Success at Kyoto will need agreement on a method of calculating emissions reductions. The United States favours what has become known as the ‘net’ approach. According to this method, a country's inventory of ‘man-made’ carbon emissions will include carbon released into the atmosphere from the clearing of forests. It will also take account of carbon removed from the atmosphere from, for example, the planting of trees. This is controversial, partly because it is not clear how this carbon will be calculated.

Credit: BRIDGEMAN ART LIBRARY/HOKUSAI, ‘THE GREAT WAVE OF KANAGAWA’

Another issue will be the ‘basket’ versus the ‘gas-by-gas’ method of calculating emissions. The European Union supports the idea that reductions should be made collectively to a basket of three gases: carbon dioxide, methane and nitrous oxide. But environmentalist groups oppose this on the grounds that it would allow countries to make disproportionate reductions to methane and nitrous oxide, in comparison to carbon dioxide, which constitutes 80 per cent of developed country greenhouse gas emissions.

Also at issue will be the period over which reductions can be made. Some countries — the United States again — would like five years to reduce emissions. Others want specific annual targets.

Finally there is the crucial question of which ‘legal instrument’ to use. If countries do agree on targets, the climate convention will need to be changed. The change could take the form of an amendment to the convention. This will require signatures from at least three-quarters — more than 120 — of the countries which have signed and ratified the convention. But the amendment will not enter into force — the point at which emissions targets become legally binding — until all these countries have ratified the change to the convention in their national parliaments. This is not expected to happen before 2010.

The alternative method of changing the convention is through what is known as a ‘protocol’. The main advantage of a protocol over an amendment is that countries have more freedom to decide when it enters into force. They can, for example, decide entry into force after it has been ratified in the national parliaments of, for example, just 50 countries. But a protocol's drawback is that it needs a consensus of all the parties. In other words, a single, dissenting country can veto the whole process.

European government lawyers anticipated this potential difficulty nearly a year ago, and have tabled an advance amendment to the convention which says that a protocol should be allowed to be adopted at Kyoto by a three-quarters majority vote. This is a high-risk strategy and bound to be opposed by countries such as Saudi Arabia and Australia. “When you've got 48 hours to go [at Kyoto], everyone's dead tired, and one country is blocking progress, the chairman will need to pull a rabbit of the bag,” says one government lawyer. This procedure could well be that rabbit.