You are right, Ludwig. It is even harder to imagine India or China, with more than a billion people each, quaking in their boots because we have 35 million or even 50 million people rather than 20 million.

Cohenite,

Mark O'Connor merely made those maps available on his website. They are the work of Dr. Chris Dixon of the CSIRO. I am surprised that a CSIRO scientist and the US Department of Agriculture should be considered to "have no pretensions to science". The US rainfall map is from Wikipedia, but average rainfall is hardly controversial. As for sustainability, soil resilience is ranked along with soil performance in the US Dept. of Agriculture map. There is no point in developing land if what you intend to do with it will wreck it in a few years and reduce or eliminate its value for its previous lower intensity use.

Desalination plants are very expensive and prodigious users of electricity. Costs vary, but generally it is claimed that desalinated water is 4 to 6 times as expensive as dam water. See for example

http://www.theage.com.au/business/water-waste-of-our-dam-money-20081116-685h.html

The newest plants are more efficient, but electricity is also getting a lot more expensive. They might be worthwhile for coastal cities, but the energy costs of pumping the water inland would be prodigious. Remember that about 70% of the water we use is for agriculture.

There's another one of those pesky elephants in the room.
If you fly over the eastern areas of Qld at certain times of the year, you'll see thin long verdant corridors of irrigated land lining the rivers, where everywhere else is brown and dry.
Yes, water is essential to agriculture, undeniably so; but the recent drought demonstrated 2 things very clearly.
Firstly, it showed just how unreliable our river systems are. If we had been totally reliant on these rivers and the resultant agriculture, many would have starved.
The second point is much more interesting. Many farmers during the drought, were restricted to using no more than 2% of the water quota they had paid for. The vast bulk of the available water was diverted to keep the people of Brisbane and the SE corner happy and wet.
And after all these urbanites had used this water, where did it go?
The most certain, most reliable -and nutrient enriched!- supply of water is not from rainfall or from rivers.
It's not in the Far North, thousands of kilometres from the major markets.
It's already where the bulk of the population lives.
Instead of looking for more water to waste, why don't we just use the water we already have?

Why is it so many fail to look beyond the tip of their nose when contemplating future prospects and development? Some other countries plan decades or even centuries ahead, while we generally look only to the next election or two.

The Ord River Scheme and the development of agriculture around Kununurra are massive success stories. So what if the relevant infrastructure may never be fully paid for? They will continue to be productive for the long haul, and offer a productive model and base-point from which to plan and implement future effective expansion. Why? Well, whether AGW predictions are correct or not, the capacities and future potentials for the southern agricultural areas (MD Basin, Murrumbidgee Irrigation Area) are finite and relatively limited, and, whether we like it or not we will have to increase our future food production if only to maintain GDP as our mining boom becomes a trickle.

Short sighted? Because Oz failed to go into debt to develop our mineral resources, most of the returns therefrom have gone to foreign investors, with Oz settling only for modest royalties. We didn't sell the farm, we just rented it at an extraordinarily cheap rate. What are we doing now? Selling the productive capacity (which could well be massive food-production capacity) of Cubbie Station to foreign interests - because we are hooked on foreign investment. Are we so timid and uncertain that we cannot risk doing something big for ourselves? Next stop is the Tasmanian Dairy industry - the processing side is already sold, so why not the farms as well?

One day we may be looking at renting all of our productive capacity from various foreign investors - share farmers in our own land. Now that's a future it should be worth avoiding, even if it costs a few bucks and some hard choices along the way.