SDGs are that the Sustainable Development Goals are the blueprint to achieve a better and more sustainable future for all. They address the global challenges we face, including those related to poverty, inequality, climate, environmental degradation, prosperity, peace and justice. The biomass is bearing material recycling of the earth. The flow of material recycling can be increased by increasing the biomass. To solve SDGs by 1.6 G ha afforestation so that all the CO2 emission by the use of fossil fuels can be fixed. To collect $25 per 1 ton of CO2 discharge by using the fossil fuel and to spend environmental protection such as growing up the forest. This leads to solve the problems related to poverty, inequality, climate, environmental degradation, prosperity, and peace and justice.

SDGs are that the Sustainable Development Goals are the blueprint to achieve a better and more sustainable future for all. They address the global challenges we face, including those related to poverty, inequality, climate, environmental degradation, prosperity, peace and justice. The reason why SDGs issue develops is externality of the market so to solve SDGs is to get rid of externality of the market for example carbon prices. The right carbon prices($25/t-CO₂) and the lowest cost($6.4/t-CO₂) carbon reduction which is afforestation are proposed to solve SDGs.

Several scientific societies around the world have stated that the global climate is changing and its effects have already been observed. The results of Nordhaus’ DICE model demonstrate that emission reductions are difficult to achieve without reducing population, living standards, and carbon intensity. The reason why global warming is a troublesome externality is that it is global and that it is a problem of cost/benefits for future generations. As a result, the Kyoto mechanism has failed to significantly reduce emissions and to participate in agreements with many countries. As an issue after the Paris Agreement, in order to avoid the free-rider problem, high levels of carbon prices and tariff frameworks in international trade should be linked to motivate as many countries as possible to join the agreement.

本稿では，液化天然ガス（LNG）の未利用冷熱を活用して大気中の二酸化炭素（CO₂）を直接回収する技術「Cryo-DAC^®」の概要と，その開発状況について紹介する。Cryo-DAC®は，LNGの極低温を利用して気体のCO₂を固体（ドライアイス）へと相転移させ，この過程で生じる減圧環境を用いてCO₂を吸収したアミン系吸収液からCO₂を再生する点に特徴がある。これにより従来必要とされていた加熱操作が不要で，エネルギー消費を抑えたCO₂回収が可能となるポテンシャルを有する。現在，プロセスのスケールアップに向けて，コンセプト実証を目的としたベンチスケール装置の運転を開始している。

二酸化炭素（CO₂）の排出削減を促進する手法の１つであるカーボンプライシングについて，多くの学術論文が発表されている．論文の理解には経済や気候等に関する多様な専門知識が必要となる．本研究では大量のテキストデータを使ってトレーニングした大規模言語モデルの一種であるBERTを用いてカーボンプライシング関連論文の内容把握・分析を試みた．具体的には，インターネット上で収集したカーボンプライシング関連論文について，人手でラベル付けし学習データとして用いることで，BERTによる文章分類器を作成した．SHAPによってBERTの判断根拠を可視化し，カーボンプライシングに関するワードがモデルの判断に用いられていることを確認するとともに，BERTopicによるトピック分析を実施し，カーボンプライシング関連論文が６つの主要なトピックに分けられることを示した．

This paper refers to how Austrian-born concept of opportunity cost was accepted and established as a basic economic concept in current economics and economic education. The concept of opportunity cost was created by von Wieser and transferred to the United States via London. The key person who transmitted the concept to America was Robbins at LSE. There was another route of transmission of the concept; some Austrian economists like von Haberler brought it directly to the United States in the 1930’s. In the United States, this concept was accepted mainly by Chicago school economists like Knight and spread wide in the country by their hands. But the process was not straightforward, and I will trace it back to Samuelson’s Economics. The term of opportunity cost was first introduced in the 5th edition (1961) of the book. At the same time, JCEE introduced opportunity cost as a fundamental economic concept in the standard economic teaching (Task Force Report), and the concept was beginning to prevail nationwide in K-12 school education in the United States. It has become a fundamental economic concept ever since at the university level and even in the preschool education. In Japan, the concept was introduced in economics instruction at university in the 1980’s, but it was hardly taught at junior or senior high school at that time. Opportunity cost has an important role in making economic decisions. As it is an invisible cost, there is much difficulty in understanding it. Besides, opportunity cost is a subjective expense and its definition is difficult. It is necessary to teach it with firm definition and prepare many examples to make students understand the concept. A lot of effort is required to develop an economic way of thinking through opportunity cost among students.