It's been an unfortunate iron law of the modern era that greenhouse gas emissions grow at the same time that economies do. The higher the standard of living in a country or metro area, the larger, per capita, its environmental footprint becomes. In practice, this means that wealthier economies trade foot traffic for cars, small homes for larger ones, local travel for airplane tickets, small-scale industry for major manufacturing, and homemade products for cheaper goods produced half a world away.
Research has shown that if you know a country's GDP, you can pretty accurately estimate its carbon emissions. There's "almost a mechanical relationship" between the two. And as a depressing corollary: Emissions rise much faster in good times than they fall during, say, a global recession.
Cities in some parts of the world are already doing a substantially better job at decoupling these two trends than others, wringing the most wealth out of the smallest carbon footprint. These are the cities that produce the greatest amount of GDP per ton of greenhouse gasses emitted. The Carbon Disclosure Project, along with AECOM and the C40 Cities, have calculated this "economic efficiency" for dozens of global cities that participated in a questionnaire on how they are preparing for climate change.
The full report argues for how climate action can help make cities healthier and wealthier at the same time (as they save money on LED light bulbs, or expand bike lanes that also get people active). But what's most interesting is the below graphic, which underscores how cities need to be thinking in a fundamentally different way about their economies. The goal can no longer be mere economic growth. Instead, it should be efficiency, a metric on which European cities are outclassing virtually everyone else:
These are the cities included in the above sample:
- European cities: Amsterdam, Athens, Barcelona, Basel, Berlin, Copenhagen, Greater London, Hamburg, Istanbul, Lisbon, Madrid, Greater Manchester, Milan, Naples, Oslo, Paris, Rotterdam, Stockholm, Turin, Venice, Vilnius, Warsaw, Zaragoza, Zurich.
- Latin American cities: Belo Horizonte, Bogotá, Buenos Aires, Cali, Caracas, Goiánia, Mexico City, Montevideo, Rio de Janeiro, Santiago, São Paulo.
- East Asian cities: Kaohsiung, Hong Kong, Taipei, Tokyo, Seoul, Yokohama.
- North American cities: Atlanta, Baltimore, Chicago, Cleveland, Dallas, Denver, Los Angeles, Miami, Minneapolis, Montreal, New Orleans, New York, Philadelphia, Portland, San Diego, San Francisco, St. Louis, Toronto, Vancouver.
The Asian sample obviously includes none of the burgeoning Chinese megacities, where economic growth and emissions are rapidly on the rise. But it's a worthwhile comparison to note that North American cities are producing substantially less wealth per ton of carbon emissions than European cities are. Undoubtedly, this has as much to do with the particular form of sprawling, car-dependent U.S. cities as the kinds of economies they have.