Every day, stressed young men in brightly coloured jackets scream their way through multi-million pound deals at London's International Petroleum Exchange (IPE).

As the world's governments gather in Buenos Aires to discuss action against global warming, these traders have their eyes on what will soon become a highly-prized commodity: the permission to pollute.

At last year's conference in Kyoto, the industrialised countries of the world agreed in principle to legally-binding cuts in emissions of the "greenhouse" gases widely believed to be changing the world's climate - each country has its own target, but the average amounts to a 5% cut between 1990 and 2010.

London's International Petroleum Exchange

That may sound a straightforward commitment, but before the Kyoto agreement can come into force, a highly complex system of rules needs to be sorted out which will make these cuts more than just a promise on a piece of paper - the devil is most definitely in the detail.

There is no guarantee of finding a way through the international squabbles which have bogged down the first few days of the meeting in Argentina.

One of the key arguments centres on the role that market forces will play in sharing out the pollution cuts - and this is where the traders come in.

The IPE wants the UK government to go ahead and set up a system of emission permits which could be traded in the City of London.

The Buenos Aires forum - where the world's governments will attempt to agree on how to respond to global warming

The chief executive of the exchange, Lynton Jones, says that companies which are good at cutting pollution will have spare permits which they can then sell to companies which are not so good at it, and so long as the total bank of permits is reduced year by year, the cuts can be achieved most efficiently.

The City traders had a disappointment this week when a government-commissioned report by the British Airways chairman Lord Marshall said it was too soon to set up this kind of system, and recommended instead an energy tax to encourage business to pollute less.

But he did suggest that "dry run" trials should be set up to see how the permit-trading system might work.

BP goes ahead

Some companies are choosing not to wait for the politicians to set the rules.

The oil giant BP is setting up its own system of international emissions trading between a dozen of its major worldwide business units.

The system is aimed at achieving a 10% cut in pollution caused by its rigs, refineries and operations like the "nodding donkeys" pumping oil to the surface near Poole Harbour in Dorset.

Tim Hirsch: "Traders have their eyes on a highly priced commodity"

The chief executive of BP Exploration, Rodney Chase, says this system will ensure that clean-up money goes to the best places.

While the principle of trading is now widely accepted, and is written into the Kyoto protocol, there are fears that if it's not controlled properly, it could open up a loophole threatening the whole process.

Because of the collapse of the former Soviet economy since 1990, Russia and the Ukraine could end up with a huge bank of cheap, spare emission permits.

If they are bought up by American companies, the world's biggest polluter could end up escaping real efforts to clean up its industry.

Dr Paul Ekins of the environmental think tank Forum for the Future says unless trading is confined to countries with well-regulated financial markets, the Kyoto agreement could be dead in the water.