As for the royal society not being hippies, they did manage to publish this:

 "While there are larger concentrations of other gases in the atmosphere, such as nitrogen, because they do not have these heat trapping qualities they have no effect on warming the climate whatsoever."

 An "other gas" water vapor is responsible for all the heat that is trapped in the atmosphere. The CO2 capability for trapping heat in the atmosphere is based on hypothesis that have not been proven, not even through experiments.

And as always: prove me wrong.

I was astounded by the quote of the Royal Society by steven_12 so I searched for it on Google and came up with this:

http://www.science-academy.org.uk/page.asp?tip=1&id=6777

which carries on as stated by Richard above. It is like making a quote  "jumping off tall buildings is good" but missing out "if you want to die" afterwards.

It is well beyond the ability of the space here, or any of the people writing here (I suspect) to provide proof of the greenhouse effect of CO2. On the other hand I expect Steven is arguing 1. Global warming doesn't exist and 2. but if it does its not caused by man and 3. in any case there is nothing we can do about it. This has been the steady progression of fall back positions adopted by people who made up their minds and now simply refuse to accept any arguments that may show their entrenched positions may be wrong.

The greenhouse effect results from absorbtion and emission  of infra red radiation which slows down the cooling of the earth at night. The effects of this versus the concentration of CO2 and the relative effects of other greenhouse gases (water vapour, methane etc.) which also have infra red absorbtion spectra is very, very complex. The theory of the physics is well understood but how this affects the climate is complex because of the reactive effects of the climate and numerous other phenomena that can also affect climate. The only way the analysis can be done reliably is to build up sophisticated computer models that try to take into account as many of the interfering effects as possible and to see how these models, when applied retrospectively, would have predicted the climate in the past. When this has been shown to be reasonably accurate they can be assumed to have a reasonable chance of predicting future effects. This is not a black vs white scenario and there can be no concrete proof about the effects of the rise of CO2. However, I think that the evidence pointing to its effect is substantial and I cannot think of any way to get better information and analysis that what has been done. It convinces me that there is enough evidence to suggest that we should act to reverse the rise of CO2 as soon as possible. Those who think otherwise are entitled to their opinions but, to my mind, are ignoring the best information available in favour of a blind belief or that there is some vast conspiracy.

So Stephen, how do you explain that all the scientific associations in America and the UK (to quote the countries which I know about), whose job it is to study these things in depth and not to rush to ill-founded judgements, that these scientific societies have fallen victim to the "pseudo-science" of which you speak?

There's a clear distinction between a hypothesis and a theory (which is synonymous for law). For example, Newton's laws of physics are widely accepted and are so far not disproved.

Newton's law however coincides with quantum mechanics and quantum physics. Through developments in these fields scientists have discovered that while Newton's laws are a perfect match to everything that isn't nano in size these laws a sometimes contradicted in quantum physics.

This however does not lead to the consensus that Newton's laws are proven wrong. The current consensus is that there are two fields - one describing the nano-sized world and another one describing everything that's bigger than nano.

These are examples of accepted theories and accepted consensus. Then there are hypothesis.

Turing's hypothesis is one example. This hypothesis is largely accepted through consensus since through empirical evidence it hasn't been disproved yet. However, since there is not yet a mathematical prove found it remains an hypothesis.

This is an example of a consensus about an hypothesis.

Man-made global warming is clearly an hypothesis. A large consensus doesn't do anything to turn it into anything else, let alone a theory.

The scientific facts unearthed largely through geological records are sufficient to disprove any relationship between the current warming trend and man-made greenhouse emissions.

Thus: there is scientific evidence that disproves the hypothesis beyond a reasonable doubt and there are no scientific facts to prove it.

You may have a different view on the scientific method but you should understand that if you want to elevate man-made global warming beyond a hypothesis supported by consensus you will have to accept that any hypothesis supported by a crowd of fanboys will no longer have to provide proof what-so-ever to become proper scientific theory. Notable examples would be the law of intelligent design and the flighing spaghetti monster theory.

You will also have to understand that scientific theories that are universally accepted - notably those in physics, biology, chemistry and mathematics and in many other domains - do no longer have to be supported by any scientific evidence.

It's all fine and well to try to prove man-made global warming is a scientific theory through philosophical rhetorics. But that's not sufficient. You will also have to defend why man-made global warming resides on the same plateau as widely accepted and proven-beyond-a-doubt scientific theories and laws that don't support on these kind of rhetorics.

I would be very happy to track your efforts to this end.

Steven, you are misunderstanding, to some extent, how science works. Newton's laws are not really laws but theories. The use of the word "law" is convenient, but strictly, incorrect. The theories are wrong because they do not agree with measurements that are more accurately described by newer theories within quantum mechanics or relativity. Of course they are approximately correct and the accuracy is good enough in everyday life for the objects we deal with and at the speeds we deal with. In fact, to now, nobody has a single theory which explains quantum mechanics and relativity (there is a new theory that may work but has not yet been put to the test). All the theories are good enough to explain the parts they are aimed at until someone finds an exception. Then a rethink is needed. This is true of the whole of science. The essence is that nothing in science can be proven, only disproven.

The correlation between the current warming trend and man-made greenhouse gas emmissions has been disproved. It's as simple as that.

You will go on with your political games but it doesn't change the simple scientific fact that the current warming trend is not man-made, as was the case for the previous one and the one before that and the one before that.