Here is a little game to pass the time. Key the words "world population" into Google and add the year of your birth. The results, in every case, will be intriguing. For example, in 1950, when I was born, there were 2.5 billion people on the planet. Today there are around 6.8 billion while the UN predicts there will be more than 9 billion by 2050. Thus, in 40 years, the Earth's population will rise by a figure equivalent to its total population in the 1950s, with most living in the developing world. "If you think the world feels crowded now, just wait a few decades," says Friedman.

As for the "hot" of his title, it reflects a future in which the burning of "fuels from hell"  his term for the world's underground supplies of coal, gas and oil  will bring calamitous warming, while the term "flat" refers to the levelling of the world's economic playing fields. This will create a soaring global middle class and a spiralling demand for cars, microwaves, mobile phones and computers that devour "energy, natural resources, land and water and emit climate-changing gases".

It is a striking scenario expertly assembled by Friedman, though his is no mere cry of doom and despair. As is made clear in the book's subtitle  "Why the world needs a green revolution and how we can renew our global future"  the author also believes we can get ourselves out of this mess, the lessons of the recent credit crunch being particular important. As a result, Friedman has substantially rewritten Hot, Flat and Crowded for its paperback release to include an analysis  and it's a convincing one  of the 2008 financial crisis and its importance to our survival.

"The parallels between what has been happening in the Market and in Mother Nature are eerie," he states. Thanks to lack of proper regulation both are being swept by crises  financial and ecological  that should be rare but are now common. Hence, we need to rein in our profligate ways, get rid of inefficient energy sources and invest heavily in renewable power. Easier said than done, of course.

There can be few writers so adept at catching the American mood as Thomas Friedman. In The Lexus and the Olive Tree, published in 1999, the influential New York Times columnist celebrated globalisation in triumphal fin-de-siècle fashion as a process whose end-point is universal Americanisation. The paean continued in The World Is Flat, which appeared in 2005, but by then globalisation was not looking so unambiguously benign and the subtext of Friedman's jubilation was the threat it was posing to the American way of life. One of the book's messages was that the US needed to reduce its dependency on imported oil.

American 'energy independence' would allow the US to delink itself from the global market. In this way, the prophet of globalisation seemed to be suggesting, the US could turn its back on the frighteningly unAmerican world that globalisation was actually producing.

Friedman's latest book synthesises ideas that have been floating around in America ever since the scale of the disaster in Iraq became undeniable. Supporters of the war believed that once Iraq's oil had been seized and privatised, the price of oil would come down, with Paul Wolfowitz arguing that the invasion would be self-financing and result in a global economic boom. In fact, exploiting Iraq's oil assets proved very difficult, production was lower than under Saddam and the oil price spiralled upwards.

At this point, even neoconservatives, who had hitherto looked on green thinking as a dastardly leftist plot, became interested in energy conservation. Not himself a neocon - on many issues his views are liberal, even social democrat - Friedman was at one with the neo-cons in urging a fundamental rethink of American environmental policies. Hot, Flat and Crowded is the result.

The book is archetypal Friedman. Breathlessly upbeat in style, seemingly written in a succession of airport lounges, it is a compendium of the bullish delusions of US politics over the past two decades. He instructs the reader in what he calls 'the First Law of Petro-Politics', which says that when the price of oil goes down, freedom goes up. A drop in the price of oil to $20 a barrel will trigger democratic revolutions throughout the Gulf, he believes, and in one sense he is right. A collapse in the oil price would destabilise existing regimes and might well result in a spread of democracy. But in most cases, certainly in Saudi Arabia, which remains vital to Western oil supplies, it would be an Islamist version of democracy, hostile to Western interests, that would come to power.

Friedman makes much of the example of Bahrain, where he tells us the prospect of oil running out is leading to democratic reforms. But the upshot of this democratisation is unclear and the so-called Law of Petro-Politics is in general not much more than a formula for wishful thinking.

At other times, Friedman is refreshingly realistic. 'Rapid economic growth and population expansion,' he writes, 'are driving the destruction of forests and other ecosystems at unprecedented rate. The destruction of these forests and biodiversity-rich environments, in turn, contributes to climate change by releasing more carbon in the atmosphere.' Here Friedman recognises the interconnections that underlie the environmental crisis and which necessitate a shift in our whole way of doing things. He is robust in recognising that any effective response to climate change must include hi-tech solutions such as nuclear power, although his proposal for an 'Energy Internet' ('one big seamless platform for using, storing, generating and even buying and selling clean electrons') sounds impractical. A large-scale fusion of information technology and energy technology could have many benefits, but in a world of states competing for energy resources, and using these resources as geopolitical levers, there is no prospect of such a scheme operating at the global level. Even so, Friedman's focus on technical fixes for environmental problems is closer to reality than mainstream green thinking, which clings to a utopian faith in political transformation.

Friedman's discussion of the environmental challenges facing the world contains valuable insights. Yet in the context of the book as a whole, these insights are almost inadvertent. Hot, Flat and Crowded is only incidentally about the environment. As is always the case with Friedman, its real subject is not the world, but America. The concluding paragraph is toe curling in its parochialism: 'We need to redefine green and rediscover America and in so doing rediscover ourselves and what it means to be Americans. We are all Pilgrims again. We are all sailing on the Mayflower anew.'

An Americo-centric perspective of this kind might have made some sense 20 years ago. In today's world, where the US is a tottering power, it is comically deluded. It is not America that will decisively shape the global response to climate change and energy crisis. It is emerging nations, above all China, which is definitely not sailing on the Mayflower. True, Friedman gives China's rulers grudging praise for their environmental awareness, but only on condition that China ends up being more like America: 'They will never say so, but I do not think they can go green without, over time, going at least a little orange - à la the Orange Revolution in Ukraine in 2004'.

Since that was written, events have altered the picture. Russia's self-assertion in the Caucasus has revealed the geo-political forces that are shaping world politics and the future of the orange revolutions is looking less assured than it did only months ago. More to the point, at least from Friedman's navel-gazing perspective, Americans now have other concerns. The environmental anxieties that followed the Iraq debacle are fading, along with the war itself, from the centre of American politics. The struggle to avert a catastrophic depression is now all-consuming. The American psyche is grappling with a well-founded fear of economic collapse and it is hard to see it being energised by Friedman's green-tinged nationalism.

The upshot cannot be known, but as fear tightens its grip, drilling for oil off its coastlines and reopening coal mines may be what the US resorts to. History has moved on, the American mood has shifted and for once Friedman has been left behind.

Global affairs: three to read

The Wrecking Crew by Thomas Frank (Harvill Secker)
A primer on American conservatism, revealing the corruption and self-interest at the heart of the movement that has been the ascendant force in US politics for three decades.

The Post-American World by Fareed Zakaria (Allen Lane)
The editor of Newsweek argues that American power may be waning, but this is no bad thing; if the US learns how to broker and mediate, it can remain a force for good.

What Next: Surviving the Twenty-First Century by Chris Patten (Allen Lane)
The former governor of Hong Kong identifies and offers 'rational' solutions to the many challenges facing the world, from climate change to drug trafficking.

 John Gray's Black Mass: Apocalyptic Religion and the Death of Utopia is published by Penguin

How much difference will the departure of George W Bush make to the politics of climate change? The answer as of today is: not enough. Both candidates for his job have acknowledged the need for action, but not such as to threaten the inalienable right of US motorists to cheap gas. And the boldest initiatives that now seem politically feasible in America will scarcely make a dent in the problem.

For one thing, there is much less of a consensus in the US about the nature of the threat than exists in Europe, and powerful vested interests stand in the way. Four of the key swing states - Ohio, Pennsylvania, Tennessee and West Virginia - are built on coal, while others such as Iowa have big biofuel interests.

For another, the sheer complexity of America's energy system is a serious barrier to progress. To take one example, there are more than 3,000 separate electric utility companies spread across the country, all of them given incentives to sell as much power as possible from the cheapest energy sources. There are three regional grids, with limited interconnection. And there are armies of sometimes competing regulators, at local, state and federal level.

Hence the importance of Thomas Friedman's new book. In many ways, it's a maddening read for Europeans, and not just because it ignores the EU and the lead that it has taken on this issue. Friedman's style is all-American. He believes the vital role of the US is to stand as "a beacon of hope and the country that can always be counted on to lead the world in response to whatever is the most important issue of the day". But his arguments are pitched squarely at American readers, and his is an influential voice. His last book, The World is Flat, became required reading in the corner offices of Fortune magazine, and his latest offering is designed to win over the same sceptical audience.

The starting point is that ending America's addiction to oil is not just an environmental necessity - it is also a strategic and economic imperative. Oil dependency makes dictators stronger, democratic countries weaker and radical terrorists richer. Rather than staying on this course, business and the country as a whole should see the development of a clean energy infrastructure as a source of competitive advantage. Friedman claims that the greatest thing that the US could do today for itself, and for the whole world, would be to announce its intention to "outgreen China" - by taking a commanding lead in the race to build the next great global industry: clean power.

Not only would such a goal bring strategic, economic and environmental benefits, it might also help to strengthen the role of civil society in China, as citizens start to speak out against environmental excesses. "The Chinese Communist party will not be able to deliver on its promise to its people of the freedom to breathe unless it gradually but steadily starts to grant more of them the freedom to speak." And the best way to do all this is not through rules and regulations, or international treaties, but by way of "the most effective and prolific system for transformational innovation and commercialisation of new products ever created on the face of the earth - the US marketplace".

Friedman's big idea is the creation of what he calls the energy internet - a world in which consumers of electricity will be empowered by innovative technology to maximise energy efficiency, choose different sources of supply at different times and at different prices, and sell any power they generate themselves back into the grid. Most of what's needed already exists, at least on paper: the challenge is to bring down the cost and change the rules to make it all possible.

All this is aimed at those who think climate change is a hoax devised by pony-tailed tree-huggers. Technology and America's spirit of innovation will do the trick, and bring economic benefits into the bargain. But it's not enough to rely on market forces, at least in the way that they currently operate. Friedman recognises the vital role for government, in introducing demanding targets to spur industrial change; in setting standards to raise the energy efficiency of goods and services; above all, in giving price signals that the market needs in order to operate effectively. That could mean the introduction of a carbon tax, a floor price for oil, a cap and trade system for reducing greenhouse gas emissions - or some combination of all three. California has started down this road. But it will be a very hard sell across the rest of the US, as Senators Warner and Lieberman found with the failure of their attempted legislation this summer.

Even the ever-optimistic Friedman occasionally seems daunted by the scale of the challenge. There are no quick fixes, despite the flood of US publications offering articles such as "205 Easy Ways to Save the Earth". The US is going to have to redefine its ideas of a middle-class lifestyle and set a very different example to the world. But in doing so, Friedman suggests, it can rediscover its sense of national purpose. As short-term economic problems pull political and public attention away from long-term threats to the environment, America needs a forceful advocate like Friedman to make this case for change.

 Richard Lambert is director general of the CBI