Finalmente la verità

Even as one of the principal architects of the Iraq war washes his hands of the whole bloody mess, there is still only a vague understanding of the real reason behind the invasion, but evidence of the intense interest of the international oil companies continues to build. Only last week, ExxonMobil chief executive Rex Tillerson said in London: "We look forward to the day when we can partner with Iraq to develop that resource potential." Despite their interest and influence, however, the decision to attack was not taken in the boardroom. Iraq was indeed all about oil, but in a sense that transcends the interests of individual corporations, however large.
The elephant in the drawing room was the fact that global oil production is likely to peak within about a decade. Aggregate oil production in the developed world has been falling since 1997, and all major forecasters expect world output excluding Opec to peak by the middle of the next decade. From then on everything depends on the cartel, but unfortunately there is growing evidence that Opec's members have been exaggerating the size of their reserves for decades.

Oil consultancy PFC Energy briefed Dick Cheney in 2005 that on a more realistic assessment of Opec's reserves, its production could peak by 2015. A report by the US Department of Energy, also in 2005, concluded that without a crash programme of mitigation 20 years before the event, the economic and social impacts of the oil peak would be "unprecedented". The evidence suggests these fears were already weighing heavily with Cheney, Bush and Blair.

In a world of looming shortage, Iraq represented a unique opportunity. With 115bn barrels, it had the world's third biggest reserves, and after years of war and sanctions they were the most underexploited. In the late 1990s, production averaged about 2m barrels, but with the necessary investment its reserves could support three times that. In a report to the security council, UN inspectors warned in January 2000 that sanctions had caused irreversible damage to Iraq's reservoirs. But sanctions could not be lifted with Saddam still in place.

Cheney knew, fretting about global oil depletion in a speech in London the following year, where he noted that "the Middle East with two thirds of the world's oil and lowest cost is still where the prize ultimately lies". Blair too had reason to be anxious: British North Sea output had peaked in 1999, while the petrol protests of 2000 had made the importance of maintaining the fuel supply excruciatingly obvious.

Britain's and the US's fears were secretly formalised during the planning for Iraq. It is widely accepted that Blair's commitment to support the attack dates back to his summit with Bush in Texas in April 2002. What is less well known is that at the same summit, Blair proposed and Bush agreed to set up the US-UK Energy Dialogue, a permanent liaison dedicated to "energy security and diversity". Its existence was only later exposed through a freedom of information inquiry.

Both governments refuse to release minutes of Dialogue meetings, but one paper dated February 2003 notes that to meet projected demand, oil production in the Middle East would have to double by 2030 to more than 50m barrels a day. So on the eve of the invasion, UK and US officials were discussing how to raise production from the region - and we are invited to believe this is coincidence. The bitterest irony is, of course, that the invasion has created conditions that guarantee oil production will remain hobbled for years to come, bringing the global oil peak that much closer. So if that was plan A, what on earth is plan B?

· David Strahan is the author of The Last Oil Shock: A Survival Guide to the Imminent Extinction of Petroleum Man