Understood, although we have no way to know if there have ever been similar events, as the geologic record is something of a low-pass filter.

Just for the sake of argument, let's say you find yourself in a car in the second scenario, with no known way to stop it. What would you do? I say this as a pragmatist - if we take the headlines at face value, and we only have ~10 years to avert a catastrophe, then the only realistic way to avert it is if 90% of the world's population spends that 10 years planting trees before killing themselves.