Foreign governments concerned about climate change may soon be spending more time dealing with Sacramento than Washington. President-elect Donald J. Trump has packed his cabinet with nominees who dispute the science of global warming. He has signaled he will withdraw the United States from the Paris climate agreement. He has belittled the notion of global warming and attacked policies intended to combat it. But California — a state that has for 50 years been a leader in environmental advocacy — is about to step unto the breach. In a show of defiance, Gov. Jerry Brown, a Democrat, and legislative leaders...