Here's a recent well-researched post that comes to essentially the opposite conclusion:
The basic conclusion of all of this is simple. Nuclear war is definitely not an existential threat to humanity, much less to all life on the planet. Most people even in major urban areas would survive the initial attack, along with a surprising amount of infrastructure. This isn’t to minimize the effects, as it would be a humanitarian catastrophe unprecedented in human history, as the global economy breaks down and regions are pushed back on their own resources. This could easily kill more people than the war itself, particularly in densely-populated areas, but I would expect things to stabilize at a technology level of maybe the late 19th/early 20th century and start back up.
The main difference is that he concludes that nuclear winter is mostly a myth. His main evidence is that the effect on weather of the soot produced by the oil wells burning in Kuwait in 1991 did not match the nuclear winter theory predictions. It would be interesting to reconcile these two disparate conclusions.
The basic conclusion of all of this is simple. Nuclear war is definitely not an existential threat to humanity, much less to all life on the planet. Most people even in major urban areas would survive the initial attack, along with a surprising amount of infrastructure. This isn’t to minimize the effects, as it would be a humanitarian catastrophe unprecedented in human history, as the global economy breaks down and regions are pushed back on their own resources. This could easily kill more people than the war itself, particularly in densely-populated areas, but I would expect things to stabilize at a technology level of maybe the late 19th/early 20th century and start back up.
https://www.navalgazing.net/Nuclear-Weapon-Destructiveness
The main difference is that he concludes that nuclear winter is mostly a myth. His main evidence is that the effect on weather of the soot produced by the oil wells burning in Kuwait in 1991 did not match the nuclear winter theory predictions. It would be interesting to reconcile these two disparate conclusions.