One of the hallmarks of western “civilisation” is our belief that we can master the forces of nature through the power of reason. Ever since our ancestors first gathered in cities about 6000 years ago, they believed that engineering know-how would make us less vulnerable than those in the hinterland. But at certain moments this belief seems like hubris.

We saw this last year when the bushfires burnt right over small towns and singed the edges of cities, and as COVID-19 shut down urban life as we know it. And we saw it again this week as floodwaters from the Hawkesbury, Nepean, Hastings, Macleay and other great rivers inundated low-lying houses and washed some away.

The flooding illustrates what Aboriginal people have long known: that the European idea of the river, a body of water flowing steadily and obediently between two banks, does not adequately capture the Australian watercourse that can turn so quickly from trickling stream to vast floodplain.

The extreme weather associated with climate change has thrown into question the way we build our cities. The 20th century template for urban growth, of the steady, confident march of detached dwellings to the horizon, is unsustainable. We need a moratorium on greenfield residential land releases, particularly in places vulnerable to river and sea water, and to fire.

In recent history, Sydney – the nation’s most densely populated conurbation – has made some progress in this direction. But the bar is not particularly high and by the standards of most European and Asia cities, we are still highly dispersed in our carbon-hungry lifestyles, too reliant on our cars, on air-conditioners and too enamoured with our right to houses with private gardens.

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Despite all the talk about remote work over the past year, the flight of the sea and tree changers, the astonishing auction clearance rates in recent weeks demonstrate we have resumed the pattern of population centralisation that has been in place since the industrial revolution. With a few exceptions such as post-industrial Detroit, most big cities are not going to depopulate rapidly.

The challenge is to manage urban growth sustainably. The Cumberland County Plan adopted by the NSW government in 1951 laid out a Sydney surrounded by a green belt, as had London’s Abercrombie Plan. But, unlike London, which retains the green girdle intact, ours was largely carved up from the late ’50s by venal politicians and developers.