Here's an extract from wikipedia:
The Great Global Warming Swindle is a polemical documentary film that suggests that the scientific opinion on climate change is influenced by funding and political factors, and questions whether scientific consensus on anthropogenic global warming exists.
The film, made by British television producer Martin Durkin, presents scientists, economists, politicians, writers, and others who dispute the scientific consensus regarding anthropogenic global warming. The programme's publicity materials assert that man-made global warming is "a lie" and "the biggest scam of modern times." Its original working title was "Apocalypse my arse", but the title The Great Global Warming Swindle was later adopted as an allusion to the 1980 mockumentary The Great Rock 'n' Roll Swindle about British punk band the Sex Pistols.
The UK's Channel 4 premiered the documentary on 8 March 2007. The channel described the film as "a polemic that drew together the well-documented views of a number of respected scientists to reach the same conclusions. This is a controversial film but we feel that it is important that all sides of the debate are aired." According to Hamish Mykura, Channel 4's head of documentaries, the film was commissioned "to present the viewpoint of the small minority of scientists who do not believe global warming is caused by anthropogenic production of carbon dioxide."
Although the documentary was welcomed by global warming denialists, it was criticised by scientific organisations and individual scientists (including one of the scientists interviewed in the film and one whose research was used to support the film's claims). The film's critics argued that it had misused and fabricated data, relied on out-of-date research, employed misleading arguments, and misrepresented the position of the Intergovernmental Panel on Climate Change. Later broadcasts corrected three errors which had been found in the original film. The film's producer, Martin Durkin, has asserted that the errors were minor and did not affect the film's conclusions. 
Viewpoints expressed in the film
The film's basic premise is that the current scientific opinion on the anthropogenic causes of global warming has numerous scientific flaws, and that vested monetary interests in the scientific establishment and the media discourage the public and the scientific community from acknowledging or even debating this. The film asserts that the publicised scientific consensus is the product of a "global warming activist industry" driven by a desire for research funding. Other culprits, according to the film, are Western environmentalists promoting expensive solar and wind power over cheap fossil fuels in Africa, resulting in African countries being held back from industrialising.
The film won best documentary at the 2007 Io Isabella International Film Week.
A number of academics, environmentalists, think-tank consultants and writers are interviewed in the film in support of its various assertions. They include the Canadian environmentalist Patrick Moore, former member of Greenpeace but now a critic of the organisation; Richard Lindzen, professor of meteorology at the Massachusetts Institute of Technology; Patrick Michaels, Research Professor of Environmental Sciences at the University of Virginia; Nigel Calder, editor of New Scientist from 1962 to 1966; John Christy, professor and director of the Earth System Science Center at University of Alabama; Paul Reiter of the Pasteur Institute; former British Chancellor of the Exchequer Nigel Lawson; and Piers Corbyn, a British weather forecaster.
Carl Wunsch, professor of oceanography at the Massachusetts Institute of Technology, was also interviewed but has since said that he strongly disagrees with the film's conclusions and the way his interview material was used.
Assertions made in the film
The film takes a strongly denialist view of current scientific thinking on climate change. It argues that the consensus on climate change is the product of "a multibillion-dollar worldwide industry: created by fanatically anti-industrial environmentalists; supported by scientists peddling scare stories to chase funding; and propped up by complicit politicians and the media".
Using a series of interviews and graphics, the film sets out to challenge the scientific consensus by focusing on what it says are inconsistencies in the evidence, and the role said to have been played by ideology and politics.
The film highlights what it asserts are a number of contradictions and inconsistencies in the evidence supporting man-made global warming.
* Atmospheric carbon dioxide levels and temperature change since 1940. The film asserts that records of atmospheric CO2 levels since 1940 show a continuing increase, but during this period, global temperature decreased until 1975, and has increased since then.
* Variations in warming rate. The programme states that all models of greenhouse effect-derived temperature increase predict that the warming will be at its greatest for a given location in the troposphere and at its lowest near the surface of the earth. The programme asserts that current satellite and weather balloon data do not support this model, and instead show that the surface warming rate is greater than or equal to the rate in the lower troposphere.
* Increases in CO2 and temperatures following the end of ice ages. According to the film, increases in CO2 levels lagged (by over 100 years) behind temperature increases during glacial terminations.
EPICA and Vostok ice cores display the relationship between temperature and level of CO2 for the last 650,000 years.
* Relationship between atmospheric carbon dioxide levels and temperature change. The film asserts that carbon dioxide levels increase or decrease as a result of temperatures increasing or decreasing rather than temperatures following carbon dioxide levels, because as the global climate cools the Earth's oceans absorb carbon dioxide, and as the climate warms the oceans release carbon dioxide.
* Influence of oceanic mass on temperature changes. The programme argues that due to the very large mass of the world's oceans, it takes hundreds of years for global temperature changes to register in oceanic mass, which is why analysis of the Vostok Station and other ice cores shows that changes in the level of atmospheric carbon dioxide follow changes in global temperature by 800 years.
* Influence of water vapour on climate change. According to the film, water vapour makes up 95% of all greenhouse gases and has the largest impact on the planet's temperature. Water particles in the form of clouds act to reflect incoming solar heat, but the film argues that the effects of clouds cannot be accurately simulated by scientists attempting to predict future weather patterns and their effects on global warming.
* Influence of carbon dioxide on climate change. The film states that carbon dioxide comprises only a very minuscule amount—just 0.054% of the Earth's atmosphere. According to the film, human activity contributes much less than 1% of that, while volcanoes produce significantly more CO2 per year than humans, while plants and animals produce 150 gigatons of CO2 each year. Dying leaves produce even more CO2, and the oceans are "the biggest source of CO2 by far." Human activity produces a mere 6.5 gigatons of CO2 each year. The film concludes that man-made CO2 emissions alone cannot be causing global warming. (Durkin subsequently acknowledged that the claim about volcanic CO2 emissions was wrong, and removed the claim from later versions.)
* Influence of the sun on climate change. The film highlights the solar variation theory of global warming, asserting that solar activity is currently at an extremely high level, and that this is directly linked to changes in global temperature. The posited mechanism involves cosmic rays as well as heat from the sun aiding cloud formation. The film argues that the activity of the sun is far more influential on global warming and cooling than any other man-made or natural activity on Earth.
* Previous episodes of warming. The programme asserts that the current episode of global warming is nothing unusual and temperatures were even more extreme during the Medieval Warm Period, a time of great prosperity in western Europe.
I'm not a climate scientist (although I am a scientist, just not a very good one) and I haven't studied the evidence first hand so I can't give a definitive answer. It's controversial, sure, but at the end of the day we have to follow the evidence and not lead it.