BRUSSELS (Reuters) - U.S. special climate envoy John Kerry and European Union climate policy chief Frans Timmermans on Thursday held their first call under the new U.S. administration, kicking off renewed transatlantic cooperation on tackling global warming. After four years without U.S. federal leadership on climate change under former President Donald Trump, the United States and the EU - the world’s second and third-largest emitters of greenhouse gases, respectively - are now seeking to combine their diplomatic firepower to convince other big polluters to take urgent action to safeguard the planet. A European Commission spokesperson said Timmermans had “discussed our ambitions to work with the U.S. and other partners to raise global ambition at COP26 in Glasgow.” The United Nations climate summit in November, known as COP26, serves as a deadline for nearly 200 countries to submit a national plan to curb emissions faster this decade. The EU is one of only a few large economies to have done so. Globally, countries’ current climate pledges would fail to rein in planet-warming emissions fast enough to avert catastrophic temperature increases. President Joe Biden committed the United States to rejoin the 2015 Paris climate accord on Wednesday - a move that requires the country to this year pledge deeper emissions cuts. Biden is also expected to convene a summit of leaders from large-emitting countries within the first 100 days of his presidency, as part of a diplomatic push to rally urgent global climate action. China, the world’s biggest polluter, plans to become carbon neutral by 2060 but has yet to unveil a short-term plan to reduce emissions.