sagan et al overstated amount of soot from full nuclear exchange from targets most susceptible to large scale fires by 10x-ish and this is the only way they could come up with actual nuclear winter

when counterexample happened during gulf war they dropped it, but when people forgot this was a thing they brought it up again. this is not how you do science https://en.m.wikipedia.org/wiki/Nuclear_winter#Criticism_and_debate