London (CNSNews.com) - British environmental groups reacted with skepticism and scorn Friday to a new documentary claiming that the threat posed by global warming had been overblown, but the television channel that aired it said it was part of the broader debate.

Broadcast here on Thursday night, "The Great Global Warming Swindle" charged that the scientific establishment has become too heavily invested in the theory that climate change is caused by man.

Drawing on interviews with scientists around the world, along with recent research into effect of solar radiation on the Earth's atmosphere, the documentary argued that the Earth's climate is always changing.

Scientists filmed by director Martin Durkin contend that reducing the amount of carbon dioxide being emitted will do little to stop rising global temperatures and that hotter years are actually themselves the cause of higher levels of CO2.

Tim Ball, a professor emeritus of geography at the University of Winnipeg, is quoted as saying that ice samples taken from glaciers show that there is no correlation between the levels of CO2 in the atmosphere and the earth's temperature in past millennia.

Other figures in the film suggest that solar activity is responsible for global warming and that efforts to reduce CO2 is strangling development in the Third World.

Greenpeace spokeswoman Mhairi Dunlop said Friday her group had been interviewed by Durkin but none of the material had made the documentary.

"They interviewed us but I guess what we said didn't fit in with the [story] they were peddling," she said.

Dunlop charged that some of the scientists interviewed by Durkin had been funded by groups tied to the oil industry. Greenpeace wasn't "going to bother" doing a full rebuttal to the documentary, she told Cybercast News Service.

Tim Lenton, a climatologist with the University of East Anglia, agreed Friday that many proponents of man-made climate change often oversimplified their arguments.

However, he said the documentary, which was broadcast on the British Channel 4, had also been guilty of gross exaggeration.

Lenton said the documentary overstated the best estimates of the strength of solar activity. Just because previous warm periods were not linked to CO2, that was no predictor of what would happen in the future, he said.

Moreover, "they said that more carbon dioxide comes out of volcanoes than human activity each year and that's patently wrong," Lenton added.

Martin Rees, president of the Royal Society -- the government-sponsored academy of sciences for the United Kingdom -- said in a statement Friday that many factors contributed to global warming but it was clear that emissions of "greenhouse gases," particularly CO2, are to blame for most of the temperature rise.

"Those who promote fringe scientific views but ignore the weight of evidence are playing a dangerous game," he said. "They run the risk of diverting attention from what we can do to ensure the world's population has the best possible future."

Long regarded as an iconoclastic filmmaker, Durkin has made a handful of documentaries during the last few years which critics have attacked as sensation-seeking -- including one in which he suggested that artificial breast implants reduce the dangers of breast cancer.

In 1997, Channel 4 broadcast "Crimes Against Nature," another Durkin-directed film, in which mainstream environmentalists were depicted as the "enemies" of science.

After people interviewed by Durkin claimed that their views had been distorted, the Independent Television Commission watchdog forced Channel 4 to issue an on-air apology.

Channel 4 spokesman Matthew Robinson said Friday the network had recently broadcast several other documentaries which argued the case for man-made global warming.

He told Cybercast News Service that Channel 4's airing of Durkin's film was part of the greater debate and that it was a chance for other views to be heard.

Although there are currently no plans to broadcast the documentary abroad, a spokeswoman for Durkin's production company said that a DVD would be available for purchase by Americans within a few weeks.