Going for broke: the real impact of cities on the climate

Cities have been known to be responsible for over 70% of global greenhouse gas emissions. But a report by C40 Cities suggests that the impact has been underestimated: if urban consumption (and not production) is considered as a primary measure of emissions, the footprints of many cities would be 60% higher than previously estimated.

Evaluations of urban climate impacts usually focus on greenhouse gas emissions within a city boundary but ignore the impacts of consuming goods and services that have been produced elsewhere. The report takes a new stance on this issue by considering the impacts of consumption and trade on greenhouse gas emissions across 79 global cities.

The formula is simple: take emissions produced locally, subtract the ones exported with products and services, and then add the imported ones. The authors say that almost two-thirds of the consumption-based emissions come from supply chains, which highlights the importance of local actions on global supply chains. For example, officials can choose to source less carbon-intensive products through public procurement policies, while citizens can buy carbon-neutral products and services and make other effective choices to lower their climate impacts.

And, as the study shows, those choices really matter a lot.

“By revealing the scale of emissions generated by the urban consumption of a range of everyday goods and services, including the food on supermarket shelves, air travel or online shopping and home delivery, consumers and policy makers can make better informed decisions about the impact their choices are having,” says Mark Watts, executive director of C40 Cities. “Mayors need accurate data and scientific advice in order to make good policy decisions. This new research will help city policy makers to better understand the true impact of their city on global climate change, and so play an ever bigger leadership role in delivering climate action.”

The situation is particularly grave for “consumer” cities like London, Paris and New York, who have over three times higher consumption-based emissions, as compared to standard estimates. According to Mark Watts, it is because of their choice to outsource production to other parts of the world. The burden is however layed on the “producer” cities, concentrated mainly in Asia and Africa.

Meanwhile, this doesn’t leave the “consumer” cities unscathed as they depend heavily on products exported from parts of the globe, which are often the ones most vulnerable to climate change.

The authors think that turning to consumption-based impacts can help people understand the real price of their choices. That could inspire them to become more mindful consumers and more responsible citizens. The report also places special emphasis on collaboration as only through joint actions regarding both consumption and production can we avoid displacing responsibility and meet the real impacts of climate change face-to-face.