I'm not a global warming denier.  I think the evidence is fairly clear that there is some warming occurring.  However, I think the extent of that warming is being overblown.  More importantly, I'm not convinced that it's caused by man.  While there is some evidence that may point in that direction, there is also ample evidence that there are other causes, over which we have no control, like the sun.  Moreover, I think there isn't enough evidence to force the sorts of large societal changes that many want to force on people.

However, whenever evidence is brought up that contradicts the current popular belief that man has caused it all, the question is always raised by the true believers... "If it isn't caused by man, then why are there so many scientists and politicians who strongly believe it?  How can you so blindly ignore all those people?"  It's a very fair question, and one I'll try answer here.

The theory of man-made global warming is the only theory that offers a vehicle for changes that they want to make anyway.  It offers another excuse for more control over our lives.  The same people who have pushed the man-made warming theory are the same people who have been fighting for more environmentally friendly laws for years.  The problem is that it was often hard going, as the cost of their proposed changes in both money and inconvenience was many times found to outweigh any purported benefit.  Global warming now offers the kind of wide scoping global cataclysm that they needed to institute the changes they've always wanted.  And saying it's man-made offers the vehicle to institute the laws they want.  If we caused it, then changing how and what we do is the solution.

But if they problem isn't man-made... what happens then?  The reality is that if the problem is not man-made, the solution may actually be to increase industrial output in order to create some other solution that will allow us to cope with a change we can't stop.  That isn't very good for the environmentalists out there.  It also means that there is less reason for new regulations and controls over our lives.  Even if it only means we continue to do what we're currently doing, the environmental lobby still won't be happy.

Besides, it's never popular for a politician to say "There is a big problem, and there's nothing we can do about it."  Man-made global warming is the popular theory, because it has to be for those who study it.  Anything else would lead to less money, and less control.  And you just can't have that now can you?

Update:  As if on cue, a new television documentary is going to air in England on exactly what I mentioned:

With a packet of claims that are almost certain to defy conventional wisdom, a television documentary to be aired in Britain this week condemns man-made global warming as a myth that has become "the biggest scam of modern times."

The program titled "The Great Global Warming Scandal" and set for screening by TV Channel 4 on Thursday dismisses claims that high levels of greenhouse gases generated by human activity causes climate change. Instead, the program suggests that the sun itself is the real culprit.
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The truth, he says, is that global warming "is a multibillion-dollar worldwide industry, created by fanatically anti-industrial environmentalists, supported by scientists peddling scare stories to chase funding, and propped up by compliant politicians and the media."

Via Ol' Broad.