The new world order is consigned to the rubbish heap, and the outlines of the world in which we will live over the coming century have become clearer. The end of secular ideology has not brought peace. It has simply changed the character of war. In the Persian Gulf and central Asia, in Africa and the South China Sea, we see nations playing out new struggles. Those struggles are about the control of scarce resources. Ideological conflicts are being replaced by geopolitics. The strategic rivalries of the cold war are being followed by resource wars.
This, in many ways, is a return to normalcy. The ideological struggles of the 20th century were extremely anomalous. Throughout history, wars have been fought over gold and diamonds, access to rivers and fertile land. If we find the emergent pattern of conflict unfamiliar, it is because we are still haunted by 19th-century utopian visions in which the spread of industry throughout the world ushers in an age of perpetual peace.
Until mid-Victorian times, most thinkers regarded scarcity in the necessities of life as the natural human condition. They agreed with Malthus that there are limits to growth - particularly in human numbers. The earth's resources are finite; they cannot be stretched to accommodate the unlimited wants of an exponentially growing human population. As John Stuart Mill argued, this does not mean there is no prospect of improving the quality of human life. New inventions can bring a comfortable and leisurely existence to increasing numbers of people, so long as overall human numbers are themselves kept in check. Human progress cannot transgress the limits imposed by natural scarcity.
With the accelerating advance of the industrial revolution, this insight was lost. With few exceptions, the great economists and social theorists of the late 19th and early 20th centuries believed that, with the rise of industrialism, scarcity could be overcome. Marx and Keynes disagreed on many fundamental points, but they were one in believing that in modern industrial economies natural resources are basically irrelevant. If Marx envisioned a world in which goods had become so abundant that they need not have a price, Keynes was not far behind in declaring that mankind's economic problems had been solved.
Towards the end of the 20th century, Hayek voiced a similar view, when he insisted that in a world ruled by the free market there were no insuperable limits to economic growth. This fantasy has become part of the conventional wisdom of all mainstream parties, whose leaders never tire of reciting the Nineties mantra that we live in weightless economies that are decreasingly dependent on the limited resources of the earth.
The belief that resource scarcity can be transcended by industrialism unites many seemingly antagonistic political standpoints. When neoliberals announced that the collapse of communism meant the end of history, they showed how much they have in common with their Marxist opponents. They assumed that once the struggle of capitalism with central planning had ended, so would geopolitical conflict. In the global free market, as in Marx's vision of world communism, there would be no shortage of the necessities of life.
It did not occur to these breathless missionaries of the free market that worldwide industrialisation might trigger a new and dangerous kind of conflict. Like Marx, they took it for granted that wars of scarcity are relics of the pre-industrial past.
Yet the neoliberals, unlike Marx, had a clear example of a resource war waged by an advanced industrial society right under their noses. Even more clearly than the likely war in Iraq, the Gulf war was fought to retain control of western energy supplies. If Saddam had been allowed to take Kuwait, he would have controlled a crucial part of the world's oil reserves. There is plenty of oil left in the world; but most of it is much more expensive to extract than the oil that lies in the regions around Iraq and Kuwait. The Persian Gulf contains the world's last great pool of cheap conventional oil. Any protracted disruption of supply or price increase in this vital resource would be disastrous for advanced industrial countries such as the US and Japan. This economic vulnerability - and not the threat posed by radical Islam - is the chief reason why the Gulf is the focus of global conflict.
That does not mean the threat of radical Islam is unreal or insignificant, but rather that it is mostly indirect. Whatever Osama Bin Laden may now say, al-Qaeda's strategic goals are regional, not global. Its central aim has always been to topple the House of Saud. To be sure, achieving that objective has embroiled it in a global struggle against US power. As things stand, Saudi Arabia - the most important of the Gulf producers - supplies oil to the west in return for American protection. It is implicit in the logic of this situation that al-Qaeda and the US should be deadly enemies. Even so, the threat posed by al-Qaeda does not come from its demonstrated ability to mount terrorist operations in the west. It comes from the fragility of the Saudi regime.
Saudi Arabia is almost entirely dependent on oil for its income. In addition - and here the Reverend Malthus makes an appearance - it has a population that is expected to double in roughly 20 years. (In this it is no different from other countries in the region.) The combination of high population growth with near-complete reliance on a single depleting commodity is not a recipe for political stability. Largely because of population growth, the country's per capita income has fallen by between a half and three-quarters since the early 1980s. If this decline continues over the next 20 years - a certainty unless the price of oil rises substantially - the result can only be severe economic and political strain.
Radical Islam is well placed to benefit. Heavily subsidised through the Saudi education system, it stands to recruit millions of unemployed and displaced young males as the economy deteriorates. The demographic explosion, combined with falling incomes and the advancing power of Islamic fundamentalism, makes the Saudi regime inherently unstable. It is a bold forecaster who predicts that it will be in existence a decade from now.
For some members of the Bush administration, the weakness of the Saudi regime is a reason for trying to reshape it in a way that better suits US interests and values. These strategists do not confine their designs to Saudi Arabia. They aim to engineer regime changes throughout the region. Their policies cannot be explained entirely in geopolitical terms. As is often the case in US foreign policy, they contain an incongruous element of idealism.
American policy-makers who support regime changes across much of the Middle East genuinely believe that democratic regimes installed on the back of American military power will be more popularly legitimate than indigenous tyrannies. In this, they are dangerously deluded. In a region where American power attracts implacable hatred, any attempt at political engineering by the US can only inflame anti-American feeling. The larger risk is that it will boost support for al-Qaeda and other radical Islamic groups to the point of triggering uncontrollable upheaval in several countries. In that event, America's geopolitical interests in the region will be among the casualties.
It is natural to focus on the Gulf when thinking of the role of oil in global conflict, but it is only one piece of the geopolitical jigsaw. In central Asia, the great powers - the US, Russia and China - have re-started the Great Game. No doubt the sudden rapprochement that blossomed between Russia and America after the attacks of 11 September was partly to do with the need for greater co- operation in counter-terrorist strategies, but its deeper rationale has to do with the belief in the Bush administration that the US must diversify its energy supplies. Well before al-Qaeda's attacks, American planners were considering changes in policy aimed at diminishing US reliance on Gulf oil. The prize that Bush seeks in his dealings with Vladimir Putin is secure access to the natural riches of the Caspian Basin. A similar imperative underpins America's renewed interest in Africa, where large oil reserves have been found.
Beyond the current turmoil in the Gulf, still larger conflicts are shaping up. It would be wrong to think that the return of geopolitics results chiefly from flaws in US policy. It is an integral feature of industrialisation worldwide. You can catch a glimpse of the future in the struggles that are emerging around the South China Sea. Stretching from Taiwan and China to the Philippines, Indonesia, Malaysia and Vietnam, this is an area rich in undersea resources, particularly oil and natural gas. Competition for this natural wealth has triggered many bitter maritime disputes, in which the protagonists seem fully prepared to use military force. As a result, it is the site of an intensifying regional arms race.
The conflicts in the South China Sea are important chiefly in what they portend for the future. As Asia industrialises, its energy needs will rise steeply. Inevitably, Asian countries will find themselves in competition - with each other and with the west - for scarce reserves of hydrocarbons. It may be this prospect that underlies the conviction of some American military strategists that the long-term threat to US security comes not from radical Islam but from China. How will this vast country supply its energy needs when it is fully industrialised? If it comes into competition with the US for the world's remaining reserves of oil and natural gas, can there be any assurance that the conflict will not escalate into war?
If the 21st century looks set to be punctuated by resource wars, the reason is not that a few countries - the US now, China in the future - are greedily seizing the wealth of the planet. The logic of resource war is deeper. Intensifying competition for natural resources flows inexorably from worldwide industrialisation - a process that is seen by practically everyone today as enabling humanity to emancipate itself from scarcity. In fact, industrialisation creates a new set of scarcities.
The continued growth in human population increases strain on the environment - not least on the habitats of other species. The pressure is enhanced when this growing population demands an industrial lifestyle that has hitherto been confined to a few. The combined impact of population growth and industrialisation is producing environmental changes on a scale unprecedented in history. In parts of the world, fresh water is becoming a non-renewable resource. Globally, climate change is altering living conditions drastically for billions of people. In these circumstances, it is difficult not to see the Gulf war and war in Iraq as precursors of other and perhaps larger conflicts.
Military planners in many countries accept that the risk of resource wars is serious and increasing, but it continues to be denied by economists and avoided by politicians. In the case of politicians, the reason is clear: voters have little appetite for bad news. With economists, particularly those of the sectarian neoliberal variety, denial of the reality of resource wars has more complex sources. Like Marx, they believe that, given the right economic system, technology can rid humankind of the immemorial evils of scarcity and war. For Marxists, the best system is socialism; for neoliberals, the free market. What ideologues of both camps possess is the faith - and it is faith, not a result of any rational inquiry - that technology will allow human beings to make a break with history and create a new world.
The trouble with the cult of technology is not that it exaggerates the power that comes with the practical application of scientific knowledge. It is that it forgets the unregenerate human beings who use it. Developments in genetics may allow the eradication of inherited defects that produce painful or disabling diseases; but they also allow for the creation of genetically selective bioweapons. New types of energy may be invented which greatly reduce the role of hydrocarbons in industrial economies. If so, we can be sure they will soon be turned to military uses.
It may be true that in a much better economic system, new technologies could spin out natural resources endlessly. I very much doubt that this is possible - if only because the laws of thermodynamics seem to rule out perpetual motion machines. But even if a world without scarcity were technically feasible, it would remain humanly impossible. Historic human conflicts would prevent it from ever coming into being.
The neoliberals who greeted the collapse of communism as the end of history made a monumental error. This was partly because, blinded by simple-minded economic formulae, they failed to take account of certain rather familiar facts of geography and history. Natural resources are not spread equally around the world. They are distributed unevenly, often in regions wracked by long-standing conflicts. This is most obviously true of oil: America's geopolitical strategy in the Gulf could further aggravate the region's intractable divisions. In the South China Sea, too, rival claims over coastal resources inflame historic enmities.
It is not only neoliberals who failed to anticipate the return of geopolitics. Blinded by a naive faith in technology, few people have yet perceived the ironies of history that are unfolding before our eyes. In using their technology to assert control of natural resources, the world's most advanced economies show that they remain dependent on the finite and fragile earth for their prosperity and even their existence. At the same time, they are being drawn into ancient wars of religion and ethnicity. As might have been foreseen, the new era of perpetual peace that was announced just a few years ago has turned out to be a high-tech rerun of the most old-fashioned conflicts.
John Gray's most recent book is Straw Dogs: thoughts on humans and other animals (Granta)