Complaint to Ofcom Regarding The Great Global Warming Swindle

2. Complete Transcript and Rebuttal

Page 40



[Dr Tim Ball]

If you take CO2 as a percentage of all the gasses in the atmosphere – the oxygen and nitrogen and argon and so on, its.054%. Its an incredibly small portion. Then of course youve got to take that portion that supposedly humans are adding, which is the focus of all the concern, and it gets even smaller.


CO2 is a greenhouse gas. Greenhouse gasses themselves only form a small part of the atmosphere. Whats more, CO2 is a relatively minor greenhouse gas

[Dr Tim Ball]

The atmosphere is made up of a multitude of gasses; a small percentage of them we call greenhouse gasses; and of that very small percentage of greenhouse gas, 95% of it is water vapour, its the most important greenhouse gas.

[Prof John Christy]

Water vapour is a greenhouse gas – by far the most important greenhouse gas.

[Comment 47: These comments are highly misleading, and apparently intentionally so, in a number of ways.

First, the notion that, because greenhouse gases, and especially carbon dioxide, make up only a small part of the atmosphere they must have only a small effect, is false: without greenhouse gases the Earths surface would be around 33 degrees Celsius colder than it is (see:

Second, although it is true that water vapour is the most important greenhouse gas, carbon dioxide is the second most important, accounting for around 20% of the natural greenhouse effect (see Kiehl and Trenberth, 1997, Bulletin of the American Meteorological Society, at (PDF) and Realclimate:

Third, water vapour does not directly drive climate change, although it does amplify existing temperature trends (in climate science terminology it is a feedback rather than a forcing”). The reason for this is that, whereas carbon dioxide remains in the atmosphere for an average of more than 100 years after entering it, water vapour only remains in the atmosphere for around 10 days on average, before condensing again. Average atmospheric water vapour levels are therefore determined solely by the temperature: pumping extra water vapour into the atmosphere (as happens, for instance following a volcanic eruption) does not increase atmospheric water vapour levels for long enough for its greenhouse properties to be a driver of climate change – within days, the extra water vapour condenses again. Water vapour is therefore extremely important in amplifying CO2–driven global warming (because warmer air holds more water vapour, thus increasing the greenhouse effect); but it does not drive global warming (see also Realclimate:

Carbon dioxide therefore has a very significant effect on the climate, which is reinforced by water vapour, contrary to the impression given by the narrator and interviewees.

Continued …

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Comment 47: Misrepresentation of the physics of water vapour]


Page 40 of 176

Final Revision

Last updated: 11 Jun 2007