I tried to respond to Bishop Hill on this question over at his blog, but squarespace ate my comment (a frequent problem on squarespace blogs that I think is caused by a bad interaction with my Flock browser). It was also around then that I discovered that copying the text I wrote in Flock doesn’t actually save it if I exit the browser when I’m running it on Linux. Grrr. So I’m posting it here instead. :-)
Frank, I don’t know anything about the volcanos argument. Can you give me some links to support what you are saying? Which contributors are you saying have been repeatedly found to be unreliable? All of them?
For me, Lindzen and the maker of the documentary in particular. There aren’t actually a lot of contributors to the documentary with authority to challenge. At least two that I saw were weather forecasters and not climatologists. Some of the others do have authority but not in this field. At least one scientist that appeared claims they were misled and misrepresented, and they do in fact believe in man made global warming. As far as the volcanos argument goes, I understand that the ‘documentary’ claims somewhere that volcanos emit more CO2 than humans. I don’t recall seeing this claim made personally, but I have only watched the first hour of the documentary so far. However, I have seen this claim relayed by two people who have seen it (one pro- and one anti- the documentary) so I have no reason to doubt it. It is also a very common argument of the type offered by AGW deniers (as were some of the others offered by the documentary). The problem is (assuming they said this) it’s not true. According to the US geological survey, human activities result in more than 150 times as much CO2 emissions as volcanoes each year:
Scientists have calculated that volcanoes emit between about 130-230 million tonnes (145-255 million tons) of CO2 into the atmosphere every year (Gerlach, 1999, 1992). This estimate includes both subaerial and submarine volcanoes, about in equal amounts. Emissions of CO2 by human activities, including fossil fuel burning, cement production, and gas flaring, amount to about 22 billion tonnes per year (24 billion tons) [ ( Marland, et al., 1998) - The reference gives the amount of released carbon (C), rather than CO2.]. Human activities release more than 150 times the amount of CO2 emitted by volcanoes–the equivalent of nearly 17,000 additional volcanoes like Kilauea (Kilauea emits about 13.2 million tonnes/year)!
Volcanic Hazards: Gases (sulfur dioxide, carbon dioxide, hyrdogen chloride, and hydrogen fluoride) And of course, if someone claimed that 17,000 additional volcanoes might change the climate, it would not seem like hubris. Another error in the documentary is in relation to the 800 year lag between temperature rise and CO2 rise:
There is some evidence to suggest that the rise in carbon dioxide lags behind the temperature rise by 800 years and therefore can’t be the cause of it.
The Great Global Warming Swindle from Channel4.com This (“therefore can’t be the cause of it”) is not a scientific error but a logical one. If I have to push a car 800 metres to get its engine started and it is later found doing 70mph on the motorway, that doesn’t mean that the engine is not responsible for its speed, even though it could not have been responsible for the first 800m of acceleration. And in fact CO2 is thought to be an amplifier of warming and not a cause of it, so it is also a strawman.