Leading article: Running on empty

Carbon-based business as usual, then? Not quite. The price of oil shot up because of the short-term effect of Hurricane Katrina. But the long-term pressures of rising demand from China and India mean that the economic facts of life are changing permanently. As we report today, the former president Bill Clinton says that world leaders ought to welcome the fact that crude oil prices have doubled in the past two years. "It is a good thing because, believe me, this is going to concentrate minds all around the world," he told us.

As he says, too, it is difficult for sitting politicians to endorse high oil prices - as Gordon Brown, the Chancellor, went rather too far to demonstrate last week, with his pointless call on Opec to increase production. But there are opportunities here to advance the green cause. More expensive oil highlights the world's dependence on carbon fuels and tilts the economic balance in favour of solar, wind and other renewables - and, most importantly, towards saving energy. Green taxes on polluting or scarce resources can be made feasible if they are offset by reductions in taxes on labour, such as income tax or national insurance. They also reinforce market expectations that oil will become ever more expensive.

The Chancellor made a big mistake by abandoning the fuel price escalator at the time of the last fuel protests. Mr Clinton's belated conversion to environmentalism may be better late than never, but hardly makes up for his record in office (and that of his "green" vice-president, Al Gore). They not only failed to introduce their planned energy tax, but let the use of fossil fuels - and emissions of the greenhouse gases that cause global warming - soar out of control. Anything, even £1-a-litre petrol, that prods the world into reducing these emissions is to be welcomed.