United Press International: An U.S. Environmental Protection Agency finding on the dangers of global warming could force a change in national policy, environmental groups said. The conclusion that greenhouse gas emissions are dangerous was sent to the White House on Friday, The Washington Post reported. The newspaper said the finding could have major implications for the U.S. economy and environment. “This is historic news,” Frank O’Donnell of the public watchdog group Clean Air Watch told the Post. “It …