Before I read the new Sustainable Cities Index published by ARCADIS, I gave some thought to how I would put together a sustainable cities index. (Disclosure: I work in the same industry as this company, but have no affiliation with it.) Here is what I would try to do, at least for the environmental component (I haven’t given much thought to the social component):

• Estimate the consumption (food, water, energy, and materials) of people in that city. Also estimate the waste produced – solid waste, air emissions, and water pollution – that is not recycled in some way.
• Try to figure out roughly where this food, water, energy, and stuff came from, whether from within the city or without. Figure out the impact on soils, water bodies, the atmosphere, and natural ecosystems of producing all these materials. You could try to express this in land terms, energy terms, dollar terms, theoretically even information terms – there is no best or perfect way, although “ecological footprint” in terms of land is possibly the most intuitive.
• Figure out, if everybody on Earth lived in cities exactly like a particular city, whether the Earth could support that indefinitely, and what the ultimate state of the remaining natural ecosystems would be.

By doing this, you would have an absolute benchmark to compare any city against, rather than just a relative benchmark to compare cities to each other. The problem with a relative benchmark is that it doesn’t tell you whether your best cities are good enough.

A possible variation would be to attribute impacts to the city where a particular corporation or industry is headquartered, rather than where the demand is. Let’s say a particularly unsustainable, sprawling development pattern is built in India, but is designed by a firm based on Singapore, or Geneva, or wherever. Or people in a city with very clean air and water eat food grown on plantations owned by corporations headquartered in the city, but grown in recently burned-down rainforests overseas. You could assign all or a portion of the blame to the designer or owner rather than the people living where the impact is actually occurring, who may not always have had much of a choice.

Now, let’s see what ARCADIS did. I don’t mean to be too critical – good for them for doing something and giving people something to think about, which is more than most companies do.

The People sub-index rates transport infrastructure, health, education, income inequality, work-life balance, the dependency ratio and green spaces within cities. These indicators can be broadly thought of as capturing ‘quality of life’ for the populace in the respective cities.

The Planet sub-index looks at city energy consumption and renewable energy share, recycling rates, greenhouse gas emissions, natural catastrophe risk, drinking water, sanitation and air pollution.

The Profit sub-index examines performance from a business perspective, combining measures of transport infrastructure (rail, air, other public transport and commuting time), ease of doing business, the city’s importance in global economic networks, property and living costs, GDP per capita and energy efficiency.