Metaculus' Ragnarok series explores threats to the human race. Several define a "global catastrophe" to mean a period of 5 years or less where the world population declines by 10% or more. Despite humanity's tumultuous history, including World Wars 1 and 2, the 1918 Flu pandemic, and the COVID-19 pandemic, the only events likely to meet this criteria would be the Black Death of 1347 and the year 560 Plague of Justinian. For other estimates of major pandemics, see here.
Metaculus has some other estimates of extinction or near extinction (all estimates as of December 29, 2021):
- 2% chance of extinction by 2100.
- 25% (or less) of extinction conditional on a decline to 100 million humans by year 2345.
- 25% of extinction within 20 years, conditional on a decline to 400 million humans by year 2100.
The Ragnarök Series attempts to forecast the relative severity of various existential risks, such as Climate, Nuclear War, Artificial Intelligence, Biological Engineering and Biological Weapons, and Nanotechnology. While those these recieve the majority of attention and concern in 2021, there may be risks resulting from unforseen future developments, or risks from dangers currently known but recieving insufficient attention. For this question, we'll ask about the risk of population decline by any cause as a point of comparison.
Ragnarök Question Series: if a global catastrophe occurs, will it reduce the human population by 95% or more?
This question will resolve as Yes if, after the world population declines by 10% (in any period of 5 years or less), the global population is less than 5% of the pre-decline population at any point within 25 years after the catastrophe. This question will resolve as No if there is a global population decline of 10% in 5 years or less, but there is no population decline of 95% in a 25-year period. If there is no such population decline of 10% in any 5-year period between January 1, 2000 to January 1, 2100, this question will resolve as Ambiguously.
This question is part of the Ragnarök Question Series. Check out the other questions in the series:
Also, please check out our questions on whether a global catastrophe will occur by 2100, and if so, which?:
All results are analysed here, and will be updated periodically.