Dylan Matthews’ claim that nuclear war would cause “much or all of humankind” to suddenly vanish is unsubstantiated. The idea that billions of people worldwide will die from nuclear war is not supported by models with realistic numbers of nuclear warheads. “Much” is a very vague term, but speculation that every (or nearly every) human will die is a false alarm. Now that is easy to forgive, as it’s a common belief within EA anyway and probably someone will try to argue with me about it.
Could you expand on this or give sources? I do hear EAs talking about nuclear war and nuclear winter being existential threats.
Well, deaths from nuclear explosions will obviously be a small minority of the world.
Large numbers of people will survive severe fallout: it’s fairly easy to build safe shelters in most locations. Kearny’s Nuclear War Survival Skills shows how feasible it is. Governments and militaries of course know to prepare for this sort of thing. And I think fallout doesn’t become a truly global phenomenon, it is only deadly if you are downwind from the blast sites.
Here is one of the main nuclear winter studies, that uses a modern climate model. They assume the use of the entire global arsenal (including 10,000 US and 10,000 Russian weapons) to get their pessimistic 150 Tg scenario, which has a peak cooling of 7.5 degrees celsius. That will still leave large parts of the world with a relatively warm temperatures. However, the US has already gone down to 1,800 weapons in the actual strategic arsenal, with 4,000 in the general stockpile. Russia’s stockpile is 7,850 with only 1,600 in the strategic arsenal. The use of all nuclear weapons in a war is an unrealistic assumption because countries have limited delivery systems, they’ll want to still have some nuclear weapons in case they survive, and they won’t want to cripple their own country and allies with excessive global cooling. Also, the assumption that all weapons will detonate is unrealistic—missile defense systems and force-on-force strikes will destroy many nuclear weapons before they can hit their targets. So even their moderate 50 Tg scenario with 3.5 degrees celsius of cooling seems implausible, it would still require nearly 7,000 weapons detonated. It seems like we are really looking at 2-3 degrees celsius cooling from an unlimited exchange—approximately enough to cancel out past and future global warming. The temperature also recovers quite a bit in just a few years.
The issue is that there are many sources of uncertainty of nuclear winter. When I developed a probabilistic model taking all these sources into account, I did get a median impact that was 2-3 C reduction (though I was also giving significant probability weight to industrial and counterforce strikes). However, I still got a ~20% probability of collapse of agriculture.
Could you expand on this or give sources? I do hear EAs talking about nuclear war and nuclear winter being existential threats.
Well, deaths from nuclear explosions will obviously be a small minority of the world.
Large numbers of people will survive severe fallout: it’s fairly easy to build safe shelters in most locations. Kearny’s Nuclear War Survival Skills shows how feasible it is. Governments and militaries of course know to prepare for this sort of thing. And I think fallout doesn’t become a truly global phenomenon, it is only deadly if you are downwind from the blast sites.
Here is one of the main nuclear winter studies, that uses a modern climate model. They assume the use of the entire global arsenal (including 10,000 US and 10,000 Russian weapons) to get their pessimistic 150 Tg scenario, which has a peak cooling of 7.5 degrees celsius. That will still leave large parts of the world with a relatively warm temperatures. However, the US has already gone down to 1,800 weapons in the actual strategic arsenal, with 4,000 in the general stockpile. Russia’s stockpile is 7,850 with only 1,600 in the strategic arsenal. The use of all nuclear weapons in a war is an unrealistic assumption because countries have limited delivery systems, they’ll want to still have some nuclear weapons in case they survive, and they won’t want to cripple their own country and allies with excessive global cooling. Also, the assumption that all weapons will detonate is unrealistic—missile defense systems and force-on-force strikes will destroy many nuclear weapons before they can hit their targets. So even their moderate 50 Tg scenario with 3.5 degrees celsius of cooling seems implausible, it would still require nearly 7,000 weapons detonated. It seems like we are really looking at 2-3 degrees celsius cooling from an unlimited exchange—approximately enough to cancel out past and future global warming. The temperature also recovers quite a bit in just a few years.
The issue is that there are many sources of uncertainty of nuclear winter. When I developed a probabilistic model taking all these sources into account, I did get a median impact that was 2-3 C reduction (though I was also giving significant probability weight to industrial and counterforce strikes). However, I still got a ~20% probability of collapse of agriculture.