McClatchy Newspapers: President-elect Barack Obama’s choice of John P. Holdren as his science adviser sends a strong signal that Obama sees global warming as an urgent problem and wants bold suggestions for action. The Harvard University environmental policy professor has argued that the world already is experiencing dangerous climate change as a result of fossil fuel combustion. He’s said there’s still time to avert catastrophe, but only with a strong and rapid global effort. At a recent talk in …