If you've been reading the newspapers this week, you will already know what the next Big Thing is going to be. No, it's not Microsoft's stunning new computer games console, the Xbox 360, nor even its rival from Sony, the PlayStation2.

We are talking seriously big numbers. The next Big Thing is likely to be carbon trading. This is not the name of one of the games to be played on the new consoles (though, doubtless, some budding entrepreneur could easily devise one).

Carbon trading is an attempt by governments to use market forces to curb the potentially apocalyptic consequences of excess carbon emissions accelerating global warming.

The European commission started an emissions trading scheme at the beginning of the year, and this week saw London's newly-established carbon trading market achieve lift-off, raising hopes that the city will be the main global market place for carbon trading, especially when futures trading gets under way and the hedge funds move in.

It works roughly like this: the government sets a limit for the amount of noxious emissions companies are allowed to make. If a corporation uses less than its limits, then it is allowed to sell the amount by which it undershot (measured in tonnes of carbon) in the market place. There, it will be purchased by companies that have exceeded their limits.

The trading all takes place on the web, which is why the allusion to computer games is not as far-fetched as it might seem. You could easily produce a simulation of the trading as a game - the only difference would be that real money would not be exchanged.

Trading schemes are thought to have such potential that analysts are already speculating whether they could be applied to people as well. Every household could be given emissions limits and, if they exceeded them, would have to trade with their next-door neighbour or, say, someone in Germany, to bring themselves back within the fold.

This week, after a period of calm, the price of an allowance to emit a tonne of carbon dioxide almost doubled to $20 (£10) in the middle of the week. This may not be enough to have a major impact on global warming, but it indicates the potential.

The main reason for the rise was that the soaring price of oil and natural gas has led electricity generating companies to use more coal burning plants which are much more carbon intensive - hence the need to buy permits to bring their quota back down under the ceilings.

But the trouble is that the world's potential to pollute is moving faster than its efforts to contain pollution. While governments participate in worthwhile schemes such as emissions trading, they are also planing vast expansions of runway capacity to accommodate the continuing boom in air travel that contributes so much to global warming.

Some environmentalists are questioning whether all but essential trips in aircraft can be justified if the outlook for global warming is as bad as most scientists think.

As George Monbiot reminded us recently, a single jumbo jet doing the round trip from London to Miami every day releases the climate change equivalent of 520,000 tonnes of carbon dioxide a year. That would be a lot of business for the London trading exchange if aircraft pollution was included with tough limits.

Emissions trading such as this, however, will be only of limited use as long as the US - sadly but unsurprisingly - stays out of the scheme and Britain, while trying to become a world leader in curbing pollution under prime minister Tony Blair, is simultaneously appealing to the European courts to get its carbon limits reduced.

It's a shame there isn't a market in London for exchanging hypocrisy vouchers. Britain and the US would be big players.