Scientific foundations of advocacy?

(Warning: this is a rant) OK … the antidote to my hopefulness. I just walked home from the el, which I took to work today because the rain threatened this morning and put me off of bicycling. Greenpeace has a bunch of their summer student employees out and about spreading the word about Mother Earth, their mission, etc. One of them approached me (very politely, may I add) and asked if I wanted to hear about environmental issues. I told him that I teach environmental economics and was in the middle of finals week, so he might want to talk to someone else. He was intrigued and asked me what I thought about environmental issues like global warming. I told him that I think property rights matter, that private enterprise and ingenuity are crucial to a clean environment, that a healthy economy is an important foundation of a healthy environment, and that CO2 is not a human toxin. In response, he said, “oh, you mean acid rain?” I said, “No, that’s SO2, CO2 is the global warming that you are worried about. That’s one reason why you should take an environmental economics course.” Bless his soul, at that point he realized that talking to me was not going to get him where he wanted to go. I am not mocking or faulting this earnest, well-intentioned, polite young gentleman, but if Greenpeace is going to send out folks to canvass, they should teach them some SCIENCE first!