The protesters who expect to be arrested this weekend in the campaign to close down Hazelwood power station may break the law, but they have justice on their side.

With scientists predicting runaway climate change unless we take drastic action in the next five years, and the manifest failure of our democratic system to respond adequately to the overwhelming threat posed to our future, it is legitimate to step outside the usual boundaries of protest.

Last year, six British Greenpeace protestors scaled the smokestack of the Kingsnorth coal-fired power plant in Kent and painted a slogan on it. They were arrested and charged with criminal damage. In court they did not dispute that they had caused damage but argued that they acted to prevent a greater harm — the damage to the atmosphere being caused by carbon dioxide emissions from Kingsnorth.

The 40-year-old Hazelwood power station is Australia’s largest single source of carbon pollution and symbolises everything that is wrong with greenhouse policy in this country.

An industrial relic, Hazelwood was due to be decommissioned this year. The owners applied for an extension of its life to 2031. In 2005 the panel appointed by the Victorian government to review the application concluded that, if Hazelwood’s electricity output were replaced by natural gas turbines, carbon dioxide emissions would be two-thirds lower.

But Big Coal won and the Victorian Labor government extended Hazelwood’s license to pollute to 2031. The extension of its life will add around 340 million tonnes of carbon dioxide to the atmosphere. By comparison, in 2007 the whole electricity sector in Australia was responsible for 200 million tonnes of greenhouse gases.

Over the next two decades, the carbon emissions from Hazelwood will wipe out more than half of the emissions savings from the Rudd Government’s 20 per cent renewable energy scheme.

The jury in the Kingsnorth trial heard the arguments from defence and prosecution. They accepted that the protesters had a lawful excuse for damaging the power plant and acquitted them.

The law was applied and they were found not guilty.

While anyone can claim that their cause justifies civil disobedience, few receive such an unambiguous endorsement for their ‘law-breaking’ from fellow citizens. In history’s league table of great causes, fighting global warming is up there with campaigns for the suffrage and civil rights and against slavery and apartheid.

In fact, it puts all others in the shade because the fate of the planet hangs in the balance.

Global warming is uniquely dangerous because victory can come too late. Unless it occurs now a sudden awakening by governments to the peril will be too late; the global climate system will have shifted course and the future will have been taken out of our hands.

We are lucky to be citizens of a country that is peaceful, prosperous and governed by the rule of law. Yet runaway climate change jeopardises the stable and civilised community that our laws and our democracy are designed to protect. Those who have overcome the natural tendency to avoid or play down the facts and so recognise the awfulness of the threat we now face must ask whether they are bound to submit to laws that protect those who continue to pollute the atmosphere in a way that threatens our survival.

The people who will gather at the gates of Hazelwood this weekend are some of the most law-abiding in the country. They are among the most civic-minded, the most committed to democratic participation, and the most respectful of laws that serve the common interest.

They and thousands of others around the country have pursued every avenue — petitions, letter-writing campaigns, media events, delegations to MPs, lobbying, peaceful protests and elections. It is now clear that the influence of the energy and mining companies swamps the effect of community campaigns and drowns out the warnings of our best scientists.

Disobeying the law should be a last resort when all other avenues have been exhausted. And they have been. Given the moral imperative for decisive action on global warming, the protesters who plan to trespass at Hazelwood this Saturday are morally justified in breaking the law.

Their target is not the laws against trespass or criminal damage, but the failure of our governments to make laws that would see Hazelwood and other coal-fired power plants in Australia closed down in short order.

Many hoped a new dawn had broken with the election of a Labor Government promising to take far-reaching measures to tackle Australia’s contribution to global warming. Many believed the Prime Minister when he declared that climate change is the greatest moral challenge of our generation. But it is now apparent that its true intentions were business-as-usual. It is now clear that beneath the superficial differences there is bi-partisan agreement that short-term commercial interests must come first and as little should be done as governments can get away with.

The scattered acts of disobedience we have seen to date in Australia and other countries are a mere taste of what is to come. The only hope for the world lies in a campaign of radical activism aimed at shifting power away from those who do not care about the future.

Never has a campaign been more necessary. It is a campaign for all of those who understand that the lives of our children and grandchildren are at stake.

Clive Hamilton is Professor of Public Ethics at Charles Sturt University.