“Global warming isn't cool. Stopping it is.” That's the motto of a new star-studded ad campaign from ClimateStar.org, founded by Union of Concerned Scientists, designed to raise awareness on global warming. Here's Mischa Barton beckoning an audience in a white angelic dress, windswept hair and the tagline “Let's Clear The Air.” There's Kevin Bacon in a tough-guy stance beneath the declaration: “Six degrees can make a world of difference. Not Separation – temperature.”