If the human population decreases by at least 10% in any period of 5 or fewer consecutive calendar years, which we will define here as a "global catastrophe", resolves to the principal cause. Otherwise, resolves to "no global catastrophe".

See https://www.metaculus.com/questions/1493/global-population-decline-10-by-2100/ and https://www.metaculus.com/questions/2568/ragnar%25C3%25B6k-seriesresults-so-far/ for more precise definitions of these categories and for related forecasts.

By 2100, will the human population decrease by at least 10% during any period of 5 years?

The aggregate of 273 Metaculus community forecasters was 38% on Jul 21, 2023.