This post started with a chat with a friend. We were talking about wars and climate, and he threw a question at me: does the war in Ukraine change the weather, through the change in emissions that the conflict causes? And then, more to the point, how would you actually answer that? I didn't have a good answer, but I liked the second part of the question more than the first. Most of my work is short-term forecasting, hours to days ahead, where the atmosphere you start from matters more than almost anything else. Climate projections are a different animal:...