90% of scientists from the relevant field as well as 90% of all scientists agree with anthropogenic climate change. In the world of science, this is what we call a "scientific consensus" and it's a pretty overwhelming one at that. If man is indeed affecting the climate, then at the very least we can reduce the things we are doing that affect it.
I can never get over just how fervent the climate change denialist religion is. On one side of the argument, we have 90% of all scientists, representing every conceivable nationality, set of political views, economic status, and funding source. On the other side of the argument, we have a small group of "scientists" from a single political ideology from a narrow range of customers all of whom draw their paychecks from oil companies, coal companies, and/or right wing think tanks. The most prominent, most published, most cited member of this group is someone either so incompetent he literally doesn't know degrees from radians, or is a staggeringly deceitful fraudster.
http://crookedtimber.org/2004/08/25/mckitrick-mucks-it-up/
Based on work of this quality, millions of conservolibertarians have concluded that 90% of the scientists in the world are participating in a vast and incredibly complex conspiracy to... what? Make American rightists feel bad? Conservolibertarians never seem to be very clear on the goals of this massive and complex international supposed-conspiracy.
Ah well. Once someone adopts a religious view, they will cling to it no matter what evidence is presented to them.