The old economics is dead. Its death knell was sounded last week, not by a practitioner of the dismal science but by Tony Blair's chief scientific adviser. Sir David King said concentrations of greenhouse gases were already at a level where the warning signs were flashing red: a comment that starkly illustrates the impending clash between economic orthodoxy and environmental sustainability. Economics is a discipline in which the factors of production - capital and labour - are supposed to be harnessed to maximise production at the cheapest price. By this yardstick, an economy is doing twice as well if it is growing at 4% rather than 2% and disastrously badly if consumers are not in the shops from dawn till dusk. Globalisation is seen as the ultimate form of a market economy, according to the prevailing model, because a more efficient use of the factors of production leads to lower prices and therefore permits higher levels of consumption. In a globalised world, you're only as good as your last GDP number.