How certain would the experts have to be to get such coordinated action?
With close approaches, it seems (as a layman) that there are always pretty large ranges of just how close they will be. I dont think you'd know "a comet is headed directly at us" until way too late. Instead you'd get some warning that there is a 10% chance or something. Over time that would go up to a near certainty. Maybe I'm pessimistic, but I would predict something more similar to climate change with deniers and paralysis.
This remark reminds me of the book, "Seveneves" by Neal Stephenson. He plays with a similar 'what if?' doomsday scenario. Around 80% of the book revolves around testing and pushing humanity at it's extremes.
With close approaches, it seems (as a layman) that there are always pretty large ranges of just how close they will be. I dont think you'd know "a comet is headed directly at us" until way too late. Instead you'd get some warning that there is a 10% chance or something. Over time that would go up to a near certainty. Maybe I'm pessimistic, but I would predict something more similar to climate change with deniers and paralysis.