United Press International: A U.S.-Australian study has determined high humidity levels, through a process called water vapor feedback, can aggravate global warming. Texas A&M University Professor Andrew Dessler says warming due to increases in greenhouse gases will lead to higher humidity in the atmosphere. And because water vapor itself is a greenhouse gas, this will cause additional warming. “It’s a vicious cycle,” said Dessler. “Warmer temperatures mean higher humidity, which in turn leads to even …