Leaders of the United States and other countries have set ambitious new goals today to slow the planet from heating up.They left open exactly how they would accomplish those goals as they met in a virtual long-distance gathering. William Brangham has our report.With dozens of world leaders in attendance virtually, President Biden said it was urgent for the world to address climate change.This is a moral imperative, an economic imperative, a moment of peril, but also a moment of extraordinary possibilities.The president pledged to cut America's greenhouse gas emissions in half from 2005 levels by 2030. And he urged other nations to follow suit.All of us, all of us, and particularly those of us who represent the world's largest economies, we have to step up.And some of the world's largest carbon emitters seemed to heed the call. China's President Xi Jinping cited an earlier pledge to phase out the use of coal.China will strive to peak carbon dioxide emission before 2030 and achieve carbon neutrality before 2060.The prime minister of the Republic of India.And India's prime minister, Narendra Modi, repeated a promise to boost renewable energy projects by 2030.We in India are doing our part.But commitments to new benchmarks came from elsewhere. Japan said it would cut emissions by 46 percent below 2013 levels by the end of the decade.