Bloomberg: Earth Hour, an event created in Sydney two years ago by environmentalists keen to cut energy use and reduce greenhouse gas emissions, may prompt 1 billion power users worldwide to turn lights off tonight, organizers say. Lights at 829 iconic landmarks including the Empire State Building in New York, London’s Big Ben, the Eiffel Tower in Paris and the Las Vegas Strip will be cut from 8:30 p.m. local time, according to an Earth Hour statement. A total of 83 countries and 2,848 cities …