Imports to some cities raise carbon emissions by as much as 60 percent above current estimates, a study by C40 Cities shows.
The report, Consumption-based GHG emissions of C40 cities, argues that the carbon footprint of a city based on the energy consumed by households and vehicles does not take into account the emissions it produces through supply chains that meet residents’ demand for goods and services. Cities such as London, Paris and New York that import from other countries at high volume produce three times the level of CO2–based on consumption within the city boundary.
“Producer cities in India, Pakistan or Bangladesh are generating a lot of industrial pollution in the manufacture of products that will be sold and consumed in Europe and North America,” said Mark Watts, Executive Director of C40 Cities.
The findings reflect an analysis of 79 cities (15 of which are in Europe and North America) that uses a different calculating method from the widely-used sector-based approach. Analyses based on sector tend only to account for goods and services consumed by residents outside of the metropolitan area, while consumption-led data cover emissions from homes and vehicles as well as goods and services, though exclude carbon emissions resulting from export from a city or from consumption by visitors, such as tourists and migrant workers.
Sector-based measurements are often used because they typically play to the strengths of urban leaders by supplying a reliable metric on which to base climate goals, and because they conform to directives by the United Nations Framework Convention on Climate Change (UNFCCC).
Watts added that the paper’s aim is to present urban leaders with new evidence showing how imported consumption reveals “the true impact of their city on global climate change”.
The report however says that cities cannot exercise direct influence on the carbon intensity of power used to manufacture imported products. Instead, it suggests that urban leaders tackle these emissions at the consumer level, with the goal of shaping future demand around sustainable urban living.