The makers of a documentary which claims that global warming is a swindle have been accused of fabricating data by one of the scientists who participated in the film.
The Great Global Warming Swindle was broadcast on Britain's Channel 4 on March 8 and has been criticised by leading scientists for errors, distortions and misrepresentations.
The documentary has also been referred to the regulatory watchdog Ofcom, which is considering a complaint from 37 scientists that the programme breached the broadcasting code on the misrepresentation of views and facts.
Now even a climate sceptic whose dissenting views were used by the film- makers to bolster their claims about the "lies" and "swindles" of global warming has accused the documentary of promulgating falsehoods.
Eigil Friis-Christensen, director of the Danish National Space Centre, has issued a statement accusing the film-makers of fabricating data based on his work looking at the links between solar activity and global temperatures.
Dr Friiss-Christensen said a graph he had produced some years ago showing the link between fluctuations in global temperatures and changes in solar activity - sunspot cycles - over the past 400 years had been doctored.
The documentary used the graph to pour scorn on the idea that the global warming in recent decades was the result of man-made emissions of carbon dioxide. Solar activity, the programme stated, was the cause of global warming in the late 20th century.
However, Dr Friiss-Christensen has issued a statement with Nathan Rive, a climate researcher at Imperial College London and the Centre for Climate Research in Oslo, distancing himself from the C4 graph. He said there was a gap in the historical record on solar cycles from about 1610 to 1710 but the film-makers made up that break with fabricated data that made it appear as if temperatures and solar cycles had followed one another very closely for the entire 400-year period.
"We have reason to believe that parts of the graph were made up of fabricated data that were presented as genuine. The inclusion of the artificial data is both misleading and pointless," Dr Friis-Christensen said.
"Second, although the commentary during the presentation of the graph is consistent with the conclusions of the paper from which the figure originates, it incorrectly rules out a contribution by anthropogenic [man-made] greenhouse gases to 20th century global warming," he said.
Dr Friis-Christensen, a physicist, believes that solar cycles play an important role in climate change and that not enough effort has gone into addressing the theory. The fabricated data did not, he said, make any difference to the overall view he takes but he is still critical of the way the film handled the scientific evidence.
The C4 programme also used out-of-date solar cycle data relating to the past 30 or 40 years which made it appear as if temperatures and solar activity were rising together when in fact solar activity had levelled off for the past few decades. "After 1985 we don't see any rise or shortening of the solar cycles compared to what we saw in the temperature [record]," Dr Friiss-Christensen said.
Meanwhile, Professor Carl Wunsch of the Massachusetts Institute of Technology said that the way his interview was edited gave the misleading impression that he was not concerned about rising levels of carbon dioxide - a diametrically opposite view to his stated position.
Martin Durkin, who wrote and directed the programme, admitted in an email to Mr Rive that the graph was wrong. "Thank you for highlighting the error on the 400-year graph," the email said. "It is an annoying mistake which all of us missed and is being fixed for all future transmissions of the film. It doesn't alter our argument."
However, the graph and its fabricated data have been included in the DVD version of the programme now on sale in Britain.
The advertising for the DVD says: "Everything you've ever been told about global warming is probably untrue. This film blows the whistle on the biggest swindle in modern history."
The scientists who wrote to Ofcom had called for changes to the programme before the DVD version was released.
"So serious and fundamental are the misrepresentations that the distribution of the DVD without their removal amounts to nothing more than an exercise in misleading the public," they say.