It's the box-office sensation credited with confronting the world with the honest reality of climate change. But yesterday, a High Court judge in London made some distinctly inconvenient criticisms of An Inconvenient Truth, the Oscar-winning documentary on global warming made by Al Gore.

Mr Justice Burton was pondering whether the film should be shown in classrooms after criticism from a politically active school governor in Kent, who had accused the Government of "brainwashing" children.

Yesterday, the judge found that the "broadly accurate" film can indeed be screened – as long as it is accompanied by material from the climate change-denial fraternity. But, in a somewhat more damaging move, the judge forensically examined the documentary's "one-sided" case and found "nine scientific errors" in its content.

The outspoken ruling comes after the Government sent out copies of the film to all schools in England, with the Scottish and Welsh assemblies following suit.

Mr Gore's international reputation has soared as that of the US President, George Bush – to whom he lost the presidency in 2000 – has nosedived around the world. Mr Gore, who won the popular vote, was defeated after the Supreme Court handed the Electoral College the final say.

Since then, Mr Gore has reinvented himself as a champion of the environment and – some believe – has used the platform of his highly personalised documentary to launch a repeat campaign. Last night he was still refusing to rule out a re-run for the Democrats, and it was unclear as to what impact the London ruling would have on his credibility.

But the "errors" highlighted by Mr Justice Burton were detailed. He described the assertion that a sea-level rise of up to 20 feet would be caused by ice melting in West Antarctica or Greenland "in the near future", as "distinctly alarmist". This would happen only "after, and over, millennia", the apparently expert judge said.

Meanwhile, it was countered that the disappearance of snow on Mount Kilimanjaro in East Africa could not be directly attributed to global warming. The judge also said of the idea that polar bears were drowning while "swimming long distances – up to 60 miles – to find the ice": "The only scientific study that either side before me can find is one which indicates that four polar bears have recently been found drowned because of a storm."

Lawyers for Stewart Dimmock, the governor who brought the case, claimed it to be a "landmark victory". The judge awarded Mr Dimmock two-thirds of his legal costs of about £200,000 against the Government.

This is not the first time Mr Gore's environmental credentials have come under scrutiny. In February, the right-wing Tennessee Centre for Policy Research said he deserved a "gold statue for hypocrisy" for his 20-room mansion in Nashville, which reportedly consumes more electricity in a month than the average American household does in a year.

When the Government announced the move to send the film to schools, David Miliband, the then environment secretary, said: "I was struck by the visual evidence the film provides, making it clear that the changing climate is already having an impact on our world today."

Yesterday's ruling will no doubt be greeted with glee among climate-change deniers. But green opponents have come under similar criticisms over their own claims on the hotly contested issue. Earlier this year, Channel 4 broadcast The Great Global Warming Swindle, which was widely panned by critics. Eigil Friis-Christensen, the director of the Danish National Space Centre whose work was used in the programme, was asked by The Independent whether the message was accurate. He replied: "No, I think several points were not explained in the way that I, as a scientist, would have explained them... it is obvious it's not accurate."

The British Antarctic Survey said: "Any scientist found to have falsified data in the manner of the Channel 4 programme would be guilty of serious professional misconduct."

(By James Macintyre, The Independent, 11/10/2007)