I’ve written before about understanding the importance of selection bias before attributing significant behavioural influences to the physical environment. More often than not, it’s the characteristics of the people that explain more about their behaviour than the type of neighbourhood or housing they live in.
The Australian Conservation Foundation’s well-known Consumption Atlas illustrates this point well. The ACF estimated the per capita environmental impacts of household consumption at the statistical local area level by matching household expenditure patterns with an input-output analysis for various categories of goods and services.
The research turned up some surprising results for the city centre and the inner city. There’re many reasons to suppose inner-city populations would have a smaller negative impact on the environment than other Australians, especially compared to suburbanites living in large detached houses with two-car garages.
After all, the residents of inner-city Paddington, Northbridge and Fitzroy tend to occupy small apartments, townhouses and terraces and have tiny gardens. They live in relatively walkable, mixed-use neighbourhoods and have ready access to public transport. On average, they also have lower rates of car ownership than middle-0 and outer-suburban residents.
Yet the ACF’s research shows inner-city populations have the largest adverse impact on the environment — and by a considerable margin — of any group in the country. For example, per capita GHG emissions average 20-22 tonnes in metropolitan areas in Queensland and 15-17 tonnes in rural areas. Yet in inner-city Brisbane they average 28-32 tonnes per capita.
Ecological footprint for Sydney (source: ACF)
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In NSW, the areas with the highest per capita ecological footprint are in the inner city, especially around Sydney Harbour. In Victoria, the highest per capita water consumption is in the inner city and inner suburbs — the biggest water wallys live in Prahran and on the edge of the CBD in Docklands and Southbank.
The fact is the green benefits bestowed by the physical characteristics of the inner city are nullified — the ACF actually says “overwhelmed” — by two key attributes of the population that chooses to live there.
The first attribute is wealth — inner-city residents are richer on average than other Australians. Income is very strongly correlated with environmental impact. Wealthier people buy more “stuff” such as food, furniture, electronics and clothes that has a high direct and indirect negative impact on the environment. They fly a lot more than others too, both for work and leisure.
“While high-income households spend more on high-cost, low-impact activities such as entertainment and other services, they also spend more on electricity and most other categories of goods. Some activities with high greenhouse impacts, such as air travel and construction and renovation, tend to be concentrated in high-income groups.”
The second attribute is household size — inner-city residents live on average in smaller households, mostly of one and two persons. Their per capita environmental impact is consequently large because they don’t take advantage of economies of scale.