Climate change climbed onto the debate stage a year ago, when Jon Huntsman diverged sharply from his opponents in the Republican primary by declaring that the Earth is warming because of human activity. Now, Republican strategists anticipate that Mitt Romney could adopt a similar position tonight in his first debate with President Obama, as the former Massachusetts governor strives to attract moderate voters while defusing attacks that link him to anti-climate conservatives. Go to story #1

As desert sands yield to asphalt and concrete, the climate is shifting in Arizona's "Sun Corridor," an expanding urban region that includes Phoenix, Tucson, Prescott and Nogales. Researchers are now finding that efforts to offset the climate shift may carry side effects of their own. Go to story #2