How likely is Russia to use nuclear weapons in Ukraine, and how likely is escalation to other countries? How likely are test vs offensive detonations? Tactical vs strategic weapons? Military vs civilian targets? If one type of nuclear strike occurs, how likely is escalation?
A large collection of Manifold prediction markets seeks to forecast these questions to better understand the risks of nuclear conflict. This page is my attempt to organize some of them to help readers and forecasters find the information they're looking for and see how they interrelate to each other.
Note: The prediction market data shown below updates in real-time, but my commentary here is updated manually (most recently updated October 11), so it may not always match the real-time prediction market data.
How accurate should you expect these markets to be?
Expect error bars of a few percentage points, generally - don't expect particularly fine-grained accuracy around 1-5% and definitely don't expect much accuracy below 1%. More details on this at the end.
Any nuclear detonation (including test detonations)
Forecasters predict a substantially elevated chance of nuclear weapons being used in the next couple months. They predict that if a nuclear detonation occurs in the next few months, it will very likely be either Russia or a North Korean nuclear test.
North Korea has recently conducted a large number of missile tests, and satellite imagery and intelligence indicates the North Korea has completed preparations for a nuclear test at their underground test site. South Korean intelligence agencies are expecting a nuclear test in the next few weeks.
Test vs offensive detonation
Forecasters predict a much lower chance of offensive use of nuclear weapons compared to test detonations. The forecasts predict both that the first nuclear weapon use would likely be a test, and that the chance of escalation from a test detonation to an offensive detonation by the end of the year is low.
Additionally, forecasters predict a moderate chance that the use of an offensive nuclear weapon will be somewhat predictable in the week leading up to it, as opposed to being a surprise.
Mass casualty events
The chance of nuclear conflict causing a large number of deaths is forecasted to be much lower than the chance of any offensive detonation, but still concerningly high. This is largely because forecasters predict that offensive nuclear detonations will most likely target military assets (see section Military vs civilian targets below).
Reaction to a Russian nuclear weapon and potential escalation paths
Forecasters predict that if Russia uses a nuclear weapon in Ukraine, there is a high chance of direct military conflict between NATO and Russia, as well as a high chance of China stepping away from their partnership with Russia.
They predict a much lower chance of escalation to use of nuclear weapons by NATO or full-scale nuclear war.
Nuclear weapons beyond Russia and Ukraine
Forecasters predict that if an offensive nuclear detonation occurs, it will most likely be Russian nuclear strike on Ukraine. They predict a small but still concerningly high chance of escalation of nuclear conflict outside Ukraine.
Tactical vs strategic weapons
Forecasters predict that the first nuclear weapons are used are much more likely to be tactical instead of strategic weapons. Forecasters predict a low chance of escalation from tactical to strategic weapons.
Military vs civilian targets (counterforce vs countervalue)
Forecasters predict that nuclear conflict is likely to only target military assets (counterforce targeting), rather than targeting civilian populations.
Metaculus's description of countervalue vs counterforce targeting:
Countervalue targeting is "the targeting of an opponent's assets that are of value but not actually a military threat, such as cities and civilian populations". Compared to nuclear strikes against counterforce targets or battlefield targets, countervalue nuclear strikes would typically cause both many more immediate fatalities and much more smoke (increasing the risk of nuclear winter).
Deliberate vs accidental, unauthorized, or inadvertent
Forecasters predict that the next nuclear detonation will most likely be deliberate, but still assign a substantial chance to inadvertent, accidental, or unauthorized detonation.
Other nuclear risk forecasting
The Metaculus Nuclear Risk Tournament has a large series of forecasts on similar questions as above, and I've used them heavily both in formulating the questions here and in making predictions on them
A couple superforcasting teams with strong track records have published detailed reports:
Cautionary notes on prediction market accuracy
Some of these markets synthesize the predictions of several forecasters with strong track records, while other markets are new and are based on a small number of unreliable data points. You can check out the comments in the markets to get a better sense of where the prediction is coming from.
Also, the market structure of prediction markets (both in general and Manifold in particular) means they tend to be somewhat inaccurate at forecasting events with probabilities near 0% and 100%. There are several reasons for this, partly it is because some types of trading (limit orders) only accept whole numbers, so the lowest they can go is 1% and they can't distinguish 1.5% and 2%; another reason is that it takes a large amount of funds to correct small mispricings close to the extremes.
Don't expect particularly fine-grained accuracy in the 1-5% range.
Definitely don't expect much accuracy below 1%. E.g. if the true probability is 1 in a million I wouldn't be surprised for a market to be at 0.1% or 1%. Some strategies to get better estimates of these probabilities included chaining multiple conditional probabilities together and using amplified odds markets.
Common definitions and resolution criteria used in my questions
I'm mostly using the same definitions as Metaculus, to lower ambiguity and increase consistency and comparability.
Other authors are often using different definitions and criteria than me. Read resolution criteria carefully, as wording like "in combat" can have very different meanings to different authors.
In general, nuclear detonations may include deliberate, inadvertent, or accidental/unauthorised detonations. Questions that do not explicitly specify otherwise include any of these potential causes of a nuclear detonation.
In questions that do not specify "offensively", a test detonation would count towards question resolution.
A strategic nuclear weapon is a weapon designed mostly to be targeted at the enemy interior (away from the war front) against military bases, cities, towns, arms industries, and other hardened or larger-area targets, while a tactical (non-strategic) nuclear weapon is a nuclear weapon designed mostly to be used on a battlefield, near friendly forces, or on or near friendly territory. There is no exact definition on weapon yields or ranges. But note that this question is about the type of weapon, not the type of target; it's conceivable that a non-strategic weapon could be used against the sort of target strategic weapons are designed for or vice versa.
Countervalue: A detonation is considered countervalue for the purpose of this question if credible media reporting does not widely consider a military or industrial target as the primary target of the attack (except in the case of strikes on capital cities, which will automatically be considered countervalue for this question even if credible media report that the rationale for the strike was disabling command and control structures). Counterforce is the opposite.
For the purposes of this question, a country's territory will include the 12 nautical mile territorial sea.
For the purposes of this question, Ukrainian territory will be defined as internationally recognized prior to 2014 (that is, including Crimea, Donetsk, Luhansk, Kherson, and Zaporizhia).
For the purposes of this question, to qualify as within a country, the nuclear weapon must be detonated less than 100 kilometers above Earth's mean sea level.
Fatalities must be caused by the immediate effects of the detonation, so fatalities caused by things like fallout, rioting, or climate effects will not count towards question resolution.
Detonation unless otherwise specified means nuclear explosion. If a nuclear weapon were launched/dropped/etc but the nuclear weapon did not detonate (due to malfunction, interception, etc), that would not count as detonation. If a conventional explosion occurs but no nuclear explosion, that does not count.
More markets can be found in the Nuclear Risk group.
Since there are a ton of questions about related attributes/criteria, I made a spreadsheet to help organize some of them.