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My specialty is a research field called environmental economics. Traditional economics has contributed to economic growth by studying the transactions of goods and services in the market and making proposals to make transactions smoother. However, human economic activities often create a burden on the environment, and if market transactions continue without being aware of this, it could cause serious environmental problems. A healthy environment is a prerequisite for us to carry out economic activities, and even if economists make proposals to facilitate market transactions, if they lead to environmental destruction, they will deprive ourselves and future generations of their benefits. Based on this idea, environmental economics goes beyond the market transactions and human activities that economics has studied to analyze the impact on the environment.

Within the field of environmental economics, I am interested in environmental problems caused by household consumption behavior and corrective measures. Specifically, I have been working on themes closely related to household finances and daily life, such as energy saving behavior, recycling activities, and the use of organic agricultural products and eco-cars (Professor Shigeru Matsumoto's research theme). Most recently, I have been conducting research on energy consumption behavior in the home, hoping to contribute to global warming countermeasures by encouraging energy saving behavior in households. My research style is to grasp environmental problems from familiar places and find corrective measures. When I get a glimpse of people's behavioral patterns through my research, I feel like I understand other people's feelings, which is fun.

[Distribution of monthly electricity consumption by households in Japan (0-500 kWh)]

* Prepared by Onuma and Matsumoto based on data from the Ministry of the Environment
* Survey period: October 2014 to September 2015 (Onuma and Matsumoto)
A tiered pricing system is widely used for electricity rates, where the unit price increases according to the amount of usage, but Tokyo Electric Power Company's unit price differs in three tiers (<120kWh, 120-300kWh, >300 kWh).

[Energy consumption by use]

Source: Japan (Institute of Energy Economics, Japan, 2020), Europe (Eurostat, 2017), United States (US Energy Information Administration, Residential Energy Consumption Survey, 2015)
*Data for the United States does not include energy for cooking, so caution is required when comparing with other countries.

Nobel Prize-winning economist Joseph Eugene Stiglitz has said that "economics is the science of choice." The idea behind economic models is to determine what choices to make from among options under various constraints and conditions. Typically, companies make choices by considering how to act in order to maximize profits, while consumers make choices by considering what purchasing behavior they should take in order to maximize utility (satisfaction). In research, we first consider this economic model, collect a lot of data to confirm the actual situation, and perform statistical analysis. In the process, we take into account costs, including environmental impact, and utilize knowledge of economics to propose feasible corrective measures based on the results of the economic model and data analysis.

I was originally an engineer, and studied agricultural civil engineering at university, learning things like surveying forest roads and designing dams. The process of calculation is essential in the process, so I acquired basic mathematical knowledge, including the basics of determinants, linear algebra, differential and integral calculus, and statistics. I went on to graduate school in environmental studies, where I met a professor who specialized in environmental economics, which was rare in Japan at the time. I was very interested in what he had to say, and felt that it matched my intuition, which is what led me to pursue this path.

Environmental issues have been attracting attention since the 1970s, but the initial challenge was to overcome the pollution problem. There was lively discussion about how to restore an environment where people could live in peace. Since then, there have been several big waves of thinking about environmental issues, and we can say that we are now in the midst of the SDGs movement. Around 1990, when I was a student, interest in global environmental issues such as problems in developing countries, global warming, and biodiversity was growing, and I remember that in graduate school I seriously thought about how I could somehow solve these issues on my own, and became absorbed in research. After that, I studied economics in earnest at a graduate school overseas, and since then, I have been researching environmental economics from the perspectives of both a science engineer and an economist.

In general, economics tries to explain social problems by modeling patterns of human behavior, while engineers place more importance on the smooth functioning of calculation-based mechanisms. In today's economics, where complex issues intersect, both of these perspectives are important. Environmental economics in particular overlaps with science and engineering, so this aspect is strong, and I feel that what I learned in college has been very useful. In addition, views on environmental issues can be related to personal lifestyles and life philosophies, but as a researcher, I believe it is important to take a neutral stance toward research without making my own claims the premise. My job is to clarify people's behavior based on detailed data analysis and make it widely known to society, and I believe that the selection of specific measures to solve problems should be discussed and decided by society as a whole.

In recent years, environmental awareness has increased, which is affecting consumer behavior and corporate activities. On the consumer side, we are seeing an increase in the number of products from companies that practice environmentally friendly production, even if they are somewhat more expensive, and the environmentally conscious market seems to be expanding. From the company's perspective, there are also situations in which it will be difficult to raise funds if environmentally conscious behavior is not adopted, so it can be said that consumer behavior is influencing corporate activities. However, depending on the household's economic situation, there are cases in which such consumer behavior is not possible, and it is easy to imagine that people will choose to simply purchase a cheap product. From the perspective of consumer cost burden, it is unknown how far the environmentally conscious market will expand, and I believe it will be difficult to solve the problem through individual consumer behavior alone.

On the other hand, from the perspective of corporate management, it is natural to want to keep production costs as low as possible. Even if the production process places a burden on the environment, there is no cost involved. Conversely, if you try to shift to a method that does not place a burden on the environment, it will cost you. Thinking about it this way, it is unlikely that all companies will voluntarily bear the costs to reduce the environmental burden of their production activities. In other words, I believe that a sustainable society cannot be realized simply by leaving environmental considerations entirely up to the discretion of companies. Some kind of environmental policy, such as regulations or taxation, is needed to encourage companies to take action, and it is at such times that the research findings of environmental economics are useful.

As mentioned above, environmental economics has two aspects: the environmentally conscious actions of companies, and the actions of consumers, such as how they evaluate and select products and services and the companies that provide them. I focus on consumer choices and try to find ways to reduce environmental impact.

[Average annual CO2 emissions hybrid vs. gasoline vehicles]

From K.Iwata, S.Matsumoto/ Transportation Research Part D 46(2016) 200-206

In addition, the book "Carbon Pricing in Japan (Springer 2020, Editors: Toshi H. Arimura and Shigeru Matsumoto)," edited by Professor Toshihide Arimura of Waseda University, won the 2021 Environmental Economics and Policy Studies Association Forum Award. "This is the first comprehensive research book on Japan's carbon pricing policy, and it is composed of an analysis of the effects of policies that have been introduced so far, as well as simulation analysis of policies currently under consideration, such as a national carbon tax and emissions trading system. It shows how to use it effectively while overcoming various challenges, and provides important insights, especially for government officials and policy makers in countries and regions seeking cost-effective measures. Furthermore, it is an educational book that meets the needs of not only researchers but also the general public who are interested in climate change issues and their solutions, and raises the importance of carbon pricing to society." This award is given to works in books, pamphlets, general magazines, etc. that are recognized as making a significant contribution to actively raising issues and raising awareness in the general public. The books in question are published in open access format, and as of May 2022, a year and a half after their publication in 2020, they have been downloaded more than 45,000 times.

When confronting social issues, for example, law students will analyze the phenomenon through the lens of law, sociology students through the lens of sociology, and economics students through the lens of economics. It can be said that any social issue can become a research subject for each academic field when viewed through the lens of each field. At Aoyama Gakuin University 's College of Economics, faculty members have a wide range of research themes, from social security to environmental issues. Whatever social issue a student is interested in, there is a stage available for them to pursue it from an economics perspective.

In addition, whether or not a study matches your own sensibilities and preferences is also an important factor in deepening your academic knowledge. In my case, I prefer to think about things that I can touch and interact with myself rather than economic theory, and I have approached academic studies from the consumer's perspective.

Economics tends to be seen as a liberal arts field, but there are also times when an approach from a science perspective is useful. Data science has been attracting attention in recent years, and I feel that the importance of using data is rapidly increasing in the field of economics. When selecting a particular social policy, quantitative data analysis is required to predict the impact it will have, and in such work, having basic mathematical ability is a great advantage. It is expected that the trend toward such numerical ability will become even stronger in the future. Economics is expected to become an academic field that requires an increasingly multifaceted perspective, so I would like you to challenge yourself with an open mind, but the economic perspective you acquired at university will be of great help when you enter society and face various problems.

(Published in June 2022)