Well, yes, Arrhenius did make errors in his calculations and his understanding of the mechanism was extremely crude by today’s standards, but lets not forget that his quantitative paper on the ‘greenhouse effect’ was published in 1896, nine years before any kind of understanding of the physics he would have needed to correctly identify the mechanism even existed.

Atmospheric physics is heavily dependent on statistical physics, the first published paper on which did not appear until 1905 – it’s actually Einstein’s paper on Brownian motion which would be rather more famous than it is were it not for his having also published his Special Theory of Relativity in the same year.

Yes, I believe that the feedbacks are known with less certainty at higher temperatures (this does of course mean they may be more positive – I’ve seen a list of possible positive feedbacks which aren’t currently included in calculations), I guess it could be the same at the other end. But then we have good records from the last ice age so I think they can be more certain about that. I think the estimates are believed to be pretty good for current temperatures.

This is a red herring – the “hot spot” does not specifically relate to AGW, to the extent that it is predicted it would be expected as a result of surface warming from any source.

See

http://www.realclimate.org/index.php/archives/2008/05/tropical-tropopshere-ii/

for a discussion around the issues surrounding measurements of tropospheric temperature.

What we would specifically expect as a result of AGW, as opposed to solar forcing for example, is cooling in the stratosphere, which has been observed.

Where in any of the 11 climate models used by the IPCC is there an 11 year gap in the warming?

We don’t have an 11 year gap in warming – you are being very selective with your dates. As for the models, they predict long term trends but there is a known natural variation which means that over short periods of time the rate of warming will vary and even appear to cease altogether. Further take into account events such as the el Nino of 1998 and la Nina of 2008 the changes in temperature over the last decade are entirely consistent with the predictions of the models.

3. If the science is settled, why are there 11 climate models? Shouldn’t there just be one?

The science is pretty settled as far a the reality of AGW is concerned but that does not mean that there are not still uncertainties in our overall understanding of how our climate works. There is still work to be done and the models will play a part in that. Modelling is not an exact science and not everyone will make exactly the same assumptions when cresting them – aside from the issue of scientists wanting to use models they created themselves rather than by others, having a number of different models is useful in order to see how results diverge between them.

Nor do I….although I’m open to the idea that which feedbacks predominate will be different at different temperatures.

Which at extremes of course they must be…..either we would still be in an ice age as you say, or we would never have had ice ages at all.

Sure, but although the writer has overstated the accuracy of his predictions, getting close to the upper end of the known range is not bad for a calculation no one had tried to do before.
Anyway, the essential point is that he was predicting that human CO2 emissions would cause warming before it even happened and that the theory of AGW is based on science which goes back to the 19th century, and so it can’t be said that it is something which modern scientists have plucked out of thin air for reasons of expediency.

The difference between the direct effect and the total effect is because we don’t know what the balance of feedbacks is. Not even, with any great certainty, which direction preponderates.

But the IPCC figures which you seem to accept show a positive feedback, in fact I don’t know of any serious piece of research which suggests the feeedbacks are negative. If they were we would still be in an ice age.

Larry, perhaps you would like to answer my questions in the comment right above this one. That would show you don’t suffer from the same thing you say skeptics suffer from.

I would add a couple of questions for the warmists.

1. Where is the fingerprint the IPCC said would be there–the hot spot in the troposphere? 50 years of weather balloons and 30 years of satellite observations have found no such hot spot.

2. Where in any of the 11 climate models used by the IPCC is there an 11 year gap in the warming?

3. If the science is settled, why are there 11 climate models? Shouldn’t there just be one?

4. How does the ERBE/Ceres data hold up regarding the feedback per the AGW theory? Does it show a decrease in radiation from the earth with warming?

I’ll assume most of the readers don’t have the foggiest idea what these issues are or how they defend or destroy their belief in AGW.

This post was mentioned on Twitter by libcon: :: Climate change sceptics? Really? http://bit.ly/7PtfHN...

“By the end, Arrhenius had estimated that doubling the amount of the gas would cause global temperatures to rise by 5C-6C. Extraordinarily, that is almost exactly the conclusion reached by today’s scientists, armed with superfast supercomputers – which has led to the giant climate summit, to be attended by more than 100 heads of government, that opens in Copenhagen on Monday.

In fact, the science of global warming is even older than Arrhenius – who later won a Nobel Prize for entirely different research. It stretches back to 1824 when a French physicist, Joseph Fourier, discovered the “greenhouse effect”, whereby gases in the atmosphere trap heat like the glass in a conservatory. And 37 years later, an Irish physicist, John Tyndall, identified carbon dioxide as one of its causes.

Despite all the lurid claims that a handful of present-day scientists have contrived to hoax the world and all its governments, this basic science has not been successfully challenged in nearly 200 years. It would be surprising if it had been, for it accords with the very laws of physics. ”

It’s laughably wrong. In fact, in scientific terms, it’s pure tripe.

1) Arrhenius was wrong in his calculations. I’m even told (although this going beyond my knowledge base) that he had the wrong mechanism.

2) The direct physics effect of a doubling of atmospheric CO2 is 0.7 oC (yes, zero point sevon degrees). This is in the IPCC report. It is not in doubt.

3) Current scientists do not claim that a doubling of atmospheric CO2 (or CO2-e) will lead to a 5-6oC rise in temperatures. The actual statement is 1.5-4.5 oC with the most likely value being 3 oC. (IPCC again).

The difference between the direct effect and the total effect is because we don’t know what the balance of feedbacks is. Not even, with any great certainty, which direction preponderates.

Please, if you want to use a writer as a poster child for “rational and balanced” could you at least find someone who is still actually on the scientific reservation rather than some loonie wondering lonely as a cloud?