David Harsanyi asks Who Doesn't Trust Science Now?:
It is true that most reasonable people concede there has been warming on the planet and that most concede they can't possibly fully understand the underlying science. I certainly can't, despite my best efforts.
The problem is that reasonable people also understand economic trade-offs. Many don't like intrusive legislation. Others can sniff out fear-mongering for what it is. Some even trust in humanity's ability to adapt to any changes in climate trends.
In the end, though, the burden of proof is on the believers. And if they're going to ask a nation -- a world -- to fundamentally alter its economy and ask citizens to alter their lifestyles, the believers' credibility and evidence had better be unassailable.
This is a good summary of the reasons for my skepticism from the beginning on both the existence of and dangers posed by anthropogenic global warming. I don't deny that there is evidence of a warming trend in the earth's climate, although it appears that warming has leveled off in the last decade or so. I don't pretend to know what caused this warming and whether it’s been brought about by one particular factor or a combination of several. I also don't know exactly how this warming would impact the world were it to continue in the future. There's a lot about climate that I don't know.
But I also have never been convinced that there was irrefutable evidence that this most recent warming has been caused largely by man. Anthropogenic global warming is a theory that explains the warming, one of several. But there simply is not enough proof to say with conviction that it is THE ONLY explanation. And even if one were to accept that it was, there is even less irrefutable evidence that the impacts of the warming would be catastrophic enough to require drastic action to mitigate it now. Warmists argue that we need to apply the "precautionary principle." That even if the evidence is not irrefutable, we need to act as if it is to prevent harm. But most versions of the precautionary principle involve some form of cost-benefit analysis and while evidence of the cost of the proposed "solutions" to global warming are clear, the benefits of preventing it are dubious at best and based far more on fear than fact.
And when the "solution" that we're talking about is moving away from carbon based energy--literally the fuels that allowed us to build the modern world that we know today--we better damn well be absolutely sure we're doing it because we have no other choice. Warmists like to argue that even if it turns out that, aw shucks I guess we were all wrong about the whole global warming danger--our bad, the steps taken to mitigate it are ones that we should take anyway. This might be true if the proposed actions were prudent, reasonable, and cost effective. The reality is that they aren't and what they really want us to do is alter lifestyles, impose harsh economic burdens, and curtail not only the continuing advancements in already developed countries, but the advancements that less developed countries will need to make to raise the standards of living for hundreds of millions of people around the world. Such sacrifices are not to be undertaken lightly and should not be made unless we KNOW that they will in fact reduce global warming and avoid environmental catastrophe. The truth is the we--including all the scientists who make up the "consensus" on global warming--simple do not know enough about the earth's complex climate system today to make that claim with certainty. Until we do, reasonable skepticism would seem to be in order.