Complaint to Ofcom Regarding The Great Global Warming Swindle

2. Complete Transcript and Rebuttal

Page 46




The documentary is committing a logical fallacy (false dilemma) by suggesting that because rising temperatures have caused CO2 concentrations to rise in the past, therefore CO2 concentrations could never cause temperatures to rise. This is analogous to the saying that because increasing the number of fertilised eggs in a chicken coop will eventually lead to an increase in the number of chickens, that proves that increasing the number of chickens in a chicken coop could not possibly lead to an eventual increase in the number of eggs. It works both ways – when temperatures rise, atmospheric CO2 levels rise (but this happens slowly, over hundreds of years); and when CO2 levels rise, this results in temperatures rising (but this happens much more quickly, over a few decades).


The programmes suggestion that the theory of the greenhouse effect somehow depends on the ice core data is also extremely disingenuous and misleading. The theory of the greenhouse effect is well-established physics that dates back 150 years. It is covered in the most elementary text books on climate physics. The ice core data is not – as the film maker pretends that it is – important evidence supporting the theory, still less is it the most fundamental assumption behind the theory. However, the ice core data does reinforce the theory, because in the absence of the greenhouse effect it would be more difficult to fully account for amplitude of temperature changes inferred from ice core data, for the reasons described above.


Atmospheric CO2 levels dont spontaneously increase for no reason; rises have to be triggered by something. In the past they were triggered by rising temperatures, now they are being caused by human CO2 emissions. In the absence of human emissions, as during recent deglaciations, rises of atmospheric CO2 were likely triggered by rising temperature. Hence it is not surprising that in the past, temperature rises started before the atmospheric CO2 level began to rise. But those CO2 rises then greatly increased the temperature.

Note: We know that the present increases in atmospheric CO2 are caused by humans for two reasons. By accounting for how much we are emitting via burning fossil fuels and how much the natural carbon cycle absorbs, we know we are emitting more than is being absorbed. Another (independent) method of determining this is by checking what kinds of carbon atoms (isotopes) are found in the CO2 in the atmosphere. The CO2 respired by living plants contains a different type of carbon isotope mix compared to that of CO2 emitted from burning of fossil fuels. By measuring changes in the isotope mix in the atmosphere over time, we see that increases are indeed due to human activity (see Realclimate:

Finally, it is worth noting that the apparent lag (800±600 yr) of CO2 to temperature in the historical record is not firmly established. In a discussion paper in Climate of the Past Discussions, Loulergue et al. (2007), (PDF), suggest that:

The phase relationship between CO2 and EDC temperature inferred at the start of the last deglaciation (lag of CO2 by 800±600 yr) is overestimated and that the CO2 increase could well have been in phase or slightly leading the temperature increase at EDC.

Continued …


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Final Revision

Last updated: 11 Jun 2007