GREENHOUSE GAS EMISSION BASELINES ■ 39Ramaswami and others (2008) may help cities develop a more holistic GHG
emissions footprint that shows the overall impact of a city’s activities on global
GHG emissions.
Policy Impact
Incorporating a full Scope 1–2–3 accounting provides city residents with
a measure that helps connect their everyday activities with GHG emissions.
Important activities such as food consumption and airline travel that appear
in personal GHG calculators and in national accounts also now appear in city-
scale GHG accounts. Th is facilitates public understanding of GHG emissions
and can also spur the development of win-win strategies for GHG mitigation
that link demand for materials and energy in cities with their production. For
example, accounting for embodied emissions associated with cement in Den-
ver resulted in the city’s adopting green concrete policies that require 15 per-
cent fl y ash inclusion in concrete to reduce cement consumption at the city
scale (Greenprint 2007). Inclusion of airline emissions resulted in proposals to
off er air travel off -set programs directly at Denver International Airport.
Furthermore, a Scope 1–2–3 emissions assessment can avoid unintended
credit being given to policies that may merely shift emissions “out of boundary.”
For example, large-scale use of hydrogen-powered cars within city boundaries
may result in zero PTW Scope 1 emissions, but signifi cant WTP GHG emis-
sions can occur outside city boundaries (Scope 3) if the hydrogen is produced
from coal or natural gas. Conversely, many cross-sector strategies may be used
to reduce a city’s overall Scope 1–2–3 footprint. For example, information and
communication technologies such as teleconferencing and telepresencing may
increase energy use in buildings while displacing airline travel. Once again, a full
Scope 1–2–3 GHG accounting protocol would support such innovative cross-
sector, cross-boundary GHG reduction policies and strategies in a manner that
boundary limited (Scope 1–2) accounting does not.
Methodology, Challenges, and a Proposed Framework
for Scope 3 Inclusions
In the few studies that have included out-of-boundary impacts, the methodol-
ogy has varied. In estimating GHG emission for Delhi and Kolkata, we estimate
that Sharma, Dasgupta, and Mitra (2002) used national average consumption
data for some of the urban materials studied and coupled these with nonen-
ergy GHG emission factors for these materials as specifi ed by the IPCC. Th us
a city-specifi c material fl ow analysis was not conducted, and only partial emis-
sions (nonenergy) associated with these products (rice, milk, cement, steel)