Why should any layman regard global warmism as credible when the "consensus" rests on political...?

The same thing is true of the so called scientists who signed a doent denying global warming. I guess you can get a bunch of people to sign anything if you try long enough. Despite what you seem to believe, there is a great deal of evidence including average temperatures taken around the world for the past several decades indicating a warming trend. I have seen a lot of evidence to this effect. Naturally the big oil companies and other big corporations want to deny it since doing anything to reduce CO2 or the greenhouse effect will hurt their profits. They pump a lot of money into the rejection of man-made warming. How can you be certain of your beliefs when you can read all sorts of material on both sides? As a science teacher and science major with a BS and MS in Biology and Chemistry, I believe that there is warming taking place. The whole question is how much is caused by man-made processes.