SIR — Your News Feature “That’s oil, folks” (Nature 445, 14–17; 2007) highlights the debate over depletion of the world’s oil
reserves. I would like to make some additional points.

First, the proponents of the peak-oil theory are predominantly Nature’s constituency — scientists — whereas the vocal opposition are, to a significant extent, economists.

They seem to believe that the geological reality of finite conventional oil resources and the thermodynamic constraints on energy production from alternative hydrocarbon sources can be overcome by a sufficiently high price signal.

Second, there are many statistical and energy-production data supporting predictions of imminent energy decline. For example, a chart of annual discoveries of oil during the twentieth century shows that, despite tremendous advancement in discovery and extraction technology during this period, oil discoveries have been on a downwards trend for nearly 50 years (see ASPO Newsletter 73; January 2007).

Although huge, non-conventional oil resources exist — for example: tar sands, shale oil and even biofuels — harvesting these resources is likely to produce little or no energy profit.

Third, scientists warning of energy decline are seriously disturbed by this issue, for many reasons. One is the annual increase in the world’s human population. Until recently this has been sustained by increasing grain production, made possible by the oil-driven ‘green revolution’. However, grain consumption now exceeds production and reserves are dwindling rapidly. The availability of food will be further eroded by the diversion of grain to production of biofuel.

Most people lack sufficient scientific training to appreciate the strong evidence for, and dire consequences of, an imminent decline in oil production. They are easily lulled into complacency by those with a vested interest in delaying any mitigating responses. The scientific community must unite behind the issue of energy decline.

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