The United States has returned to the Paris climate accord. Secretary of State Antony Blinken says climate change and science diplomacy “can never again be ‘add-ons’ in our foreign policy discussions.” World leaders are applauding Friday’s formal return to the mostly voluntary 2015 agreement, saying it’s symbolic and important. They say they expect the U.S. to show leadership in the fight against warming by setting strong targets for carbon pollution cuts by 2030. The Trump administration announced the U.S. withdrawal from the Paris accord in 2019, but it didn’t take effect until Nov. 4, 2020. American cities, states and businesses still worked to reduce heat-trapping gases but without the federal government.