CNN International: Public concern about global warming and trust in climate leaders has dropped sharply in the U.S. according to a survey. Fifty-seven percent of Americans polled at the end of 2009 and early 2010 believe climate change is happening compared with a figure of 71 percent in October 2008. The report, “Climate Change in the American Mind” published jointly by Yale University and the George Mason University Wednesday also reveals a picture of falling trust in scientists, politicians …