The UK's North Sea oil is past its peak now, as are the giant fields in Alaska, the

The extraordinary prosperity of the twentieth century was built on cheap oil and gas. When they are no longer either cheap nor reliably available, the economic consequences will be far greater than can easily be imagined. Beneath the seabed off the coast of Saudi Arabia, there is an oil field called Manifa. It is a giant, and its riches are almost untapped.1 There is, however, a snag. Its oil is heavy with vanadium and hydrogen sulphide, making it virtually unusable. One day, the technology may be in place to extract and dispose of these contaminants, but it will not be for some time and when, or if, it does happen, it will do no more than slightly reduce the rate at which world oil supplies slip away towards depletion. However, even this field has advantages relative to the massive reserves of oil which Middle East suppliers are said to hold ready to keep oil prices low and secure the future of civilisation. Unlike those fantasy fields, Manifa actually exists. For the last twenty five years, there has been a tacit consensus that oil depletion has almost no place on the environmental agenda. This is partly a reaction to the criticism of the Club of Rome's (1972) study, The Limits to Growth, which drew attention to the existence of limits to the oil resource 2. The study was revisited and ably defended 3, but the weight of criticism was crushing, and environmental policy turned instead to sustainable development. The question of resources- oil included- came to be regarded as an embarrassing phase in the environmental movement's early days 4. But now, it is back with a vengeance. In region after region, the story is of ageing oilfields, of the wrong sort of oil, of nitrogen being pumped into wells to keep up the flow, of exploration turning to unpromising areas such as West-of-Greenland