Cities are just one aspect of a civilisation. Societies across the world collapsed after a massive volcanic eruption in Indonesia circa 630 AD heralded the well-named dark ages. Access to cheap energy which with today's technology is principally carbon based (of which fossil fuels are only part, refer the work of Thomas Gold The Deep Hot Biosphere) - but which in future will be nuclear, hydrogen or electromagnetic based, is our only defence against the gargantuan forces of nature. As Lang Hancock observed, 'eco-nuts - let them freeze in the dark'. When are we going to get real and stop the nonsense of pretending we can change the climate by restricting production of a trace gas in the atmosphere, life enhancing carbon dioxide? When are we going to get rid of complex tax laws which inhibit creativity and innovation?

John McRobert

Interesting article Edward. But I feel that something major is missing.

You talk of overstretched infrastructure, but you haven’t even alluded to continuous population growth as being in any way a factor.

Surely it is, in at least some ancient cities, and very much so in today’s declining metropolises.

It is rapid population growth that stresses infrastructure. This is surely a critical point.

While the climate may change, energy may become more expensive and hence the whole economic regime may change, it can only be made worse by heaping more and more pressure on the whole infrastructure and services system of a city via continuing population growth.

If populations stopped growing in stressed cities, then surely there would be much more available funding and human energy to be put into the repair and upgrade of overstressed infrastructure and services, rather than into building more and more new I & S for the ever-growing population.

And as the climate changes and energy becomes harder to obtain or more expensive, smaller populations will be easier to sustain, whereas larger population centres would be more inclined to fracture, suffer in-fighting, breakdown of the rule of law and general collapse of society.

Today New Orleans, tomorrow the Netherlands!

The trouble with the whole "densification" movement is that its proponentsa are not talking about dismantling the suburbs and moving people to a denser centre. Densification is just being used as an excuse for continued population growth. But the main reason cities need "infrastructure" is to bring in resources (i.e. food) and to remove wastes (e.g. sewerage). Since only a finite amount of food can be grown per hectare, as a city's population increases the area of land that must be devoted to growing food for it increases and the energy and infrastructure requried to transport that food to the city (and flush away the wastes) also increases. So ultimately, densification does not make a city more sustainable. In fact, it makes it less so since the large a city the more energy per capita its inhabitants require (see http://www.energybulletin.net/stories/2012-07-23/spatial-emergy-concentration-and-city-living )

The primary constrain on survival of a city is its food supply:

http://www.onlineopinion.com.au/view.asp?article=12863

Today New Orleans, tomorrow Cairns!

It is a wonderful sunny winter's day here in north Queensland.... but this regional city is precariously built on very low-lying land and is prone to total wideout by a cyclone-generated storm surge or a relatively small sea-level rise.

John McRobert has it correct about taxation. We've taxed labour and capital to a standstill because tax regimes repetitively favour the creation of enormous real estate bubbles.

Mason Gaffney has provided deep historical insight into how strong political leaders used land value taxation (LVT) to regenerate US cities - http://thedepression.org.au/?p=11491 . The facts can't be disputed, but where are our political leaders and town planners on LVT and urban renewal?