This varies by region. In the US transport and coal power are equal in terms of their contribution. In Nigeria it's diesel and deforestation. But I will concede that it's not "minor" (not sure why I said that...)

I'm not saying that coal is good or nuclear is bad or vice versa. As I said in my original comment, there is no one practical (in terms of safety, efficiency, cost etc) global energy solution right now. I don't believe any coal-powered plants should be built. Should existing ones be replaced by nuclear? Depends on the actual area, geo-political situation (which changes over time) etc.