Mankind can go extinct in both natural and man-made ways. Examples of natural extinction risks are asteroid strikes and supervolcanoes. Most important about the natural existential risks is that they are:

  1. Small, and
  2. Well-known.

The total natural extinction risk for the next hundred years is roughly 0.01%, or extremely small. Man-made extinction risk, on the contrary, is estimated at 17%, or 1700 times larger. Therefore, natural extinction risk is so small that it may be neglected in an existential risk discussion.

Natural extinction risk is so small that it may be neglected in an existential risk discussion.

How do we know for certain that natural existential risks are so small? All natural sources of extinction, be they asteroids, comets, volcanoes, or stellar explosions, have one thing in common: their chance did not increase greatly recently. This means that we can use historic data.

Historically, humanity has not gone extinct in its lifespan of roughly 300 000 years. Other mammals have had an average lifespan of around one million years, as we know from their fossil track record. Apparently, there were no  asteroids, comets, volcanoes, or stellar explosions in this period wiping them out. For these reasons, the natural extinction risk for humanity can with certainty be estimated to be very small (around 0.01%) for the next hundred years. 

Natural risks are the risks we have to worry least about.