One doesn't have to understand all the science to believe that something is real. When your doctor tells you that you have heart disease, you don't (generally) say, "I don't believe you, prove it. I want to examine all the science that lead up to that conclusion." One cannot become an expert in every field. So, you have two choices, either believe the experts or believe the non-experts. Or, don't believe either.

Sure, experts have been wrong before, and some non-experts have been right, I expect. But, it is a matter of probability. You generally go with the most probable.

And as another poster pointed out, there are plenty of reasons other than global warming to cut down on air pollution. If you ever are in the local mountains around L.A. in the summer you can look down on a total blanket of brown air over the city--you can't even see the city. I can't see how that can be a good thing. We all know what caused that brown air.