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Key Message to Policy Makers

• Japan's mitigation target in 2050 is set to be by 80 % reduction by the 4th Environmental Basic Plan.

• The existing target is set based on the available technologies, that is to say,

the bottom-up approach.

• Top-down decision is also requested for the ambitious reduction target.

• The options to achieve the ambitious target have been available.


In 2013 and 2014, the IPCC 5th Assessment Reports were approved. In this report, it is concluded that “It is extremely likely that human influence has been the dominant cause of observed warming since the mid-20th century” (IPCC 2013). The IPCC 5th Assessment Report mentions that, in order to achieve the 2 oC target, which is to limit the increase in global mean surface temperature to less than 2 oC, the GHG emissions in 2050 and 2100 will have to be reduced by 41–72 % and 78–118 %, respectively, compared with the 2010 level (IPCC 2014). Figure 4.1 shows the future GHG emissions, and the right blue range (430–480 ppmCO2eq) is the emission pathways to achieve the 2 oC target likely.

Fig. 4.1 Total GHG emissions in all IPCC AR5 scenarios

Toward the achievement of the 2 oC target, Japan has set several GHG mitigation targets after ratifying the Kyoto Protocol. In the following sections, mitigation target will be discussed and the quantification figures using the AIM (Asia-Pacific Integrated Model) are explained.

From the Kyoto Protocol to Middle-Term Target

Figure 4.2 shows the trend of GHG emissions in Japan from 1990 to 2013. The actual GHG emissions during the 1st commitment period in Japan exceeded the emission target set by the Kyoto Protocol, but if the effects of carbon sink and Kyoto Mechanism such as mitigation outside of Japan are taken into account, the emissions in Japan could achieve the emission target. On the other hand, the trend of GHG emission after 2010 would increase because of the Great East Japan Earthquake and Fukushima Daiichi Nuclear Power Plant accident in March 2011. Figure 4.3 shows the sectoral GHG emissions in Japan. Among the sectors, the emissions from commercial and residential sectors increased after the nuclear power plant accident.

In 2015, the COP21 of UNFCCC will be held in Paris. At this meeting, the post2020 target will be discussed. Prior to the COP21, INDCs (Intended Nationally Determined Contributions), that is to say, the new ambitious target of GHG emission reduction, will be announced by each country by March 2015. Japan has been discussing this issue under the joint committee between the Ministry of the

Fig. 4.2 GHG emissions from 1990 and Kyoto target (Data source: GIO 2014, 2015)

Fig. 4.3 Sectoral GHG emissions in Japan (Data source: GIO 2015)

Environment and Ministry of Economy, Trade and Industry. On April 30, the new GHG mitigation target in 2030 was announced by the government. The value is 1.042 GtCO2eq, and this is 26.0 % reduction from the 2013 level. If the base year is set to 2005, the value of the reduction target becomes 25.4 %. The outline of the mitigation target in Japan in 2030 is introduced in Table 4.1.

The GHG mitigation targets in Japan have been changed when the government was changed. In 2008, in order to discuss the GHG mitigation target in 2020 at COP15 held in Copenhagen, the committee on the midand long-term target in Japan was organized at the Cabinet Secretariat. At that discussion, three types of

Table 4.1 Mitigation target in Japan in 2030

Fig. 4.4 Six options discussed in FY 2008 to FY 2009 (Note: The red triangle shows the mitigation target of all greenhouse gas emissions by the Kyoto Protocol. The white triangle shows the mitigation target of CO2 emissions from energy use)

models were utilized, global enduse model, Japan enduse model, and Japan economic model, and the proposed six options were quantified. Finally, 15 % reduction in 2020 compared with the 2005 level was selected as a target by former Prime Minister Mr. T. Aso. Figure 4.4 represents the contents of six options.

After the change of the government, the new Prime Minister, Mr. Y. Hatoyama, announced the 25 % reduction compared to 1990 at the United Nations Climate Change Summit held in New York in 2009. In reaction to this new mitigation target, the road maps to achieve this 25 % reduction target were quantified at the Central Environment Council. But just after they completed the road maps to achieve the target, the Great East Japan Earthquake and the accident of Fukushima Daiichi Nuclear Power Plant of Tokyo Electric Power Company (TEPCO) happened on March 11, 2011. Due to the nuclear power accident, the GHG mitigation road map and the future energy mix should be reconsidered, because those at that time relied on nuclear power. In 2012, the Energy and Environment Council forecasted that the GHG emissions in 2020 would be 5–9 % reduction compared to 1990 level in the case of the prudent economic growth case.

After the next change of the government, the new GHG mitigation target was officially revised to be 3.8 % reduction compared to the 2005 level under the assumption of the no nuclear power at the COP19 of UNFCCC in Warszawa in 2013. But this target is equivalent to +3.1 % to the 1990 level. At that time, assessment using models was not implemented. Figure 4.5 shows the GHG emission forecasts in 2020 for the high economic growth case by using the AIM/Enduse [Japan] model executed in 2012. In this figure, the target of 2013 is represented by the red line. And Fig. 4.6 shows the relationship between the additional investment cost and saved energy costs. From this figure, the total saved energy costs for the lifetime of each equipment can exceed the total additional investment costs to install the energy-saving equipment. That is to say, if we have long-term perspectives, the energy-saving investment will bring the benefit to the economy in Japan. But in the actual world, the investment is decided from the short-term scope, and then, the introduction of the energy-saving technologies is difficult.

Table 4.2 summarizes the brief history of decision of GHG emission mitigation in Japan and the world.

Fig. 4.5 GHG emissions in 2020 under the high economic growth case (as of June 2012)

Fig. 4.6 Necessary additional energy-saving investment and saved energy costs (as of June 2012)

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