Cities are often blamed for exacerbating climate change, but their emissions of greenhouse gases vary widely in some surprising ways, reports a new study of more than 100 cities in 33 countries.
Cities in Nepal, India and Bangladesh emit less than half a ton of carbon dioxide equivalent per person per year while the highest emitters –Rotterdam, Denver, Sydney, Washington, Minneapolis and Calgary, respectively — emit more than 17 tons per capita, according to the study by the International Institute for Environment and Development, a London-based independent and non-profit group.
“Many cities have very low emissions, as do many city dwellers in even the most industrialized countries,” lead author Daniel Hoornweg, an urban specialist at the World Bank, says in announcing the findings. He says poor residents in wealthy cities can have a relatively low carbon footprint by buying few goods and using little power.
The study, to be published in the peer-reviewed journal Environment and Urbanization, calls for policymakers to distinguish among cities and to consider not only how much CO2 they produce but also how much they consume by buying products made elsewhere.
“Lifestyles and consumption patterns are key drivers of greenhouse gas emissions in emissions in far off cities, as in the case of Western consumer demand for Chinese goods,” Hoornweg says. “From the production perspective Shanghai has high emissions but from the consumption perspective its emissions are much lower.” In contrast, he says a wealthy city can a have a high-consumption lifestyle but low per capita production emissions.
The study estimates that if all production and consumption-based emissions are included, urban residents and their associated affluence likely account for more than 80% of global greenhouse gas emissions.