With environment ministers from around the world meeting in Milan this week, global warming is set to be a subject of acrimonious debate. The Kyoto Protocol, signed in 1997, aims to cut emissions of the most damaging greenhouse gas, carbon dioxide, to 95 per cent of 1990 levels. But after the United States, the world's largest producer of the gas, withdrew its support in 2001, there have been increasing doubts as to whether the treaty would be ratified by a sufficient number of countries. In the lead-up to the summit, various countries have geared up for combat by stating their positions. Russia, whose support is critical, has signalled it may not sign up because of financial considerations. Analysts see the move as an attempt to strengthen the country's bargaining position in its negotiations with affluent countries such as Japan over the reduction of emission levels through so-called carbon trading. The German government has published a scientific study warning that the melting of the west Antarctic ice sheet and the Greenland ice cap as the world heats up would cause sea levels to rise by up to 10 metres, submerging some of the world's major cities including London, New York, Miami, Mumbai, Calcutta, Sydney, Shanghai, Lagos and Tokyo. Sticking to its guns, the US has reiterated that implementing the protocol, which is about using existing technology to reduce emissions, would only slow economic growth. It argues that emissions should be reduced by using breakthrough technology that transforms how energy is produced and consumed. Citing US-led efforts to introduce a hydrogen-powered economy, it says only new technology will allow growth to continue. The US position is dubious in that it is difficult to see why new and existing technology could not be used at the same time to reduce emissions. Presumably, implementing the accord would provide powerful incentives for accelerating research into new technology and its application. For example, fuel-cell technology is already used in so-called hybrid vehicles, which are powered by petrol and batteries and discharge lower levels of carbon dioxide. But these vehicles remain unpopular because they are more costly to produce, and so are beyond the means of the average consumer. But as critics have pointed out, hybrid cars - and fully electric ones for that matter - are expensive only because they are not being mass produced. The established vehicle manufacturers have so much at stake in continuing to profit from making conventional cars that they are not keen on promoting cleaner vehicles. But a forward-looking government of a country with a sufficiently large market such as the US could change the economics of the less-polluting vehicles by setting high emissions standards.