Harmonization vs. Fragmentation: Overview of Climate Policy Scenarios in EMF27
Geoffrey J. Blanford, Elmar Kriegler, and Massimo Tavoni
Supplementary Material
8
7
GtCO2 per Year
6
5
4
3
2
1
BAU
FP
G8
550 CO2-e
450 CO2-e
Figure S1. Total radiative forcing for five policy scenarios under default technology assumptions.
Results are shown for all models reporting the variable.
1
2090
2070
2050
2030
2010
2090
2070
2050
2030
2010
2090
2070
2050
2030
2010
2090
2070
2050
2030
2010
2090
2070
2050
2030
2010
0
60
50
Baseline Range
40
AIM-Enduse
GtCO2-e per year
DNE21
30
EC-IAM
ENV-Linkages
20
GCAM
GRAPE
10
IMAGE
MERGE
MESSAGE
0
REMIND
TIAM-WORLD
-10
WITCH
CO2 (FFI)
CO2 (LUC)
2010
2020
2030
2040
2050
2060
2070
2080
2090
2100
2010
2020
2030
2040
2050
2060
2070
2080
2090
2100
2010
2020
2030
2040
2050
2060
2070
2080
2090
2100
-20
Non-CO2
Figure S2. GHG Emissions by Sector in 550 CO2-e policy scenario with default technology assumptions.
Chart includes only models that cover at least CO2, CH4, and N2O and solved the 550 CO2-e policy case
(corresponding baseline range also shown).
2
Figure S3: Atmospheric CO2 concentration in 2100 as a function of cumulative global CO2 emissions over
the period 2011-2100 for the three most stringent climate policy scenarios.
Figure S4: Cumulative CO2 emissions (left panel, as of 2010) and airborne fraction of anthropogenic CO2
(right panel) for the 450 ppm CO2e scenario. Airborne fraction was calculated by assuming 1750 GtCO2
of anthropogenic CO2 emissions over the period 1750-2005 (CDIAC).
3
Figure S5: Global time averaged carbon price over the period 2010-2100 (discounted at 5%) plotted
against cumulative CO2 emissions reductions in the fossil fuel and industry sector as a fraction of
cumulative emissions in the baseline.
Figure S6: Cumulative CO2 land use emissions reductions (left panel) and Non-CO2 gases emissions
reductions as a function of average carbon price over the period 2010-2010 (discounted at 5%).
4
2. Policy scenario descriptions
The following excerpts Section 2 from the EMF 27 Scenario protocol, along with Appendices A3-A6, in
which the specification for the policy cases is provided as implementation guidance for modelers
participating in the EMF27 joint exercise.
2.1. Baseline:
This scenario should not include any new climate policies beyond those in place as of January 1, 2009.
This implies an assumption that the Kyoto Protocol (KP) is executed in those countries in compliance
with the KP, but is not replaced upon expiration in 2012. Non-climate policies may be included in the
baseline. Each technology case will have its own baseline except for the “No CCS” case.
2.2. RCP 2.6 W/m2 equivalent climate target :
This case aims to reflect the mitigation stringency of the RCP 2.6 emissions / concentrations pathway
that is currently investigated by a suite of climate models. A MAGICC calculation of the radiative forcing
levels in the year 2100 emerging from the RCP 2.6 emissions pathway reveals the following (www.pikpotsdam.de/~mmalte/rcps/. MAGICC version 6.3.09. Higher versions show approx.. 0.15-0.3 W/m2
higher forcing values in the various categories.1 ):
Forcing definition
Forcing agents included
Forcing level in RCP
2.6 in the year 2100
2.63 W/m2
Natural and
anthropogenic
forcing
Total anthropogenic
forcing
AN3A2 forcing
Includes solar forcing and all forcing agents of
anthropogenic origin. Volcanic forcing is set to
zero in 2100.
Includes all forcing agents of anthropogenic
2.44 W/m2
origin.
Includes all anthropogenic forcing agents except 2.86 W/m2
1
The results of the MAGICC version 6.3.09 (used to determine the forcing outcomes of the RCPs) remains a useful
yardstick, even though the current MAGICC6.6 shows a somewhat larger carbon cycle feedback, but a similar
temperature response to emissions. MAGICC6.3 output lies well within the uncertainty range of the current
MAGICC6.6 output. In addition, the MAGICC 6.3.09 results for the RCP2.6 were only used to determine the target
level of the 450 ppm CO2e scenario (= 2.6 W/m2 full forcing) in the AN3A forcing metric. This remains valid for
updated climate model versions as long as the difference between full forcing and AN3A forcing in an RCP2.6
setting does not change. Integrated assessment models have used their own atmospheric chemistry-climate
modules to translate the forcing constraint to emissions, and a few of them used the latest MAGICC version, while
others made different choices. The CO2 budgets for models that do not directly link to forcing were determined by
a regression on previous results from full forcing IA models, and already took into account the current MAGICC6.6 .
2
Abbreviation AN3A stands for Anthropogenic Not including land Albedo changes, mineral dust Aerosol, direct
nitrate Aerosol.
5
Kyoto gas forcing
of direct forcing from land albedo changes,
mineral dust and nitrate aerosols.
Includes all Kyoto gases, but excludes aerosols,
tropospheric & stratospheric ozone, Montreal
gases, and stratospheric water vapor (NonKyoto substances).
2.89 W/m2
In this study, we only include those radiative substances in the climate target that were studied by
source in the RCP work (Abbreviation for the set of substances – AN3A): Kyoto gases (CO2, CH4, N2O,
HFCs, PFCs, SF6), substances controlled under the Montreal Protocol (Chlorides, halons, bromine),
tropospheric and stratospheric ozone, stratospheric water vapor, and aerosols (sulfate, black and
organic carbon from fossil fuel and biomass burning, indirect aerosol cloud albedo forcing, black carbon
on snow albedo forcing). Forcing from land-surface albedo changes, direct forcing from nitrate aerosols,
and forcing from mineral dust are not included in the target. The forcing from the latter three sources is
assumed to be negative, and in the range of -0.3 to -0.4 W/m2 in 2100 in the RCP 2.6.
We therefore specify an AN3A forcing target of 2.8 W/m2 broadly consistent with the RCP 2.6
pathway. This refers to the aggregate forcing from the AN3A forcing agents listed in the previous
paragraph. The target is to be achieved in 2100, overshooting before 2100 is allowed. Full when (to the
extent permitted by the model) and where flexibility of emissions reductions as of the first model year
after 2010 should be assumed. Flexibility in balancing different forcing contributions (“what flexibility”)
is left to the modeler’s choice. Not all AN3A forcing agents counting towards the target may be priced by
the forcing constraint.
Models not accounting for all AN3A substances are requested to adopt an alternative climate target that
is tailored to the collection of radiative agents represented by the model. According to a survey of
models participating in EMF27, the situation is as follows:





AN3A forcing target: Will be adopted by GCAM, IMAGE, MESSAGE, MERGE, ReMIND, and
GRAPE. AIM-Enduse and AIM-CGE will use AIM-Impact, and DNE21 will use MAGICC to translate
the AN3A forcing target into model specific target (i.e. Kyoto gas pathway until 2050 / 2100). All
these models should include a comprehensive reporting of the concentration, forcing, and
temperature outcomes of their scenario runs. Modelling teams should make an effort to match
the mean estimates of radiative forcing by substance for the year 2005 as given in Table 2.12 of
the Fourth Assessment Report of WGI of the IPCC.
Kyoto gas forcing target: Will be adopted by WITCH. TIAM-World will adopt an exogenous
pathway for radiative forcing from F-gases to complement its representation of Kyoto gas
forcing. These models should include a comprehensive reporting of Kyoto gas concentration and
forcing in their scenario runs (including F-gases).
Kyoto gas emissions budget (until 2050): Will be adopted by ENV-Linkages
CO2 concentration target or CO2 total emissions budget (until 2100): Will be adopted by BET
and FARM. Include reporting of CO2 concentrations if available.
CO2 Fossil fuel and industry emissions budget (until 2100): Will be adopted by IMACLIM and
Phoenix. Since it is not possible to reconstruct a Kyoto gas budget for fossil fuel and industry
emissions from the existing database, the POLES and EC-IAM models (representing Kyoto gas
6
emissions from fossil fuel combustion and industry) will also adopt the CO2 FF&I emissions
budget, and price the other greenhouse gases at the level of CO2 price emerging from the CO2
budget.
[Addendum: In their final submission, some models deviated from these assignments. BET and FARM
implemented a budget for CO2 emissions from fossil fuel combustion and industry. EC-IAM used a
climate model to project onto Kyoto gas emissions budgets.]
These alternative targets are listed in the table below (emission budgets rounded to the nearest 50
GtCo2). They were derived with an analysis of mitigation pathways from an ensemble of full forcing
integrated assessment models3. The set of ranges for the various targets were found to be associated
with an RCP 2.6 forcing in 2100, with the ranges indicating the existing uncertainty across IAMs
(reflected in different emissions portfolios under the target) and the conversion to radiative forcing. The
targets are provided so that models with different representation of gases would run scenarios with
similar mitigation effort. However, due to climate and IAM uncertainty, and due to the limited ensemble
of IAMs on which the analysis was based, the collection of targets should not be misread: achieving one
of the targets (e.g. the mean value for the CO2 concentration target) does not imply achieving any of the
other targets. In principle, models will only be able to speak to climate targets referring to radiative
forcing agents they account for. However, a climate target outside the ranges in the table has a high
probability of not being compatible with achieving an RCP 2.6 forcing level in 2100 if emissions and
forcing pathways were extended to the full set of radiative substances.
Target type
Mean
Range
Year 2100
AN3A RF (W/m2)
(overshoot before 2100 allowed)
2.8
Year 2100
Kyoto RF (W/m2)
CO2eq total (GtCO2e,
Kyoto gases)
CO2 conc (ppm)
(overshoot before 2100 allowed)
2.9
2.7 – 3.2
2005-2050
1700
±200
2005-2100
2100
±200
Year 2100
410
390 – 430
3
The emissions from the IAMs covering all radiative substances were run through a reduced-form atmospheric
chemistry-climate model (MAGICC) capturing the uncertainty about forcing and climate response. The ensemble of
combined IAM-MAGICC model runs was weighted according to the proximity of model realizations to the forcing
target. This lead to the identification of a distribution over associated Kyoto gas forcing, CO2 concentration, and
emissions budgets described by the full forcing models. The mean and the one standard deviation range of these
distributions are listed in the table.
7
(overshoot before 2100 allowed)
CO2 total (GtCO2)
CO2 FF&I (GtCO2)
2005-2050
1100
±200
2005-2100
1100
±300
2005-2050
1100
±100
2005-2100
1100
±200
2.3. 3.7 W/m2 climate target:
A forcing of 3.7 W/m2 corresponds to a 550 ppm CO2 equivalent concentration. The target is not to
exceed (NTE) throughout the 21st century. Full when (to the extent permitted by the model) and where
flexibility for emissions reductions as of the first model year after 2010 should be assumed.
Analogous to the RCP 2.6 equivalent forcing target, the 3.7 W/m2 radiative forcing target refers to the
aggregate contribution of the following radiative substances (Abbreviation AN3A): Kyoto gases (CO2,
CH4, N2O, HFCs, PFCs, SF6), substances controlled under the Montreal Protocol (Chlorides, halons,
bromine), tropospheric and stratospheric ozone, stratospheric water vapor, and aerosols (sulfate, black
and organic carbon from fossil fuel and biomass burning, indirect aerosol cloud albedo forcing, black
carbon on snow albedo forcing). Forcing from land-surface albedo changes, direct forcing from nitrate
aerosols, and forcing from mineral dust are not included. This definition of radiative agents corresponds
to the set of agents that were studied by source in the RCP work. Flexibility in balancing different forcing
contributions (“what flexibility”) is left to the modeler’s choice. Not all RCP forcing agents counting
towards the target may be priced by the forcing constraint.
Models not accounting for all RCP substances are requested to adopt an alternative climate target that
is tailored to the collection of radiative agents represented by the model. According to a survey of
models participating in EMF27, the situation is as follows:



AN3A forcing target: Will be adopted by GCAM, IMAGE, MESSAGE, MERGE, ReMIND, GRAPE.
AIM-Enduse and AIM-CGE will use AIM-Impact, and DNE21 will use MAGICC to translate the
AN3A forcing target into model specific target (i.e. Kyoto gas pathway until 2050 / 2100). All
these models should include a comprehensive reporting of the concentration, forcing, and
temperature outcomes of their scenario runs. Modelling teams should make an effort to match
the mean estimates of radiative forcing by substance for the year 2005 as given in Table 2.12 of
the Fourth Assessment Report of WGI of the IPCC.
Kyoto gas forcing target: Will be adopted by WITCH. TIAM-World will adopt exogenous pathway
for radiative forcing from F-gases to complement its representation of Kyoto gas forcing. All
these models should include a comprehensive reporting of Kyoto gas concentration and forcing
in their scenario runs (including F-gases).
Kyoto gas emissions budget (until 2050): Will be adopted by ENV-Linkages
8


CO2 concentration target or CO2 total emissions budget (until 2100): Will be adopted by BET
and FARM. Include reporting of CO2 concentrations if available.
CO2 Fossil fuel and industry emissions budget (until 2100): Will be adopted by IMACLIM and
Phoenix. Since it is not possible to reconstruct a Kyoto gas budget for fossil fuel and industry
emissions from the existing database, the POLES and EC-IAM models (representing Kyoto gas
emissions from fossil fuel combustion and industry) will also adopt the CO2 FF&I emissions
budgets, and price the other greenhouse gases at the level of CO2 price emerging from the CO2
budget.
[Addendum: In their final submission, some models deviated from these assignments. BET and FARM
implemented a budget for CO2 emissions from fossil fuel combustion and industry. EC-IAM used a
climate model to project onto Kyoto gas emissions budgets.]
These alternative targets are listed in the table below (emission budgets rounded to the nearest 50
GtCo2). They were derived as described above for the case of the 2.6 W/m2 target. Due to the inherent
uncertainty in these alternative target levels, the collection of targets must not be misread: achieving
one of the targets (e.g. the mean value for the CO2 concentration target) does not imply achieving any
of the other targets. It should be noted that emissions budgets may allow a temporary overshoot of the
permissible forcing under the not to exceed target. This needs to be carefully checked when comparing
results from models that adopted different types of targets.
Target type
Mean
Range
AN3A RF (W/m2)
NTE
3.7
Kyoto RF (W/m2)
NTE
3.7
3.4-4.0
2005-2050
1950
±200
2005-2100
2950
±400
NTE
470
440-500
2005-2050
1400
±200
2005-2100
1850
±400
2005-2050
1300
±200
2005-2100
1850
±400
CO2eq total (GtCO2e,
Kyoto gases)
CO2 conc (ppm)
CO2 total (GtCO2)
CO2 FF&I (GtCO2)
2.4. G8 target with incomplete participation:
9
The G8 target foresees 50% reduction of global emissions (CO2 equivalent emissions including all Kyoto
gases calculated on the basis of 100 year GWPs as provided in the 4th Assessment Report of the IPCC) in
2050 relative to 1990. In this scenario, Group I and II countries adopt the G8 target, and aim at a 50%
reduction of their combined emissions relative to 1990. After 2050, reductions of 2% per year of
emissions (CO2e) from Group I and II countries should be aimed for. Regional emissions caps are
distributed as follows (for the grouping of countries into three groups see Appendix A.3):
Group I: 80% emissions reductions relative to 1990 in 2050. Caps in years between the present and 2050
are determined by applying a linear schedule originating at baseline level for 2012 (which
includes KP commitments, see above; actual implementation depends on time step
configuration).
Group II: Adoption of emissions constraints through 2020 corresponding to Copenhagen pledges. These
include a variety of instruments (notably intensity targets for China and India), and many
countries in this group made no pledges. See Appendix A.4 for the regional breakdown of
2020 pledges (if any). Group II countries make reductions necessary to achieve the goal of 50%
reduction in combined Group I and II emissions by 2050. This allowable total is allocated
across regions/countries in the second group according to 2020 allowable emissions
(grandfathering), and a linear schedule between the two points will determine the constraints
in intermediate periods.
Group III: Unconstrained emissions throughout the 21st century. This group of countries includes fossil
energy resource owners that may have little or no incentive to participate in a global climate
policy regime. It is modeler’s choice to either cap the emissions at baseline level, or allow for
leakage effects pushing Group III emissions above baseline level.
Full when and where flexibility of emissions reductions among Group I as of 2012, and among Group 1
and 2 countries as of 2020 should be allowed in two periods: until 2050 and after 2050. No borrowing of
emissions rights from the second period is allowed in the first period. Due to when and where flexibility,
physical emissions will differ from emissions rights assigned by individual caps. Volume and value of
emissions rights transfer between participating regions should be reported.
Modeling teams are encouraged to report the climate outcome of their G8 scenario.
2.5. Fragmented climate policy (FP):
Describes a fragmented international climate policy regime with individual caps for countries in different
groups, and no specified global climate protection target.
Group I: Adoption of a cap of 50% emissions reductions (CO2e) relative to 2005 in 2050. Caps in years
between the present and 2050 are determined by applying a linear schedule originating at
baseline level for 2012 (which includes KP commitments, see above; actual implementation
depends on time step configuration). After 2050, emissions (CO2e) caps are reduced by 2%
per year. Full where flexibility of emissions reductions within Group I should be allowed.
10
Trading with Group II countries is not allowed before 2020. After 2020, total net exports from
Group II (i.e. imports into Group I from Group II) must be limited to 20% of the mitigation
requirement of Group I (i.e. the difference between baseline emissions and emissions
allowances under the cap). Full when flexibility should be allowed within two periods: before
2050 and after 2050. No borrowing of emissions rights from the second period is allowed in
the first period.
Group II: Adoption of emissions constraints through 2020 corresponding to Copenhagen pledges. See
Appendix A.4 for the regional breakdown of 2020 pledges (if any). After 2020, Group II
countries make emissions reductions relative to their baseline. Appendix A.5 lists the emission
reduction targets relative to BAU from 2030 to the time of 50% emissions reductions relative
to baseline for 14 sub-regions of Group 2. These targets were calculated with the MERGE
model based on the premise that reductions of magnitude similar to the Group I targets for
2050 (50% emissions reductions) will be adopted when incomes reach the Year 2050 levels of
Group I countries. They may be aggregated to model regions based on 2005 CO2-e emissions
(included in Appendix A.5). Once a Group II country has reached the 50% reduction mark, its
emissions allowance (CO2e) is reduced by 2% per year thereafter. Actual emissions cap will
depend on the baseline emissions and will vary across models, although all models should
apply the same percentage reduction based on Appendix A.5. Until 2020, no when and where
flexibility of emissions reductions within Group II, nor with countries outside of Group II shall
be allowed. After 2020, Group II regions can import emissions rights amounting to up to 20%
of their mitigation requirement from Group I or other Group II regions. Full when flexibility of
emissions reductions should be allowed within a Group II region.
Group III: Unconstrained emissions throughout the 21st century. This group of countries includes fossil
energy resource owners that may have little or no incentive to participate in a global climate
policy regime.
Emissions caps (i.e. allowable emissions) in the FP scenario should be calculated by applying the
prescribed percentage reductions to emissions in Scenario EMF27G1. The same cap should be applied
across all technology scenarios (even though reference emissions may be different).
Modeling teams are encouraged to report the climate outcome of their Fragmented Climate Policy
scenario.
11
A.3: Definition of country groups
A regional differentiation of the climate policy regime is relevant for some of the policy cases above. We
assume three groups of countries.
Group I: USA, Japan, Canada, Australia, New Zealand, and “Greater Europe”, consisting of EU-27,
Norway, Switzerland, and Iceland, and the Non-EU Eastern European countries including
Belarus, Ukraine, Moldova.
Group II: Essentially all developing countries with the exception of several identified non-participants
(the third group). Technically, all countries not included in Group I or III. Included are China,
India, Brazil, South Africa, OECD members Korea, Mexico, and Turkey, and most other
countries in Asia, Latin America, and Africa.
Group III: The third group of countries includes fossil energy resource owners that may have little or no
incentive to participate in a global climate policy regime. Included are Russia, the (Central)
Asian Former Soviet Union countries (Armenia, Azerbaijan, Georgia, Uzbekistan, Turkmenistan,
Kyrgyzstan, Tajikistan and Kazakhstan), as well as Middle East OPEC countries Saudi Arabia,
Iran, Iraq, Algeria, Libya, Kuwait, Qatar, and UAE.
It is clear that different regional breakdowns in individual models will not allow an exact representation
of the three country groups across all models. Modelers are advised to choose the grouping of countries
closest to the grouping proposed above based on the regional resolution of their model. The differences
to the grouping above should be clearly documented.
12
A.4: Copenhagen pledges until 2020
Group I emissions allocations for 2020 are already determined by the linear reduction schedule between
current (2012) emissions and the 2050 target. It is expected that this formula will result in allocations
similar in most cases to nationally announced targets. However, modeling groups may elect to
represent specific Copenhagen pledges more explicitly for Group I regions of interest.
These pledges are summarized by the UNFCCC here: http://unfccc.int/home/items/5264.php.
Group II targets for 2020 based on the Copenhagen Accord should be represented according to the table
below, which is intended to be a simplified approximation of the actual UNFCCC communications. It
includes only targets articulated by the seven most significant countries. For the most part, the
remaining non-Annex 1 participants in the Accord are small and submitted non-quantitative pledges.
Nearly all non-Annex 1 countries (with Korea apparently an exception) made their pledges voluntary and
explicitly conditional on financial resources from developed countries. Thus it is not clear whether it is
reasonable to assume any of these targets will represent reductions in addition to the binding targets
pledged by Annex 1. (Brazil specifically includes the CDM as one possible means of financing.) The
proposed compromise is to enforce only the targets pledged by the seven large developing countries as
a proxy for expected reductions from the full group of non-Annex 1 participants in the Accord.
Modeling teams must choose the best way to represent these targets within their regional structure. In
addition, teams must evaluate based on their own BAU assumptions how the targets translate into
absolute emissions caps (particularly for the intensity targets in China and India). Finally, since the
majority of reductions pledged by Brazil and Indonesia are expected to occur in land-use-related sectors,
an adjustment must be made to calculate a cap on energy-related emissions. The proposed adjustment
is listed in the table.
Country
China
India
Korea (South)
South Africa
Mexico
Brazil
2020 Target under Copenhagen Accord
40-45% reduction in emission intensity relative to 2005
20-25% reduction in emission intensity relative to 2005
30% reduction in emissions relative to BAU
34% reduction in emissions relative to BAU
30% reduction in emissions relative to BAU
36% reduction in emissions relative to BAU
(10% reduction in energy-related emissions)
Indonesia
26% reduction in emissions relative to BAU
(5% reduction in energy-related emissions)
The complete list of Non-Annex 1 communications to the UNFCCC is here:
http://unfccc.int/home/items/5265.php
13
A.5: Group II country emissions reductions from baseline
In order to better normalize the Muddling Through scenario across models, we propose using income
projections from a single model (MERGE) to determine reduction targets from BAU to be used by all
models (see A.6 for the methodology). Because regional definitions with Group 2 differ across models,
the following table shows target reductions based on MERGE income projections for 14 sub-regions
within Group II. The table also shows the year in which the income threshold has been met, triggering
the 2% annual reduction regime as described above. These sub-regions form the basis for aggregation
into larger model regions in MERGE. For example, China and India remain separate regions, but Korea,
Indonesia, and the three “Other Asia” groups were combined into a single “Other Asia” region for actual
model runs in this exercise. Other models should aggregate as well as possible to their own regional
definitions using 2005 CO2-e emissions as reported below.
BRA
CHN
IDN
IND
KOR
MEX
TUR
ZAF
XAF
XAS1
XAS2
XDA
XLA1
XLA2
2005 CO2-e
emissions
2030
2040
2050
2060
2070
2080
2090
2100
0.992
7.166
0.646
2.031
0.524
0.645
0.399
0.495
1.115
0.630
1.220
0.347
0.459
0.598
23%
24%
11%
8%
42%
25%
25%
27%
0%
28%
1%
46%
28%
12%
30%
32%
19%
17%
46%
30%
31%
34%
0%
34%
10%
49%
33%
18%
37%
38%
27%
25%
44%
44%
35%
32%
50%
47%
41%
40%
45%
46%
47%
49%
49%
38%
38%
42%
0%
40%
18%
43%
44%
48%
3%
46%
25%
47%
48%
11%
18%
23%
27%
31%
34%
37%
39%
39%
27%
43%
33%
46%
37%
48%
40%
50%
42%
44%
Subregions composed of multiple countries are defined as follows:
XAF
XAS1
XAS2
XDA
XLA1
XLA2
Other sub-Saharan Africa
Other mid-income Asia
Other low-income Asia
Other high-income Asia
Other mid-income Latin America
Other low-income Latin America
excludes AGO, NGA (oil-exporters)
= MYS, THA
= HKG, SGP, TWN
= ARG, CHL, URY
excludes VEN (oil-exporter)
14
A.6: Methodology to calculate emissions reductions from baseline as a function
of income levels
For per capita income x, expressed in thousands of year 2000 USD (PPP equivalent), the target agreed to
under the Kyoto protocol as a percentage below projected BAU in the time period 15 years hence were
noted by Frankel (2007) to follow this formula:
 4 .5 
ln 30 
4 .5
ln x
Percent below BAU
= 0.25
Countries with an income below $4,500 in 1997 did not agree to targets representing a departure from
BAU in 2012. Countries with an income of $30,000 in 1997 (the wealthiest countries) agreed to targets
equivalent to roughly 25% below the projected 2012 BAU. Countries with income levels between these
two thresholds appeared to adopt targets approximately consistent with the formula above (though not
all were ratified or implemented).
For EMF 27, we propose a similar formula for determining quantitative targets after 2020 for Group 2
countries based on projected income in the reference scenario. However, we propose a formula more
stringent than that implied by the Kyoto negotiations. In the above formula, the quantity 0.25,
representing the maximum percentage reduction below BAU, is replaced by 0.5. Similarly, the quantity
30, representing the maximum per capita income, is replaced with the average per capita income of the
Group 1 countries in 2050 (according to each model’s reference scenario). The quantity 4.5,
representing the minimum per capita income, should remain unchanged (except to adjust to a different
year currency). Additionally, the target reduction is calculated for the same year as the argument per
capita income (rather than with the 15 year lag in the Kyoto formula). Finally, for models using
exclusively a currency denominated in base year MERs, income projections for Group 2 regions should
be scaled by the base year PPP: MER ratio as specified by the most recent World Bank report. Models
using PPP should apply the formula directly to their projected income levels in PPP without regard to
additional information on MER projections they might produce.
EMF 27 Formula:
Percent below BAU in time t
= A ln x(t )  B for 4.5 < x ≤ xG1(2050), or zero for x ≤ 4.5
where A 
0.5
x (2050) 
ln  G1
4.5 

B
0.5 ln 4.5
x (2050) 
ln  G1
4.5 

and
15