Scientific American: As you sit round the Christmas tree, consider the TLC you give O Tannenbaum: plenty of water and a relatively comfortable climate. Wouldn't want to dry out the tree, after all. Now consider that in the house we all live inthe planetwere hardly giving the same courtesy to your Christmas tree's wild cousins. (Who, I might add, are actually still alive.) As the planet warms, droughts are getting even drierand they're getting hotter too. In fact it's getting so bad that researchers are now forecasting...