US Climate Envoy John Kerry arrives in China on Sunday for three full days of talks that will test the ability of the world’s top two greenhouse gas emitters to collaborate in the fight against global warming despite deep discord over other issues. Kerry’s visit is the latest front in a diplomatic push aimed at reestablishing connections between the superpowers that frayed amid tensions over export controls and human rights, as well as then-House-Speaker Nancy Pelosi’s trip to Taiwan last August. It will also mark the first protracted climate negotiations between the two countries in nearly a year, since Beijing...