Firstly, he fails to present any really convincing evidence for the shortage of gas. He points out the stagnation in North American gas production, and generalises this to the whole world, using one small graph of annual discoveries from Laherrere (it's noticeable that all these peak oil theorists endlessly cross-reference each other's work but don't quote that of researchers with other views). He suggests that global gas production is going to begin declining in 1 or 2 decades, while even his graph seems to show that production could grow for at least 30-40 years, and other writers see scope for increases in global gas production out to 2070.

Secondly, the whole thesis of the book is contradictory. We are running out of gas, he suggests. Then he suggests we shouldn't even use the gas we have due to the need to reduce energy use to protect the environment. If we really do have to decrease energy use now, then surely the amount of gas we have left doesn't matter. It seems to me that he's just using the argument of peak gas to argue against big investments in a natural gas economy, which would further postpone his vision of a low energy world. The great danger of this is that he may put people off using natural gas, in which case they may well continue to rely on much more environmentally damaging fuels such as coal and oil.

Thirdly, the book contains numerous errors of fact which undermine his arguments. For example: he states that energy is required to keep the Earth revolving (literally) - what is this energy? Solar, geothermal...? So if the Earth somehow 'runs out' of energy, will it stop spinning...? His simplistic explanation of the drivers for growth in the economy conflicts with any standard economic theory. He attacks capitalism for its record on the environment, but condescendingly mentions that 'Communism was not any better' - I think it would be only fair to say that Communism has been far, far worse for the environment than capitalism - Chernobyl, for instance. Or visit a Soviet-era oil field versus a Western one. He suggests that the main gas suppliers to the US are anti-American (pandering to popular paranoia) - the main current and future gas suppliers being countries such as Canada, Trinidad and Tobago, Norway, Australia, Qatar, Russia, Nigeria - these countries have their problems, and sometimes disagreements with the US, but I hardly think any of them could be described as anti-American. Darley stresses how important natural gas is to make fertiliser, but in mature economies, this represents only 2-3% of gas use, and in any case, substitute feedstocks are available. He says that we are exceeding the energy budget we get from the sun, but the inflow of solar energy is more than 1000 times human use of energy in all forms. I could quote more errors, but I hope the point is clear: would you support a plan to reduce the human population by some 80%, based on the opinion of someone with such a shaky understanding of science, geopolitics and economics?

Fourthly, he is solidly against increase in efficiency and technological solutions because he believes they just allow more economic growth and environmental degradation. Yet the switch from coal to oil and now to gas has dramatically improved air quality in Western cities (compare the 'pea-soupers' of 1950s London with the situation today; or look at the big amelioration in pollution in Delhi with the recent adoption of CNG (compressed natural gas) vehicles). Considerable further reductions in environmental impact are possible, for instance carbon dioxide sequestration (which Darley does not mention at all), which would tackle the very real issue of global warming. He misses the fact that, since 1970, American energy use per capita has been almost flat due to efficiency prompted by energy price increases. He quotes the 'Limits to Growth' report approvingly, without acknowledging that this report turned out to be fundamentally flawed because (a) it believed that energy use would not decrease in response to rising prices and (b) that further investment and technology would not discover new resources or substitutes for the apparently depleting supplies of oil, copper, tin, etc. It seems a counsel of despair, and very odd to say the least, coming from an environmentalist (as I also classify myself, by the way) to dismiss the very great gains in efficiency that are easily achievable even with today's technology. Again, the risk is that he will dissuade people from investing in technological advances that could really help the environment.

Finally, the whole argument of the book suggests that it is too risky to depend on natural gas and we should therefore dramatically reduce population (from 6 billion to 1 billion) and energy use (and by implication, material well-being). I would ask: what is more risky - to depend on LNG (liquified natural gas) imports into the US, a proven technology that has powered the economy of Japan for over 30 years with no serious incidents, or drastically to re-engineer the whole of global society? Is he suggesting that the average North American or European reduce their energy use to that of the average African? This seems almost inconceivable - Darley himself would certainly not be able to run his website with so little energy, certainly if he confines himself to today's technology. If Western energy use remains somewhere above Darley's supposed sustainable level, then is it right to expect the average African not to increase their energy use beyond the current, low levels?