It means the point at which we cannot develop new oilfields as fast as the old ones tail off.

With demand rising unstoppably, as the poor attempt to follow the rich up the ladder, Peak Oil looked like being the call for Last Orders in the Last Chance Saloon, when it came.

Well, according to some, it has already come – about a year ago.

An American investment advice service called Raymond James is the latest to read the signs and get the same message. And the Raymond James opinion was reported in a serious tone last week in the Wall Street Journal, which used to regard Peak Oil as an amusing hippy nightmare, about as likely to come true as the return of the dinosaurs.

The Journal summed up: "Raymond James notes that non-OPEC production apparently peaked in the first quarter of 2007, and given precipitous falls in output from Russia to Mexico, there's not much hope of a recovery. OPEC production peaked a little later, in the first quarter of 2008.

"The contention rests on a simple argument: OPEC production actually fell even as oil prices were above $100 a barrel – a sign of the 'tyranny of geology' that limits the production of ever-more crude.

"If true – and the analysts note that true historical peaks are only visible in the rear-view mirror – then expect oil prices to jump back towards triple digits."

The conclusion is disputable, of course. The oil business has always got a reason why there is no need to cut back yet – the oil sands of Canada and Alaska; or the prospect of "fuel cells", meaning super-batteries, which could be charged up from gas or solar power...

But if those solutions can be had, they will not be cheap.

Look down on a western country from a plane at night and it is clear the prospect of the North Pole melting has failed to put much urgency into the switch-it-off campaign.

The world after Peak Oil would be likely to substitute hard economics for propaganda about polar bears. In view of that, it might be thought significant that almost nobody except the readers of Raymond James and the Wall Street Journal noticed the story.

Concern about oil reserves has been replaced by concern about global warming.

The politicians all seem to think that saving the world from carbon dioxide is more or less the same thing as conserving the fuels which produce the gas.

"But it is most certainly not," says Peter Lloyd, a serious amateur climatologist, retired from the plastics industry to his home in Barnsley, and part of a worldwide network of scepticism about the way the climate-change issue is presented.

"If the money and effort spent on reducing CO2 were directed at substituting other fuels for fossil fuels, we would be a lot better off a lot quicker." He thinks warming is part of the natural cycle between Ice Ages and there is not much to be done about it.

Caroline Boin, an environmental affairs specialist with the International Policy Network, a pro-capitalism think tank, is more cautious about challenging the approved scientific consensus – although she suspects the politicians are leading the scientists.

But even if global warming is our fault, she argues, it is
unlikely we can stop it and we would do better preparing to
live with it.

Ms Boin said: "The politicians all say they are fighting global warming on behalf of the poor. But the poor of the world are worst affected by natural events because they cannot afford to build strong houses and buy medicines and store some harvest."

Tackling global warming
rather than saving oil also distorts energy policy. It means the money goes on windmills rather than coal, for example, until we have clean coal-burning technology, and meanwhile we buy gas from abroad to do what the windmills will not.

Sonja Boehmer-Christiansen of Hull University, editor of an energy and environment discussion journal, thinks our reluctance to burn coal is ridiculous. She has previously pointed out that "acid rain"
from coal-burning was a myth but drove political decisions for years until it quietly fell off the agenda. She suspects "the greenhouse effect" is a similar mass delusion.

She is sceptical about Peak Oil. Nobody knows what resources are in the Earth, she says. We only know what we have found with existing technology. But it will cost more and more to get buried carbon, so there is no need for emissions policies.

Dan Lewis, director of research for the Economic Research Council, another Conservative-leaning think tank, added: "Politicians should concentrate on tangible results within their own political lifetimes and the priority for ours should be security of energy supply for the next 10 years. "

On the face of it, a dash for nuclear power should satisfy both sides.

But Caroline Boin commented: "You get the impression that
if there was a way of cutting CO2 but keeping our lifestyles, a lot of people would still not be happy. It's not the CO2 they don't like, it's the modern world."