The time for denial is long over. In not much more than two centuries, we have burned significant amounts of the earth s reserves of the sun s energy accumulated over millions of years in the form of gas, coal and oil. As the atmosphere has a finite capac

The time for denial is long over. In not much more than two centuries, we have burned significant amounts of the earth's reserves of the sun's energy accumulated over millions of years in the form of gas, coal and oil. As the atmosphere has a finite capacity to safely absorb the consequent greenhouse gases, sea levels are rising and weather patterns, especially global temperatures, altering alarmingly.

The world has not experienced the current level of carbon dioxide concentrations for over half a million years. This is beginning to lead to a shrinking habitable land mass and a declining quality of life for the world's population.

The main cause is economic growth. At its heart is the requirement to fuel our energy-dependent activities. But if we do not restrict these very sharply, a devastating intensification of climate change is almost certain. We cannot go on turning a blind eye to the fundamental contradiction between the promotion of these activities and policies aimed at averting an ecological and social catastrophe.

A burgeoning world population and aspirations to ever higher standards of living make the search for an effective solution even more challenging.

So, what difference can we as responsible Camden citizens realistically make in the face of this world-embracing issue? Certainly, we must not allow our fears to be allayed by accepting without question the setting of wholly inadequate targets for the future - neither the 60 per cent reduction in carbon emissions by 2050 which has been set by the government and agreed to by all main political parties, nor the green lobby groups' coalition calling for an annual three per cent reduction.

It is wishful thinking to believe that even these targets will be able to be achieved by appeals to common sense, some gentle taxation and regulation that does not alarm those directly affected too much, and by faith in ever-improving technological advances.

It is being increasingly recognised that even the combination of all the best solutions will not enable us to maintain our energy profligate lifestyles and reverse climate change. Of course green practices should be more widely adopted. We may well be prepared to switch off the stand-by on our TVs, replace light bulbs with low energy versions and recycle more of our waste - even use public transport instead of the car for long distance journeys.

They do however need to be appraised to reveal whether they are more than tokenism and whether it is realistic to welcome them as representing sufficiently large steps, leading to far more demanding and essential behavioural changes to live fairly within the planet's means - such as hugely curtailing road and rail travel, drastically reducing or stopping flying, giving up second homes, especially abroad, choosing a job or a school which does not depend on the use of a car to reach it, and so on.

Each year on average in the UK, each of us is responsible for about 10 tonnes of carbon emissions, roughly 10 times higher than our fair share if the planet's climate is not to be seriously destabilised and the impending ecological catastrophe avoided.

We need urgently to realise that it is almost obscene to claim that, in a free society, individuals cannot be denied their right to treat the world as their oyster, now that the means of doing so by flying are increasingly available and at a cost that is allowing a rising proportion of the population to do so. Likewise, we need to seriously question the validity of particular journeys by air - a funeral in Florida, a wedding in Winnipeg, a honeymoon in Hawaii, a business deal in Beijing.

At the end of An Inconvenient Truth, Al Gore states that 'there is no magic bullet'. There is! In 1939, faced with the prospect of scarcity of a basic commodity, the government introduced food rationing. We are now in an analogous situation. The only realistic and fair way ahead is for the government to adopt an international framework to deal with this global problem. There would be little point in the UK and its citizens 'going it alone'.

Such a framework, Contraction & Convergence (C&C), was devised by the Global Commons Institute 10 years ago. Support is spreading rapidly. It is based on equal per capita shares of carbon emissions across the world's population. It involves a cap on global greenhouse gases below dangerous levels and, on the principle of social justice, their phased reduction through an equal year-on-year decrease in each person's allowance (carbon rationing) until the safe level is reached. The process creates a virtuous circle as the allowance is tradable: the energy-thrifty - people not contributing to the degradation of the climate system - become recipients of revenue arising from selling their unused allocation to those encouraged by the steadily rising costs to abandon their energy-profligate ways as speedily as possible.

Indeed, Environment Secretary David Miliband, one of Camden's most impressive and 'policy-influential' residents, has shown considerable interest in it, referring to its 'simplicity and beauty'.

What can be done locally? Camden Council has already demonstrated its commitment to supporting the C&C framework and the need to achieve international agreement on it. However, whilst the council has valuable input from its environmental health department and Agenda 21 group, sustainability has never been one of its statutory requirements. In its day-to-day work, it has to operate within limited terms of reference and the limited revenue it gets from central government and from local taxes and business rates.

This makes it all the more necessary for us as responsible citizens, to act by making considerable lifestyle changes. We need to take every conceivable step to reduce our own use of fossil fuels. We can easily work out our own annual carbon emissions from relevant websites. The calculation will prove salutary, especially when the figure is compared with the fair share of one tonne, and then when the implications of not acting on it are faced. But we would be deceiving ourselves to believe that achieving the severe cuts in our use of fossil fuels will be accomplished by more and more people opting to do so.

Our best efforts should be directed at pressuring policy makers to promote the adoption of realistic means for delivering drastic and speedy reductions in fossil fuel use. Only government has both the responsibility and the power and authority to do so in all our interests. The electorate should not shield itself behind the claim that our personal contribution is so minuscule that it is almost irrelevant. Political parties should not be allowed to get away with a fear of the electoral consequences of grasping this most essential of nettles.

The only way this is likely to happen is through the medium of a coalition of all political parties. That's what the All-Party Parliamentary Group on Climate Change, ably led by the MP Colin Challen, is aiming to do. It should have our total and vocal support. If we do not curtail our energy use dramatically, we are complicit in a process with increasingly dire prospects for ourselves and even more so for the generations ahead of us. There is no escape from this harsh conclusion.

Mayer Hillman is Senior Fellow Emeritus at Policy Studies Institute, author (with Tina Fawcett), of How We Can Save The Planet, Penguin Books, and (with Tina Fawcett and Sudhir Chella Rajan) of The Suicidal Planet: how to prevent global climate catastrophe, Thomas Dunne Books, St. Martins Press (just published in the United States).