USA Today: The Arctic keeps melting, the atmosphere keeps warming and polls keep bouncing around on what people think about global warming. After every hurricane, heat wave or hullabaloo over climate science, the polling results come, watched breathlessly for some shift in U.S. public opinion about global warming. All the hand-wringing may not have amounted to anything, suggests one long-term look at all those polls. The majority of the public pretty much understands that global warming is happening, and...