Carbon dioxide in Japan - reduction target

2023/02/13 2023/02/13

lenemas

Japan nowadays emits 1.2 billion tones of carbon dioxide annually (see Carbon dioxide in Japan - emission amount). Beccause the environmental issues are said to have originagted from the increase in the concentration of green-house gases (GHG), goverments put efforts in stopping the increase. This post shares with you the target of reduction in the GHG emission set by the Japannese goverment in a bit of details.

Reduction target in Japan

Utilimately, Japan as a nation set to achieve carbon-neutrality by 2050. The original document that declared this target was the speech by Prime minister, Mr. Suga at that time, October 2020.^[1] A more detailed target was unravailed in the following year, stating "reduction by 46% with respect to 2013 in 2030". The reference to this target was also the speech by Mr. Suga in April 2021 Climate Summit.^[2]

These quantities;

zero-emission in 2050
46% reduction (with respect to 2013) by 2030

are officially stated in a document "strategic energy plan" of Japan,^[3] meaning that these are the official goals set by the Japanese government.

What is "46% by 2030" based on?

While the goal of "zero in 2050" could intuitively be understood, what is "46% reduction by 2030 based on? The aforementioned references did not deliver any concrete evidence, and hence this post tries to address its origin. The figure below plots annual emission of carbon dioxide, whose data were adopted from National Institute for Environmental Studies,^[4] together with the targets.

* Sorry that the figure is in Japanese, but will be translated!
CO₂排出量 / 百万トン = CO₂emission / million ton, 対2013年比率 = percentage with respect to year 2013, 年 = year

The emissions these years are approximately 80% of that in 2013. The dashed orange line in the figure follows this recent trend, and is crossing the point of "zero in 2050". And, this dahsed orange line goes through the point of 54% in 2030, which corresponds to "46% reduction in 2030". Therefore, the Japanese goverment set "0% in 2050" and "100% in 2013" as a basis, and would draw a straight line between them to obtain 46% in 2030.

One may suppose that the quantity of "46% in 2030" would have been obtained by accumulative estimation from each sector; but was likely a simple extraporation...? Of course, it would also be possible that by accident the point appears on the straight line.

References

首相官邸, “第二百三回国会における菅内閣総理大臣所信表明演説”, https://www.kantei.go.jp/jp/99_suga/statement/2020/1026shoshinhyomei.html (accessed on 2022/02/16)
外務省, “菅総理大臣の米国主催気候サミットへの出席について（結果概要）”, https://www.mofa.go.jp/mofaj/ic/ch/page6_000548.html (accessed on 2022/02/16)
経済産業省，”エネルギー基本計画” 令和3年10月
国立研究開発法人国立環境研究所, 温室効果ガスインベントリ, https://www.nies.go.jp/gio/aboutghg/ (accessed on 2022/02/15)