As soon as President-elect Donald Trump assumes office Jan. 20, Republican attorneys general who have spent the past eight years battling the Obama administration’s climate change agenda will have a new role: supporting the Republican president’s complex legal effort to roll back that agenda. By contrast, states with Democratic leadership – such as California, where Gov. Jerry Brown has promised all-out war against Mr. Trump on global warming – will go from being environmental partners with the federal government to legal aggressors on their own.