bluesyemre

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).

http://www.theguardian.com/cities/2015/apr/02/where-is-the-worlds-greenest-city-ecofriendly