Environmental degradation these days is largely caused by our major export industries - mining and agriculture - and doesn't so much reflect on our ability to support the population who actually live here. The continent is also supporting part of the needs of billions of Chinese, Indians etc. The negative environmental effects of resource extraction aren't going to stay confined to the areas resources are mined/farmed, we are starting to notice the impacts elsewhere e.g. through the depletion and pollution of groundwater aquifers in W.A and Queensland, and the denuding of the Murray-Darling River system.
As for supporting the domestic population, IMO we could do a lot better if natural resources were better managed. Three years ago we had a terrible drought across the east coast, the states were all building desal plants and farmers were ruined. This year we have major floods, dams are overflowing, houses washed away, and farmers are once again, ruined. Surely someone (aside from Dorothea Mackellar) should have woken up to this cycle, and figured out how to tame it? Unfortunately its a cycle that takes 12-15 years to complete while the electoral cycle is only 3-4 years long.
Long term strategic planning is sadly lacking in our country due to short term political imperatives. This also applies to immigration, though IMO its a less important issue than made out to be by some with surreptitious racist motivations. Still it would be good to see an open debate on the matter. I expect we would find that we could support a lot more people in Australia, but only if we cap our support for China and the rest of the world - and therefore accept a reduction in our standard of living.
