Colin Challen: We must think the unthinkable, and take voters with us

Climate change means that business as usual is dead. It means that economic growth as usual is dead. But the politics of economic growth and business as usual live on.

What needs to change to bring about a political tipping point? What is stopping us from taking the radical path we need to follow today if we are to avoid dangerous climate change tomorrow?

We are imprisoned by our political Hippocratic oath: we will deliver unto the electorate more goodies than anybody else. Such an oath was only ever achievable by increasing our despoliation of the world's resources. Our economic model is not so different in the cold light of day to that of the Third Reich - which knew it could only expand by grabbing what it needed from its neighbours.

Genocide followed. Now there is a case to answer that genocide is once again an apt description of how we are pursuing business as usual, wilfully ignoring the consequences for the poorest people in the world. The DfID submission to the Stern Review on the economics of climate change makes it clear that climate change will do untold damage to the life chances of millions of people.

To accept responsibility is not merely to say "sorry". Too often saying sorry seemed to be enough, like saying we're sorry for the slave trade. Rarely do such apologies come with compensation. But the strength of our relationship with climate change is that it gives us the power to change - it is not the past, it is the future. We can discharge our responsibilities by changing our behaviour. This will only be worthwhile if we can measure the impact of our policies within an overall framework which allocates responsibilities fairly and sustainably. This was indeed the assessment at the heart of the 1992 UN Framework Convention on Climate Change (UNFCCC), that so many countries including the US signed up to.

We know that we need to reduce our carbon emissions so that we arrive at a safe concentration in the atmosphere - perhaps 450 parts per million. We also know that without developing countries being part of a global agreement, it won't work. The US Senate rejected Kyoto because it wasn't inclusive enough. The UNFCCC spoke of equity. DfID told Stern that the " mitigation of greenhouse gases poses a fundamental equity problem".

The answer is convergence - we should aim to contract our emissions while converging to a per-capita basis of shared emissions rights. If our framework is disciplined by science, and not what is simply the current economic model, we may be able to break the Faustian pact we have entered into before it ends in tears.

Contraction and convergence at the domestic level could be addressed by introducing tradable carbon rations. A national carbon budget would be set each year, with year-on-year reductions, and equal per capita quotas would be issued annually - perhaps starting at around 10 tons or 10,000 " carbon units" each. For those who didn't use all their units, they could sell their surplus to those more profligate. Such an approach would stimulate investment in both energy reduction and alternatives.

These policies are a radical departure from business as usual. But since none of the mechanisms we currently have in place are solving the problem faster than it is being created, we must look to forging a new consensus which can think the unthinkable - and take the electorate along with it.

Colin Challen is the Labour MP for Morley and Rothwell, Leeds and chairman of the All-Party Parliamentary Climate Change Group