That was my reaction also.

If I read the graph correctly it looks about 52% of people are climate change deniers and 44% of people are climate change proponents with 4 % saying they don't know.

It is certainly a very odd way for Dr Walker to present these figures.

Agreed - I think the term "Climate Change denialist," is just a modern contraction of "Anthropogenic Climate Change denialist." Walker distinguishes between those who don't believe the world is warming, and those that do but believe it's due to natural causes, but this is only one of many fine distinctions that can be made to divide those who are against pro-climate policy. I heard it put well once that there are:

Those who believe the world isn't warming (e.g. Richard Muller, until recently)
Those who believe it is, but that it's natural (e.g. Ian Plimer)
Those who believe it's anthropogenic, but not serious (e.g. Richard Lindzen)
Those who believe it is serious, but doesn't warrant market interventionism (e.g. Bjorn Lomborg).

From a policy perspective, the sum of all of these groups is likely to be problematic for pushing for pro-climate policy. That the first of the four groups is particularly small is of no great comfort.

What excellent news. People are rapidly starting to see through the CAGW scaremongering. We are getting rational. Perhaps we may, eventually, return to real science, instead of ideology-driven science.

"The European Parliament has cancelled plans to send a delegation to the UN's Rio+20 summit on sustainable development taking place in June, saying the costs are too prohibitive. “The huge increase in the estimated cost of attending the summit is simply not justifiable, especially at a time when many Europeans are faced with economic hardship,” said Matthias Groote, the chairman of the environment committee. -- Dave Keating, European Voice, 9 May 2012 http://www.europeanvoice.com/article/2012/may/meps-cancel-rio+20-participation/74321.aspx

And this reported in the Australian today (but not a word on the Converstion!)

"The Australian’ this morning:

“ONE of the nation's leading carbon-pricing experts has described as "unrealistic in the extreme" Treasury's budget forecast of a $29-a-tonne carbon price in 2015-16, and warned of a multi-billion-dollar risk to the budget and a failure of the scheme to change emissions behaviour if a floor price is not maintained.

Frank Jotzo, the deputy director of the Australian National University's Climate Change Institute, told The Australian an oversupply of credits in the UN's Clean Development Mechanism meant carbon prices would stay low and a more realistic estimate was $5.”

Read the article here:
http://www.theaustralian.com.au/national-affairs/treasury/carbon-price-denounced-as-unrealistic-by-expert/story-fndbwnla-1226352517718

Dear David,

I am very pleased to see your contribution to the conversation and find myself in agreement with most if not all of what you have posted here.

I realise that discussions of the science here are not going to reach the detail or extent necessary to determine the correctness or otherwise of the assumptions used to drive the modellig, but it nevertheless makes for an interesting exchange and one can enjoy the challenge of trying to put together some plausible arguments based on the physics which represents the various parts and behaviour of the atmospheric system. Even if we are wrong, it is still stimulating and I am pleased when I see that some one is prepared to put down some realistic ideas which provide a picture of what is going on.

I do have some other points which I would like to add and have written some of my ideas below for your consideration.:

Yours is a good and very relevant post which presents some of the ideas behind the fact that CO2 helps to warm the planet by absorbing some 30% of the ~ 280 K, black body, radiation which leaves the surface of the earth.

It is also correct that in the absence of any air or water, the surface of an approximately black body earth (emissivity ~1.0) would be about 255 K. As you would know, this is not difficult to calculate in a reasonably straight forward manner on a desk top PC (or even a laptop!). This temperature includes the fact that directly under the tropical sun, the surface of the earth reaches a temperature of about 119 C or 392 K and following Lambert’s Law at or near the poles, the energy received is at least theoretically zero. This occurs when the angle of the sun is at right angles to the normal to the surface. Others of your points are also correct in my view, but I am going to concentrate here on the radiation and cooling of the earth and describe a few things as I see them.

Thus, I would like to add a little more to your comments if I may and see what you think of the following:
If around the otherwise bare earth, there is some pure air present in the form of Oxygen and Nitrogen with NO OTHER gas, then all of the energy received from sunlight will of course NOT be radiated directly back to space because the air will cool the surface with which it is in contact by conduction across the interface as happens now, and in turn the air will be warmed by the contact.
Since the warmer air will be in the tropics, this will lead to upwards convection and winds will blow, as they do now, from the mid latitudes towards the tropics. These are now the well known SE /NETrades and the NW/SW Monsoons – depending which hemisphere one is considering. Thus we will have air moving over the surface, just as one has an air cooling system on motors and on the CPU in your PC.
Thus this very pure air will still be warmed and will circulate, without any assistance from Green House Gases (GHGs). This circulation will tend to cool the ground in the tropics, as happens now with the wind, and carry the energy around as it circulates into the mid latitudes where it will raise the temperature. The maximum ground temperature in the tropics will be about the same as it is now, of the order of 80 C or 353 K – not the 119 C or 392 K of radiative equilibrium.
Because the power radiated is determined by the fourth power of the temperature, the tropical region under the sun will radiate less energy than it would in the absence of air while the mid-latitudes and the Arctic regions will be warmer and radiate a little more than they otherwise would. While the warmer mid-latitudes will radiate more energy than before, it is not enough to compensate for the lower amount in the tropics and the result must be that both the average ground temperature, Tav, and the “effective” temperature, Teff, of the earth will rise – just as they do now with water vapour and other green house gases (GHGs), present which also contribute heat as you have pointed out. However, as shown by this analysis, the GHGs are not the only contributors to the warming of the earth. I will assume you are familiar with the different ways of calculating Tav and Teff.
The question now is: What will happen to the heat which has been taken up by the air which we have assumed has no GHGs which are the only components which can radiate energy from the air itself. It will obviously warm and circulate until the energy it loses in the mid-latitudes by moving over cooler surfaces is equal to the heat it picks up in the tropics while the effective temperature of the earth must rise to a point where it can now radiate the energy received from the sun, even though it is less efficient because the air still keeps cooling the surfaces in the tropics to a temperature lower than is necessary to radiate the energy received there from the sun.
Suppose we add water to the oceans, but no carbon dioxide. The water will absorb energy from the sun and evaporate as a gas which will again be warmer than the surrounding air so will rise and cause circulation. The air mixture will eventually all have the same temperature as the energy of the vapour molecules is distributed to the N2 and O2 by collisions. As this warmed air rises, it will cool and the vapour in it will condense releasing energy to the surrounding air, and at sufficient height will form clouds, which will radiate some heat as a black body. Similarly the water vapour will also radiate energy from its spectral lines or bands and since the upper atmosphere above contains little water vapour, this will escape to space.
However, much of the energy released to the air from the condensing water vapour, will not be radiated as it will be simply warming N2 and O2 molecules, which themselves cannot radiate, so the energy is retained in the air to circulate to the mid-latitudes and make these regions even warmer than when there was just air.
Let us add very small amount of CO2 – say 20 ppmv. This will augment the absorption by the water vapour although it will not absorb as much energy as the vapour because it has a more limited band structure. The absorbed energy will be redistributed through the atmospheric gases by collisions and some of this energy at lower levels, will be radiated by the water vapour and may escape to space. However, the strong absorption by the CO2 means that 98% of the energy it absorbs, is absorbed in the first few hundred metres of the atmosphere even though concentration is comparatively low – about 20 ppmv.
However, above the clouds, where there is very little water vapour and practically none to radiate energy from condensation to space, the carbon dioxide is now available to perform that radiation and cool the upper reaches of the atmosphere.
If the amount of CO2 is increased, the absorption level will change from the first few hundred metres of the atmosphere to the first 100 m. This will not involve significantly more energy, but will concentrate the energy in a thinner layer at a somewhat lower level which will be expected to provide for enhanced convective rising and hence stronger circulation. In the upper atmosphere, the carbon dioxide will be at lower densities and will continue in its role of radiating energy to space. In the centre of the bands, this will involve a radiation process which is in fact not very different from before, although the bands where it is radiated may be a little cooler, and hence provide less radiation.

However, in spite of earlier claims that this could be measured, no measurements from satellites have provided any evidence that this is the case. In the far wings of the lines, the radiation process is weaker, but will at some point be enhanced by the increased density of carbon dioxide. Thus the question of cooling of the upper atmosphere and the effect on this process of increasing CO2 in the air, is not yet established. It is this very basic process which is the basis of assumptions by the IPCC modellers, that the increases will inevitably lead to further warming. However, there is no evidence for this and both the IPCC reports and the Bureau of Meteorology in Australia simply say, as way of justifying the assumption of warming which is injected ito their models: “We believe that most of the increase in global temperatures during the second half of the twentieth century was very likely due to the increase in the concentration of atmospheric carbon dioxide.” I do believe also that they should be prepared to back this up with evidence, which they have not yet done, relying totally on the output from their modelling.
John Nicol jonicol18@bigpond.com

Thanks for setting this out Mr Nicol.

The fundamental flaw in what you write is the assumption that non-greenhouse gases cannot cool by radiating energy. Doug Cotton's comments on "The Conversation" pieces a few months ago laboured under the same misunderstanding; my recollection is that Mark Harrigan sought to help Doug out of his confusion.

Another point is that there are three Hadley Cells operating in each hemisphere, with low pressures at Equator and ~60 deg N and S, and high pressures at poles and ~30 deg N and S.

Finally, the presence of water makes a huge difference to earth's climate. For a start, the presence of frozen water at high latitudes increases earth's reflectance relative to the no water case, and hence modifies Tav and Teff.

Given these difficulties, criticism of other climate studies are not well supported by your description.

Thanks David.

I hadn't remembered the earlier exchange between Dioug Cotton and Mark Harrigan and am intersted to know more about the radiation from Oxygen and Nitrogen at the low temperatures of the atmosphere and earth which I guess are always within the range of 200 to 400 K, with corresponding wavelengths of any significant black body radiation between 1 micron and 50 microns (200 and 10,000 cm^1), is that correct?

Since I believe the molecules which can radiate from the air, be they O2, N2, CO2 or H2O, need to be excited to available states within their radiation/absorption bands, by collisions with enrgetic molecules whose energy is defined by the temperature. Again you might comment on whether or not this assumption is correct?

So from that, I would believe that they must have a set of allowed transitions for which the upper state is fairly easily excited by collisions between comparatively low energy molecules whose energy range is determined by the gas temperature, thus again being at a level which will emit Infra red photons.

I had always thought that their (O2 and N2) resonant wavelengths always corresponded to the visible region, which, yes can be excited by a VERY small number of molecules in the high energy end of the Maxwell distribution of velocities at the temperatures around 350 K, but obviously there are bands which can be much more readily populated.

I would appreciate it very much if you could give me a list or at least an indication of the wavelengths at which Oxygen and Nitrogen do radiate as they would be important even in an atmosphere where carbon dioxide and water vapour dominate as green house gases? Cheers, John

Wavelengths at which O2 and N2 can radiate?

ALL wavelengths, where wavelength is determined by changes in molecular speed (kinetic energy) (see, eg, http://en.wikipedia.org/wiki/Kinetic_theory; googling translational energy levels might also help). It's described by the Maxwell-Boltzmann distribution.

Exchange occurs by collision between molecules, excitation occurs by interaction with radiation. At higher altitudes (lower densities), interactions with radiation make up a larger proportion of events which alter a molecule's energy levels.