WHY indeed ? ? ? ? ? ?

Stop all immigration now. Hunt down people here illegally and send them packing. Don't vote for any politician who supports immigration.

Neatly reasoned questioning, Kevin. One of the essential components of an increased population is space - space to live, space to relax, space to grow food.
We should also realise that a bigger population means a larger domestic economy - our goods and services thus gain a far larger market than at present.
I guess one of our inhibiting factors may well be cultural. We've grown accustomed to living in this 'wide, brown land' and the idea of a larger population living in it with us could fill some with dismay.

One possible policy consideration could be to incentivise rural living expansion by allocating worthwhile taxation concessions for those who choose to live outside of existing high density cities, whether simply as residents and consumers, or to set up businesses.

With this would flow the critical infrastructure expansion of things such as transport, power and water supplies, hospitals, schools and universities, and resulting commercial ventures based around the support of local economies and lifestyles.

Many of our migrants come from densely populated parts of the earth; it just may be possible to market a less crowded, freer lifestyle whilst still retaining close cultural bonds.

>'Has anyone in the "high immigration" tent perhaps wondered whether the current disastrous drought across much of southeastern Australia might not presage early signs of climate change and compromising of the country's future physical "carrying capacity"'

Of course. But carrying capacity is not fixed. The limits to what we can produce are economic not technical.

>'A lot is said about a larger population being necessary for economic growth? But is that the only drumbeat to which a civilised society should march? What about residential liveability, social cohesion and inclusion, quality of life, environmental quality, etc?'

Yes, these are all important. But they can be achieved whether or not we have high population growth.

>'We are told Sydney and Melbourne are on the path (principally through immigration) to population sizes of around 8 million. How likely is it that an addition of 3 million people to both cities will make them better places to live? Some people undeniably look forward to those mega-city developments. But many certainly do not.'

I remember seeing on TV Dick Smith lamenting Balmain not being how it used to be. And I thought: so what? If you want to live somewhere resembling a country town, we have plenty of actual country towns available! And so it is with our big cities: they will get bigger, but there will be plenty of alternatives available.

Unless we limit couples to a maximum of just two children, the population will continue and possibly double in the next fifty years, Even as many jobs are replaced by automation! Including many white collar jobs.

Our cities are already too full for their infrastructure and our arable land and water is both limited and shrinking via desertification. This is bite bullet time.

Decisions cannot be endlessly deferred or kicked down the road because they're hard or politically unpopular.

We could accommodate five-six times our present numbers if we built an inland canal to guarantee viable water and irrigated arable land.

The key and an essential is ultra-cheap energy. That cheap, clean, safe energy is MSR thorium!

Typical muddling backbiting politics won't do anything but worsen the situation. And none of our current visionless self-serving pollies are up to the job!

Can't even say nuclear, so instead, say technology agnostic. And then only if we can get some tax avoiding, price gouging, profit repatriating foreign firm to do it for us?

Or maybe we should just throw our hands in the air as the climate worsens, our food production becomes parlous, and we hit our mineral peak.

As our hopeless leaders forever blame shift or max out the credit card, as their only (allowed) response!

Let the cattle starve and the fruit rot on the ground as the other crops wither and die as we wait for rain or a leader with the imagination and testicular fortitude to take on the unavoidable challenge!

And a hopelessly divided Australia, will never ever hold them to account? Until it's way too late! Go figure?
Alan B.

The homeless population isn't large enough yet and need to double or treble to put downward pressure on wages? As well a send real estate prices skyrocketing through the roof!? And we haven't got enough Professors driving taxicabs or Ubers yet either.

Perhaps if things are just allowed to drift toward some lowest possible common denominator and the lamebrains start blaming this or that ethnic community, the Chinese can just walk in and take the joint over.

Who'll stop them? A nation divided against itself and by deliberate design for base political purpose?
Alan B.

Fascinating article! Thanks! Thirty-five years ago when I came to Brisbane, the population was 750,000. Now it is just over 2,000,000 with projections for another 2,000,000 in Southeast Queensland over the next 20 years. Given the expansion of infrastructure, Brisbane has coped rather well, and I think it will continue to do so. I expect that over the next two decades the corridor of open spaces between Noosa and the Gold Coast will continue to close up as more and more land is developed. To cope with such development, town planners will have to seriously expand transport and traffic flow by increasing appropriate roads, rail links, and other necessary infrastructures that will make life in such developing suburbs comfortable and pleasant.

Of course i am talking about a tiny part of Australia - one that is well geared to accommodate a doubling or tripling of population given appropriate planning. IF this can be extrapolated across Australia, it may very well be possible to envisage a population growth with 100,000,000 by the end of the century.

The only know population component that we know is going to fall dramatically is our natural growth as our actual number of deaths doubles. That is what happens 80 years attest a baby boom, a death bust.

Anyone who is silly enough to think the Johnny come lately bunch are going to be happy, or even willing to pick up the burden of aborigines & old age pensioners is soft in the head. The Africans & middle eastern mob are here to collect welfare, not pay for it for the existing population.

The Asians are willing to study & work hard, & take over many lucrative professions, but Asia doesn't have a tradition of tax payer funded old age support, & will not support it if they can avoid it.

Once these people, with their influx & rapid breeding get enough political clout, watch out oldies & aborigines, you'll be for the high jump.

"We could accommodate five-six times our present numbers if we built an inland canal to guarantee viable water and irrigated arable land."

WHY ? ? ? ? ? ?

"if we built an inland canal to guarantee viable water and irrigated arable land."?
Wot!....and give up watching the footy, downright blasphemous
Come to Australia and learn how you can have your rights without responsibility and get reimbursed for it.
Wonderful word 'if'...two letters that have the potential of changing the way one views the world and your neighbours.
If I were,... if he/she was...immeasurable potential....if they weren't intellectual pygmys....yep a real game changer.
and how is it that when speaking of colonization, which was obviously British, it becomes European in negative aspects but reverts to British in the positive and to para quote Churchill 'England is British not European'
History according to the Anglo Saxon/Celtic
The political claim is that when the Aborigines ware being massacred it was by the Europeans, but the law,the permissions and majority of white populace was English. Aboriginal artifacts, bones relics ended up in England.
The American Indians had it pegged well, white man speaks with forked tongue meaning 'two faced and without honour' and unfortunately the rest of the world has caught up in the art, to the point where the law has become somewhat irrelevant and societies are reverting to 'the quick and the dead'
The wheel turns , maybe ever so slowly, but turns nevertheless and Anglo Saxon political predominance is coming to a conclusion and will be replaced by a predominant Asian/Chines,e for a time yet to be determined. The art of being two faced is here to stay.
Australians on the whole work hard to do what has to be done in an effort to avoid what needs to be done.

All of the population boosters here should take a look at some of the World Bank's statistics. Most of what isn't desert in Australia is semiarid range land that might feed a scattering of sheep or cattle in a good year. Problems of insufficient water are compounded by poor soils and ferocious evaporation rates. Only 6.2% of Australia is arable, and the average quality of that arable land is very low by European or North American standards, as is clear from the World Bank's tables

http://data.worldbank.org/indicator/AG.YLD.CREL.KG

Total grain production is a good indicator of ability to feed people because grain is the direct or indirect source of around 80% of our calories. If you multiply hectares of arable land by average grain production, you can see that France can feed around a quarter to a third again as many people as Australia in most years, even when we are having a good year and feeding around 60 million people. Our production is cut in half in a drought year, and 8 or 9 year droughts are not uncommon (Federation drought, Millenium drought). We also have severe problems with land degradation (sacrificing tomorrow's production for today's).

Letting safety margins get too thin is profoundly foolish. What really killed or forced out all those people in the Irish Potato Famine wasn't the late blight. It was that so many people were living on plots of land that were too small to feed a family on anything but potatoes.

To Divergence- Good point