Climate change knows three realities: science reality, which is what working scientists deal with every day; virtual reality, which is the wholly imaginary world inside computer climate models; and public reality, which is the socio-political system within which politicians, business people and the general citizenry work.
The science reality is that climate is a complex, dynamic, natural system that no one wholly comprehends, though many scientists understand different small parts. So far, science provides no unambiguous evidence that dangerous or even measurable human-caused global warming is occurring.
The virtual reality is that computer models predict future climate according to the assumptions that are programmed into them. There is no established Theory of Climate, and therefore the potential output of all realistic computer general circulation models (GCMs) encompasses a range of both future warmings and coolings, the outcome depending upon the way in which they are constructed. Different results can be produced at will simply by adjusting such poorly known parameters as the effects of cloud cover.
The public reality in 2008 is that, driven by strong environmental lobby groups and evangelistic scientists and journalists, there is a widespread but erroneous belief in our society that dangerous global warming is occurring and that it has human causation.