varieties if there were no artificial fertilizers and pesticides. If that were true or if scaling of tools were difficult, then we could have much worse agricultural productivity than preindustrial Europe.
Loss of rapid communication would likely imply fragmentation of large countries, if it is true that empires can only be maintained with I think a ~14 day communication radius. Furthermore, it is possible that cooperation outside of 100 person groups is lost, particularly because of fear of the disease. In this case, I think it is likely with current preparation to only be able to do hunting and gathering. In addition, the hunting and gathering population density could be much less than historic, because the overshoot in population density could mean that plants and animals that are good to eat could be driven to extinction by desperate humans.
Though it is possible that current food storage could be protected well, it is not clear to me that there would be a strong defense advantage. The desperate attackers would have weapons as well. If we go significantly above the carrying capacity and food is distributed fairly equally, then everyone would starve.
I would like to see these sorts of bio-catastrophes discussed in more detail. On my naive understanding, the threat of engineered pandemics seems likely to usher in an age of disruption and surveillance and to completely undermine current liberal democratic norms
You don’t think regulating the sale and use of the technologies necessary to engineer diseases would be enough?
My thought would be that getting the level of international coordination required would be extremely hard. (I am speaking from a position of ignorance here)
Maybe there could be groups of countries that agree to coordinate on this, and isolate themselves physically from countries outside their own groups?
I guess there might be ways to deliver disease through the air or wild (wild animals), or just sneaking into a country. The solution to that is domes. :P
At this point, that would be at least as easy a task as removing the 400 million firearms in private American hands.
IOW, good luck with that.
https://carnegieendowment.org/2018/04/17/new-killer-pathogens-countering-coming-bioweapons-threat-pub-76009