We are entering an age of scarcity - in food, water and energy. Rioting has broken out in dozens of countries as food prices spiral, driven upwards by the pressure on land to meet biofuels targets at the expense of food production. Meanwhile, the price of oil is rocketing and, as resources of carbon dwindle, arguments are breaking out over which economies should be allowed to emit greenhouse gases.
Scarcity, especially of carbon, will transform the nature and language of politics. According to the recent report of the intergovernmental group the Commission on Growth and Development, avoiding catastrophic climate change while still allowing poor countries the chance to grow their way out of poverty will require the US and Canada to reduce their per capita emissions from 20 tonnes per head to roughly two.
Rich countries have two options. First, they can increase the carbon efficiency of their growth. The depth of technological transformation required, however, is comparable only to the industrial conversion of the US and European economies to arms production during wartime. Given the time lag in disseminating new technologies, much of this conversion will have to be based on existing technologies, such as renewables. But so far the news is not good: the current levels of funding fall far short of the scale needed. If rich economies cannot clean up, they must cut down, accepting limits to their growth. The first option is a daunting political and technological challenge, while the second risks political suicide.
Meanwhile, developing countries have to be helped to find a low-carbon growth path that has yet to occur in any country in history. Countries normally start dirty and then, sometimes, clean up as they get richer. The atmosphere's heavy load of carbon no longer permits such a luxury. If we fail to find a way of transforming the nature of growth, we face catastrophic climate change and economic decline. At worst, a "carbon curtain" will fall between the haves and the have-nots. Poor communities and entire countries will be left languishing in a new dark age.
Avoiding such dystopian predictions requires massive and rapid redistribution of power, opportunities and assets. We need a global version of the US's New Deal. For a 21st century equivalent we cannot afford to wait for the shocks of war and catastrophe that delivered that change. Many impacts of climate change, such as melting glaciers or permafrost, are irreversible. World leaders must build the will and capacity to act before disaster strikes.
That means reforming global institutions like the World Bank, the UN and the World Trade Organisation that are far too weighted towards the views and interests of powerful countries. But deep shifts in public attitudes are also essential. Changes of this magnitude, from the abolition of slavery to women's suffrage, have always been driven by public action, as well as the weight of evidence and argument. A change is needed in the actions of campaigners, media, academics and others to force governments to confront the challenge, rather than slide into denial.
We do not yet know if Darwin or Gandhi will be the genius of the age of scarcity - whether we are facing the survival of the fittest or effective global co-operation. But the stakes could not be higher. As Martin Luther King wrote 40 years ago: "Human progress is neither automatic nor inevitable ... Over the bleached bones and jumbled residues of numerous civilisations are written the pathetic words: Too late."
Duncan Green, Oxfam's head of research and author of From Poverty to Power.