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Q. The recent documentary, The Great Global Warming Swindle, was full of heavyweight scientists who argued that global warming is nothing but fear-mongering, which is a highly profitable cause (for some). Importantly, they did not doubt that the climate was changing. They did, however, say that climate change was a cycle that the Earth is constantly going through and that it has nothing to do with man’s impact on the environment.
The film exposed Al Gore’s An Inconvenient Truth to be mostly a glossing over of hard facts and portrayed various scientists in high ranking positions as incredibly incompetent. So my question is this: who are we to believe? The scientists who tell the truth with nothing to gain, or the fear-mongers who foretell the end of the world? (Wayne, Cumbria)
A. I think you need a third category in your question: "Who do we believe? The scientists who tell the truth with nothing to gain, the fear mongers who foretell the end of the world, or naysayers who present incomplete, out-of-date or poorly-founded evidence?” You may also wish to think about whether the denial of climate change may be a "profitable cause". Of course I would recommend you believe the scientists who tell the truth! As a scientist I expose all my work to independent review prior to publication, which I do not believe is standard practice in the making of TV programmes.
It is possible for TV documentary makers to present a case which seems quite compelling for the non-expert, but does not stand up to scrutiny. Documentary makers are, of course, entitled to their views, but when watching programmes on climate change, you should ask yourself things like: how old is the data they are using? Does that graph really show what they are saying it shows? Has this person being interviewed exposed their argument and methods to independent scientific scrutiny? Can you find their results in the peer-reviewed literature? Is anyone being taken out of context? Is the programme telling me the whole story or just part of it? Are they using very carefully hedged words which don't quite say what you think they are saying? Your use of the word "portrayed" is very telling, as this often seems to be used to mean a biased representation.
If you don't know who to believe, because the two sides are presenting cases which appear equally slick, you should decide for yourself by looking at the scientific assessment of all the latest evidence which has been exposed to extensive review by a vast number of people (including "climate sceptics".) You can download the report at http://ipcc-wg1.ucar.edu/wg1/wg1-report.html and the reviews and authors responses at http://ipcc-wg1.ucar.edu/wg1/Comments/wg1-commentFrameset.html. It is a fully open process and its conclusions have been subject to extensive, rigorous and informed debate. You may also be interested in http://www.jri.org.uk/index.php?option=com_content&task=view&id=137&Itemid=83.
Q. It has been announced that cows produce more methane and that scientists are going to change their diets to try to stop this, but how? All they appear to eat is grass and hay, so what could possibly be proposed!? (Ross Baber, Baron)
A. I take it you mean that it is the cows that eat grass and hay, not the scientists... :-)
Yes, cows (and other ruminant animals) produce significant quantities of methane in their guts during the process of digestions. It is called "enteric fermentation" and is a natural consequence of the breakdown of food. Actually, you also produce a bit of methane yourself when digesting your food... So I think you must be referring to the suggestion that a reduced demand for beef would be expected to reduce the need for large numbers of cattle and hence reduce total methane emissions from livestock.
