VALERIE VOLCOVICI THE United States officially rejoined the Paris climate agreement on Friday, reinvigorating the global fight against climate change as the Biden administration plans drastic emissions cuts over the next three decades. Scientists and foreign diplomats have welcomed the U.S. return to the treaty, which became official 30 days after President Joe Biden ordered the move on his first day in office. Since nearly 200 countries signed the 2015 pact to prevent catastrophic climate change, the United States was the only country to exit. Former President Donald Trump took the step, claiming climate action would cost too much. U.S.…