23

Research Perspectives on Future Scenarios toward
Achievement of the 2 Degree Target
Toshihiko MASUINational Institute for Environmental Studies (NIES)
16-2, Onogawa, Tsukuba, Ibaraki, 305-8506, Japane-mail:masui@nies.go.jp

Abstract
The Paris Agreement entered into force in 2016, with the world rushing to realize the 2°C target forholding the increase in the global average temperature to well below 2°C above pre-industrial levels. On theother hand, there is a big gap between the aggregate of existing mitigation targets of each country after 2020and emission pathways that would achieve the 2°C target, and this means that more ambitious GHG
reductions will be needed toward 2050 and later. Some countries have already submitted their long-term low
greenhouse gas emission development strategies. Although Japan proposes a 26% reduction of its GHG
emissions by 2030 compared to those in 2013 and an 80% reduction by 2050, it has yet to engage inthorough discussions of its long-term strategy and roadmap. The existing analyses indicate an 80% GHG
emission reduction is technologically feasible, but there are many challenges to realizing it. This paper
introduces discussions in Japan toward achieving the 2°C target, and considers what will be needed in Japanto realize the 2°C target.
Key words: long-term low GHG emission development strategy, mitigation target, Paris Agreement, 2°C target

1. Introduction: Paris Agreement andGreenhouse Gas Emission Reduction Target
The Paris Agreement was adopted at the 21stConference of Party (COP21) of United Nations
Framework Convention on Climate Change (UNFCCC)
in Paris in 2015 (UN, 2015). In November 2016, theParis Agreement entered into force after the threshold forthat of the Paris Agreement was achieved, which was forat least 55 Parties to the Convention, accounting in total
for at least an estimated 55% of the total global
greenhouse gas (GHG) emissions, to have deposited theirinstruments of ratification, acceptance, approval oraccession with the depositary.
It is said that climate policies and actions have moved
to a new phase by the Paris Agreement. Now the UnitedStates has announced its withdrawal from the ParisAgreement, but many states and private companies in theUSA have indicated their intention to remain in the ParisAgreement. Recently in many areas, climate changeimpacts have become obvious. The movement to realize
the Paris Agreement will not be stopped but will
accelerate in the future.
Article 2 of the Paris Agreement describes the global
average temperature target as follows: “Holding theincrease in the global average temperature to well below
2°C above pre-industrial levels and pursuing efforts tolimit the temperature increase to 1.5° C above preGlobal Environmental Research
21/2017: 023–027
printed in Japan

industrial levels, recognizing that this would significantly
reduce the risks and impacts of climate change.”
Article 4 of the Paris Agreement mentions the global
emission pathways as follows: “In order to achieve thelong-term temperature goal set out in Article 2, Parties
aim to reach global peaking of greenhouse gas emissions
as soon as possible, recognizing that peaking will takelonger for developing country Parties, and to undertake
rapid reductions thereafter in accordance with best
available science, so as to achieve a balance between
anthropogenic emissions by sources and removals bysinks of greenhouse gases in the second half of thiscentury, on the basis of equity, and in the context ofsustainable development and efforts to eradicate
poverty.” Moreover, that “All Parties should strive toformulate and communicate long-term low greenhousegas emission development strategies, mindful of Article
2, taking into account their common but differentiatedresponsibilities and respective capabilities, in the light ofdifferent national circumstances” is also mentioned (COP,by decision 1/CP 21, paragraph 35, invited the Parties tocommunicate by 2020 to the secretariat, mid-century,
long-term low greenhouse gas emission development
strategies in accordance with Article 4, paragraph 19, ofthe agreement). That is to say, in order to achieve climate
targets such as the 2°C target, global GHG emissions willneed to peak-out as soon as possible, and show a negative
trend during the latter half of the 21st century.
©2017 AIRIES24

T. MASUI

2. The 2 Degree Target and INDCs
Prior to COP21, all countries had to submit their own
intended nationally determined contributions (INDCs) tothe UNFCCC. All the submitted documents are listed on theUNFCCC’s website (http://www4.unfccc.int/submissions/indc/Submission%20Pages/submissions.aspx). The INDCs
cover not only the targets for GHG mitigation reductions
but also the targets for adaptation in each country. Somedeveloping countries focus on climate change impacts andadaptation rather than GHG reduction targets.
Table 1 shows the mitigation targets of majorcountries and regions of the world. From Table 1, it canbe seen that the GHG mitigation targets reflect thesituation of each country. Most of the developed
countries have adopted absolute targets for GHG
emissions. On the other hand, many developing countries
have adopted intensity targets or relative reduction of
their emissions in a BaU (business as usual) case.
Moreover, some developing countries such as Indonesia
and Thailand have adopted two types of targets: one
unconditional target and a separate conditional target
contingent on other countries’ support.
The UNFCCC (2016) has summarized the all

Table 1 E
 mission reduction targets of major countries and regions.
CountryTarget

China

To reduce carbon intensity by 60% to 65% by 2030 below 2005 levels.

India

To lower emission intensity of GDP by 33% to 35% by 2030 below 2005 levels.

Indonesia

An unconditional 2030 GHG emission reduction target of 29% below BaU including land use, land-use change and forestry(LULUCF) emissions, and a conditional 41% reduction below BaU by 2030 (with sufficient international support).

Japan

To reduce emissions by 26% below 2013 emission levels by 2030.

Korea

To reduce GHG emissions by 37% below BaU by 2030.

Malaysia

To reduce GHG emission intensity of GDP by 45% by 2030 relative to the emissions intensity of GDP in 2005.

ThailandAn unconditional 20% reduction in emissions by 2030 compared to BaU levels. This could increase to 25%, conditional
upon international support.

Vietnam

An 8% reduction in emissions by 2030, compared to BaU. This could be increased to 25% conditional upon international support.

USA

To reduce economy-wide emissions by 26% to 28% below 2005 domestically.

EU

To reduce GHG emissions by at least 40% domestically below 1990 levels by 2030.

RussiaLimiting anthropogenic GHG to 70－75% of 1990 levels by 2030.

BrazilTo reduce GHG emissions by 37% below 2005 levels by 2025.

Source: UNFCCC (2015)Fig. 1 Comparison of global emission levels in 2025 and 2030 resulting from the implementation ofthe INDCs and under other scenarios. Source: UNFCCC (2016)

25

Research Perspectives on Future Scenarios toward Achievement of the 2 Degree Target

proposed GHG reduction targets. Figure 1 shows thevarious global GHG emission pathways, including
emissions upon achieving the INDCs. This figure showsthat the INDCs can reduce GHG emissions compared tono GHG reductions in the world by 2025 and 2030, butvery large gaps remain in GHG emissions between theINDCs and the 1.5°C / 2°C scenarios. In order to achieve
the 2° C target after following the INDCs, very steep
GHG emission reductions will be needed after 2030.
That is to say, more ambitious targets in 2030 will beneeded to achieve the 2°C target according to this figure.
The Paris Agreement mentions the “global stocktake”
which assesses collective progress towards achieving thepurpose of the Paris Agreement and its long-term goals.
For each country, “Each Party’s successive nationallydetermined contribution will represent a progression
beyond the Party’s then current nationally determined
contribution and reflect its highest possible ambition,reflecting its common but differentiated responsibilities
and respective capabilities, in the light of different
national circumstances.”

3. Long-term Low Greenhouse Gas Emission
Development Strategies
The Paris Agreement requests each Party to submit a“long-term low greenhouse gas emission development
strategy” by 2020. As of the end of June 2017, a total of
six countries had submitted their own strategies: theUSA, Mexico, Canada, Germany, France and Benin.
Among these countries, the USA, Mexico, Canada,
Germany and France have indicated long-term GHG
emission reduction targets, as shown in Table 2. Although
the benchmark years are different, many countries haveindicated GHG reductions of more than 75% by 2050. In
particular, Germany mentions a 95% reduction by 2050
compared to its emissions in 1990.

4. Discussion on Japan’s Long-term Strategy
The Government of Japan (2015) approved Japan’s
INDC at a Cabinet meeting on July 17, 2015. The GHG
reduction target for 2030 was set at a 26% reduction
compared to the 2013 level. After that, Japan alsoapproved a Climate Action Plan at a Cabinet meeting onMay 13, 2016. The Climate Action Plan stipulates an 80%
reduction of GHG emissions in Japan by 2050. Figure 2
shows previous trends and future targets for GHG
emissions in Japan. Although Japan achieved its GHG
mitigation target during the 1st commitment period (2008－2012) by using carbon sinks and credits, no sharp GHG
reduction could be observed from 1990 to 2015. In order

Table 2 G
 HG emission reduction targets under long-term low GHG emission development strategies.
CountryDate submitted GHG reduction targetUSA

Nov. 16, 2016

80% reduction of GHG in 2050 compared to 2005 level

MexicoNov. 16, 2016

50% reduction of GHG in 2050 compared to 2000 level

CanadaNov. 17, 2016

80% reduction of GHG in 2050 compared to 2005 level

Germany

Nov. 17, 2016

80－95% reduction of GHG in 2050 compared to 1990 level

FranceDec. 28, 2016

75% reduction of GHG in 2050 compared to 1990 level

GHG emissions [GtCO2-eq]

Source: UNFCCC (2017)

1.5
1.4
1.3
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0

1990

1995

2000

2005

2010

2015

2020

2030

2040CO2 Energy industries

CO2 Industries

CO2 Transporta�on

CO2 Commercial

CO2 Residen�alNon-energy CO2CH4N2OHFCs

PFCsSF6

NF3Fig. 2 G HG emission trends through 2015 and future emission targets in Japan.
Source: Greenhouse Gas Inventory Office of Japan (2017) and Government of Japan (2015)2050

26T. MASUIto achieve the GHG emission targets for 2030 and 2050, areal break in this trend will be needed from now on.
Although the Climate Action Plan mentions an 80%
reduction of GHG emissions in Japan by 2050, a detailed
concrete roadmap to achieve the 80% reduction target
has yet to be quantified. To discuss the long-term target
for Japan, the Sub-committee on Long-term Low-Carbon
Vision was organized under the Central Environment
Council in July 2016. In March 2017, the sub-committee
presented its long-term low-carbon vision (2017). In thisvision, “simultaneous solution” of economic and social
problems such as aging of society and climate change isregarded as a background issue. The long-term GHG
reduction target for 2050 is clearly set at 80%, and inorder to achieve this target, the vision stresses improved
energy efficiency, increased low-carbon energy supply,
and a switch to low-carbon energies in end-use. In
addition to that, the “carbon budget” concept isintroduced, in which the global mean temperature change
is related to cumulative GHG emissions from the preindustrial level, and it gives the clear message that thetime to act is “Now.” If infrastructure and large-scale
facilities including coal thermal power plants, whichhave long life times, are introduced now, the CO2
emissions may remain high over time. Such “lock-in”
effects will have to be avoided to keep the GHG
mitigation opportunity as high as possible. The vision
points out that development and deployment of new
innovations are key to long-term significant GHG
emission reductions. Not only innovation in technology,
but also innovations in economic and social systems andlifestyles will be needed to realize drastic GHG emission
reductions. The transformation will contribute toemission reductions both in Japan and worldwide. To
support the various actions toward a low-carbon society,the role of “carbon pricing” will be very important.
Carbon pricing will provide the necessary information
and a good incentive to reduce the GHG emissions.

5. Is an 80% Reduction of GHG emissions inJapan by 2050 Achievable?
There have been several studies assessing 80%
reduction of GHG emissions in Japan by 2050. The firstof these was the Japan Low Carbon Society (LCS)
Scenarios toward 2050 Project (2050 Japan Low-Carbon
Society Scenario Team, 2008). This was a research
project of the Global Environmental Research Fund (S-3)
of the Ministry of the Environment, Japan. In this project,
two types of socio-economic scenarios were proposed,
and by using the Asia-Pacific Integrated Model (AIM), it
found quantitatively that a target of 70% reduction ofCO2 emissions by 2050 compared to the 1990 level inboth scenarios would be achievable. Later the GHG
mitigation target for 2050 was changed from 70% to80%, and the new target was also found to be realizable.
The Deep Decarbonization Pathways Project (DDPP)
is another example of a quantitative analysis. The
Sustainable Development Solutions Network (SDSN)

1 400 MtCO2eq
1 200
1 000
Reduction by800

non-CO2600

energy efficiency
shift to low-carbon sources

400

CCS200GHG emissions0(All)2010

Reference Mixed No-Nuclear

Limited CCS

2050

Fig. 3 CO2 emissions by case and decarbonization wedges for thethree scenarios.

and the Institute for Sustainable Development andInternational Relations (IDDRI) initiated it todemonstrate how countries could transform their energy
systems by 2050 to achieve a low-carbon economy andsignificantly reduce the global risk of catastrophic
climate change. The project currently comprises 16
country research teams, composed of leading research
institutions from countries representing about 70% of
global GHG emissions and at very different stages ofdevelopment.
From Japan, the AIM project team is participating inthis project, and by using the AIM/ Enduse [Japan] (adynamic recursive technology selection model for mid-to
long-term mitigation policy assessment in Japan), itassesses GHG emission pathways in Japan through 2050
(Kainuma et al., 2015). It has prepared three scenarios toassess 80% GHG emission reduction in Japan by 2050: amixed scenario in which all technology options areavailable; no nuclear scenario; and limited carbon captureand storage (CCS) scenario, in which 100 MtCO2/year ofCCS is allowed, i.e., half the amount considered in themixed scenario.
Figure 3 shows the CO2 emission reductions for thesethree scenarios in 2050. The DDPP shows the threepillars of decarbonization as a whole: energy efficiency,decarbonization of electricity and electrification ofend-uses. In the case of Japan, these pillars are also
important, and the report concludes that “With largescale diffusion of low-carbon technologies, Japan’slong-term GHG emission reduction target is technicallyfeasible, even if the availability of nuclear power and/orCCS is limited.” Although the marginal costs of CO2
reduction in the no-nuclear and limited CCS scenarios
are more expensive than that in mixed scenario, thesethree scenarios can achieve the 80% reduction of GHG
emission by 2050.

6. How can Japan Contribute to the 2°C Target?
From the existing quantitative analyses, the 80%
GHG emission reduction in Japan by 2050 is aResearch Perspectives on Future Scenarios toward Achievement of the 2 Degree Target

technologically feasible target, but to realize this target,
we face many challenges. From Fig. 2, no sharp GHG
emission reduction can be observed in Japan from 1990to 2015. This means that the general level of engagementwith climate change mitigation is still slow.
To ensure the 2°C target is reached, an 80% reductionin Japan by 2050 is inevitable. From the existing studies,the 80% reduction target can be achieved using theexisting and forecasted technologies. Various innovationsof technologies and socio-economic systems can help
implement the mitigation actions.
It is important to show how to support implementationof the mitigation technologies in the actual world. For
example, if the payback period can be considered long,that is to say, decision making with a long-term viewpoint
can be realized, the mitigation costs decrease, and more
mitigation technologies including energy saving
technologies and renewable energies will be able to beintroduced.
Climate change measures to achieve the 2°C target
will have to continue more than 100 years, and strengthenyear by year. On the other hand, the year 2050 is not thedistant future. The target of 80% reduction will have tobe realized before high school students at this moment
reach 60 years of age. A long-term perspective during thedecision making process can help avoid lock-in effects.
The research also will have to contribute toimplementation of GHG mitigation technologies in thereal world to provide a concrete roadmap. For that
purpose, in addition to mitigation technologies, socioeconomic activities in the future will have to be
discussed, and more detailed analyses taking into accountthe local circumstances and stakeholders’ conditions will
be needed in addition to macroscopic analyses.

27

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2016/cop22/eng/02.pdf> (accessed on 1 October 2017)
UNFCCC (United Nations Framework Convention on Climate Change)(2017) Communication of long-term strategies.<http://unfccc.
int/focus/long-term_strategies/items/9971.php> (accessed on 1October 2017)

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UNFCCC (United Nations Framework Convention on Climate Change)(2016) Aggregate Effect of the Intended Nationally DeterminedToshihiko MASUI
Toshihiko Masui has worked at the National Institutefor Environmental Studies since 1998. His major
field is modeling and simulation of environmental
policies, especially assessment of climate mitigation
policies. He is in charge of the AIM (Asia-PacificIntegrated Model) project at NIES. He is a subcommittee member of the Central Environment
Council. He also works at the Tokyo Institute of Technology as a visiting
professor. He lectures on the global environmental modeling and environmental
economics and policy theory for both undergraduate and graduate students.

(Received 16 October 2017, Accepted 19 October 2017)