Greenhouse Nonsense

Last month the Royal Society of Chemistry issued a press release, Downing Street petition demands reversal of catastrophic decline in school science exam standards, about the ‘dumbing down’ of school science exams in the UK:

Armed with the first hard evidence of a catastrophic slippage in school science examinations standards, the Royal Society of Chemistry (RSC) has launched a Downing Street e-petition calling for urgent intervention to halt the slide.

The RSC report, also being supplied to industrialists and educationalists, raises major concerns over the disappearance from schools science examinations of vital problem-solving, critical thinking and mathematical manipulation.

However, the RSC is hardly free of blame itself. In this post we will demonstrate how the RSC is contributing to muddle-headedness in teaching. For the background, I’m grateful to a friend who works as a lab technician in an English school who brought to my attention that the RSC promotes an experiment in classrooms about the role of CO2 in ‘global warming’; details can be downloaded from the RSC website. Now, it’s one thing to jump on the global warming bandwagon to try to be ‘relevant’ and trendy; it’s quite another to be a party to promoting disinformation and claptrap about physics. The exercise in question relates to the English National Curriculum. Briefly, the trial compares the increase in temperature of a transparent plastic bottle filled with 100% CO2 and illuminated by a heat lamp, with a control bottle filled with atmospheric air under a similar lamp. As the bottle filled with CO2 is seen to warm faster than the control bottle filled with air, the inference to be drawn is that CO2 is contributing to global warming.

Now this is dumbed down science if ever we saw it, and the test is accompanied by teachers’ notes that contain falsehoods about the physics, which the teacher is encouraged to pass on to the class.

A very similar experiment is described for teaching purposes on the National Weather Service website of the US Government’s National Oceanic and Atmospheric Administration. By contrast, there (as of November 2, 2009) the background information provided is the plain truth: even though the bottle with the carbon dioxide warms more than the control, there is as yet no scientific evidence that carbon dioxide is causing global warming, so extrapolating the results to the role of carbon dioxide in climate is pure conjecture:

It has been thought that an increase in carbon dioxide will lead to global warming. While carbon dioxide in the atmosphere has been increasing over the past 100 years, there is no evidence that it is causing an increase in global temperatures.

In 1997, NASA reported global temperature measurements of the Earth’s lower atmosphere obtained from satellites revealed no definitive warming trend over the past two decades. In fact, the trend appeared to be a decrease in actual temperature. In 2007, NASA data showed that one-half of the ten warmest years occurred in the 1930’s with 1934 (tied with 2006) as the warmest years on record…

The 1930s through the 1950s were clearly warmer than the 1960s and 1970s. If carbon dioxide had been the cause then the warmest years would have understandably been in the most recent years. But that is not the case.

The largest differences in the satellite temperature data were not from any man-made activity, but from natural phenomena such as large volcanic eruptions from Mt. Pinatubo, and from El Niño.

The behavior of the atmosphere is extremely complex. Therefore, discovering the validity of global warming is complex as well. How much effect the increase in carbon dioxide will have is unclear or even if we recognize the effects of any increase.

CO2 is present in the atmosphere at less than 400 parts per million, a concentration less than 0.04% by volume. To draw any meaningful inference in relation to our atmosphere from the behaviour of carbon dioxide in a sealed bottle at 100% concentration (i.e. more than 2500 times the concentration in the atmosphere) is invalid. This is taking induction, inference and extrapolation to an absurd level. A much more interesting, meaningful and illuminating experiment would be to see how long a column of CO2 gas needs to be to absorb 90% of the infrared radiation within the absorption bands of CO2 (at standard temperature and pressure) when the concentration of CO2 is the atmospheric level of 380ppm. The surprising result is that the column of gas, vertically, would be less than the height of most school buildings. The length is only a few metres. Armed with this knowledge, students would see that since practically all the infrared radiation emitted from the school playing field (within the CO2 absorption bands at standard temperature and pressure) is captured within a height equivalent to the height of their school building, then increasing the CO2 concentration in the atmosphere is going to have little, if any, effect on heating the planet.

The RSC experiment is objectionable for its manipulation and false inferences. But there is also a howler in the teachers’ notes: the CO2 in the atmosphere is likened to the glass in a greenhouse in (supposedly) blocking infrared radiation. The teachers’ notes (with spelling mistakes) state under ‘Teaching points’:

Much of the Sun’s radiation arrives as [sic] the Earth’s surface as light radiation. There much of it is absorbed and re-transmitted as infrared (heat) radiation. By letting most of the Sun’s light radiation through, and only letting a smaler [sic] amount of the resultant infrared radiation out again, these gases help to maintain the relatively warm temperatures that allow the oceans to exist and life to flourish on Earth. Because they act in a similar way to the glass panes of a greenhouse (ie letting in more light radiation from the Sun than they let infrared radiation out), they have been nicknamed ‘greenhouse gases’.

But the glass panes in a greenhouse do not act by this physical mechanism. Such an idea was debunked a hundred years ago by R.W Wood in his Note on the Theory of the Greenhouse, published in the Philosophical Magazine (1909). Wood wrote

There appears to be a widespread belief that the comparatively high temperature produced within a closed space covered with glass, and exposed to solar radiation, results from a transformation of wave-length, that is, that the heat waves from the sun, which are able to penetrate the glass, fall upon the walls of the enclosure and raise its temperature: the heat energy is re-emitted by the walls in the form of much longer waves, which are unable to penetrate the glass, the greenhouse acting as a radiation trap.

By experiment, Wood demonstrated that the temperatures in greenhouses are barely affected when glass is replaced by material transparent to visible light that is transparent to infrared radiation as well. He concludes

This shows us that the loss of temperature of the ground by radiation is very small in comparison to the loss by convection, in other words that we gain very little from the circumstance that the radiation is trapped.

Greenhouses do not work by reflecting, trapping or re-radiating infrared radiation but by preventing the escape of warm air. Conduction and convection are the primary heat transport mechanisms, which are blocked by the greenhouse glass, PVC sheet or whatever; and the effect of infrared radiation is almost negligible. The same is true in a parked motor car, and anyone who uses a greenhouse or a motor car knows that opening a window near the top of the cabin even a small extent leads to a significant drop in temperature, though the amount of glass all around is the same. The hot air rises and escapes through the slightly open window – it’s as simple as that. Greenhouses warm by trapping heat not radiation, and any chemist who doesn’t know the difference between heat and radiation should not be teaching physics. The RSC would have teachers present a fiction that ‘these gasses…act in a similar way to the glass panes in a greenhouse’. Well, since the glass panes in a greenhouse keep the greenhouse warm by preventing convection to the atmosphere at large, to teach that CO2 behaves in the same way, i.e. preventing convection in the atmosphere, is to teach a complete falsehood.

So here we have the RSC directing the teaching of students to induce them to believe a theory that was discredited a hundred years ago. More to the point, since the RSC are tracing the downgrade in teaching by comparison with what was taught up to 50 years ago, let’s see what warnings were given about classroom instruction on this very matter 25 years ago. In the Journal of Applied Meteorology in 1973, R. Lee wrote a paper entitled The ‘greenhouse’ effect in which he remarked:

The misconception was demonstrated experimentally by R. W. Wood more than 60 years ago (Wood, 1909) and recently in an analytical manner by Businger (1963)… In spite of the evidence, modern textbooks on meteorology and climatology not only repeat the misnomer, but frequently support the false notion that ‘heat retaining behavior of the atmosphere is analogous to what happens in a greenhouse’ (Miller, 1966), or that ‘the function of the [greenhouse] glass is to form a radiation trap’ (Peterssen, 1958)…The problem can be rectified through straightforward analysis, suitable for classroom instruction.

As Gerlich and Tscheuschner commented in their paper Falsification of the Atmospheric CO2 Greenhouse Effects within the Frame of Physics,

Lee’s paper is a milestone marking the day after [which] every serious scientist or science educator is no longer allowed to compare the greenhouse with the atmosphere, even in the classroom…

One has long come to expect the BBC to promote pseudo-science and falsehood, and in this they are true to form. They state

A greenhouse works because of the glass panels that line the roof and walls. The glass is transparent to the visible light from the sun, so sunlight can shine in and warm things inside the greenhouse. Now a body at about 35°C emits mostly infrared radiation…The glass panels are opaque to infrared light. The result is that the glass lets the energy of the sun in, but won’t let it back out. This keeps the inside of a greenhouse warm.
Replace the greenhouse with Earth and glass panels with atmosphere in the above example, and that is how the Earth’s greenhouse effect works.

That’s an outrageous falsehood.

The worst example (because they should know better) emanates from the Met Office, specifically the Hadley Centre for Climate Prediction and Research – that body which is held up as an authority and ‘gold standard’, consulted by governments and quoted by climate alarmists the world over. They state (with an illustration to back it up, showing the mechanism that was disproved 100 years ago)

In order to understand the greenhouse effect on Earth, a good place to start is in a greenhouse. A greenhouse is kept warm because energy coming from the Sun (in the form of visible sunlight) is able to pass through the glass of the greenhouse and heat the soil and plants inside. But energy which is emitted from the soil and plants is in the form of invisible infrared (IR) radiation; this is not able to pass as easily through the glass of the greenhouse. Some of the infrared heat energy is trapped inside; the main reason why a greenhouse is warmer than the garden outside.

When the Met Office, the BBC, and Royal societies are peddling nonsense about physics, what hope have we in the UK for a sound public education on matters scientific?

Advertisements

6 Responses to “Greenhouse Nonsense”


  1. 1 jarrodhart July 9, 2009 at 8:44 pm

    Very interesting post, thanks.
    However, I would like to point out that while convection prevention may be the primary mode of operation of a greenhouse, overnight cooling can be retarded by IR opaque materials. The simple test done by Wood did not measure the outward radiation from the box which can be very significant on a clear night where the sky can behave like a black body (good radiative absorber).
    Therefore the ‘greenhouse effect’ is really a combination effect, and the BBC comments are not wrong, they just neglect the important effect of convection.
    A useful illustration is the effect of a sheet of plastic on frost formation. This popular frost protection mechanism relies upon the “radiation” greenhouse effect, not on the convection effect…surely?

    ScientistForTruth replies:

    I’d have to study it. A greenhouse would give some protection against convection frosts. Another type of frost, hoar frost, is mainly a ‘radiation frost’ where there is radiative heat loss from the ground resulting in a local temperature inversion. I would have to think whether a greenhouse structure helps or hinders a temperature inversion within or around the greenhouse.

    As for plastic film, the most commonly used is LDPE, which (unlike glass) is transparent to IR in the 7-14um range, so offers little protection to IR radiative loss. It’s possible to improve on this, though, and give some measure of frost protection, by adding mineral fillers, but these make the films opaque and retard photosynthesis.

    But let’s assume the glass/plastic absorbed all the energy radiated from the ground, then it is just like a black body. It won’t ‘reflect’ the radiation, neither will it noticeably warm – the outside temperature will ensure that. However, as a black (or ‘grey’) body at a temperature well above that of space it will radiate some energy towards the ground, therefore the net energy loss by radiation is somewhat reduced, I grant you. The effect is small compared to the convection effect when radiation is flooding in from the sun, but every little helps to stave off frost.

  2. 2 wormthatturned March 9, 2010 at 8:36 pm

    Interestingly the RSC & National Curriculum CO2 bottle experiment you have discussed above was repeated on Newsnight- 17th Dec 2009 to try to convince a selected cross-section of the public. There is a review on wattsupwiththat:

    http://wattsupwiththat.com/2009/12/24/bbc-botches-grade-school-co2-science-experiment-on-live-tv-with-indepedent-lab-results-to-prove-it/

    It’s perplexing that people like chief scientific adviser Professor David King who was there and involved with the experiment can hold such a position and call himself a scientist.

    ScientistForTruth responds

    I’m afraid I can’t regard Sir David King as a scientist any more. He had the crass stupidity to suggest it was dark foreign forces who hacked into UEA, when he had not a shred of evidence for that. He is completely besotted by the climate agenda. Once upon a time science did proper research. Now look what Sir David is involved with at Oxford: he’s Director of the Smith School of Enterprise and Environment, which has research centres as follows: The Centre for Climate and Development, the Centre for Low Carbon mobility, and the Centre for Catastrophic Risk Management; to which is to be added a centre for environmental economics, a centre for facilitating a switch to low carbon, and a centre for climate science and regulation etc etc. Keynote speakers at the Smith School World Forum last year were Al Gore and the stunt-man president of the Maldives. As their website says “The event ended with a rousing speech from Al Gore”. I’m sorry to see so much money being poured into political advocacy and policy formation under the suggestion that this has got anything to do with science. On the climate issue, Sir David says, “The scientific consensus is absolutely clear and the information rolling in year after year simply underlines how sound the science is” (Oxford Today, Vol 22, No.2, 2010). For a start, any talk of ‘consensus’ is a political point. Secondly, the information rolling is is drastically undercutting any scientific basis for the AGW claims. So the guy is just a liar, but it suits him and those making an absolute fortune out of all this to continue to tell lies.

  3. 3 wormthatturned March 11, 2010 at 9:30 am

    Yes indeed, sad but I suspect true. Also regarding your statement I have quoted below, do you know where I could find further info where this more valid experiment has been tested? It would be a very powerful refutation of AGW.

    “A much more interesting, meaningful and illuminating experiment would be to see how long a column of CO2 gas needs to be to absorb 90% of the infrared radiation within the absorption bands of CO2 (at standard temperature and pressure) when the concentration of CO2 is the atmospheric level of 380ppm. The surprising result is that the column of gas, vertically, would be less than the height of most school buildings. The length is only a few metres. Armed with this knowledge, students would see that since practically all the infrared radiation emitted from the school playing field (within the CO2 absorption bands at standard temperature and pressure) is captured within a height equivalent to the height of their school building, then increasing the CO2 concentration in the atmosphere is going to have little, if any, effect on heating the planet”

    ScientistForTruth responds

    A starting place would be Heinz Hug. I have seen peer-reviewed papers, but I will have to find them again.

  4. 4 Trevor Ridgway December 25, 2010 at 10:39 am

    The universally used “falsehood” taught to all and sundry is
    that HOT AIR RISES. Whilst that may be the observed effect ,people should be taught the truth and understand that COLD AIR , BEING MORE DENSE ,DISPLACES WARM AIR ( USUALLY UPWARD )and that is the basis of air movement.

  5. 5 Trevor Ridgway July 21, 2012 at 4:24 pm

    ps. You used this “hot air rises” falsehood in your explanation about heat-trapped in a car and how convection allows it to cool.

    ScientistForTruth responds

    Falsehood? Nobody was suggesting that ‘hot air rises’ was meant in the teleological Aristotelian sense. The cooler air outside the car is denser than the warmer air in the car so, if it can get in through a window, the cooler air will sink into the car displacing the warmer, less dense, air in the car upward and out of the window. The hot air really does rise because it is displaced by cooler air. That’s what convection is all about. What’s the problem?

  6. 6 xyila March 8, 2013 at 4:40 am

    Please don’t throw in the towel – this is GREAT STUFF. Your piece back in 2009 on post normal science ullustrates just how prescient Mr Cargo Cult Feynman really was. Hence we now see smart grid microwaves bathing the planet while called “green”.


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s




Archives


%d bloggers like this: