By Roger Harrabin
BBC Environment Analyst
I have spent much of the last two decades of my journalistic life warning about the potential dangers of climate change, but when I first watched Al Gore's An Inconvenient Truth I felt a flutter of unease.
Not because the central message - that climate change is happening and almost certainly caused by mankind - is untrue; but because in several points of the film, Mr Gore simply goes too far by asserting or implying facts that are contentious.
This leaves the film open to attack by the ever-dwindling band of sceptics who do not want to accept that climate change is anything to do with humans, and indeed a successful attack is exactly what has happened in the UK.
Because although Mr Justice Burton agreed in Wednesday's High Court ruling that An Inconvenient Truth is mainly based on consensus science, his judgement will be trumpeted more for finding that the film was studded with green "errors".
The judge listed nine areas where Mr Gore had swayed from the scientific consensus position, and it was the "errors" that made the headlines in the media.
The man who brought the complaint, Stuart Dimmock, expressed his delight that this "shockumentary" had been exposed.
Mr Dimmock is a member of the "New Party", apparently funded by a businessman with a strong dislike of environmentalists and drink-drive laws.
When asked on the BBC's World Tonight programme who had under-written his court costs, he paused long and loud before saying that "someone on the internet" had offered him support.
It always looked likely that Mr Dimmock would make some headway with his court case because, as the judge observed, when the film was first circulated it did not supply teachers with the material needed to help pupils distinguish which of Mr Gore's factoids were still subject to serious mainstream debate.
The film was made as a polemic, not an educational tool for children. The government would have been on safer ground if it had chosen Sir David Attenborough's climate change programme which passed the BBC's own anguished impartiality test.
In the event, ministers seized on the slick, powerful and informative Gore movie as a tool to persuade children, and presumably by extension their parents, to worry about the climate.
And this points to the essentially political nature of the film, and the decision to show it in schools.
There is now a strong political consensus throughout Europe that climate change is a dangerous problem needing urgent solutions; but politicians consistently tremble when they tentatively advance any of those solutions towards a public confused by the noisy media debate about climate change.
A recent poll by Ipsos Mori showed that 82% of people were personally concerned about climate change, but a majority (56%) believed that many leading experts still question if human activity is contributing to climate change.
This latter conclusion is simply wrong - all the world's major scientific institutions believe the man-made climate change theory - but the Gore court judgment will confuse people even more.
So why did the vice-president, who reveals himself in the movie to be a master of factual recall and presentation skill, produce a film in which assumptions became assertions and worst-case scenarios became the norm?
The answer lies in the conflicted politics of climate in the US.
Remember that Al Gore, who first studied climate science when he was at university, has been trying to alert the public to climate change for a quarter of a century.
Ice cores have trapped details of past climate conditions on Earth
Along with that other failed Democratic candidate John Kerry, he launched Senate hearings on climate in the 1980s. Then he signed the Kyoto Protocol nine years ago on behalf of the US, only to see President Clinton refuse to back it.
He then spent impotent frustrating years in the White House, and later outside it, watching climate sceptics - some well-meaning scientists, but many in the pay of the oil industry - discredit the global warming theory.
The sceptics knew that they did not need to win the battle of climate facts, they just needed to keep doubt alive.
Smoothing the wrinkles
An Inconvenient Truth is a response to that often cynical campaign, attempting to put climate change beyond doubt and remove ambiguity from presentation of the scientific facts.
The problem is that climate science is a massive and messy field; and although even the White House now accepts that the climate is changing and humankind is more than 90% likely to blame, there are still wrinkles in the science, signposts that point in the opposite direction to the one we expect.
The Intergovernmental Panel on Climate Change (IPCC) deals with these wrinkles by expressing its prognoses in bands of uncertainty: the climate is likely to warm by between 1.8C and 4.0C by the end of the century.
But movies are not made of piffling equivocations like this, so Mr Gore dispenses with many of them.
Mr Justice Burton takes exception with nine such simplifications, or "errors". He notes that Mr Gore attributes to climate change the melting of the snows of Kilimanjaro, the demise of polar bears, the drying of Lake Chad and bleaching of coral reefs.
Correctly identifying the scientific consensus, the judge says debate is still open on these issues, as it is over hurricane frequency, also instanced by Mr Gore.
The judge says (again taking the IPCC as gospel) that there is little support for Mr Gore's implication that the Gulf Stream will shut down soon, and that the great ice sheets will cause catastrophic sea level rise soon.
Here the judge is on slightly more contentious ground, because the IPCC science is itself out of date on Arctic melting, which is advancing at a pace that many worst-case scenarios had failed to predict.
On the remaining point - Mr Gore's implication that ice core records prove that CO2 rises drove shifts in Ice Ages - the judge is spot on.
The vice-president cleverly lures the viewer into making the calculation that CO2 drove historical climate change by presenting graphs and asking the audience if they fit.
Well, the graphs do fit - but what Mr Gore fails to mention in the film is that mainstream scientists believe that historically the temperature shifted due to our changing relationship with the Sun, with warmer climes unlocking CO2 from the oceans, which amplified global temperature rise.
The movie is product of a political debate - as is the court case
I challenged Mr Gore about this in an interview for the BBC's Newsnight programme in March.
He responded, accurately, that scientists believe that CO2 is now driving climate change - but that was not what his misleading historical graph showed.
And after the interview he and his assistant stood over me shouting that my questions had been scurrilous, and implying that I was some sort of climate-sceptic traitor.
It is miserable when such a vastly important debate is reduced to this. The film and the High Court row are, though, products of their time.
If the conservative IPPC forecasts are accurate our children may rue the years we spent squabbling over climate change rather than tackling it.