This report presents the methodology and results of a study investigating the consumption based greenhouse gas emissions (GHG) from 79 cities, carried out by the C40 Cities Climate Leadership Group (C40) in partnership with the University of Leeds (United Kingdom), the University of New South Wales (Australia), and Arup.
Cities rely heavily on the supply of goods and services from outside their physical boundaries. The results of this study show that the GHG emissions associated with these supply chains are significant, particularly for C40 cities in Europe, North America and Oceania. Over 70% of consumption-based GHG emissions come from utilities and housing, capital, transportation, food supply and government services.
Cities in these regions, and other cities that have high consumption-based GHG emissions, are recommended to use consumption-based GHG inventories alongside their sector-based GHG inventories, or incorporate key supply chains into the latter. This would encourage more holistic GHG emissions assessments; enable decision-makers to consider a wider range of opportunities to reduce global GHG emissions; and provide an additional perspective with which to engage other stakeholders in climate action.
To support cities take on this challenge, further research is needed to improve the evidence base, and better understand the mechanisms by which cities can influence transboundary supply chains GHG emissions, in addition to those occurring locally.