The biggest emitter of planet-warming pollution managed to take almost the whole world by surprise. In a September speech to the United Nations, Chinese President Xi Jinping put a 2060 end date on his country’s contribution to global warming.

No other nation can do more to keep warming below the 1.5C threshold set in the Paris agreement. Yet diplomats, climate activists, and even policy experts inside China for the most part had not anticipated this pivotal turnabout.

Just days before Xi’s U.N. appearance, in fact, European leaders including European Commission President Ursula von der Leyen and German Chancellor Angela Merkel had pressed him directly on a videoconference to follow the EU’s example in setting a climate-neutrality goal. Notes from the call reviewed by Bloomberg Green indicate that Xi gave no hint he was about to abandon China’s long-established policy against climate restrictions on economic growth.