National Public Radio: Almost everyone has heard about Hurricane Katrina’s toll on the residents of New Orleans. But Gulf Coast trees also took a wallop. Hundreds of millions of trees were destroyed or badly damaged and have become an unexpectedly large contributor to global warming, according to new research. In fact, trees killed by Katrina will release about as much global warming pollution into the air as all the trees across the nation soak in over the course of one year, according to a study by Jeff …