I think for those who are open-minded and could be convinced one way or the other, the problem is that too many of the solutions and responses on both sides seem to favor political agendas rather than either science or practical factors.
For example, the tree-huggers who live along Route 28 have been fighting a 4-inch natural gas pipe for more than a decade, despite the fact that it would enable tens of thousands of residents to switch from oil, wood, or propane to natural gas, which is at least cleaner than what it would be replacing.
Or the ones who install wood stoves and pretend that they're doing the environment a favor, when all they're really doing is depriving the fossil fuel industry of an infinitesimal portion of its profits while
increasing carbon emissions -- and that's not even counting the emissions from harvesting, cutting, and transporting the wood, nor the energy used to dry it if it's kiln-dried.
I also lump the anti-nuclear folks in the group of eyebrow-raisers, especially those who oppose even thorium research, which would eliminate at least some of the problems associated with uranium-based energy technology, while providing an emissions-free way to produce hydrogen in addition to electricity.
Or speaking of hydrogen, we also have the people who oppose all hydrogen research because the present hydrogen infrastructure is owned by oil companies (it's a by-product of their processes), and they would be the initial beneficiaries of a large-scale implementation of hydrogen. Hydrogen is about as perfect a fuel as exists, yet
many oppose it solely because "Big Oil" might initially profit from it.
Enough of these so-called "solutions" that consistently favor a particular politico-economic position (in this case, hating fossil fuel companies), with little if any practical environmental benefit (or in some cases, a decidedly negative effect on the environment), can't help but make people in the middle wonder whether AGW is in fact a political scheme rather than a scientific fact, especially if they don't personally understand the science.
The arguments coming from the other side tend to be simpler to explain (sunspots, cosmic rays, natural cycles, etc.). They also are less obviously insulting to common sense, unlike the arguments of people who oppose a gas line that would
reduce emissions, but who think that
increasing emissions by burning wood is somehow good for the environment. That doesn't mean the arguments are true, mind you. It just means they make more sense to someone who doesn't understand the more complex science of the other side, that they're less obviously-motivated by political beliefs, and that they
seem less full of inherent contradictions.
The self-interest part of it is obvious, but the "deniers" don't even attempt to "deny" that part. It would make them look as silly as the greenie who burns wood instead of propane and believe he or she is saving the planet by doing so.
In short, it's not the science that turns off open-minded people in the middle. It's the absurdity and inherent contradictions of the politics that has grown alongside the science. I actually feel bad for the scientists because they are dependent upon the politicians, but the politicians are more concerned with their agendas than they are with the science. It must be very frustrating.
Rich