This is a comment about global warming. To begin we might ask how to make a decision about the following:
1. Is Global Warming (GW) a fact?
2. If so, is a significant part of it due to humans?
3. If not, how can we correct the claims for GW?
4. If 1 or 2 is correct, should we do anything about it?
First I note that science is not a democratic process. Both the education and experience of a writer are very important as well as their recognized expertise. Within mathematics and physics (my areas), the important problems are most often set by experts in the field. There is also a general consensus about the identity of the experts. While there are exceptions (else new experts might seldom emerge) there are standard paths by which one becomes an expert. (A Cincinnati boy, Thomas Kuhn, discusses this in The Structure of Scientific Revolutions---I hasten to add that GW falls in the area of Kuhn's "normal science.")
While consensus indicates a kind of democracy, one should not think that there are "votes" on the important problems in graph theory. Nor are there "votes" on the direction that particle physics should take.
With that in mind, I will refer the reader to the NASA website on Climate Change:
http://climate.nasa.gov/evidence/
There are links to the IPCC (Intergovernmental Panel on Climate Change) at the NASA site.
We find there this statement:
"The current warming trend is of particular significance because most of it is very likely human-induced and proceeding at a rate that is unprecedented in the past 1,300 years."
There is also a quote from the IPCC:
"Scientific evidence for warming of the climate system is unequivocal."
