As for extinction, the reason that won't happen is because rapid population decreases are a kind of negative feedback. Eventually we would get back to close to the carrying capacity of the Earth, even if at that point there were only say a million people left alive worldwide. The only real threat of total extinction I can think of is abrupt global warming combined with some kind of mega-pandemic for which there is no cure. Climate change alone won't do it.
Apparently you missed my post (s). I refer you to those posts above for reference before responding to this comment.
Long story short, In an event of rapid population decrease, it's almost certain (please refer to my post for more detailed information) that more than one, possibly nearly all, (
depending of the heroics and ingenuity of the nuclear engineers at the sites and the speed of the population decrease) - of the 450 nuclear reactor spent fuel rod containment facilities around the world, especially in already unstable regions, will melt down catastrophically in a Fukishima style event. This time, however, it's going to be the version of Fukishima WITHOUT any ability to remedy the situation like Japan and the rest of the world mobilized to do - Multiplied by 450.
Can you please explain to me how even JUST 1 million humans ( even 20 million or 70 million. The number doesn't really matter so long as it's an extreme event like you're describing) will be able to survive the spent fuel rods from 450+ nuclear reactors all over the world melting down simultaneously?
I'm not trying to sound pessimistic, or argumentative. I'm honestly concerned for life on this planet, especially the life that large apes depend upon for survival. Dr. McPherson presents evidence that abrupt change in climate or an abrupt event that reduces human population is certainly on the cards.
Heck, even if we weren't undergoing abrupt climate change, all it would take is an orchestrated 9-11 style attempt by terrorists to release an enormous amount of radiation into the atmosphere (I will not go into details but if you do research on the topics I've discussed you can use your imagination). That ALONE would reduce human population rapidly enough to cause meltdowns of all the other nuclear spent fuel rod containment facilities on the planet within a relatively short period of time. To suggest that something far more catastrophic, like a reduction in human population down to 10 or even 100 million from present levels, wouldn't cause unimaginable levels of radiation being released into the atmosphere is, quite frankly, not very open minded.
I find it difficult to imagine a scenario where large apes somehow survive an extinction event event that is already claiming 75%+ of insect biodensity within a 20 year time frame - and we're only at 1.5C above baseline. Add incomprehensibly copious quantities of gamma radiation circulating through the atmosphere, for thousands of years... it's Permian extinction in 250-300 years instead of thousands + gamma radiation. 99+% of all life on the planet will perish in a very short period of time. Humans, ruminants, birds, and all other forms of life that we recognize as our co-habitants will perish all within the same time period. Sure, there's going to be some apes in bunkers who survive, for a while. How long can they stay in those bunkers? CO2 and radioactive isotopes last thousands and thousands of years.
In Conclusion:
1. I'm genuinely interested in a direct response (especially from someone with experience in nuclear physics and atmospheric science).
2. I'd also like to understand how the atmosphere of earth is going to respond to the radiation emitted from the melt down of spent fuel rods from the 450+ nuclear reactors all over the planet?
3. I honestly do apologize for the bad news. I don't want to ruin anyone's day. I honestly don't think many have considered the spent fuel rod situation. I encourage everyone here to do some research on the fragility of these facilities.