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Will our current peace be shorter than the Pax Romana?

The Pax Romana was a period of relative peace, which lasted for approximately 206 years from 27 BC to AD 180. The peace was not absolute, though, and the historian Walter Goffart wrote, "The volume of the Cambridge Ancient History for the years A.D. 70–192 is called 'The Imperial Peace', but peace is not what one finds in its pages".

Similarly, there have been wars in the post-ww2 era, despite the era being relatively peaceful. The post-WW2 peace has also lasted for only about 72 years as of the writing of this question, making it only about 35% as long as the Pax Romana. In order to last as long as the Pax Romana, our peace would have to endure until 2151.

There are many things threatening peace, from seemingly perpetual unrest in the middle-east to an increasingly tense situation on the Korean peninsula. Yet, a major global conflict in the near future seems unlikely.

When predicting whether a major global conflict will occur within a longer timeframe, effects such as climate change and rising inequality (potentially due to AI?) might play a bigger role and the probability of conflict becomes more uncertain.

It is asked: Will a world war begin before January 1st 2151?

We define a world war as a war that either,

  • involves at least 50% of the world's countries, representing at least 50% of the world's population, with countries on at least 4 different continents participating and that kills at least 0.5% of the global population at the beginning of the war within 10 years.
  • OR
  • involves at least 10% of the world's countries, representing at least 25% of the world's population, with countries on at least 3 different continents participating and that kills at least 1% of the global population at the beginning of the war within 10 years.

The beginning time of the hypothetical war will be defined as the time when for the first time at least 5% of the world's nations were involved in the war or countries representing at least 5% of the world's population were involved in the war.

Should there be countries that have not declared war, but for whom the sum of the fatalities they have suffered and those they have inflicted on others exceeds 10000 within the first 10 years of the war, those countries should be counted as having participated in the war.

Given the extremely long timeframe of the question and that the likelihood of getting reliable data on fatality counts might be slim (use a geometric mean if given several estimates), I think it is unwise to predict on this question with points in mind.

Still, I urge people to predict in good faith. The question resolution date has been set to January 1st 2161, to provide for 10 years after January 1st 2151.


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