Dayton Kitchens
Banned
No, it wasn't. Some other scientists found that nuclear winter might be less severe than Sagan first claimed which was then jumped on by the winnable nuclear war hawks as a repudiation. But debunked it was not.
https://en.wikipedia.org/wiki/Nuclear_winter#Criticism_and_debate
It was the leftists at Discovery magazine IIRC that "re energized" the belief in nuclear winter.
At any rate, I've never seen an unbiased group of scientists that provided evidence that nuclear winter was a serious danger.