 undermine the programme's credibility".
Who are we to believe?
Durkin's film argued that most global warming over the past century occurred between 1900 and 1940, and that there was a period of cooling between 1940 and 1975 despite a post-war economic boom that accelerated greenhouse gas emissions. The fact that temperature went down then, rather than up, therefore shows global warming has little to do with man-made emissions.
Durkin was right to argue that the earlier rise in global temperature was temporarily halted. But he failed to mention the reason: namely, the impact of atmospheric pollutants called sulphate aerosols pouring out of industry at this time.
By reflecting sunlight, the aerosols had a cooling effect which temporarily masked the warming effects of greenhouse gases. In recent decades, as sulphate pollution has been reduced, the underlying warming effect has been starkly revealed.
Moreover, while the programme-makers labelled the source of their world temperature |
|
 |
 |
 |
| In a sample of 928 scientific papers, not one disagreed that humans cause climate change |
|
|
data as 'NASA', the Independent found no such graph existed. There was a comparable graph based on out-of-date information, but "crucially, the axis along the bottom of the graph has been distorted", it reported.
Prof Wunsch's complaint is that the documentary is no more than propaganda. "I was misled as to what it was going to be about," he now says. "I was told about six months ago that this was to be a programme about how complicated it is to understand what is going on. If they had told me even the title of the programme, I would have absolutely refused to be on it."
Wunsch describes the film as an "out-and-out propaganda piece, in which there is not even a gesture toward balance or explanation of why many of the extended inferences drawn in the film are not widely accepted by the scientific community".
The fact remains that in a sample of 928 peer-reviewed scientific papers published between 1993-2003 not one disagreed with the consensus position that human activity is causing climate change. 
FIRST POSTED MARCH 22, 2007
|
