Research Institute of Innovative
Technology for the Earth

Global and Domestic CO2 Emissions Pathways: The 2014 Revision
November 18, 2014
Systems Analysis Group, RITE

Introduction
The global CO2 emissions pathways developed by RITE have been used by the Japanese

government and many other organizations for policy making and evaluating counter measures against
global warming as fundamental data. Recently, we reviewed the pathways based on the latest historicalemissions and economic trends. The followings are our new pathways of energy-related CO2
emissions up to 2050 by major region in the world.

The pathways of the global energy-related CO2 emissions

Based on CO2 emission statistics up to 2011, economic trends by region up to 2012 and the future
economic growth outlook, CO2 emissions are estimated using one of the most advanced assessment
models in the world. The pathways in this paper are estimated under the current policy where
measures against global warming will be continued (see Figure A-2 for the baseline scenario without
any particular measures).
Figure 1 shows the global energy supplies. Fossil fuels (coal, petroleum, natural gas) which are anemission sources of CO2 are important energy, accounting for 82% of the total in 2012. In the future
up to 2050 fossil fuels are projected to continue to be crucial and largely dominate energy supplies.
The global energy-related emissions in 2011 are 32.3 billon tons and with the fossil fuel supplies
increased, emissions in 2020 are estimated 37.8 billion tons, and 56.3 billion tons in 2050 (Figure 2).
The emissions in developed countries were significantly reduced temporarily, affected by global
financial crisis but the global CO2 emission trend is forecasted to continue to increase. The regionalemission shares have significantly changed since 1990 and are estimated to change further toward2050. The CO2 emissions by country that belongs to Annex I will account for less than 40% of the
global CO2 emissions in 2020 (Figure 2). It should be noted that these estimates are close to themedian values in the Intergovernmental Panel on Climate Change Fifth Assessment Report (IPCC
AR5 2014) which includes a number of collected scenario studies of the world (see a comparison in
Figure A-2). We can say that in the long-term significant emission reductions and promotion ofeffective emission reductions by major emitters are crucial to suppress the climate change. In addition,
we can also say that deployment of Japan's variety of energy-efficient technologies and products
would contribute to effective emission reductions in the world.
The main updated points of “Global CO2 Emissions pathways” published in August 2011 are theoutlooks for nuclear power generation and fossil fuel prices (Ref. 2 is referred for nuclear power
generation and Ref. 3 for fossil fuel prices.). Nuclear power generation has been revised downward
from the August edition, 2011 and fossil fuel prices, particularly gas prices have been revised
downward due to the effects of shale gas development in the United States.
1

Using DNE21 + model, we have estimated the marginal abatement cost of mitigation policy which would haveconducted in 2010 and mitigation policy has been estimated to cost less than the marginal abatement cost after
2010. Marginal abatement costs of major countries (Japan, US, UK, France and Germany) have been estimated$61/tCO2, $15/tCO2, t $28/tCO2, $6/tCO2 and $30/tCO2, respectively. The wind power and solar power
generation which have been increasingly introduced by various policies are estimated to generate more
electricity than that 4), 5) at the latest since it is difficult to predict policy trends

1Research Institute of Innovative
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Low gas prices would accelerate the replacement of the old low-efficient coal-fired power generationin the US by gas-fired power generation but conversely lower the incentives for energy efficiency
improvement. Without any GHG mitigation policy, the global emissions in 2050 will be revised
upward from 56.6 billion tons in the August edition 2011 to 60.5 billion tons (not including CO2
emissions from international aviation and international). However, with the effect of the current policy,
emissions are estimated 56.3 billion tons which is slightly lower than that of the August 2011.

Figure.1 Pathways of the world total primary energy supply (IEA statistics4), 5) from1990 to 2012)

Figure.2 Pathways of energy-related CO2 emissions by the world major country andregion (IEA statistics6) up to 2011)2

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1990

Other NonAnnex I,
17.0%

2005

Other NonAnnex I,
20.3%

US, 23.2%

US, 21.7%

Brazil, 1.0%
Brazil, 1.2%

Korea, 1.1%

India , 2.8%

EU15,
15.0%

China,
11.6%

Korea, 1.7%

EU15,
12.2%

India , 4.5%

EU28(+13),
2.8%

China,
20.3%

EU28(+13),
4.9%

Other
Annex I,
18.3%

Japan, 5.1%

2010
2011

Other
Annex I,
10.9%

2020
US, 15.1%
EU15, 8.5%

US, 17.0%

Brazil, 1.3%

Other NonAnnex I,
21.2%

Other NonAnnex I,
24.5%

EU15, 9.2%

China,
27.8%

Japan, 3.2%

Other
Annex I,
9.6%

India , 7.8%

US
10.7%

EU15
7.7%

Korea
1.9%
India
10.2%

China
27.3%

EU15
5.6%

2050
US
13.3%

Other NonAnnex I
26.7%

Other
Annex I,
8.1%

China,
27.8%

2030

Brazil
1.4%

EU28(+13),
1.8%

EU28(+13),
Brazil, 1.4%
2.3%
Korea, 1.9%
Japan, 3.8%

Korea, 2.0%

India , 5.8%

Japan, 4.5%

EU28(+13)
1.6%

EU28(+13)
1.3%
Other
Annex I
6.6%

Other NonAnnex I
33.1%

Japan
2.4%
Other
Annex I
7.6%

Brazil
1.7% Korea
1.4%

Japan
1.5%

China
22.7%

India
15.4%

Figure 3 Regional shares in energy-related CO2 emissions(IEA statistics for 1990, 2005, 2011, RITE estimate for 2020, 2030, 2050)
Note) CO2 emissions from international aviation and marine are not included.

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Pathways of the global GHG emissions

Figure 4 shows the pathway of GHG emissions which include non energy-related CO2, N2O, CH4,
F-gas under the Kyoto Protocol target, added to energy-related CO2. GHG emissions are estimated53.9 billion tons in 2020 and 76.4 billion tons in 2050. The regional share in GHG emissions (Figure5) increases more than the regional share in only energy-related CO2 emissions in other Non Annex I
countries, so that the emission share in Annex I countries slightly decreases in 2020 (33%). This is due
to more agriculture-related emissions of N2O and CH4 in other Non Annex I. Chinese emissions are
estimated to peak in 2040 even under the current policy and mitigation. (Similarly, the emissions peakis around 2040 under baseline scenarios, as shown in Figure A-2.)

Figure 4 Pathways of GHG emissions by major country and region(UNFCCC7) for Annex-I, IEA statistics6) for Non-Annex I up to 2010)
Note) GHG emissions from LULUCF are not included4Research Institute of Innovative
Technology for the Earth

1990

Other NonAnnex I
25.1%

US
19.4%
Other
NonAnnex I
22.6%

Brazil
2.2%
Korea
0.9%

India
4.1%

EU15
13.3%

China
12.4%

Other NonAnnex I
25.8%

US
18.2%

EU15
10.6%

Brazil2.8%
Korea
1.4% India
5.3%

EU28(+13)
4.2%

Other
Annex I
17.0%

2005

EU28(+13)
2.5%

China
20.7%

Japan
Other3.4%
Annex I
10.1%

Japan
3.8%

2010

Other NonAnnex I
26.7%

US
15.5%

2020
US
13.3%
EU15
7.7%

EU15
8.6%
Brazil
2.5%

EU28(+13)
1.6%
EU28(+13)
2.1%

Korea
1.5%
India
6.3%

Brazil
1.4%

Japan
2.8%

China
25.7%

Korea
1.9%

Other NonAnnex I
35.5%

US
11.8%EU15

6.8%

2050

China
26.3%

Other
Annex I
7.6%

US
EU15
9.8%
5.2% EU28(+13)
1.3%

EU28(+13)
1.6%

Brazil
2.3%
Korea
1.5%

China
27.3%

India
10.2%

Other
Annex I
9.1%

2030
Other NonAnnex I
30.1%

Japan
2.4%

Japan
1.3%
Other
Annex I
6.8%

Japan
2.0%
Other
Annex I
7.6%

China
22.2%
Brazil
2.4% Korea
1.2% India
14.2%

India
10.0%

Figure 5 regional shares in GHG emissions(UNFCCC7) for 1990, 2005, 2010 Annex-I, IEA statistics6) for 1990, 2005, 2010 Non-Annex-I, RITE
estimate for 2020, 2030, 2050)
Note) CO2 emissions from international aviation and marine and LULUCF are not included.

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Figure 6 and 7 show GHG emissions pathways per GDP and per capita. Emissions per GDP ofJapan, EU15 and the United States are in a low level, which means that economic activities in thoseregions are less dependent on GHG emissions. Although the other countries are expected to improvein the future, emissions per GDP are estimated more than the status quo emissions of Japan, the UnitedStates and Europe even in 2050 (for example, China's emissions per GDP is as high as those of USA
in 2000). On the other hand, emissions per capita of Annex I countries (the United States, EU andJapan) and other Annex I countries (Russia, etc.) in 1990 are high. However, emissions of the othercountries has increased along with the economic development, and Korea’s emissions per capita has
exceeded the EU15 and Japan level in 2000 and also in 2010 China’s emissions per capita weresimilar to the level of EU15 and Japan and are estimated to exceed in the near future. As emissions per
capita are affected by various factors such as industrial structure and climate in each country, being
equal is not necessarily equitable. However, in the ideal, it is considered desirable to be in a direction
to converge to some extent.

US
EU15
EU28(+13)
Japan
Other Annex I
China
India
Korea
BrazilOther Non Annex I

Figure 6 GHG emissions pathways per GDP by major country or region(UNFCCC7) for Annex I, IEA statistics6) for Non Annex I up to 2010)
Note) CO2 emissions from international aviation and marine and LULUCF are not included .

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Research Institute of Innovative
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EU15
EU28(+13)
Japan
Other Annex I
China
India
Korea
BrazilOther Non Annex I

Figure 7 GHG emissions pathways per capita by major country or region(UNFCCC7) for Annex-I, IEA statistics6) for Non Annex-I up to 2010)
Note) CO2 emissions from international aviation and marine and LULUCF are not included .

Pathways of Japan’s energy-related CO2 and GHG emissions

Figure 8 shows Japan's primary energy supply pathways (CO2 emissions pathways under the current
policy and mitigation to be continued (footnote 1)). For the current situation as of November 10, 2014
the government has stopped nuclear power generation. The government is assumed to restart nuclear
plants sequentially and all of the nuclear power plants to meet the '40 standard (154 billion kWh/yr) in
2030. Thereafter up to 2050 it is assumed that nuclear power plants continue to generate the sameamount electricity as in 2030. It should be noted that the current policy pathways of IEA WEO20133)
show 174 billion kWh/yr power generation of nuclear power in 2030, which is the higher level than
RITE estimates. In this case, GHG emissions are expected to peak in 2015 and decline (Figure 9). The
Figure shows 2% GHG emission reductions in 2020, 10% GHG reductions in 2030 and 30%
reductions in 2050 compared to 2005. The current policy pathways of IEA WEO20133) show 1078
million tons of energy-related CO2 emissions in 2030, while RITE estimates 1038 million tonemissions. There can be seen no big differences between the two.

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Solar
Window
Hydro/geothermal
NuclearBiomass
Natural gas
Oil
Coal

Figure 8 Japan’s primary energy supply pathways (IEA statistics4) up to 2012)

Energy-related CO2
GHG

Figure 9 Japan’s energy-related CO2 and GHG emissions pathways(IEA statistics6) for energy-related CO2 up to 2011 and UNFCCC7) for GHG up to 2011)8

Research Institute of Innovative
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Methodology and key assumptions to estimate the global CO2 emissions pathways
The world's energy-related CO2 emissions pathways are estimated using the assessment model for
global warming, DNE21+1) developed by RITE. In this model, the world is divided into small regions
and many mitigation technologies are bottom-upped. Energy use and CO2 emissions that are consistent
with economic and production activities are evaluated over the time period up to 2050 with this model.
To estimate CO2 emissions pathways, UN, World Population Prospects: The 2012 Revision8) isutilized for statistics and UN, World Population Prospects: The 2008 Revision (medium
variant)9) for assumption of the future population trajectory. (Figure 10 shows the world population
will reach 9.1 billion in 2050.) As to the GDP trajectory assumption, we estimated the trajectory basedon the most recent economic situation, including the world economic crisis after the Lehman Shock.
(Figure 11 and 12. The world average of real GDP growth rate from 2010 to 2020 is 3.1% per annum,from 2020 to 2050, 2.4%. The Japanese average of real GDP from 2010 to 2020 is 1.7%, from 2020 to2030 0.8%, and from 2030 to 2050 0.1%.) The IEA statistics are used for historical energy-related CO2
emissions. The pathway is assumed the current policies to be continued up to 2050 and drastic
reduction in CO2 emissions can be achieved in the future with the world efforts to cut emissions.

Figure 10 World population projections

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Figure 11 World GDP projections (Market exchange rates (MER) conversion)Note) Shown in the 2000 real price (2000 exchange rate)10Research Institute of Innovative
Technology for the Earth

Brazil Other Non2%
Annex I
14%

Other NonAnnex I 1990
Korea
12%
1% Brazil
2%
India
1%

US
30%

Other
Annex I
6%

EU28(+13)
1%

Japan
13%

Other NonAnnex I
17%

2011
US
29%

2020
US
27%

Brazil
2%
Korea
2%

India
2%

India
3%

China
9%

EU15
21%

Japan
12%

Other
Annex I
6%

EU28(+13)
1%

Other NonAnnex I
18%

China
13%

US
25%

EU15
18%
EU28(+13)
1%

Japan
11%

Other NonAnnex I
22%

2030

2050
US
22%

Brazil2%

Brazil
2%
Korea
2%

Other
Annex I
6%

EU15
23%

EU15
26%

Korea
2%

India
4%

India
2%

China
6%

Japan
17%
EU28(+13)
2%

Other
Annex I
6%

US
31%

Korea
2%

China
2% Other
Annex I
7%

Other NonAnnex I
16%
Brazil
2%

2005

EU15
12%

Korea
1%
EU15
15%

China
17%

Japan
9%

India
7%

EU28(+13)
2%

China
21%

EU28(+13)
2%
Japan
6%
Other
Annex I
5%

Figure 12 Regional share of GDP (Market exchange rates (MER) conversion)

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Reference to this paper

If this pathway of CO2 emissions is to be cited in any work, please notice us at the address below
in advance.



Pathway update

Let us note that this paper may be occasionally updated without notice so that the latest
information on historical emissions, economic trends and energy prices can be reflected in thepathway.



Reference

1) RITE, 2009; ‘RITE GHG Mitigation Assessment Model’(http://www.rite.or.jp/Japanese/labo/sysken/about-global-warming/download-data/RITE_GHGMit
igationAssessmentModel_20090529.pdf)
2) IAEA, 2013; Energy, Electricity and Nuclear Power Estimates for the Period up to 2050 (2013
Edition), IAEA.
3)

IEA, 2013; World Energy Outlook 2013, OECD/IEA.

4)

IEA, 2014; Energy Balances of OECD Countries, OECD/IEA.

5)

IEA, 2014; Energy Balances of Non-OECD Countries, OECD/IEA.

6)

IEA, 2013; CO2 emissions from fuel combustion, OECD/IEA.

7)

UNFCCC, GHG data from UNFCCC,
http://unfccc.int/ghg_data/ghg_data_unfccc/items/4146.php (access on October 3, 2014)8)

UN, 2012; World Population Prospects: The 2012 Revision9)

UN, 2008; World Population Prospects: The 2008 Revision

Contact to:
Kohko Tokushige, Fuminori Sano, Keigo Akimoto
Systems Analysis Group
Research Institute of Innovative Technology for the Earth (RITE)
9-2 Kizugawadai, Kizugawa-shi Kyoto 619-0292 JAPAN
PHONE: +81-774-75-2304 FAX: +81-774-75-2317 E-mail: sysinfo@rite.or.jp

12Research Institute of Innovative
Technology for the EarthAppendix 1 Outline of GHG mitigation model of RITE
The model consists of 3 modules: Key Assessment Model DNE21+, for energy-related CO2;
Non-energy CO2 emission scenario, that assumes specific non-energy CO2 emissions independent of
mitigation levels of energy-related CO2 emissions; 3 Non-CO2 GHG Assessment Model, for mitigationof the 5 kinds of greenhouse gas emissions (Figure A-1).

DNE 21+ Model• Assessment model forenergy-related CO2
emissions• 54 regions in the world• Bottom-up modeling(About 300 specifictechnologies are modeled)

Non-Energy CO2Emission Scenario

Non-CO2 GHG
Assessment Model• Projection module fornon-energy CO2 emissions• 54 regions in the world• Estimates of sectoral
non-energy CO2 emissions
to be consistent with GDP
and production activities• Assessment module for 5
non-CO2 GHGs (CH4,
N2O, HFCs, PFC, SF6)
• 54 regions in the world•The methodology is similar
to the USEPA assessment

Estimates of the 6 GHG emissions
Emission reduction costs and potentials
Recommendation of specific mitigation technologies (energy-related)

Figure A-1 Outline of GHG mitigation model
DNE21+ model is an optimization type liner programming model, minimizing the total worldwide
energy system costs over all the assessment period (up to 2050). Figure A-2 shows outline of energy
flows in DNE21+ model. The energy supply sectors are connected to the energy end-use sectors,
energy export/import are considered, and the lifetimes of facilities are taken into account, so thatassessments are made while maintaining complete consistency across the energy supply & demandsides. Based on the population and GDP scenarios developed by RITE, service demand scenarios (e.g.,
the production amount of crude steel in Iron & Steel sector, the traffic amount in the transportation
sector) are bottom-upped for major energy-consuming sectors (energy-intensive industrial sectors,
road transportation sectors and some equipments in residential & commercial sectors), and otherremaining sectors are top-downed and their energy demands are exogenously assumed. The model
solves the best mix of technologies to meet these demand scenarios. Here, costs and energy
efficiencies of individual technologies used in both the energy supply sectors and the end-use sectors
are explicitly modeled. So, detail evaluation of technologies is conducted and this is one of the salientfeatures of our model. As another feature of the model, the fine regional segregation (the world isdivided into 54 regions in country level.) is noted because it enables to analyze with regional
differences in consideration (e.g., potentials of renewable energy).

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Figure A-2 Outline of energy flows in DNE21+ model
For non-energy CO2 emission, one specific scenario is developed based on historical data of
UNFCCC and IEA and the cement production scenario which is used in DNE21+ model.
The Non-CO2 GHG model has been developed based on the studies by US EPA with someadjustments by latest historical data. The regional baseline emissions (emissions without GHG
mitigation policy) were estimated for five gases: CH4 in seven sectors, N2O in six sectors, HFCs in
one sector, PFC in one sector and SF6 in one sector. The emission reduction is calculated by usingelasticity representing the relationship between non-CO2 GHG mitigation ratio relative to the baseline
emissions and marginal abatement costs based on the database for emission reduction amounts andreduction costs of individual measures in non-CO2 GHG mitigation. So, the model is not a directbottom-up model; however, marginal costs and potentials of non-CO2 GHG mitigation are eventuallybased on the bottom-up analysis of the US EPA.
This is the model outline. More information is available in reference1).

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Research Institute of Innovative
Technology for the EarthAppendix 2 The pathways of energy-related CO2 and GHG emissions in the baseline scenario
Figure A-3 shows the pathways of global energy-related CO2 emissions without mitigation policy(the baseline scenario) and with continuous current mitigation policy in this paper (the current policies
and mitigation). In the continuous current mitigation policy scenario, CO2 emissions are estimated37.8 billion tons in 2020 and 56.3 billion tons in 2050, while in the baseline scenario, emissions are
estimated 40.1 billion tons in 2020 and 62.5 billion tons in 2050 (38.8 billion and 60.5 billion tons
excluding aviation and international shipping, respectively), which has been revised upward from thebaseline scenario in the August 2011 edition. Figure A-4 shows the CO2 emissions in the baseline
scenarios organized by IPCC AR5. The median value in 2050 under the standard assumptions of themodel (Default) is estimated about 60 billion tons, which two of our scenarios are close to.
Figure A-5 shows the pathways of global GHG emissions without mitigation policy (the baseline
scenario) and with continuous current mitigation policy in this paper (the current policies andmitigation), as Figure A-3. In the future baseline scenario, emissions are estimated 56.2 billion tons in2020 and 82.6 billion tons in 2050. Appendix Figure A-6 shows GHG emissions in the baseline
scenario organized by the IPCC AR5. The median value in 2050 is estimated about 80 billion tons,
which are close to RITE estimates as energy-related CO2.

Figure A-3 Energy-related global CO2 emissions in the baseline and the current policies
and mitigation (IEA statistics6) up to 2011)15

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Figure A-4 CO2 emissions in baseline scenarios organized by IPCC AR5 WGIII
Note) Default (grey range) shows the standard assumptions of models used for projections.
Fast (gold range) shows the substantial improvement of energy intensity. The red circle shows RITE
estimate.

Figure A-5 Global GHG emissions in the baseline and the continuous current mitigation policy
scenarios (Annex-l: UNFCCC7), Non Annex-l: IEA statistics6) up to 2010)16

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Figure A-6 GHG emissions pathways by IPCC AR5 WGIII
Note) The red circle shows RITE estimate.

Figure A-7 shows the trajectories of energy consumption per GDP (energy intensity) and CO2
emissions per energy consumption (CO2 intensity) whose values are normalized to 1 in the year 2010.
Energy intensity is projected to improve in the future though the current situation has been stagnant
due to the rapid development of China from 2000 up to now. In addition, as to CO2 intensity majorchanges cannot be seen as energy intensity because increase of fossil fuel consumption is larger thanthat of nuclear power and renewable energy, as shown in this paper so that in the future up to 2050
CO2 intensity is estimated rather worse than in 2010. These levels are consistent with the medianestimates organized by IPCC (Fig.8).

Figure A-7 Trajectories of the global energy intensity of GDP and CO2 intensity of energy in acontinuous mitigation policy scenarios and baseline scenarios (IEA statistics4), 5), 6) up to 2011)17

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Figure A-8 Trajectories of the global energy intensity of GDP and CO2 intensity of energyorganized by IPCC AR5 WGIII
Note) Default (grey range) shows the standard assumptions of models used for projections.
Fast (gold range) shows the substantial improvement of energy intensity. The red circle shows RITE
estimate.

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