Serious answer: With the climate crisis some areas in the world will become impossible to live in (look up wet bulb temperature). Now you have a massive amount of refugees who want to go somewhere else, if necessary by force.
When there’s suddenly millions of people pushing against country borders all it takes is a few shots and you have a war.
But then it’s not natural! If I’m a future space billionaire, of course I’d want the real stuff with animal suffering involved, duh.