As economies become richer, they can rely less and less on the brute force of capital spending, coupled with a steady flow of cheap rural migrants, to fuel their expansion.

But the ten years of drought before this efflorescence followed a huge expansion of irrigation in the 1970s and 1980s that reduced the flow of the Murray to a trickle.

This poleward expansion could significantly alter such crucial elements as jet stream flow patterns and the course of storm tracks.