Can you put a price on pollution? Some of the world¡¯s biggest economies are doing just that as they wrestle with how to make good on grand pledges to tame planet-warming emissions.

Matters are coming to a head.

China, Japan and South Korea have all followed the European Union in pledging to cut emissions to ¡°net zero¡± in recent weeks, where they release only as much as they remove from the air. U.S. President-elect Joe Biden made the same promise in his election campaign.