The Pew Research Center for the People & the Press did a recent polling of 1500 adults regarding the issue of whether global warming is caused by man made activities. The result is that only 57% of those polled believe that there is strong scientific evidence that that the Earth is warming due to man's actions. This dropped considerably from 77% in 2006 and 71% in 2008.
What is happening here? There are more sceptics out there that are getting public exposure to "challenge" the scientific evidence. Because of the 24/7 news cycle and the variety of different methods to express your opinion via the Internet and other forms of electronic communication, there is a larger audience that is being exposed to this counter position.
In addition, although this happened after the polling, more than 3000 emails and documents from the University of East Anglia's Climate Research Unit (CRU) were released to the public after their servers were hacked. According to news reports, there is evidence in these documents and e-mails that certain scientists were working together to exclude or "massage" certain data in order to unequivocally reach the conclusion that man is causing global warning. Also, it has been reported that there were efforts to exclude scientists who were critics of this position.
Unfortunately, this new news might push that 57% down to a level where the majority believes that man is not causing global warming. More importantly, the scientific community is now facing an issue of credibility. They already had a hard time convincing people beforehand. Now, they are facing a more sceptic public with a lack of credibility. Good luck. I am going to start working on that Ark.