With global climate stress growing ever more apparent, the world’s biggest polluter is setting aside its lofty environmental ambitions as it confronts an unprecedented slowdown in growth. China, which spews more carbon into the atmosphere than the U.S. and European Union combined, is being forced to give greater priority an economy that had wilted during the trade war with Washington and is now being flattened by the coronavirus epidemic. Increasing economic headwinds are prompting Beijing to roll back restrictions on industrial pollution, slow its transition away from coal and slash subsidies for cleaner energy and transportation. A carbon market slated for this year may not live up to its billing, and there are signs that the government is unwilling to set a higher bar this year for its climate goals.