More seriously, it would at best delay things for 10 years, and that’s if our current understanding of the climate turns out to be wrong and a nuclear winter could indeed actually happen in the first place.
The theory behind a nuclear winter was that in the 80s some scientists thought the secondary fires caused by detonating a bunch of nukes simultaneously in forested areas would combine to be powerful enough to carry the ash into the upper atmosphere. In the 2010s hover Australia had a wildfire big enough that according to the nuclear winter theory it should have easily demonstrated said effect, but dispite careful observation it didn’t, which is also what more modern climate science predicted.
Fun bonus fact: In a full scale nuclear war the majority of the projected casualties come from a breakdown in gobal trade leading to a lack of western produced fertilizer and subsequently food being grown in Africa. The same food production that is going to be heavily hampered by climate change. Thankfully there’s more time to mitigate it with climate change, but it’s still liable to be one of the biggest issues in a 2+C world.
