On the ABC today is an article which gives one the impression that Australia could face starvation from climate change. Whilst I have heard (and know) that Australia will face agricultural problems as a result of man-made global warming, if it really is true that Australians do not want forty million people here in a country that can sustain about two million without its surfeit of mineral resources, then such a majority must overcome its passivity to protest to eliminate subsidies to water and energy use.
People do not realise that, in ecological terms, water in Australia should cost far more per unit than it does in Europe or North America or New Zealand. Owing to the need for dense proteoid root systems, Australian rivers have extraordinarily low runoff ratios compared to those of comparable climates overseas. Because these low runoff ratios reflect a requirement of around 300 millimetres (twelve inches) of rain before the dense rooting systems allow any runoff at all, variability in Australian streams is twice as high or more as those with the same rainfall and identical precipitation variability in Eurasia, North America, or New Zealand. Thus, for the same size of storage in Australia, only around a fifth as much water can be yielded even when reservoir evaporation is ignored.
This would require Australian water prices uniformly at least five times those of Europe, North America or New Zealand. Given the dryness of Australia's climate south of the nineteenth parallel, one could argue ten times Northern Hemisphere prices as more reasonable.
The trouble is that in a free market any increase in prices would fail to disturb the enormous economic advantage Australia's farmers have. In a free market, entrepreneurs would know they could gain much by building a pipeline from the relatively well-watered portion of the continent north of the nineteenth parallel to allow farming on the dirt-cheap land in southern Australia. It is indeed very easy to see that this – or large-scale desalination – could be the way the world feeds itself unless people see an ecological duty to not eat Australian-grown foody.
The consequence of reversing a natural hydrology typical of the Mesozoic rather than the Quaternary, however, will be drastic for all Australia’s freshwater and terrestrial systems. Even those that survive man-made global warming will be destroyed if all the water from the well-watered north is turned to irrigate the arid south. How the northern rivers’ ecology would change from such moves is not known, but it would be very likely to destroy most species who are adapted to the extreme climate of the drought/flood tropics.