My big problem with the global warming debate has to do with the very nature of consensus itself. Science is not a discipline where truth is sought through majority voting. Truth in science is arrived at through experimentation, and demonstrable, repeatable, verifiable results.
If solid scientific evidence existed, there wouldn't be a consensus, there's be a universal, un-questioned agreement.
Wasn't going to bother with the consensus debate because it is largely nonsense, but I feel I have to respond to this.
There definitely are scientific questions that have been resolved - is the earth flat? If not what is the diameter of the earth? Does the earth revolve around the sun? How far are we from the sun? And so on.
But then there are the difficult questions - questions that gave rise to quantum physics. And there are the questions along the way to scientific 'proofs' - the answers to them represent the best knowledge we have at this time. I've often seen science referred to as peering through the mist dimly at obscure shapes - finding out what those shapes are, or at least what we think they are, and moving on to the next shape and trying to see what that one is and how it relates to the first one.
Very few questions in science these days are of the nature that most insist science is. We build things like the LHC to try and get more data to test a hypothesis and see if it stands up. If it does, it isn't proven, it just didn't fail. The next experiment we devise may completely destroy the hypothesis, or may cause it to be altered somewhat.
The consensus on climate science amongst climatologists who are active and publishing (see Naomi Oreskes - Beyond the Ivory Tower) is relatively clear for those that have eyes to see. Most who follow the debate at all can name the handful who do not largely agree with the general premise, those names crop up again and again. That's not to say they are wrong, but they are a minority.
The consensus position is not about voting for truth - it is about establishing who is doing what and who sees what when peering through the mist at those dim shapes, whose hypothesis is still valid after it has been checked and re-checked by hundreds of others, what data is good and what is bad. At the moment those guys have some pretty good ideas about what they are seeing, I've heard it said that the degree of confidence in what they understand is greater than most physicists would express about their confidence in General Relativity. GR is the best fit for what we know at present, and the same is true of the theory of anthropogenic global warming.
AGW and evolution are both attacked as mere theories by those who either don't or won't understand that aside from a few certain facts about the universe, all science is based upon theories that try and express what we know about what we have seen. A theory has data behind it, a lot of data that hasn't falsified it. They are open to demolition to falsification, but that usually comes from within the field, not from without, because usually the expert knowledge is within the field - so that is why consensus is meaningful but not absolute, a decent poll but not an authoritative vote. Ignore it and dismiss it if you will, as I'm sure the internet will, because of course the internet is where all the experts are, and some are calling scientists hoaxers whilst admitting they've never looked at the data.
To scientists, a theory is extremely well supported, has survived hundreds of tests and potential falsifications, and is accepted as a valid explanation of the world. But Reagan is confusing that meaning with the everyday meaning of theory as a "wild hare-brained scheme"...Science is always about challenging hypotheses and testing them and never reaches a point where a scientific idea is "believed" or is "infallible"...
...We still do not have a full understanding of the mechanism by which gravity works {actually see "Intelligent Falling" in the Onion - Iain], but that does not change the fact that objects fall to the ground.
- Prothero "What the fossils say and why it matters"
In reality, after a scientist publishes a paper with an idea or observation, other scientists usually look upon it with justifiable suspicion. Many papers, perhaps most of them, harbor misconceptions or plain errors. After all, research (by definition) operates past the edge of the known. People are peering through fog at a faint shape, never seen before. Every sighting must be checked and confirmed. Scientists find confirmation of an idea all the more convincing when it comes in from the side, using some entirely different type of observation or line of thought. Such connections among different realms are especially common in a science like geophysics, whose subject is intrinsically complex. Scientists may start with something they learned about the smoke from volcanoes, put it alongside telescopic observations of Venus, notice the chemistry of smog in Los Angeles, and plug it all into a computer calculation about clouds. You cannot point to a single observation or model that convinced everyone about anything.
- Weart, "Discovery of Global Warming"
