He has a sinecure, in effect, zero power or influence, he gets to posture and pretend to be important and attend all the right dinners and parties. No doubt people speak to him as if he's important, and probably many snicker later about how pompous he is.
China already signed the Paris Accord, to the extent that means squat, and they want to push emissions higher until 2030 when they can then pretend to cut from a lofty level, and they might cut some a bit for a while. They can keep running a bunch of old coal plants and then shutter them in 2030 and claim to be doing stuff. Yay.