Freeman Dyson explained....

...in a cartoon at Idiot Tracker, too direct honest iconoclastic impious heretical cheeky to be reproduced here.

Check it out.

Update: Speaking of Freeman Dyson, there is celebration of his 90th birthday this weekend in Princeton. Ashutosh Jogalekar writes at ScientificAmerican.com:

Over the past few years Dyson has become much more well-known in the public eye for his skepticism regarding climate change, a view made popular in a lengthy 2009 New York Times magazine profile. This was always unfortunate. Both his views and the article were blown out of proportion. In reality, as can be readily judged when you talk to him, Dyson’s opinion of climate change is mildly proffered, moderate to a fault and in the best tradition of the same skepticism that has guided science since its inception. He disapproves of faith in computer models and of the zealous dogmatism exhibited by some climate change activists, and both these points are extremely well taken. Ultimately Dyson is saying something simple; that science progresses only when there is a critical mass of skeptics challenging the status quo. It’s not about whether the skeptics are right or wrong, it’s about whether their voices are drowned out by the consensus.

Of course, climate scientists have hardly a mutual admiration society where they just sit back and accept whatever another of them puts out -- they constantly challenge each other's ideas. And some "skeptics" are not making good faith efforts at challenging the status quo, and their voices deserve to be drowned out.