Page 13 - Methodology to assess Net Zero progress in cities

Figure 2: In-boundary and transboundary carbon flows (Seto et al�, 2021)

In Figure 2, different perspectives for Net Zero carbon city measurement and development are
depicted:

I. From a territorial perspective, a Net Zero carbon city aims to eliminate all carbon emissions
produced within the city's administrative boundaries. This could be achieved, for instance, by
moving emission sources out of the city's administrative boundaries (which is not desirable)
or by incorporating more carbon sinks, such as planting trees (Figure 2). Additionally, some
territorial emissions, like the ones associated with airports or harbours, are not controlled by
the local Government and corresponding urban policies (Seto et al., 2021).

Community-wide infrastructure supply chain GHG footprinting expands on territorial accounting to
incorporate GHGs along supply chains of key community-wide infrastructure and food provisioning
systems that support all the local activities (residential, commercial and industrial). Cities aiming
for systemic infrastructure transitions—such as compact urban development and energy efficiency,
which reduce demand for energy and materials—often adopt a community-wide infrastructure
supply chain footprinting approach (Seto et al., 2021). In the United States, ICLEI (2021) and
the World Resources Institute (WRI, 2004) have introduced greenhouse gas (GHG) accounting
protocols. These protocols define GHG emission sources, present methods and tools for calculating
emissions (e.g., formula (1)), and establish principles for data collection.

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