50 ■ CITIES AND CLIMATE CHANGE
and surveys were developed specifi cally for determining GHG emissions rather
than urban transportation planning in general. For example, fuels sales data
could explicitly be used in model calibration. Such improvements in quanti-
fying urban GHG emissions would also likely support calculations made for
national inventories.
Further assessment of the uncertainty in quantifying urban GHG emissions
is warranted. Other than the color-coded scheme used in the GRIP studies
(Carney and others 2009), little formal analysis has been done of uncertainty in
urban emissions, such as using Monte Carlo simulation. Volume 1 of the IPCC
(2006) guidelines provides recommended approaches for uncertainty assess-
ment and quality assurance.
Improvements in the reporting of urban GHG emissions might also be
made. Under ISO Standard 14064, emissions should be reported for six indi-
vidual GHGs. Th is has not been common for cities (hence, we have not done
so here). Perhaps more important for quality assurance purposes, urban areas
should always report the activity data and emissions factors used to determine
emissions.
A further recommendation of this work is the continued development of
consumption-based measures of GHG emissions for urban areas. By including
Scope 2 and 3 emissions, as per the WRI/WBCSD, the overall methodology of
this work recognizes that emissions should be assigned to urban areas based
on end-use activities. Th ere are further consumption-based emissions that can
also be attributed to urban areas, beyond those presented in our results. Th ese
include those embodied in food and materials consumed in cities and upstream
emissions associated with the mining and refi ning of the fuels combusted in cit-
ies. Some of these emissions have been quantifi ed in a few studies (table 2.2) but
not in enough to be consistently applied to all cities at this point. Methodologies
for determining further consumption-based emissions have been developed
(Hillman and Ramaswami 2010; Mairie de Paris 2009; Ramaswami and others
2008), though perhaps they need to be compared. Th e main barrier is lack of
data on material fl ows into urban areas. Standard approaches for applying prin-
ciples of industrial ecology to urban areas need to be developed.
Notes
We are grateful to the Global Environment Facility for supporting this work. We also
wish to thank Lorraine Sugar, David Bristow, and Abel Chavez for their help in compil-
ing the results tables.
- Th is is one of the main emissions sectors in UNFCCC inventories. Th is sector refers
to emissions at industrial sites from noncombustion activities. Th e majority of emis-