BEIJING: Highways and school playgrounds in Beijing were closed Friday due to heavy pollution, as China ramps up coal production and faces scrutiny of its environmental record at international climate talks. World leaders gathered in Scotland this week for COP26 negotiations billed as one of the last chances to avert catastrophic climate change, though Chinese President Xi Jinping made a written address instead of attending in person. China — the world’s largest emitter of the greenhouse gases responsible for climate change — has ramped up coal output after supply chains in recent months were …