In addition to (eventual) climate change China has been making itself increasingly unlivable due to conventional pollution (in all forms)...but the leadership there has always seen this as a temporary cost that must be borne to catch up with the west.
Internal pressure will already force China to do something sooner rather than later; handling the problem is a good way to consolidate power internally and thus tackled enthusiastically.
Throw in the USA voluntarily ceding its position of world leadership and it's an opportunity to go from barely-tolerated semi-pariah to increasingly-respectable world leader.
In particular expect China to "save" Africa once the worst begins. But, not immediately; groundwork is already being laid, but right now they can afford to be patient.