Michael Moore and Al Gore have a lot to answer for. They popularised the campaigning documentary, with films such as Roger and Me, Fahrenheit 9/11 and An Inconvenient Truth, and now new docs are being pumped out faster than Saudi crude. And 'crude' is a decent summation of the ideas contained in most of them.Dirty Oil says this has 'staggering' environmental costs. The extraction process is messy, leaving huge pools of 'tailings', a mix of water and sand with an unhealthy dose of some nasty, bitumen-related chemicals. The film suggests that the pollution from the extraction process threatens the health of local people and wildlife. Worse, the carbon emissions from this 'dirty' oil are helping to push the world towards catastrophic climate change.The film opens by asking Americans where they think their oil comes from. 'Saudi Arabia' and 'the Middle East' are the common answers. Wrong. As a Canadian journalist notes: 'For the past seven years, Canada has been the number one supplier of oil to the United States… We are the new Saudi Arabia.' The press notes for Dirty Oil actually state that: 'It is a little known fact that America imports the majority of its oil from Canada and not the Middle East.' But this is nonsense. The biggest single source of America's oil is America itself; 36 per cent of US crude is produced domestically. It's a far cry from the glory days when the US produced all its own oil, but it does put into perspective the idea that the US is dependent on unstable dictatorships to keep chugging along, and rather makes a mockery of the idea that the Iraq War was really a war for oil.After this dubious start, obviously aimed at convincing Americans that This Stuff Really Matters, Dirty Oil takes us to the new oil boom town of Fort McMurray, where a 26-year-old worker describes how he manages to earn $100,000 per year: driving a truck that's the size of an average house. The truck is 30 feet wide, 30 feet high and 50 feet long. We are encouraged to fret about these monsters tearing up the landscape. I just thought how cool it would be to drive one. Surely the ability to organise such a huge operation – you need to shift about two tonnes of oil sand to get one barrel of oil, and yet the area produces 1.3million barrels per day – is worthy of a little awe?Dirty Oil claims that oil-sand extraction is damaging the health of local people. Down river in the town of Fort Chipewyan, Dr John O'Connor claims that he has seen an extraordinarily high number of rare cancers in a community of indigenous people who rely on fishing for food. However, far from investigating his claims – so the film tells us – the health authorities have brought a case against him for causing 'undue alarm'. The film suggests this is a case of the little man being stomped on by the big corporation. So depressed is Dr O'Connor by these proceedings that he eventually leaves the area and returns to Nova Scotia, broken by a big conspiracy against a whistle-blower.The big claim of the film is right there in the title: this is 'dirty oil'. The extraction process requires a lot of energy from natural gas, which means that the whole process produces three times as many greenhouse gas emissions as conventional oil production. However, some perspective is required. The majority of carbon emissions involved with creating and using petroleum products comes from burning them in vehicle engines. Taking that into account, petrol derived from oil sands in Canada produces only 15 per cent more carbon emissions than petrol from conventional sources.Even if we accept the wilder claims about what climate change will mean for humanity, the answer is surely to move to an economy based on low- carbon technologies, not to fret about particular sources of fuel. Alberta's oil boom will end when we no longer need the oil. That means developing forms of transport that use electricity not oil, and power sources like wind, solar, geothermal and – most importantly – nuclear. These technologies could have benefits that go well beyond reducing carbon emissions. But they need time to mature and be rolled out. We need economic growth to pay for these things – and keeping the oil flowing is crucial to that.While Dirty Oil suggests that we shift to renewable energy sources, it also provides a childish view of the relationship between big business and the rest of society. This is 'big people picking on little people and assuming that they can get away with it', says a spokesperson for the green group the Natural Resources Defense Council. The film also suggests that it is somehow our individual greed which, by creating demand for this 'dirty' oil, is screwing up the planet. But there's nothing wrong with wanting to be better off; the whole world should enjoy the living standards of the average American. Cheap, reliable energy is absolutely essential for that. Alberta's oil boom is set to continue for many years to come.