# What is the Probability of a Nuclear War?

I agree with Tyler who wrote recently that “the risk of nuclear war remains the world’s No. 1 problem, even if that risk does not seem so pressing on any particular day.”

The probability of a nuclear war is inherently difficult to predict but what strikes me in this careful survey by Luisa Rodriguez for the Effective Altruism Forum is how much higher all the expert predictions and model forecasts are compared to what we would like them to be. Keep in mind that the following are annualized probabilities. For a child born today (say 75 year life expectancy) these probabilities (.0117) suggest that the chance of a nuclear war in their lifetime is nearly 60%, (1-(1-.0117)^75). At an annualized probability of .009 which is the probability from accident analysis it’s approximately 50%. See Rodriguez and also Shlosser’s Command and Control on the frightening number of near misses including one nuclear weapon dropped on North Carolina.

These lifetime numbers don’t strike me as crazy, just crazy high. Here is Rodriguez summarizing:

If we aggregate historical evidence, the views of experts and predictions made by forecasters, we can start to get a rough picture of how probable a nuclear war might be.

^{[8]}We shouldn’t put too much weight on these estimates, as each of the data points feeding into those estimates come with serious limitations. But based on the evidence presented above, we might think that there’s about a 1.17% chance of nuclear war each year and that the chances of a US-Russia nuclear war may be in the ballpark of 0.39% per year.

**Addendum: **A number of people in the comments mention that the probabilities are not independent. Of course, but that doesn’t make the total probability calculation smaller, it could be larger.