One Nuclear War Can Ruin the Whole Climate

The new book of Mark Lynas, with Ted Nordhaus the co-author of this piece, is "Six Minutes to Winter: Nuclear War and How to Avoid It" https://www.bloomsbury.com/us/six-minutes-to-winter-97813994...

Please don't try, but doesn't the lates model predict something more similar to Nuclear Autumn? https://en.wikipedia.org/wiki/Nuclear_winter#Criticism_and_d...

So by how much does a runaway manmade hothouse climate change reduce the risk of manmade or asteroidmade radioactive snowball earth?