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Human Settlements, Infrastructure, and Spatial Planning
12
Chapter 12
2009; Larsen and Hertwich, 2009, 2010a, b; Hillman and Ramaswami,
2010; White et al., 2010; Petsch et al., 2011; Heinonen and Junnila,
2011a, b; Heinonen etal., 2011; Chavez etal., 2012; Paloheimo and
Salmi, 2013; Minx etal., 2013). Finally, the comparability of available
evidence of GHG emissions at the city scale is usually restricted across
studies. There prevails marked differences in terms of the accounting
methods, scope of covered sectors, sector definition, greenhouse gas
covered, and data sources used (Bader and Bleischwitz, 2009; Kennedy
etal., 2010; Chavez and Ramaswami, 2011; Grubler etal., 2012; Ibra-
him etal., 2012).
Across cities, existing studies point to a large variation in the magni-
tude of total and per capita emissions. For this assessment, emission
estimates for several hundred individual cities were reviewed. Reported
emission estimates for cities and other human settlements in the lit-
erature range from 0.5 tCO
2
/ cap to more than 190 tCO
2
/ cap (Carney
etal., 2009; Kennedy etal., 2009; Dhakal, 2009; Heinonen and Junnila,
2011a, c; Wright etal., 2011; Sugar etal., 2012; Ibrahim etal., 2012;
Ramaswami etal., 2012b; Carbon Disclosure Project, 2013; Chavez and
Ramaswami, 2013; Department of Energy & Climate Change, 2013).
Local emission inventories in the UK for 2005 – 2011 show that end
use activities and industrial processes of both rural and urban localities
vary from below 3 to 190 tCO
2
/ cap and more (Department of Energy &
Climate Change, 2013). The total CO
2
emissions from end use activities
for ten global cities range (reference year ranges 2003 – 2006) between
4.2 and 21.5 tCO
2
eq / cap (Kennedy etal., 2009; Sugar et al., 2012),
while there is variation reported in GHG estimates from 18 European
city regions from 3.5 to 30 tCO
2
eq / cap in 2005 (Carney etal., 2009).
In many cases, a large part of the observed variability will be related to
the underlying drivers of emissions such as urban economic structures
(balance of manufacturing versus service sector), local climate and
geography, stage of economic development, energy mix, state of pub-
lic transport, urban form and density, and many others (Carney etal.,
2009; Kennedy et al., 2009, 2011; Dhakal, 2009, 2010; Glaeser and
Kahn, 2010; Shrestha and Rajbhandari, 2010; Gomi etal., 2010; Par-
shall etal., 2010; Rosenzweig etal., 2011; Sugar etal., 2012; Grubler
etal., 2012; Wiedenhofer etal., 2013). Normalizing aggregate city-level
emissions by population therefore does not necessarily result in robust
cross-city comparisons, since each city’s economic function, trade
typology, and imports-exports balance can differ widely. Hence, using
different emissions accounting methods can lead to substantial differ-
ences in reported emissions (see Figure 12.4). Therefore, understand-
ing differences in accounting approaches is essential in order to draw
meaningful conclusions from cross-city comparisons of emissions.
Evidence from developed countries such as the United States, Fin-
land, or the United Kingdom suggests that consumption-based
emission estimates for cities and other human settlements tend to
be higher than their territorial emissions. However, in some cases,
report beyond the direct GHG emissions released from within a
settlement’s territory. Complementary accounting approaches
have therefore been proposed to characterize different aspects of
the GHG performance of human settlements (see Box 12.2). Cit-
ies and other human settlements are increasingly adopting dual
approaches (Baynes et al., 2011; Ramaswami et al., 2011; ICLEI
etal., 2012; Carbon Disclosure Project, 2013; Chavez and Ramas-
wami, 2013).
• Choice of calculation methods. There are differences in the
methods used for calculating emissions, including differences in
emission factors used, methods for imputing missing data, and
methods for calculating indirect emissions (Heijungs and Suh, 2010;
Ibrahim etal., 2012).
A number of organizations have started working towards standardiza-
tion protocols for emissions accounting (Carney et al., 2009; ICLEI,
2009; Covenant of Mayors, 2010; UNEP etal., 2010; Arikan, 2011). Fur-
ther progress has been achieved recently when several key efforts
joined forces to create a more broadly supported reporting framework
(ICLEI et al., 2012). Ibrahim et al. (2012) show that the differences
across reporting standards explains significant cross-sectional variabil-
ity in reported emission estimates. However, while high degrees of
cross-sectional comparability are crucial in order to gain further insight
into the emission patterns of human settlements across the world,
many applications at the settlement level do not require this. Cities
and other localities often compile these data to track their own perfor-
mance in reducing energy consumption and / or greenhouse gas emis-
sions (see Section 12.7). This makes a substantial body of evidence dif-
ficult to use for scientific inquiries.
Beyond the restricted comparability of the available GHG estimates,
six other limitations of the available literature remain. First, the growth
in publications is restricted to the analysis of energy consumption and
GHG emissions from a limited set of comparable emission estimates.
New estimates do not emerge at the same pace. Second, available
evidence is particularly scarce for medium and small cities as well as
rural settlements (Grubler etal., 2012). Third, there is a regional bias
in the evidence. Most studies focus on emissions from cities in devel-
oped countries with limited evidence from a few large cities in the
developing world (Kennedy etal., 2009, 2011; Hoornweg etal., 2011;
Sugar etal., 2012). Much of the most recent literature provides Chi-
nese evidence (Dhakal, 2009; Ru etal., 2010; Chun etal., 2011; Wang
etal., 2012a, b; Chong etal., 2012; Yu etal., 2012; Guo etal., 2013;
Lin etal., 2013; Vause etal., 2013; Lu etal., 2013), but only limited
new emission estimates are emerging from that. Evidence on human
settlements in least developed countries is almost non-existent with
some notable exceptions in the non peer-reviewed literature (Lwasa,
2013). Fourth, most of the available emission estimates are focus-
ing on energy related CO
2
rather than all GHG emissions. Fifth, while
there is a considerable amount of evidence for territorial emissions,
studies that include Scope 2 and 3 emission components are grow-
ing but remain limited (Ramaswami etal., 2008, 2012b; Kennedy etal.,
Box 12.2 | Emission accounting at the local scale
Three broad approaches have emerged for GHG emissions
accounting for human settlements, each of which uses different
boundaries and units of analysis.
1) Territorial or production-based emissions accounting
includes all GHG emissions from activities within a city or settle-
ment’s territory (see Box 12.1). This is also referred to as Scope
1 accounting (Kennedy etal., 2010; ICLEI etal., 2012). Territo-
rial emissions accounting is, for example, commonly applied by
national statistical offices and used by countries under the United
Nations Framework Convention on Climate Change (UNFCCC) for
emission reporting (Ganson, 2008; DeShazo and Matute, 2012;
ICLEI etal., 2012).
However, human settlements are typically smaller than the
infrastructure in which they are embedded, and important emis-
sion sources may therefore be located outside the city’s territorial
boundary. Moreover, human settlements trade goods and services
that are often produced in one settlement but are consumed else-
where, thus creating GHG emissions at different geographic loca-
tions associated with the production process of these consumable
items. Two further approaches have thus been developed in the
literature, as noted below.
2) Territorial plus supply chain accounting approaches start
with territorial emissions and then add a well defined set of
indirect emissions which take place outside the settlement’s ter-
ritory. These include indirect emissions from (1) the consumption
of purchased electricity, heat and steam (Scope 2 emissions), and
(2) any other activity (Scope 3 emissions). The simplest and most
frequently used territorial plus supply chain accounting approach
includes Scope 2 emissions (Hillman and Ramaswami, 2010; Ken-
nedy etal., 2010; Baynes etal., 2011; ICLEI etal., 2012).
3) Consumption-based accounting approaches include all
direct and indirect emissions from final consumption activities
associated with the settlement, which usually include consump-
tion by residents and government (Larsen and Hertwich, 2009,
2010a, b; Heinonen and Junnila, 2011a, b; Jones and Kammen,
2011; Minx etal., 2013). This approach excludes all emissions
from the production of exports in the settlement territory and
includes all indirect emissions occurring outside the settlement
territory in the production of the final consumption items.