On one hand many countries will invest in heavy industry, manufacturing, and fall back to fossil fuels.
On the other hand, economy overall should slow down and consumption of non-essential goods and services will drop.
I’m not expecting any definite answers or numbers, of course, just some food for thought.
No, because after the war we’ll need to start rebuilding stuff we just destroyed, so the people remaining will increase their emissions many times. Also, hypernormalisation after a war might just render public opinion towards climate change indifferent.
So imagine if the problem was deforestation and people heating with chopped wood. War means that we’ll burn all their wooden houses down, and then see them cut down even more trees to rebuild them.
Also, large wars cause baby booms.