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Samotsvety Nuclear Risk Forecasts — March 2022

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2022·EA Forum·forum.effectivealtruism.org/posts/KRFXjCqqfGQAYirm5/samot...

Authors

NunoSempere·Misha_Yagudin·elifland

Credibility Rating

3/5
Good(3)

Good quality. Reputable source with community review or editorial standards, but less rigorous than peer-reviewed venues.

Rating inherited from publication venue: EA Forum

Relevant to AI safety researchers interested in forecasting methodology for catastrophic risks and how quantitative risk estimates can ground decision-making; serves as a case study in applying superforecasting techniques to existential-level threats outside of AI.

Metadata

Importance: 62/100analysis

Summary

Samotsvety, a prominent forecasting group, aggregated expert probability estimates for nuclear risk following Russia's invasion of Ukraine in March 2022. The team produced calibrated forecasts for near-term nuclear weapon use in various scenarios, concluding the risk was real but lower than public discourse suggested. The analysis provides a methodology template for quantifying catastrophic tail risks.

Key Points

  • •Estimated ~0.01% chance per month of a nuclear weapon being used in a city given the Ukraine conflict context, rising in worst-case escalation scenarios.
  • •Used aggregation of multiple superforecasters and domain experts to reduce individual bias and produce calibrated probability estimates.
  • •Concluded that while nuclear risk was elevated, it did not justify extreme behavioral changes like evacuation from major cities for most people.
  • •Demonstrated a rigorous forecasting methodology applicable to other low-probability, high-consequence existential and catastrophic risks.
  • •Provided a reference point for how quantitative risk assessment can inform rational decision-making under geopolitical uncertainty.

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# Samotsvety Nuclear Risk Forecasts — March 2022
By NunoSempere, Misha_Yagudin, elifland
Published: 2022-03-10
*Thanks to Misha Yagudin, Eli Lifland, Jonathan Mann, Juan Cambeiro, Gregory Lewis, @belikewater, and Daniel Filan for forecasts. Thanks to Jacob Hilton for writing up an earlier analysis from which we drew heavily. Thanks to Clay Graubard for sanity checking and to  Daniel Filan for independent analysis. This document was written in collaboration with Eli and Misha, and we thank those who commented on an earlier version.*

**Overview**
------------

In light of the war in Ukraine and fears of nuclear escalation[^1tt4cl1ut8si], we turned to forecasting to assess whether individuals and organizations should leave major cities. We aggregated the forecasts of 8 excellent forecasters for the question ***What is the risk of death in the next month due to a nuclear explosion in London?*** Our aggregate answer is 24 micromorts (7 to 61) when excluding the most extreme on either side[^l2youss95ij]. A micromort is defined as a 1 in a million chance of death. Chiefly, we have a low baseline risk, and we think that escalation to targeting civilian populations is even more unlikely. 

For San Francisco and most other major cities[^cfroiodaps], we would forecast 1.5-2x lower probability (12-16 micromorts). We focused on London as it seems to be at high risk and is a hub for the effective altruism community, one target audience for this forecast.

Given an estimated 50 years of life left[^pt69xmy0uqf], this corresponds to ~10 hours lost. The forecaster range without excluding extremes was <1 minute to ~2 days lost. Because of productivity losses, hassle, etc., we are currently not recommending that individuals evacuate major cities. 

**Methodology**
---------------

We aggregated the forecasts from eight excellent forecasters between the 6th and the 10th of March. [Eli Lifland](https://www.elilifland.com/), [Misha Yagudin](https://forum.effectivealtruism.org/users/misha_yagudin), [Nuño Sempere](https://nunosempere.com/), [Jonathan Mann](https://jonathanmann.github.io/) and [Juan Cambeiro](https://twitter.com/juan_cambeiro)[^tfhokbz7tk] are part of Samotsvety, a forecasting group with a good track record — we won CSET-Foretell’s first two seasons, and have great track records on various platforms. The remaining forecasters were [Gregory Lewis](https://www.fhi.ox.ac.uk/team/lewis-gregory/)[^mz4wxunrpnc], @belikewater, and [Daniel Filan](https://danielfilan.com/), who likewise had good track records. 

The overall question we focused on was: ***What is the risk of death in the next month***[^azu0qsuph3h]*** due to a nuclear explosion in London?***. We operationalized this as: “If a nuke does not hit London in the next month, this resolves as 0. If a nuke does hit London in the next month, this resolves as the percentage of people in London who died from the nuke, subjectively down-weighted by the percentage of reasonable people that evacuated due to war

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