Agreed, not all are but some of the people that have engaged me and what I have read and seen in other places forms my opinion.
So, in your scenario on testing, does this scenario play out with the global warming crowd. Seems to me, it would have been refuted long ago.
That being said, the role of CO2 in the heat budget of the Earth is just one very, very small part. It's a very dynamic system with all kinds of positive and negative feedback mechanisms. We are getting close to doubling the CO2 content of the atmosphere, but how significant that is to the overall heat budget is not certain.
My personal take on it is that humans are highly adaptable and that if there is climate change, there really isn't much that can be done to change it one way or the other. Plus, from a technical point of view, I don't think we should be deliberately trying to manipulate the climate because of the Law of Unintended Consequences. Best to ride it out and exploit climate change, a true capitalist, conservative approach, than to impose draconian socialist measures to deal with it and cause more harm, both environmentally and economically, than any harm coming form global warming.