China wants to be carbon neutral by 2060. Is that possible?

President Xi Jinping’s surprise announcement that China plans to go carbon-neutral by 2060 has left many questions, none more important than: “How?”

China is the world’s largest energy user and greenhouse gas emitter, mines and burns half the world’s coal, and is the top importer of oil and natural gas. Transitioning that economic behemoth to carbon-neutrality within a few decades could cost $5.5-trillion, Sanford C. Bernstein & Co estimates, and require the deployment of technologies that are barely in use today.

“What’s being contemplated here has never been done before,” said Neil Beveridge, an analyst at Bernstein. “The larger the energy mix, the longer it takes to transition. This is a monumental challenge.”