Green, Greener, Greenest–Which City? Says Who? And How?


The Clifton Suspension Bridge in Bristol, 2015 Green Capital of Europe. Photograph: Destination

This is one of the environmentally-oriented rankings that many of us think about, from time to time, and then throw our hands in the air in frustration at the criteria used for judging green-ness, or what is often green-ish-ness. Thanks to the Guardian for asking the questions we want answered when it comes to rankings like this:

Where is the world’s greenest city?

Bristol is the ‘green capital’ of Europe, but its predecessor Copenhagen comes top in a Europe-wide index. Curitiba, San Francisco and Singapore all have strong eco-friendly claims too – so what’s the best way to compare cities’ greenness?

It’s easy to say we’d like our cities to be cleaner and greener. But what does that even mean? “Greenness” is a concept that’s hard to pin down – there’s no official list of the top 50 most eco-friendly cities, nor any widely agreed set of measurements for working out how green a city actually is.

In the realm of environmental science, concepts such as biodiversity can be assessed using indicators that give a standard set of measurements – for example, the number of different species of birds spotted in a given area on a given day. But for greenness or eco-friendliness, the possible indicators are endless, covering everything from road transport to recycling.

In a 2015 study published in the journal Ecological Indicators, scientists based at the Lawrence Berkeley National Laboratory in California have fine-tuned a potential method for assessing Chinese “eco-cities” using 33 key indicators. So, for example, they propose to measure renewable energy usage by looking at the percentage of total energy purchased by a city that comes from renewable sources (not including nuclear).

Other “green indicators” in this study include the share of all “trips” made by public transport, and the daily average concentrations of air pollutants – plus a surprising number of social and economic variables, such as healthcare practitioners per 1,000 citizens and unemployment rates.


The study’s researchers have also reviewed other systems for assessing a city’s greenness, coming up with 14 international-level methods. But they conclude that, in essence, there is no good system. Measuring a city’s relationship to its environment, they write, is “complex” and “challenging”, and eco-cities cannot easily be compared.

(It should also be noted that, in general usage, the term “eco-city” is ill-defined, and that despite China’s plans to establish hundreds of them, it’s not actually clear what constitutes the status “eco”.)

In the absence of an accepted scientific indicator system, the EU’s Green Capital programme at least has a rigorous shortlisting process based on a technical assessment covering aspects such as biodiversity, green spaces and how a city deals with wastewater, noise and air quality. The programme, however, is limited to European cities and, furthermore, to those that actually apply for consideration – the most recent winners are Copenhagen, Bristol (the current incumbent) and, for 2016, Ljubljana…

Read the whole story here.

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