Page 12 - Methodology to assess Net Zero progress in cities

2 Background – understanding carbon flows in cities

Understanding carbon flows in cities is essential for implementing Net Zero methodologies because
it provides a clear picture of where emissions are generated and where reductions can be most
effective. By analyzing carbon flows across various sectors such as transportation, buildings, energy,
and waste, cities can target specific areas for carbon reduction and prioritize actions that yield the
highest impact.

The physical flow of carbon within a city and its activities can be depicted in (Figure 1), while
(Figure 2) demonstrates how urban GHG accounting tracks the GHGs (CO , CH , and N O emissions
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are represented in CO equivalents) embodied in the flow of goods and services in and out of
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cities, as well as carbon sequestered or released from stocks within cities.

Figure 1: Urban carbon cycle and its linkages with urban footprint (Seto et al�, 2021)

In Figure 1, carbon flows are associated with urban activities (residential, commercial, and industrial)
and mapped to four urban carbon accounting frameworks (numbered I to IV) (Seto et al., 2021).
White areas show carbon emissions (direct and embodied) associated with homes, including
emissions from local commercial and industrial business activities that serve local homes. Gray
areas show emissions (direct and embodied) associated with commercial and industrial business
activities that either serve visitors or export to other communities; lighter and darker shades of
gray distinguish between direct emissions and emissions embodied in imports associated with the
exporting businesses (Seto et al., 2021).

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