Assuming global warming is happening, which there seems to be a fair case there is, the problem is we could eliminate all man made pollution and it would not stop it. Forest fires, volcanic eruptions, and historical climate shifts make the human impact not statistcally significant. Al Gore likes to talk about past climate changes, but we know for fucking sure humans played no role. What are we going to do, push this one back another 100 years, if even?
The real problem is when human pollution has an environmentally changing impact. Undrinkable water (both river and groundwater pollution), poisened fish & animals, and so on. I don't fucking want to eat food with mecury or other pollutants in it and I don't believe anyone else in their right mind does either. In the US we've done a pretty good job curbing it but developing countries have huge messes on their hands.
What Al Gore and other environmentalists are doing is creating a business incentive environment for their cause. They have figured out its been big business who has single handedly standed in their way for decades. They can't beat big oil but they can bring all of these new technology companies (like Google) and entrepreneurs on board. Just read a few VC blogs, these guys are sold.
There are a lot of people standing in line to catch a ride on the environmental business boom. Whether it is built on a lie or not is irrelevent at this point, it already has the necessary momentum to move forward without being stopped.
The bright side is at least Al Gore figured out the government does a horrible job at delivering solutions and can only ensure that the enivornment exists for solutions to be created by market forces. More money for you and me, less for the lower and middle class.