Senator Andrew Bartlett and Treasurer Peter Costello make a good pair: Bartlett argues for maintaining high migration levels; Costello for couples to have a third child “for the country”.
Yet even at current levels of fertility and migration, Australia’s population will pass 30 million by mid-century - one extra person for two already here.
There’s a lot of room, of course - lots of good sheep paddocks that could be turned into suburbia all the way from Melbourne to Canberra. Even more room along the Gun Barrel highway in Western Australia. Or in the Simpson Desert.
“Ah!” I hear you say. “But there’s no water in the desert.” Exactly. And there’s not enough between Melbourne and Canberra or indeed anywhere inland for large conurbations of people. Nor is there much on the coast either, given Australia’s propensity for periodic droughts. Water is a limiting resource when it comes to population growth in Australia.
Of course, we can share water around a bit more equitably between industry, agriculture and domestic consumers. The big water users, however, such as the much criticised rice and cotton growers, are not only providing for the domestic market but also helping our balance of trade through exports. Take water away from them and the current account suffers unless, of course, water going to a bigger population helps those people be productive in other ways.
But no matter how it is shared around, the bottom line is that water is a finite, limited resource. And under climate change, the southern half of the continent is getting drier. The north, on the other hand, is getting wetter.
So we all move north. But who would want to live there if temperatures rise by 6C as the Intergovernmental Panel on Climate Change predicts they might? Will agriculture up there still be viable? Probably not. The whole north of our continent could become uninhabitable.
It’s not just climate change, however, that looms on the horizon. Globally, a number of major problems are emerging. Poor ecosystem health, loss of habitat and consequently biodiversity, water shortages in many regions and declining grain production per capita are some.
But a very big problem - as big as climate change and one that threatens to cause economic meltdown if action is not taken almost immediately - is “peak oil”.
Back in 1956, J. King Hubbert, a geologist from Shell Oil, predicted oil extraction in the lower 48 states of the US would peak in 1969. He was almost right - it peaked in 1970. But what of global supply?
In March 1998, Colin C Campbell and Jean H. Laherrère, who had each worked in the oil industry for 40 years, argued in Scientific American that global demand for oil would exceed supply within the decade.
While the oil industry repeatedly argues that peak production will not occur for another three decades or more, they don’t always tell the truth about their reserves. Recently it was discovered, for instance, that OPEC producer Kuwait's oil reserves are only half those officially stated.