for Colinsett:

You can't have read a lot in this debate if you think I'm at the 'extreme'. I've written quite a bit about the shades of opinion in the AGW debate, and a summary is as follow. There are six obvious positions, and a few religious outriders.

Supporters

1 Strongest. The IPCC has raised the alarm. We must do something now, and that something is to get global agreement to curtail greenhouse gas emissions. The science is clear, and now is the time to act. This is fact the orthodox or IPCC position.

2 Partial Support. There is no doubt that adding more and more carbon dioxide into the atmosphere must increase the world’s temperature. But we don’t know yet how much extra warming there is likely to be.

3 Lukewarm support. Adding more carbon dioxide will very likely increase the temperature, but there are other factors at work too, and the effect may well be pretty small, or even positive for some part of the world. We need to know much more before we do anything.

Dissenters

4 Agnostic dissenters. The orthodox arguments rely heavily on models and conjectures. AGW is plausible and possible, but we need real evidence before we do anything. In particular, we need to be able to distinguish AGW from natural variability. A little warming may be good for humanity, as it seems to have been over the past thirty years.

5 Sceptical dissenters. Many sceptics are well informed about one or other aspect of the central AGW proposition, and can show difficulties with it; they tend to argue that the failure of the orthodox to satisfy them in these domains means that the whole AGW proposition is void.

6 Opponents. AGW theory is just a scam, a sign that the Marxists have taken over the green movement, an attempt by some to construct world government, a conspiracy, a sign of lazy journalists, the effort of bankrupt governments to stay in power, etc. There is nothing to it.

I see myself as an agnostic dissenter.

"real evidence", Mr Atkins?

As opposed to?

for bugsy:

'real evidence' versus 'conjecture'. Real evidence would be observational data showing, for example, that the effect of water vapour and clouds indeed amplified the radiative transfer mechanism through which a doubling of carbon dioxide produced a warming of 3 degrees rather than of one degree. What observational data exist, for the last century, do not support this proposition. The increase of approximately 0.7 peer cent over the last century does not suggest anything like the 3 degree increase conjectured in AR4.

Don and others.

The point is that 1 above represents the mainstream scientific view. This is the view that 97 to 98% of scientists have and every reputable scientific body in the world (if you disagree please list a reputable scientific body that disputes the thrust of the IPCC reports). If you are taking a position based on the science then views 2 to 6 are all extreme positions representing just 2 to 3% of scientific views between them. On this basis Don is at an extreme.

Of course humans base decisions on a whole variety of factors. Things like gut feel, previous experience, their own observations and, probably predominantly in this case, their political preferences. For many people cold, hard blooded science with an unpopular message takes a back seat.

I would say it is extreme to base a decision on something other than science when it comes to climate change, yet it appears to be popular among contributors on the forum. Maybe that is just because common sense is in fact not that common.

Position 1 is based on the hypothetical view of AGW.

The following extracts from physicist Dr John Nicol's paper, "Science without method", Quadrant, April 12, 2011, serve as a timely illustration.

"Conventional thinking on the greenhouse effect is encapsulated in the IPCC’s statement that “We believe that most of the increase in global temperatures during the second half of the twentieth century, were very likely due to the increases in the concentration of atmospheric carbon dioxide”.

Clearly this statement would be better worded were it to have been framed as a hypothesis rather than a belief, and treating the statement that way allows it to be rigorously tested (“beliefs”, which are unable to be tested, fall outside of the spectrum of science). In the real scientific world, for such an hypothesis to survive rigorous scrutiny, and thereby to perhaps grow in strength from a hypothesis to a theory, requires that it be examined and re-examined from every possible angle over periods of decades and longer.

Yet in contemporary research ... and despite enormous expenditure, not one serious attempt has been made to check the veracity of the numerous assumptions involved in greenhouse theory by actual experimentation.

The one modern, definitive experiment, the search for the signature of the green house effect has failed totally. Projected confidently by the models, this “signature” was expected to be represented by an exceptional warming in the upper troposphere above the tropics. The experiments, carried out during twenty years of research supported by The Australian Green House Office as well as by many other well funded Atmospheric Science groups around the world, show that this signature does not exist." (To be cont.)

(Post cont.)
"In addition, the data representing the earth’s effective temperature over the past 150 years, show that a global human contribution to this temperature can not be distinguished or isolated at a measurable level above that induced by clearly observed and understood, natural effects, such as the partially cyclical, redistribution of surface energy in the El Nino. Variations in solar energy, exotic charged particles in the solar wind, cosmic ray fluxes, orbital and rotational characteristics of the planet’s motion together provide a rich combination of electrical and mechanical forces which disturb the atmosphere individually and in combination. ... the “human signal”, the effect of the relatively small additional gas that human activity provides annually to the atmosphere, is completely lost, being far below the level of noise produced by natural climate variation.

So how do our IPCC scientists deal with this? Do they revise the theory to suit the experimental result, for example by reducing the climate sensitivity assumed in their GCMs? Do they carry out different experiments (i.e., collect new and different datasets) which might give more or better information? Do they go back to basics in preparing a new model altogether, or considering statistical models more carefully? Do they look at possible solar influences instead of carbon dioxide? Do they allow the likelihood that papers by persons like Svensmark, Spencer, Lindzen, Soon, Shaviv, Scafetta and McLean (to name just a few of the well-credentialed scientists who are currently searching for alternatives to the moribund IPCC global warming hypothesis) might be providing new insights into the causes of contemporary climate change?

Of course not. That would be silly. For there is a scientific consensus about the matter, and that should be that."