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?