I agree and that was especially true during cold war. I've read article on that.
This is different though. There are too many different sources from different countries besides RU and USA that confirm the same with models.
I too believe that a full out nuclear exchange between USA and Russia would mean the end of the life as we know it in this planet. I am not sure if its extension but definitely increase of cancer 1,000,000 % etc
As for the new cruise missile thats nothing. They are pushing for 1 trillion nuclear overhaul, as your ICBM is shit and your SLBMs are nothing unique.