Saturday, March 10, 2007

Ray Evans' 'Nine facts about climate change' debunked. Pt. 2.

Ray’s outdone himself with ‘Fiction 2’.
2. Carbon dioxide is necessary for all life on earth and increasing atmospheric concentrations are beneficial to plant growth, particularly in arid conditions. Because the radiation properties of carbon dioxide in the atmosphere are already saturated, increasing atmospheric concentrations beyond current levels will have no discernible effect on global temperatures.
Here we go:
Carbon dioxide (CO2) is a colourless, odourless, tasteless, non-toxic gas which is essential to all life on earth.
CO2 is not essential to all life on earth; obviously humans and many other organisms don’t require it. Even if all CO2 were removed from the planet, and photosynthesis stopped, some organisms would survive, so it’s not even indirectly essential to all life on earth. Some classes of organisms do not source their carbon from either directly from CO2 or indirectly from organisms that do. Such a group of organisms are the ‘hydrogenogens’, which include bacteria that utilise CO (carbon monoxide) from deep-sea hydrothermal vents as their sole carbon source.

Ray has a habit of making blanket statements which are only partly correct (or, in other words, wrong).
As concentrations of carbon dioxide increase, the rate of growth of plants also increases. Flowers and vegetables grown in hothouses are frequently fed with extra carbon dioxide for faster growth and higher yields.
Wrong. The rate of plant growth does not increase if CO2 is not limiting. Excess CO2 does provide some advantage to some plants some of the time, but certainly not all plants all of the time. Hothouses like Ray has mentioned are useless at indicating how plants will perform in the field. Due to basically ideal conditions they drastically overestimate plant response to treatments such as excess CO2. I’ve posted more on this topic here.
As atmospheric concentrations of carbon dioxide have increased from approximately 325 ppmv (parts per million by volume) in 1970 to 375 ppmv today, wheat yields in Australia have increased in the last 30 years, in part because of CO2 enrichment.
Wheat yields in Australia have primarily increased due to improved farm management and agronomic practices, along with elite varieties produced by our excellent plant-breeding programs. Excess CO2 had virtually nothing to do with it. Rays example is akin to standing in the street and blowing at the back of a car as it accelerates past you, and then claiming some responsibility when it hits 100 kph.
Changes in the natural transport of carbon, as well as human activities, have led to recent increases in atmospheric concentrations of carbon dioxide.
As usual; misleading bordering on wrong. ‘Natural’ flux of CO2 in and out of the atmosphere is basically in balance. Detection of the carbon isotopes produced from anthropogenic sources indicates that increasing anthropogenic CO2 outputs are the overwhelming source of atmospheric CO2 increases. Occurrences of ‘natural’ CO2 emitting events, such as earthquakes and volcanoes, are accounted for and obviously don’t lead to a year-after-year increases like those that have been detected.
As the graphs shown in Figures 6 and 7 show, once CO2 concentrations exceed 200 ppmv, further increases have diminishing impact on the radiation balance, and doubling present concentrations from 375 to 750 ppmv will have only marginal impact on that balance.
Ray goes on and on about something that is clearly stated in IPCC reports and well known to just about anyone who has any interest in climate science. That is: as CO2 concentration is doubled, there is only a linear radiative forcing response due to high levels of band saturation. He throws in a few graphs of results from running David Archer’s MODTRANS program to make it look all, well, professional.

Big deal, Ray! This is all well known. Surely you realise this?
Such an increase would have a marvelously beneficial effect on plant growth everywhere and, according to eminent hurricane scientist William Gray, will also lead to an increase in rainfall of about 3 per cent.
The silly plant growth statement I’ve already discussed. William Grey’s statement of a 3% increase in rain is utterly meaningless; it isn’t backed by any experimental evidence. Computer modeling in of rainfall in SE Australia, which encompasses a good portion of our agricultural production systems, shows a decrease over the coming years. What rain does fall is likely to be heavier over shorter periods. This is not what could be considered a good thing.
The IPCC’s radiation balance model of climate assumes that at the upper boundary of the stratosphere, radiation from the sun is matched by radiation from earth to space.
Wrong. The model discussed in IPCC TAR assumes radiative balance is at the tropopause, which is the upper boundary of the troposphere, and sits below the stratosphere.

The IPCC TAR states:
In an equilibrium climate state the average net radiation at the top of the atmosphere is zero. A change in either the solar radiation or the infrared radiation changes the net radiation. The corresponding imbalance is called “radiative forcing”. In practice, for this purpose, the top of the troposphere (the tropopause) is taken as the top of the atmosphere, because the stratosphere adjusts in a matter of months to changes in the radiative balance, whereas the surface-troposphere system adjusts much more slowly, owing principally to the large thermal inertia of the oceans. The radiative forcing of the surface troposphere system is then the change in net irradiance at the tropopause after allowing for stratospheric temperatures to re-adjust to radiative equilibrium, but with surface and tropospheric temperatures and state held fixed at the unperturbed values.
Ray again:
However, unlike other greenhouse gases, radiation to space from the active radiation bands of carbon dioxide is originating in the stratosphere where the earth’s temperature is about -50°C.
Ray just doesn’t seem to comprehend that most infrared photons radiated to space come from the troposphere, and that includes those from well mixed GHGs, including CO2. Wikipedia has an excellent description:
The starting point is to note that the opacity of the atmosphere to infrared radiation determines the height in the atmosphere from which most of the photons emitted to space are emitted. If the atmosphere is more opaque, the typical photon escaping to space will be emitted from higher in the atmosphere, because one then has to go to higher altitudes to see out to space in the infrared. Since the emission of infrared radiation is a function of temperature, it is the temperature of the atmosphere at this emission level that is effectively determined by the requirement that the emitted flux balance the absorbed solar flux.

But the temperature of the atmosphere generally decreases with height above the surface, at a rate of roughly 6.5 °C per kilometer on average, until one reaches the stratosphere 10-15 km above the surface. (Most infrared photons escaping to space are emitted by the troposphere, the region bounded by the surface and the stratosphere, so we can ignore the stratosphere in this simple picture.) A very simple model, but one that proves to be remarkably useful, involves the assumption that this temperature profile is simply fixed, by the non-radiative energy fluxes. Given the temperature at the emission level of the infrared flux escaping to space, one then computes the surface temperature by increasing temperature at the rate of 6.5 °C per kilometer, the environmental lapse rate, until one reaches the surface. The more opaque the atmosphere, and the higher the emission level of the escaping infrared radiation, the warmer the surface, since one then needs to follow this lapse rate over a larger distance in the vertical. While less intuitive than the purely radiative greenhouse effect, this less familiar radiative-convective picture is the starting point for most discussions of the greenhouse effect in the climate modeling literature.

Ray, however, doesn’t understand this, and is only thinking about the stratosphere. And there is something interesting going on there.

What happens in the stratosphere is that at very low temperatures, CO2 emits more radiation than it absorbs, leading to a negative radiative forcing, and to reach equilibrium, the stratosphere must cool.
Adding more carbon dioxide through anthropogenic emissions does not significantly alter the radiation to space because the temperature of the stratosphere varies little with altitude.
Clearly wrong. Even just looking at the stratosphere, observational results show recent cooling, though there is some debate over whether this is primarily caused by ozone reduction, as ozone heats the stratosphere, or an increase in CO2 concentration in the stratosphere.

Which brings me to my next point; temperatures are not static in the stratosphere anyway. Due to ozone, and unlike the troposphere, temperature rises with altitude.

This image nicely indicates the radiative effects of CO2 and ozone at different altitudes in the stratosphere.

Ray isn’t doing so well, me thinks.
The radiation to space is governed by the temperature of the emitting molecules and the projected doubling of CO2 concentrations to 760 ppmv, on the IPCC’s own hypothesis and using the IPCC’s data, further reduce IR radiation to space by less than a trivial 4 watt per square metre which generates, using the IPCC’s model, an average global temperature increase of 0.8°C.
3.7 watts per square meter in fact. As stated earlier, this is included and discussed at length in IPCC TAR (and 4AR I would assume). Ray is simply repeating (with emotive terms to give it some oomph) basic stuff.

But as usual, Ray then misleads, as radiative forcing cannot be converted to climate sensitivity in that way.


According to TAR:
...for a full understanding of the greenhouse effect and of its impact on the climate system, dynamical feedbacks and energy transfer processes should also be taken into account.
Internal climate processes and feedbacks may also cause variations in the radiative balance by their impact on the reflected solar radiation or emitted infrared radiation, but such variations are not considered part of radiative forcing.
Feedbacks are not considered in the basic radiative forcing model. The radiative forcing model is not designed to be used in this way. It has other purposes.

Climate sensitivity, or the global mean temperature response to a doubling in CO2 concentration, is estimated in 4AR at between 2 and 4.5C. Neither the IPCC, nor any scientist or relatively sensible person, predicts an average rise in global temperatures with the doubling of CO2 at 0.8C.
The IPCC’s radiation balance model of climate is seriously flawed. There is no energy balance at the top of the stratosphere; but the point remains that on the assumptions which underpin the climate models on which the IPCC relies, a doubling of atmospheric CO2 will have minimal impact on global temperatures.
If it worked the way Ray thought it did, then it would be seriously flawed. Luckily it doesn’t.

And last, but not least:
The saturation effect is something which should be fully understood by the IPCC, but it is completely ignored by the anthropogenists.
What the...!

Ray, you are a very silly man.