The very term 'greenhouse effect' is an example. It has been established for more than 100 years that greenhouses do not heat up by 'trapping' infra-red, they heat up because their enclosed structure dramatically reduces mixing with cooler outside air. But what a godsend the phrase is for alarming anyone who has ever been in a hot greenhouse.
Another example is the use of some variant of the phrase '97% of climate scientists believe in CAGW'. This is a shoddy statistic. It was derived from a poorly formulated, poorly conducted, and poorly analysed survey by an MSc student for her thesis, and, were it not for the obvious propaganda value, it would normally never have seen the light of day outside of her department.
The So-Called Greenhouse Effect
In 1909, a distingushed American physicist called R W Wood reported (Phil. Mag. vol 17, p319-320) on his experiments which showed that 'trapping' of infra-red by greenhouse glass was of no consequence as a cause of warming in the greenhouse. He speculated that infra-red radiation was likely to be of little consequence in heating the atmosphere as well.
The work of Wood has been made widely known through a paper on the history of the greenhouse effect by Jones and Henderson-Sellers (1990). From their abstract:
'One such misconception is that greenhouse research is a recent phenomenon; another is that glasshouses are warmed by the same mechanism as lies at the heart of the greenhouse effect.'
For a recent confirmation of Woods 1909 experiment see Nahle (2011). He concludes:
'The greenhouse effect inside greenhouses is due to the blockage of convective heat transfer with the environment and it is not related, neither obeys, to any kind of “trapped” radiation. Therefore, the greenhouse effect does not exist as it is described in many didactic books and articles.
Nevertheless, as revealed for example by 'Tallbloke' very recently, experiments with shining lamps on to upturned glass jars containing thermometers are promoted for classroom demonstrations to convince pupils of the reality of an atmospheric 'greenhouse effect'. The title of this blogpost by Dr Roy Spencer sums it up nicely: http://www.drroyspencer.com/2012/10/hey-school-teachers-those-greenhouse-effect-experiments-are-junk/
The So-Called 97%
The complete absence of convincing evidence of a suitably dramatic effect of man-made CO2 on the climate system has forced propagandists to look elsewhere. Notably by 'appealing to authority'.
One device is to pretend that the output of computer models provides that evidence. They of course merely provide illustrations of the ideas and methods of the programmers, and they do not even model CO2 directly - including it instead by its presumed impact as a 'forcing'.
Another is to declare that many thousands of scientists producing IPCC reports believe in it, when in fact almost all of them are focused on, and qualified to study, the effects of climate change rather than the causes. Since climate always changes, such studies could be undertaken for any era in earth's history.
A third is to assert that '97% of climate scientists' believe in it. Let me quote from an informative blog post on this published two days ago by Tom Harris, with my bolding and italicising:
' It’s a “fact” asserted by political leaders, media and activists worldwide. Important public policy and corporate decisions are based on it. Researchers and public opinion survey coordinators take it as a given. School children and college and university students are assured it is true.
It is the idea that scientists agree that we are causing climate catastrophe. It is perhaps best summed up by the following statement, one heard often over the past three years:
“97% of climate experts agree that humanity is causing dangerous global warming and other problematic climate change because of our greenhouse gas emissions.”No poll of experts has actually shown this. There has never been a reputable worldwide survey of climate scientists that has even asked the question. In fact, it has never even been demonstrated that there is any “global scientific consensus about the climate crisis”, as Al Gore continually assures us that there is.'
The post goes on a little later to say:
'Two pieces of evidence are most often cited to support the 97%/consensus argument:
- A 2010 paper in the Proceedings of the National Academy of Sciences of the United States (PNAS) by Anderegg et al.
- A poll conducted in April 2008 by Professor Peter Doran and then-graduate student Margaret R. K. Zimmerman at University of Illinois at Chicago. The survey results were summarized in a paper published in January 2009 in the science journal EOS.
The Doran/Zimmerman study, which did poll experts, has also been thoroughly debunked by many writers and so there is little point in repeating their criticisms in this blog posting. However, there are two problems with the study that have received little or no coverage to date. Both of these problems destroy the poll’s credibility as a reliable measure of the stance of climate scientists on the supposed climate crisis.'
Harris quotes some of the comments made by some of the scientists who were asked to complete the survey. He points out how these raise so many problems with the questions deployed that it is obvious that the survey should have been re-designed. It was not of course. It was, after all, 'just' a student project. One sadly destined to be shouted from the rooftops in support of alarmism.
Barry Woods also published more details of this shoddy piece of survey earlier this year. He provides references to previously published criticisms:
'The Doran paper has been criticised by many sceptics in the past, where a survey of 10,256 with 3146 respondents was whittled down to 75 out of 77 “expert” ’active climate researchers’ (ACR) to give the 97% figure, based on just two very simplistic (shallow) questions that even the majority of sceptics might agree with. Lawrence Soloman made one of many critiques of the Doran Paper here and offers a very good summary, some other reviews here, here and here.'
Woods also provides criticism and further references on deliberate deceptions using the Anderegg et al. study. He relays this quote from Paul Matthews which sums that nicely in response to an egregious claim:
'Worse still, he misrepresents the claims of that paper (he implies the 97% believe CO2 will cause major climate change in the coming decades, while Anderegg et al say 97% agree that most of the warming of the 20th C was very likely due to man-made greenhouse gases – two very different statements).'
Let us hope these 'two very different statements' are not confounded in the minds of teachers across the world, nor may they contain the emotive notion that the earth is warming like a greenhouse.