The global warming propaganda machine keeps pumping out more sales pitches to scam the public - the "news" is full of them lately. The gullible or lazy or just busy might figure it must be true if "everyone" believes it, or if Hollywood makes a movie about it or PBS puts on a TV show. But some people take the time to analyze, audit and critically review the claims and models and data. Yes, I wrote, "analyze the data". Some people do check it. Sort of makes sense - after all, would you invest in a gold mine without having experts - good, independent experts - check the mining data? Remember Bre-X?
See http://www.climateaudit.org/ for a massive compilation of data analysis and review. Some people also check out how the "policy makers' summaries" are written that the press parrots relentlessly. See http://motls.blogspot.com/ and skip down a little past the quantum gravity sections to the heading "IPCC AR4". See http://www.cei.org/pages/ait_response.cfm and click on "Read the Book" or download powerpoint presentation for a deconstruction of the AlGore movie.
There is NO "proof" that human activity is causing, or has caused the current level of warmer global average temperature. The earth was warmer about 1,000 years ago when no SUVs existed. Computer models have thousands of free parameters and poor physics about critical atmospheric components, yet still are UNABLE to model temperature changes over the past 100 years at a level that a good stock chart reader would accept. The 100+ year chart of model predicted temperature changes vs. the data is laughable - not even a fool would put trading $$$ on such predictions if it was a stock trading/ investing model. So why are we putting the world economy in the hands of its pumpsters?