Is Darwin really Australia’s most sustainable city?

So, who knew intuitively that Darwin and the Sunshine Coast are Australia’s most sustainable cities? These startling revelations are from the Australian Conservation Foundation’s newly released Sustainable Cities Index, which examined the country’s 20 largest cities across 15 indicators. Our least sustainable city is Perth, closely followed by Geelong.

And contrary to The Age’s headline that “Melbourne trails in sustainable cities index” and “pales in comparison with Darwin and Brisbane”, Melbourne is the 7th most sustainable of the 20 cities studied (Brisbane is 3rd).

I’ve previously looked at the inappropriateness of the Mercer and Economist indexes as measures of a city’s liveability and I think the ACF’s index is less useful. It seems to be more about publicity than useful research – a feeling reinforced by an absence of technical information on the methodology. It’s actually not an environmental sustainability index per se, but rather a mish-mash of environmental, quality of life and resilience indicators.

It includes indicators like subjective well-being, the rate of volunteering, unemployment levels and the proportion of the population with type 2 diabetes.

I’m sympathetic to the argument that sustainability connects deeply to other facets of life – as the ACF puts it, it’s about learning to live within our environmental means while maintaining social cohesion and liveability. But the fact is most readers of the newspapers that reported on this study (see here and here) think of sustainability as a largely environmental concept. I agree with them – there’s a danger that stretching the term to include liveability measures will ultimately devalue its usefulness and render it virtually meaningless. It would be more sensible to have two or three separate indexes rather than one.

Notwithstanding the confusion about what it’s intended to measure, does the Sustainable Cities Index approach its task in a sensible way? Straight off there are some worrying methodological issues.

First, there is no weighting of the 15 indicators – they are all of equal value. So, the level of education of a city’s citizens, for example, is just as important as their ecological footprint in assessing the relative sustainability of different cities. This is a major shortcoming. A handful of key variables usually account for most of the variation when studying social phenomena, so why would we expect this to be any different?

Second, the range of differences on some indicators is very small. For example, Darwin ranks second best on subjective wellbeing with a score of 76.6 whereas Perth ranks third last with a score of 74.3. Melbourne ranks fifth worse on public participation with only 12.6% of residents volunteering in some capacity, compared to the top city, Bendigo, where 17.5% of residents volunteer. These are small differences and the case isn’t made that they mean something, yet they feed into the overall score with the same weighting as other indicators.

Third, some of the measures are highly questionable even allowing for the inevitable simplification forced by the use of an index. Population density, for example, is used as a measure of quality of life – the higher it is, according to the report, the higher the quality of life. However anyone who’s followed the current population debate knows that there’s no consensus that higher density is better.

Many Australians, probably most, think density is bad – higher costs, higher congestion, more social conflict. The Premier knows what the polls are saying and announced a plan on the weekend to channel more growth to the regions as an alternative to further growth in Melbourne. I like density but I’m not falling for the idea that everyone else necessarily does.

The ACF seems to use density as a measure of accessibility to services like schools and medical services. It would be better to use a more direct measure that, for example, estimates the number of services available within a defined travel time, or simply use the average time it takes by different modes to get to key destinations like work.

Fourth, some of the indicators, notably the number of farmers’ markets and the number of green building projects, are simply out of scale with the other indicators which are mostly much more strategic. In regard to buildings, it would be preferable to use a much broader measure such as the environmental efficiency of all new buildings.

Overall, this isn’t a good index. It’s too unfocused about what it’s measuring and methodologically it’s made some bad choices. Darwin can get off the stage and Perth can relax. It’s hard to escape the conclusion that it’s much more about getting publicity than about adding to the body of knowledge. Coming from an institution like the ACF, that’s disappointing.

PS: in light of my comments yesterday, it’s good to see that both the hard copy and the online editions of The Age ran this story with a link at the end to the ACF’s report – we need more of this.