I’ll begin with the points on which I believe we will agree and move on from there.

“Science doesn’t operate by consensus.”
While I agree with this statement on its face, I think that we need to be cautious in discussing this. NOAA’s Robert Grumbine makes a good point when he says: “[s]ometimes people are right about a statement and then draw the wrong conclusion about it. Noting that science doesn’t ‘do’ consensus is such a case.”* So, I want to be careful not to draw the wrong conclusion here. I’ll outline and flesh out Grumbine’s points as follows: Science hasn’t progressed through people simply, without reference to data or theory, agreeing on something and declaring it fact by consensus. There is the area of “live” science, with constant research, and either confirmation or refutation—and there is the area of accumulated, well-tested scientific knowledge. Once some particular theory (or observation, or what have you) has been confirmed many times over (perhaps by the falsification and research program paradigms envisioned by Popper or Lakatos, if you like) there is the overall agreement of the community on it and it gets added to the body of scientific knowledge, and as such has the general consensus of the community. The key point though, is that it didn’t get there through mere consensus, it was tested over and over again and must continue to fit with the facts as they come in (here is where I anticipate that we would begin to disagree regarding global warming).

“other factors aside from CO2 drive the climate”
The climate system definitely has other drivers, or forcings, aside from carbon dioxide. On this point, we’re all agreed. These range from other greenhouse gases, such as methane, to various aerosols, fluctuations in solar irradiation and land use changes. See, for example Hansen’s paper in Science [1].

There are two fairly important related points, the first of which is that—at least, to the best of my knowledge—there isn’t one climate driver that explains changes in climate over all time scales. No research scientists that I’m aware of make this claim. There are many factors that need to be considered for each case, from Milankovitch cycles to plate tectonics. The second point is that, once the effects of all of the natural forcings are taken into consideration, they do not account for the recent warming trend—whereas, once the anthropogenic emission of carbon dioxide is taken into account, the warming trend is quite clear [1], even on a continental scale [2].

“the IPCC models set the sensitivity of climate to CO2 much too high”
Why is it that you say this? I know that there are several different ways of going about calculating climate sensitivity (Rahmstorf outlines these here [3]): one could look at the ice core record, factor in everything from dust to methane concentrations and perform a correlation analysis; one could use radiative forcing, take into account the relative strengths of the various feedbacks (essentially, Arrhenius’ method) or one could use model results. To the best of my knowledge, these methods have tended to lead to a climate sensitivity in the stated IPCC range (3º ± 1.5 º) [3]. As far as I can tell, the best estimate of 3º hasn’t changed much since Manabe’s work in the 1970s.

“So what would Huxley (much less Cuvier) say of the failure of climate computer models to predict the flat-lining of temperatures over the past decade?”
This is a good question. I’m guessing that he would point out—if he were informed about the reasons for choosing a 30 year period for climate when discussing global temperature: ENSO events, the PDO, etc.—that the models are meant to predict climate on the scale of 30 years, not the fluctuations on a smaller time scale. So, I would guess that he’d caution all involved about doing this. He might also look into the spread of the simulations [4], to determine which models fit better than others and determine why that was. He might discuss to what degree the lack of fit was due to the models failing to capture ENSO events, etc. (which would average out over those time scales with which a discussion of climate is concerned).

“Figure 3 shows the predictions of climate alarmist James Hansen in 1988. The blue line is Hansen’s scary Scenario A prediction; the orange line is the actual temperature.”
Regarding this, Huxley might first ask what the forcings were in Hansen’s report and double-check that the scenario being compared matches the forcings. Upon seeing that the forcings from this period more closely match Hansen’s scenario B, he might ask why the A scenario was being compared against the observations in the first place, when the forcings more closely match that of (and hence, it makes more sense to compare the observations to) the B scenario [5]. Following this, he might ask to see the results of the B scenario [6].
Huxley was an observant fellow, so he would probably ask to view the associated uncertainty due to natural fluctuations. After looking at this he might comment that, while the observations fit into the lower bound of the uncertainty and while this might be acceptable for results on computers less powerful than a modern netbook, there was certainly room for improvement (improvement that, largely, has come with present GCMs).

“Why not debate with climate skeptics? Why not crush the abstruse doubts, cavils and objections”
I think that, first of all, it should be said that there are several roads that can be taken in terms of addressing doubts and objections, only one of which is public debate (which I’ll address next). One such path is clear communication of, and access to, the science for the general public. The public does need clear access to the relevant findings with a minimum—and an explanation of—technical jargon, freed of excessive caveats, as well as the cited science (i.e. without having it locked behind subscription “pay walls”). Here, I think that the IPCC reports as well as work on the parts of researchers such as Hansen, Weaver, Rahmstorf, the Real Climate guys and organizations such as NOAA, GISS, etc. are really making a difference.
As regards debate, I think that Dr. Weaver makes two good points above: the first, when he states that there is no such debate in the peer reviewed scientific research journals (e.g. Journal of Climate, Geophysical Research Letters, etc.). The second, when he points out that it is the goal of the denial industry to make it seem as though there is a raging debate in the scientific community. For, as long as there is debate, there is excuse for inaction.
A point which is not made in the quote above, is the difficulty that people have in sorting out scientific arguments outside of the area of their expertise. For instance, in an online debate, Phillip Stott implies that global cooling was the consensus of the scientific community during the 1970s[7], when in fact, during the period of 1965-1979, 7 papers suggested cooling, 20 were neutral and 44 predicted warming [8]. This is hardly a consensus for cooling. But, to anyone unfamiliar with the literature, this isn’t clear. More, even if Schmidt calls Stott on this fact, the public is left with Stott’s word against Schmidt’s: two PhD scientists. (Of course, they can always go back and look at the material, but they can only do so after the debate.)
With that said, certain climate scientists, such as Gavin Schmidt, do choose to debate from time to time [7].

One last question: given that you work at UVic, have you discussed your questions with any of the climate scientists there or at the CCCMA?

* http://moregrumbinescience.blogspot.com/2008/12/science-and-consensus.html

[1] Hansen, J., et al. Earth’s energy imbalance: Confirmation and implications. Science, 308, 1431-1435
Online, in full: http://pubs.giss.nasa.gov/docs/2005/2005_Hansen_etal_1.pdf

[2] Here, the black line is the observed temperature trend, blue is the models with only natural forcings and pink is the models with anthropogenic greenhouse gas emissions considered (taken from the IPCC AR4, WG1 contribution): http://i.fe.imwx.com/web/fe/2008/07/aussie3.jpg

[3] See, for instance, pages 39 through 42 of Rahmstorf’s paper here: http://www.pik-potsdam.de/~stefan/Publications/Book_chapters/Rahmstorf_Zedillo_2008.pdf
Or, alternatively, for line-by-line radiative transfer models, see here:
http://pubs.giss.nasa.gov/docs/2006/2006_Collins_etal.pdf

[4] Models “baselined” to:
1999: http://www.realclimate.org/images/2008_from1999.jpg
1990: http://www.realclimate.org/images/2008_from1990.jpg
1979: http://www.realclimate.org/images/2008_from1979.jpg

[5] http://cce.890m.com/hansen88/images/forcings.jpg

[6] http://cce.890m.com/hansen88/images/scenarios-observations.jpg

[7] http://www.youtube.com/watch?v=KtPDuZzfzhw&feature=related

[8] http://ams.confex.com/ams/pdfpapers/131047.pdf

Thank you for an intelligent and informed comment. In a way, though, I think you’re making the point I want to make: other factors aside from CO2 drive the climate. In the case of the our ice age, the Pleistocene, for example: we wouldn’t have these cycles of glaciation, despite falling CO2 levels, if it wasn’t for the circumpolar current around Antarctica and the joining of North and South America, plus the upraising of the Himalyas and Rockies much earlier which, quite apart from leaching CO2, also disrupted warm air currents, especially in Asia.

In other words, at least in my view and based on the evidence I’ve seen, CO2 plays a much smaller role in climate than many other natural factors, including those you mention–the IPCC models set the sensitivity of climate to CO2 much too high.

Paul

Regarding the Ordovician Period, I don’t believe that it presents the problem that you believe it does. The matter isn’t as simple as, “according to greenhouse theory, Earth should have been exceedingly hot then.” One of the issues to consider is the fact that most of the world’s landmass was gathered at the South pole in a supercontinent known as Gondwanaland. Having the majority of the land at one of the poles allows for glaciation events even with higher carbon dioxide concentrations. Climate models showed this result back in 1999 [1]. Also of interest is the fact that the Appalachian mountains were just being created, exposing a large amount of easily weathered silicate rock to the atmosphere (which would have acted to take down atmospheric carbon), coinciding with the start of the Late Ordovician glaciation.

I’ll try to respond to a few more of your questions when I have some more time.

[1] Poussart, P. F., A. J. Weaver, and C. R. Barnes (1999), Late Ordovician Glaciation Under High Atmospheric CO2: A Coupled Model Analysis, Paleoceanography, 14(4), 542–55

I’m in California and I’m literally SURROUNDED by Global Warming Alarmists, but I for one have dared to question them. I’ve been called a tree-killer, a Democrat-hater, an un-intelligent nitwit, and many other things. I have written a speech and 4 papers on the subject, so I am not just throwing myself in a dangerous position for no reason. I am glad to see the number of people who question the facts of the Alarmists’ is growing. One final fact to leave on here: I am only in the 8th grade.

The reason I ask is that what little I have found leads me to believe that you would expect such a system would oscillate. Since chaotic implies noise then the noise would be reinforced into oscillations until overwhelmed by some other phenomenon. I do know that there are many periodic planetary weather related systems such as the Pacific Decadal Oscillation (PDO) which is “primarily a geographic rearrangement in atmospheric and oceanic circulation patterns in the North Pacific that last about 30 years” (Spencer: http://www.drroyspencer.com/research-articles/global-warming-as-a-natural-response/ ).

So the question is: does the IPCC description of the climate as a “coupled non-linear chaotic system” mean, by definition, such a system should oscillate? Or, stated differently: would such a system not varying be an unexpected result?

Thanks for a well researched and carefully crafted article. A wake-up call if ever there was one to those who have been blinded to the naked body of the emperor in his ‘new clothes.’

Rolf

A brilliantly constructed presentation of the foolishness of the “the debate is over” crowd. Ironically, what peeves them the most is that both public and scientific opinion has rapidly been shifting over the past several years as global climate cools. No surprise people are cool to their warming theory.

One would think that if the AGW crowd were composed of intellectually honest people, they would be strongly motivated to debate their position with any critics to stop their loss of public support. Evidently, they believe they’ve got politicians so much in their corner, that public support isn’t necessary.

They are all in for a very rude awakening. Any short term political victories will be overturned as reality and the cost of senseless carbon mitigation schemes become apparent.

Great piece!