How about assessments of the probability of a global nuclear war? Any decent assessment would provide a reasonable lower bound for a man-made human extinction event.
No, it wouldn’t. One needs a probability of extinction conditional on global nuclear war (generally considered quite unlikely). Perhaps this might happen if it turns out that the Industrial Revolution is a fluke that could not be repeated without fossil fuels, or if nuclear winter was extraordinarily severe (the authors of the recent nuclear winter papers think it very unlikely that a global nuclear war using current arsenals could cause extinction), or if nuclear-driven collapse prevented us from deflecting an extinction-level asteroids, but there’s a further step in the argument. I think reasonable assignments of probabilities will still give you more nuclear existential risk in the next century than risk from natural disasters, but the analysis will depend on right-tail outcomes and model uncertainty.
Is there anything, in particular, you do consider a reasonably tight lower bound for a man-made extinction event? If so, would you be willing to explain your reasoning?
Mega-scale asteroid impacts (dinosaur-killer size) come close. Uncertainty there would be about whether we could survive climatic disruptions better than the dinosaurs did (noting that fish, crocodiles, mammals, birds, etc, survived) using technology.
This doesn’t really answer the “man-made” part of “man-made extinction event” (unless you know something about mad scientists with ion engines mounted on large asteroids that I don’t know).
Sorry, I misread your question. I don’t think we have rigid uncontroversial frequentist estimates for any man-made extinction event. There are estimates I would say are unreasonably low, but there will be a step along the lines of “really?!? You seriously assign less than a 1 in 1 billion probability to there being a way for bioweapons programs of the next 50 years to create a set of overlapping long-latency high virulence pathogens that would get all of humanity, in light of mousepox and H5N1 experiments, the capabilities of synthetic biology, the results of these expert elicitations, etc?”
No, it wouldn’t. One needs a probability of extinction conditional on global nuclear war (generally considered quite unlikely). Perhaps this might happen if it turns out that the Industrial Revolution is a fluke that could not be repeated without fossil fuels, or if nuclear winter was extraordinarily severe (the authors of the recent nuclear winter papers think it very unlikely that a global nuclear war using current arsenals could cause extinction), or if nuclear-driven collapse prevented us from deflecting an extinction-level asteroids, but there’s a further step in the argument. I think reasonable assignments of probabilities will still give you more nuclear existential risk in the next century than risk from natural disasters, but the analysis will depend on right-tail outcomes and model uncertainty.
Is there anything, in particular, you do consider a reasonably tight lower bound for a man-made extinction event? If so, would you be willing to explain your reasoning?
Mega-scale asteroid impacts (dinosaur-killer size) come close. Uncertainty there would be about whether we could survive climatic disruptions better than the dinosaurs did (noting that fish, crocodiles, mammals, birds, etc, survived) using technology.
This doesn’t really answer the “man-made” part of “man-made extinction event” (unless you know something about mad scientists with ion engines mounted on large asteroids that I don’t know).
Sorry, I misread your question. I don’t think we have rigid uncontroversial frequentist estimates for any man-made extinction event. There are estimates I would say are unreasonably low, but there will be a step along the lines of “really?!? You seriously assign less than a 1 in 1 billion probability to there being a way for bioweapons programs of the next 50 years to create a set of overlapping long-latency high virulence pathogens that would get all of humanity, in light of mousepox and H5N1 experiments, the capabilities of synthetic biology, the results of these expert elicitations, etc?”