Nuclear war is unlikely to cause human extinction?

> Interesting, what would be your suggestions for preparing? Mine would be: AT ALL COST AVOID. (I mean it...ALL COST).

This gets at the heart of existential risk. Should we abandon all technology to avoid the possibility of nuclear war and just wait for an asteroid or climate change or resource exhaustion to kill us? Nuclear destruction only gets easier over time as technology progresses. My cell phone is faster than the supercomputers of the 80's used to model nuclear explosions. Even North Korea can refine uranium. Guided rockets are cheap enough to launch high school science projects. Hypersonic cruise missiles are on the horizon.

Generally I would propose we avoid nuclear war being an existential risk by going to the stars as soon as possible. That has other costs that, yes, should be balanced against the costs of nuclear war.

AGI is another path to a post-existential-threat future for humanity but probably has the greatest risks because it accelerates virtually all of the existing risky technology and climate trends, balanced only by the hope that its intelligence grows far faster than the risks and that it's value-aligned with humanity.

> AGI is another path to a post-existential-threat future for humanity but probably has the greatest risks because it accelerates virtually all of the existing risky technology and climate trends

No, it is not. The reason is this: it is science fiction. This makes it no less, or no more, dangerous than anything else I can make up with a quasi realistic chance of existing in the near term future.

When thermonuclear bombs were detonated, they thought there was a possibility that the reaction would get away from them, and incinerate the atmosphere. The first test, they were scared this actually happened as the explosion carried on longer than they expected.

The point? They actually assigned a probability (non zero) to this event, and then carried on with the test anyway. So I could say that a hydrogen bomb, using some iteration of technology just beyond our grasp is likely to kill every human on earth in the near future. Am I right? Who knows..but in conjecturing this I am no more or 'less wrong' than anyone saying AGI is the greatest threat.

If we're comparing instantaneous risks, then I agree with your arguments. The most likely thing that could kill the most people today (in the next 24 hours) is a large nuclear war, followed by things like a nearby supernova, gamma ray burst, etc. An asteroid large enough to wipe out half of humanity before Saturday is really unlikely to be close enough to not have been observed already.

In the first atomic bomb test the atmospheric ignition risk was not a conditional probability over the next 50 years or more but an estimate of P(ignition | nuclear detonation next week). Very tightly bound immediate risk. P(detonation next week) was ~1.

When risk is estimated over the next 50 or 100 years the probabilities change quite a bit, especially because it's possible (though unlikely) that every nation cooperatively disarms its nuclear stockpile. Disarmament is not possible today so it can't count against that risk. It is a factor in the 50-year risk.

Climate change, AGI, asteroids, pandemics, biowarfare, etc. all become potential risks in the longer time scales, but their conditional probabilities are much fuzzier. That doesn't mean it's useless to try to measure the probability; when assigning dollars to counter risk it makes sense to spend relative to the expected utility loss of each potential outcome, times the probability of being able to change the outcome. There's very little reason to spend money on short timescales to avoid a nearby supernova or a gamma ray burst pointed at us. There's nothing we can do. We can do things about nuclear weapons, climate change, AGI, etc. But we need accurate probabilies to avoid the failure of devoting 100% of GDP to the current biggest risk.

AGI is not a threat within the next day or probably the next year, and even if it was it would be almost certain that events are already in motion and nothing could be done. Dealing with AGI risk means spending an appropriate amount of money to offset risks that might appear more than a year or two out.

Searching the skies for unknown asteroids is worthwhile because only with enough advance warning can anything be done, and it's quite likely we could avoid a strike with enough warning (years).

It's in everyone's best interest to disarm every nuclear weapon but there's a strong defection incentive to be the last one with them which we also have to be realistic about. Achieving zero nuclear weapons is likely to require a one-world government which is unachievable in any short or medium timeframe. What do you propose we spend money on that actually moves the conditional probabilities away from global nuclear war? Do those proposals (even with ludicrous amounts of money) have a higher likelihood of success than risk-dollars-adjusted reduction of climate change for example? If not, then we can't prevent nuclear war at any cost as you originally proposed. In fact we can't prevent nuclear war in the first place; there is no set of concrete steps (short of globally synchronized sabotage) to take this year or even next. Human beings will have their fingers on the nuclear triggers for the foreseeable future. We have to mitigate the other risks that we can right now otherwise it's a waste of money. Hopefully as the world becomes more stable it will eventually become possible to actually prevent nuclear war through disarmament.

The post discusses nuclear winter briefly, but I'll cover that in more detail here:

The theory of nuclear winter is predicated on a specific chain of events:

* The mass use of nuclear weapons causes massive firestorms in large cities.

* These firestorms pump soot in unprecedented amounts into the stratosphere.

* The stratospheric soot causes massive, persistent climatic cooling.

If any of these claims fail to be true, then the entire thesis breaks down. And there is some reason to doubt all of them, especially the hyperbolic versions of the hypothesis (e.g., "going like 100 years without being able to grow food").

Let me tackle just the last one. Volcanic eruptions are the most effective stratospheric soot pumps we know of: the eruptive columns of even smallish eruptions (like the 2018 summit explosions of Kilauea) routinely reach the stratosphere. In modern history, the most powerful eruption would be the 1815 eruption of Tambora, which is calculated to have erupted about 41 km³ of tephra. The result was a well-documented global cooling (the Year Without a Summer). Now ask yourself how likely it is for even several simultaneous nuclear explosions to inject that into the stratosphere. Now also consider just how much impact the eruption had in history: it doesn't merit a mention in many history books--a far, far cry from "100 years without being able to grow food".

Full scale nuclear war means big cities will be bombed and millions of people die. What civilizational collapse are you talking about? The lack of Hollywood movies and absence of the NYSE?