"Hubbert's Peak" is the point at which oil production reaches its maximum possible, and known sources of oil then decline. It's generally thought to be something which will happen "soon" -- five or ten years from now. But Sustainability Sundays contributor Joel Makower tells of a letter at Energy Bulletin from an anonymous oil industry insider claiming that the cheap oil peak has already been reached, and we're now on the tumble down. Anonymous makes this unsettling observation: It is not a question of “if” peak oil has occurred – it has! The better question might be “when are the crows coming home to roost?”

Anonymous insiders should always be taken with more than a grain of salt, but the arguments that Anonymous and Makower make are well-worth thinking about. How does the sustainability agenda change if peak oil has already been passed?