"Governments at all levels have neither failed to plan nor failed to spend on infrastructure."

That's rubbish. There's a clear upward trend in the data from 1960-87 showing Govt revenues as % of GDP was increasing during this time (from 21% - 35% to be exact) at which point it fell (due to recession), but then stagnated during the boom years '98 onwards - this is clearly discretionary. There has been an unambiguous trend downwards in govt consumption of fixed capital as a % of GDP from 1988 onwards. (based on ABS national accounts)

This is a completely expected result as the privatisation & deregulation era was rampled up considerably in the howard years under the guise of microeconomic reform. Certainly some of the change is cyclical, but the trends are purely discretionary - it's no secret that trends to a smaller govt has been prevelant over the last couple decades. Considering all this i don't understand how you can say lack of infrastructure is not due to lack of govt policy. It's plainly wrong.

"The future fund's $70 billion would only stave it off for a few months"

My point is not that $70 billion is all we need; but it is a significant amount of money that is not being used, it is an example of govt neglecting investment in our people and our economy at the present and crucial time.

"As for letting the private sector do it with funds from overseas, do you not think they expect a good return on their investment? Every Australian will pay for it, with interest. It would be much cheaper for us if government just raised taxes."

i agree wholeheartedly. But there is no link to population growth here. Like before, this is a by-product of our government deregulating capital markets, and relying increasingly on on the private sector to fill gaps.

" that's a pretty hard statement to defend"

Ok, I concede that point of NO net effect is excessive in a static system. But in a dynamic one where developing countries are industrialising and their citizens moving into the same consumption patterns as those of the west it's hard to pin down the aggregate effect. There are feedback loops, where migration affects climate change, but climate change also affects migration. But generally I see what you're saying, and I agree with you. All the more reason to reduce our per capita footprint. Ethically speaking you can't argue for Australia to remain some magical haven (fortress) where only its citizens are allowed to enjoy higher per capita emissions. And remember when we look at why we ought to preserve the environment, reduce our impact on it, and ensure its sustainability so future generations and other life can enjoy it too, we are speaking ethically.

"If emigration sustains high birth rates in the source country, as evidence suggests it does, then the extra pressure our environment sustains may stimulate even more pressure in the source country rather than less. "

A paper by Barnet & Webber "Accomodating Migration to Promote Adaptation to Climate Change" from University of Melbourne suggests that emigration can contribute positively by building financial, social, and human capital in source countries.
In any case it's well documented that fertility rates are in decline in the developing world except in places like sub-saharan africa. These are the places we should be focussing our efforts on population policy. Elsewhere population dynamics are already at play, our best efforts are spent looking at ways to reduce per capita impacts - and that is through govt interventions in planning, increased govt investments in infrastructure, general policy and regulation.

"Does population growth increase real estate prices? Why else do you think the property industry funds so many lobby groups and think tanks to talk up the need for population growth?"

Again I implore you to look at the data on this. population growth may play a part in real estate prices if you employ the dated supply & demand method that most economists use. Certainly population growth would create an upward trend in house prices ceteris paribus. But the significant rise in house prices in australia and the oecd (for rest of the oecd this has bubble has popped and house prices are falling) to the extent that most people can't afford to buy a home, that you and most people refer to, is overwhelmingly due to increased private debt caused by financial sector deregulation and govt policies NOT population growth.
I'll point you to Steve Keen again who's doing the most promising research on this atm. He cites only one case in the last 50 yrs in Australia where population growth exceeded growth in dwellings (from 06-10), and finds a negative correlation between population and house prices. That's not to say that the relationship is generally negative, but rather than population growth is not very good at explaining the huge rise in house prices.

"This is a longer story, that I may post at another time."
would love to read it

"But if we peak at or under 10 billion, it will either be because we come to our senses soon and put a lot more resources and political will behind reducing birth rates"

again, yes but specifically in sub saharan africa, based on world bank data birth rates in other developing nations are falling as they industrialise, and birth rates in most oecd countries are already below replacement rates (would suggest industrialising nations are on a simiilar path).

"As I tried to explain, without killing a lot of people those dreaded 'inverted pyramids' of demography"

we're already trending towards that in aggregate (minus aforementioned places which we both agree require more aggressive planning), i'm happy with policies that ensure we arrive at that sooner in aggregate. I.e. australia should simply keep an eye on fertility rates.

Where we need most of the work is on per capita impacts. That's how we're going to save this planet. Not by waiting for people to die off which is why the population debate takes up too much time and effort in most parts of the world.

" And I don't get why you can't see the connection between population growth and the amount of infrastructure spending we need. Calling this an investment is another fallacy, when it is merely the recurrent cost of maintaining services as population grows"

I'm not saying there's not a connection. I'm suggesting that infrastructure spending has not been in line with what we need irrespective of whether our population has grown or not. Ofcourse it's an investment - it's well document in the case of mass transit, for example, that higher population density increases the viability of mass transit and reduces per capita emissions than the current dream of having quarter acre blocks using cars as transport. So when you plan for the future by starting to build this kind of infrastructure now, you have returns higher than the cost of that infrastructure. That has is investment. That infrastructure then facilitates a whole myriad of interactions in our world that have returns far greater than the cost of that infrastructure. Your view of investment seems to be very narrow, like saving money in a bank for interest.

So higher population densities reduces per capita impacts, reduces urban sprawl. When you talk about keeping australia's population stagnant, or reducing it, are you suggesting this so we maintain our current lifestyle of having huge blocks of land such that per capita consumption of things like water remains high by comparison to many cities around the world?

" I don't know if you're confusing federal with total spending"

i'm not. I refer you to the National Accounts. I was using General Government gross income and expenditures, which encompasses spending at all levels of government.

"The Intergenerational reports put total govt revenue about 23% of GDP, from memory - certainly nowhere near 35%. "

I said it peaked at 35% in 1987...where it stagnated and then unambiguously declined from 1998 to where it is now. check the ABS key national aggregates.

"On housing costs, I think you are misquoting Steve Keen....The speculative bubbles burst as soon as population growth eases"

Here is a direct quote from Steve Keen with no editing.

"Population dynamics gave spruikers a good story, but it wasn’t what drove house prices up.
What did instead was debt. Demand for houses is not population increase: it’s people with new mortgage loans. When you look at the relationship between new lending and the change in house prices, you finally start to see some serious long run correlations (as long as the data makes possible, anyway). The correlation coefficient here is 0.53—rather better than the minus 0.06 that applies between change in population per dwelling and change in price over 1975-2010—and it improves when the trend of rising mortgage new debt to GDP is removed. So we’ve had a debt-driven housing bubble, just as has the USA, and it’s the dynamics of debt that will determine when and how it bursts—not demographics."

That was Steve Keen. I did not misquote him.

"you leap on me for merely suggesting that persuit of rapid population growth is not a good idea"

I suppose I do that because there is an ethical need to distinguish between population growth that arises from births, and that which arises from migration. Migration does not change the population level in the aggregate.

"Australia has a moral obligation to the people and indigenous species and ecosystems of Australia."

Certainly, but Australia, its people, its indigenous species, and ecosystems do not exist in a vacuum, and so its moral obligations also extend to the greater world as well.

I suppose what i'm taking from this is that the population debate is very complex; Let's talk specifically about Australia - I definitely accept that that trend for population growth needs to be falling (it can't continue forever). This will happen naturally, with an ageing population. But I don't see the need to alarmist calls for reductions in our population if we plan for it; by making systemic moves towards renewable technologies, better urban planning (stopping sprawl, stopping new communities of mcmansions springing up on the outskirts of cities, rather consolidating residential zones in the inner cities and fringes, and servicing them better). What this requires is government planning & investment in new infrastructure, and rebuilding old ones.

If we don't do this, but we do reverse population growth to maintain current standards of living in that way, our country will have taken on a serious moral deficit.

"If you believe that Australia's population will stabilize naturally, perhaps you are unaware that our growth rate doubled in the decade to 2009?"

yeah and then fell again sharply the following year. regardless, increasing the birth rate and immigration rate through govt interventions is not a natural increase in the population growth rate is it? so it would be safe to assume that in the absence of intervention that the population would naturally stabilise.

"Because we are working so hard just to tread water, we don't have the money for a transition to a low-carbon economy. "

do you have any studies that you can direct me to? I would love to read more about what you're suggesting - i.e. that population growth, and not govt policy has led to our infrastructure deficit, to the extent that we can't fund a transition to a low carbon economy.

I would contend that economic rationalism, selling off of public assets, downsizing of the public service, and increased reliance on "public-private partnerships, has led to our infrastructure deficit. ofcourse we have the money for transition. we just need to collect it and use it. It's estimated the infrastructure deficit is between $450 to $700 billion.
The federal govt's current fiscal position is solid. It could probably borrow at least 1/3 of gdp sustainably (if not more), $400-500 billion (US public debt is currently close to 99% of GDP). Without even getting to resource rent taxes/land taxes proposed by the henry review, not to mentioned How's that for a good start. Ofcourse "economic rationalists" and politicians have completely stigmatised public debt. The interest repayment is a small price to pay for the investment. And yes it is investment, because the it will facilitate activity that will create revenues greater than the initial cost. That said, investment need not only be measured monetarily.

re steve keen. Why don't i just give you the full link, and you have a read for yourself. I'm not misrepresenting him, however he states the argument and shows the supporting evidence clearer than i can.

http://www.debtdeflation.com/blogs/2011/02/10/a-motley-crew-interview-on-australian-house-prices/

"Aggregate impact can only be reduced by reducing the footprint of existing people, not by diluting them with more people, no matter how efficiently they live."

fair point. But Clive hamilton himself has suggested that it may be possible to achieve sustainable population growth in Australia while protecting the environment from its effects. He simply questions the political feasibility of the measures required. You can check this in one of his speeches on his website, I forget which.

The point remains it can be done.

"people who haven't even acknowledged that the main reason they need to move is overpopulation and whose emigration only perpetuates high birth rates."

you keep saying this. high birth rates is why we need to help these countries develop their standard of living. I'd be interested to see if you would back the Greens' population policy? In my eyes they're the only ones with such a policy. You'll notice it's more complex and nuanced than suggesting we stop all migration immediately.

"You seem very eager to admonish people for their lifestyle choice of a detached house and garden (even though this may in fact have a lower environmental cost than high density), but seem to think it's inappropriate to suggest to them that having more than two children has a cost to society and the planet."

I don't think that's innappropriate at all, I've never said that. I've tried to distinguish between birth rates and immigration this whole time. i.e. birth rates have a net effect on world population, immigration does not. so i'm fine with the latter only.

Why don't we pursue abolition of the livestock sector? it generates 18% percent of the world's greenhouse gas emissions, over 60% of anthropogenic ammonia emissions, grazing occupies 26% of the earth's surface, the list goes on.

the point i'm trying to make again, is that the focus on population growth suggests that it is the silver bullet. ofcourse this is important, there's irrefutable evidence for the use education and family planning in areas that aren't industrialising. No one is encouraging people in the developing world to increase their fertility rates! For true sustainability we need to change our consumption patterns, technologies. the focus on population growth re immigration suggests that it is also a silver bullet but for developed countries. That's fine, insofar as the citizens of that country see themselves as living in a vacuum, content to indulge exclusively in a bounty received out of chance. You suggest that depriving those not born yet of a lifestyle choice is not ok, while depriving the living as long as they are halfway around the world is fine?

but you're right, when we talk about this with regard to australia we're talking very small numbers. Which is why I find the dick smiths and the ross gittins' on sustainability unconstructive and unimaginative.