Leading article: The American consensus of denial is crumbling

In some respects, the attitude of the US political establishment towards global warming seems as intransigent as ever. President George Bush still squirms at mentioning any link between fossil fuel emissions and global warming as the desperate haggling over the wording of the G8 communique in Gleneagles showed. And the recent "post-Kyoto" agreement the Bush administration devised with a handful of friendly countries was widely regarded as a cynical effort to forestall international pressure on the US to consider emission controls.

The US Congress also seems to be an insurmountable barrier to progress. The Climate Stewardship Bill, which would impose federal caps on emission, has been repeatedly blocked by the Senate. Many congressmen and senators continue to question the scientific evidence of rising temperatures. And the Oklahoma Senator James Inhofe has publicly described global warming as a "hoax". This is not the opinion of some political maverick. Depressingly, Senator Inhofe is chairman of the Senate Environment Committee.

The irony is that American scientists are at the very forefront of exposing the damage the uncontrolled burning of fossil fuels is inflicting on our environment. Researchers from the Institution of Oceanography in San Diego compared the rise in ocean temperatures with predictions from climate models. This has been the most comprehensive proof yet that human activity is behind climate change.

But there are signs that things are changing in America and that the old consensus of denial is crumbling. Some Republican state governors are already breaking ranks and imposing emissions limits unilaterally in the areas under their authority. Arnold Schwarzenegger is committed to legislation in California requiring car makers to cut emissions from vehicles sold in the state by 30 per cent from 2016. There are similar commitments in Republican-controlled Oregon and Washington. Six other Republican states in the north-east are working to develop emissions trading schemes. The Republican Party appears to be moving considerably faster than the President towards adopting a realistic and practical approach towards climate change.

Even American industry seems to be grasping the need for change. An increasing number of large firms such as DuPont, American Electric Power, Ford and Motorola have announced plans to rein in their energy consumption. This gives the lie to the President's claim that emissions caps would be catastrophic for business. What is lacking is the political will to make the case for them.

Global warming is given little coverage by the US media. Despite this, a poll last autumn found 51 per cent of Americans believe the phenomenon is a cause for substantial concern. The message is slowly filtering through.

Two of the Senators who are visiting Alaska - the Democrat Hillary Clinton and the Republican John McCain - are being mooted as presidential candidates for their respective parties in 2008. This trip could presage an important change to come in US attitudes. For the sake of the world's biggest producer of fossil fuel emissions - and our planet as a whole - it is to be hoped it will.