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Cities and urbanisation
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mikepepler
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PostPosted: Mon Mar 12, 2018 8:02 pm    Post subject: Cities and urbanisation Reply with quote

I'd be interested in people's opinions on the sustainability of cities, especially if there are reliable sources that can be referred to.

I've been reading a lot recently about how cities are potentially more sustainable than other settlements, because they can have public transport, people don't have to travel far to get to work/shop/pub/etc. And there's a push to make them even more densely packed, so people travel less.

For me, it doesn't quite ring true, partly because cities only survive because they suck in resources from the land around them, and also because research has shown they cause mental health problems for those living in them ( https://lsecities.net/media/objects/articles/urban-stress-and-mental-health/en-gb/ )

At best, I see cities as a necessary evil, that arise because of trade and other factors, but once they grow above a certain size no new benefits are realised.
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adam2
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PostPosted: Mon Mar 12, 2018 8:45 pm    Post subject: Reply with quote

IMHO, cities do not have to be any less sustainable than living in the countryside.
Public transport is almost always more sustainable than driving, and the greater numbers of passengers mean that public transport is more viable in cities. Walking is better still, many urban dwellers can walk to facilities that would be too far away for walking in the countryside.

Housing in cities is easier to make energy efficient than detached rural dwellings. A row of 3 story townhouses can be fuel efficient at lower cost than a detached home.

Food would have to be supplied to a city from farms elsewhere, but meat, milk, grain, and so on can be transported at little energy cost by rail, or even by truck. Grain shipped 100 miles by truck to a local bakery from whence the bread can be carried home on foot, is probably greener than that grain carried 6 miles in a car, and baked at home.
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woodburner



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PostPosted: Mon Mar 12, 2018 9:21 pm    Post subject: Reply with quote

Cities are not sustainable, unless you are going to be eating the local wildlife or take up canniballism.

Public transport is not sustainable. It is just seen as being less demanding per journey. Be careful though, where mainline trains are concerned, I doubt they are any less demanding than cars. When a coach weighs 35 tonnes and carries 40 to 60 people, that’s no better than a car can achieve.

The case for transporting food from the countryside to the city destroys the statement they not any less sustainable than living in the countryside. Stop the food supply and everyone follows the first paragraph or dies.
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clv101
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PostPosted: Mon Mar 12, 2018 9:25 pm    Post subject: Reply with quote

Depends a lot on what you mean by 'sustainable'. Was (ancient) Rome a city? Was it sustainable? Maintained well over half a million people for some 600 years. It wasn't using fossil fuels but maybe it was depleting surrounding topsoil?

Cities are as old as civilisation, as sustainable as civilisation?

Today's megacities do tend to deliver lower 'ecological footprints' than national averages, per capita (for many of the reasons you mention), but that doesn't mean they are 'sustainable'. In fact modern cities are not resilient at all - short term disruption to logistics or energy flows leave cities in a highly UN-sustainable state.
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PostPosted: Mon Mar 12, 2018 9:40 pm    Post subject: Reply with quote

Cities by themselves are not sustainable. They need the agricultural land and mines and industrial parks to provide them with all they consume. Then they need a transportation system to get those products to the city and that is why many ancient cities were on a harbor or river and Ancient Rome prospered after they invented hard surfaced roads.
What we might do away with is the suburbs which are just spread out non efficient housing which consumes a greater portion of resources then they are worth.
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mikepepler
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PostPosted: Mon Mar 12, 2018 9:41 pm    Post subject: Reply with quote

Adam - I agree with your points, though they do of course assume a fully functioning economy. But I'm kind of assuming that in the case of this discussion.

Woodburner - I agree, though the 'sustainable city' plans people propose tend to focus around walking and cycling more than heavy transport.

Chris - Rome was probably more sustainable than many cities today, but it was small. I think it's once you go above that 0.5-1 million size that the growth has more in common with a cancer than a healthy organism.

What I find particularly interesting is the mental health side of it. The proposals being bandied around would result in a restriction of personal space, both in private and public. I think when it's impossible to get away from people that can be stressful, especially for introverts (which I'm not, but Tracy is). There seems to be an idea that we can have millions of happy people in 'livable', 'sustainable' cities, but I'm not sure it's really possible. Many younger people I know who live in London have a plan to move out of there, and many older people (especially those with children) commute from somewhere more rural. There's also the loss of interaction with the natural world in a city, and I don't think the occasional park or green space is a viable substitute...
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Little John



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PostPosted: Tue Mar 13, 2018 12:40 am    Post subject: Reply with quote

Cities are not sustainable in a finite environment. Any system that consumes more than it produces in a finite environment is not, by definition, sustainable. The only pertinent question with any city is how long it can feed off the wider environment before its inevitable collapse. This may be centuries or even millennia long. But, in the end, collapse is inevitable.

Cities are the first form of complex civilisation. In a finite environment, complex civilisations are not sustainable.
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PostPosted: Tue Mar 13, 2018 12:49 am    Post subject: Reply with quote

Little John wrote:
Cities are not sustainable in a finite environment. Any system that consumes more than it produces in a finite environment is not, by definition, sustainable. The only pertinent question with any city is how long it can feed off the wider environment before its inevitable collapse. This may be centuries or even millennia long. But, in the end, collapse is inevitable.

Cities are the first form of complex civilisation. In a finite environment, complex civilisations are not sustainable.
If the wider environment can supply a surplus why would collapse be inevitable? The environment receives a constant input of sunlight so is not finite.
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Little John



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PostPosted: Tue Mar 13, 2018 1:50 am    Post subject: Reply with quote

That's why I said large complex civilisations (or cities). Additionally, a surplus does not come out of nowhere. A cost mus be paid for that surplus and this cost, is always, in the end, in the form of ecological degradation of the foundations on which complex societies are built. Soil, water and other key resources.

I have history on my side of this argument. The evidence is already in and it is more or less conclusive.
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mikepepler
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PostPosted: Tue Mar 13, 2018 9:17 am    Post subject: Reply with quote

I suppose the question is whether the city and the surrounding land should be considered as a system together? The city needs the countryside for food, energy, water, waste disposal, etc. But the countryside needs the city to supply it with manufactured goods, tourists to come and visit, etc.

But as I said above, what interests me is what you think the people living in cities will make of the proposed moves to make them sustainable (ignore the risk of societal collapse). Will these so-called sustainable cities actually be pleasant to live in, will people play along with the way they're meant to behave to make them sustainable?
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PS_RalphW



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PostPosted: Tue Mar 13, 2018 1:31 pm    Post subject: Reply with quote

Once the streets are cleared of unnecessary cars travelling at 30mph+ they can be recolonised as social spaces as they were until the 1960s, and walking will enable people to meet a far wider range of people, at least in summer months. A lot of the social stresses in city life are due to the noise and isolation, with families cooped up in small spaces for long periods.
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kenneal - lagger
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PostPosted: Tue Mar 13, 2018 1:46 pm    Post subject: Reply with quote

Very large cities are products of the fossil fuel age and are only sustainable with a large input of energy, either fossil fuel or large scale renewable energy. Cities rely on the fact that a large number of people can have their food grown by a small number of people. Once the massive energy input into the agricultural system is lost so is the ability to sustain a large numbers of people by small numbers lost.

At present the US and Australian food systems use 10 calories of fuel to produce 1 calorie of food and the European model uses 5 for 1 calorie of food. That is clearly unsustainable without a large source of external energy. I have read that one person can produce enough food for one and a half people, which I think on no evidence at all, I admit, is an underestimate. If anywhere near true it will require, when energy sources are limited, either that large numbers of people travel out from the cities every day to cultivate food, that a lot of people in cities starve or that very large cities depopulate.

Also, the manure produced in the cities is an absolute requirement for the growing of the food for those cities. That manure, historically, was carted out from the cities every night, night soil, to the surrounding agricultural land. If the cities are too large this become impossible. The energy required to cart food for long distances into the cities is also a big factor.

There is a dilemma in increasing the density of cities in that low density allows for food growing within the city whereas high density does not. There any many proponents of high rise farming who say that these buildings can provide large amounts of food within the city. The problem which arises is the amount of energy available to build them in the first place and then to pump nutrients up into these structures and get the food out. If the structure is large there is also the availability of natural light or the power to provide artificial light to consider. With careful design natural light can be used and the produce coming out can literally counterbalance the nutrients going in to an extent but it requires very careful management over time.

Overall I would say that small cities of maybe 100,000 to 200,000 people might be sustainable but anything over that isn't, long term, unless large sources of clean energy are maintained. Those systems would have to be in place long before any energy collapse came about and that is unlikely to be the case. Kunstler Report is a case in point.
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PostPosted: Tue Mar 13, 2018 1:47 pm    Post subject: Reply with quote

I suggest you look at some of the worlds most crowed cities. Singapore and Hong Kong to see where we are headed and the effects it has on people's mental health.
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kenneal - lagger
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PostPosted: Tue Mar 13, 2018 1:57 pm    Post subject: Reply with quote

Little John wrote:
That's why I said large complex civilisations (or cities). Additionally, a surplus does not come out of nowhere. A cost mus be paid for that surplus and this cost, is always, in the end, in the form of ecological degradation of the foundations on which complex societies are built. Soil, water and other key resources.

I have history on my side of this argument. The evidence is already in and it is more or less conclusive.


A recent UN report said that there are only about 60 harvests left in our soils at the current rate of consumption. The soils are being consumed by the "Green Revolution" which relies on a continual input of artificial nutrients, almost hydroponic farming, instead of the sustainable farming once used for the cultivation of those soils.

In my post above I forgot to mention the requirement to return to the soil at the end of our lives all the phosphorus locked up in our bones and the bones of all the animals that we eat.
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PostPosted: Tue Mar 13, 2018 2:47 pm    Post subject: Reply with quote

kenneal - lagger wrote:
Very large cities are products of the fossil fuel age and are only sustainable with a large input of energy, either fossil fuel or large scale renewable energy. Cities rely on the fact that a large number of people can have their food grown by a small number of people. Once the massive energy input into the agricultural system is lost so is the ability to sustain a large numbers of people by small numbers lost.

At present the US and Australian food systems use 10 calories of fuel to produce 1 calorie of food and the European model uses 5 for 1 calorie of food. That is clearly unsustainable without a large source of external energy. I have read that one person can produce enough food for one and a half people, which I think on no evidence at all, I admit, is an underestimate. If anywhere near true it will require, when energy sources are limited, either that large numbers of people travel out from the cities every day to cultivate food, that a lot of people in cities starve or that very large cities depopulate.

Also, the manure produced in the cities is an absolute requirement for the growing of the food for those cities. That manure, historically, was carted out from the cities every night, night soil, to the surrounding agricultural land. If the cities are too large this become impossible. The energy required to cart food for long distances into the cities is also a big factor.

There is a dilemma in increasing the density of cities in that low density allows for food growing within the city whereas high density does not. There any many proponents of high rise farming who say that these buildings can provide large amounts of food within the city. The problem which arises is the amount of energy available to build them in the first place and then to pump nutrients up into these structures and get the food out. If the structure is large there is also the availability of natural light or the power to provide artificial light to consider. With careful design natural light can be used and the produce coming out can literally counterbalance the nutrients going in to an extent but it requires very careful management over time.

Overall I would say that small cities of maybe 100,000 to 200,000 people might be sustainable but anything over that isn't, long term, unless large sources of clean energy are maintained. Those systems would have to be in place long before any energy collapse came about and that is unlikely to be the case. Kunstler Report is a case in point.

The port cities already have energy and transportation facilities in place and will carry on. Consider that New York had a population of 500,000 in 1850 and Brooklyn across the river 100,000. As transportation hubs they will always carry on. As to the food supply declining the food production sector is a small enough portion of our overall energy use for it to be given top priority (or second after defense) so starvation is a ways off yet. We won't be getting grapes flown in from Chile mid winter but we can adjust to that. If food shortages bite anywhere it will be in third world countries where population has outgrown food supply. An end to our exports to them and they are toast.
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