I agree with you Curmudgeon that 25% figure is too round and too big to be credible.

Our PM says he makes no apologies for a big Australia. He takes the position that bigger is better and what makes his position so easy for him is that he does not need to the change the decades long immigration policy mix of skilled migrants (the vast majority), and the smaller inflow of refugees and family /spouse / interdependent and sporting sponsorships.

Migration policy will remain on auto-pilot until we have political leaders who are prepared to call for economic modelling on the real inter-generational cost and examine the sustainability of perpetual population growth. Don't be surprised if that bell shaped curve emerges to reveal we are heading the way of other civilisations that overpopulated and collapsed.

Skilled migration is something I know a little about. For three years my company had a contract to place overseas qualified professionals into jobs. These were highly trained people often with a double degree and post graduate qualifications.
The first thing to bear in mind with these sort of professionals is that they need to be in continuous employment so that they have ongoing access both to the professional literature and to the latest developments - whilst a three month hiatus may be fine the vast majority of people that I dealt with faced a wait of up to three years before they could even begin to apply for the jobs for which they had trained. By that time they were no longer competitive in the job market. Thus the only job I could secure for a highly qualified surgeon was that of chicken boner. Most of them ended up working as taxi drivers or in various unskilled occupations. Whilst I have been out of this area for 10 years my former colleagues tell me that nothing much has changed - only about 10% of the overseas qualified professionals end up working in their area of expertise.
There is research showing that migration as with all population growth has associated with it a net cost to the whole community but of course that destroys the myth. (Ironic that labor should be pushing for it - the fewer people the higher the wages)

Curmudgeon - I don't think anyone on this thread has claimed that the government is actually spending 25 percent of GDP on infrastructure. However, as I read the original article, it was said that in order maintain infrastructure at an adequate level, that is what would need to be spent. Successive governments have failed to do this, and now we are seeing the consequences. One only has to look at the repairs to the Melbourne rail lines which have been carried out by the new operator since taking over late last year, to realise the truth of this.

As the preface to Jane O'Sullivan's article has so aptly said,
"Population growth is a virtually insurmountable challenge".

David

An excellent article. I think about the only aspect of population growth that hasn't been mentioned, is that virtually all that growth will occur in our cities.
Sadly, none of our cities were built on useless desert, or non arable land; although that is the inevitable result.
At precisely the same time that our population grows, our capacity to grow food diminishes.
From Parramatta to Penrith, Liverpool to Luddenham, Sydney has swallowed some very fine farmland, and converted it into quarter acre blocks.
In my memory, Port Macquarie (NSW) has gone from an 'exporter' of meat, vegetables and dairy products to a net importer, as it's magnificent red soil (great for veggies, mongrel stuff on yer boots) is buried under tar and cement.
Someone earlier mentioned how low Oz's population density is.
If only we could move Canberra to the Simpson desert...
And worry about communication channels later.

One point not raised is the hugely inflated infrastructure cost in times of high population growth. The billions of dollars squandered on water infrastructure in SEQs recent water crisis, some of very poor quality, is a good example. And when government turns to the private sector the public will get slugged for about six times the cost. Of course, without the population growth there would have been no water crisis and no need for toll roads.

Australia is now enjoying a period of high commodity prices. Perhaps the demands for mines and mining infrastructure could provide a means of moving away from all the population growth dependent industry. It would be a shame to squander the opportunity.