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Assessing climate change impacts on local communities is an urgent task for national and subnational governments. The impact assessment requires socioeconomic scenarios, including a long-term outlook for demographic and economic indices. In Japan, the National Institute for Environmental Studies developed the Japan Shared Socioeconomic Pathways (JPNSSPs) and presented regional population scenarios corresponding to five different storylines. However, there exists no quantitative information about changes in local economies under the population scenarios. This study examines the economic activities in Japan's 47 prefectures using statistical models and calculates changes in the major economic indices (e.g., production, capital stock, and labor population) until 2100. The economic projection is based on ten socioeconomic scenarios generated from the JPNSSP population scenarios and original productivity scenarios. The economic projection results clearly show that Japan's population aging and decline have catastrophic impacts on national and subnational economies. Even in the most optimistic scenario, assuming a massive influx of immigrants and fast productivity growth, the GDP growth rate becomes negative in the 2090s. In the most pessimistic scenario, the GDP growth rate becomes negative in 2028 and continues to decline. As a result, Japan's GDP decreases to the level of the 1970s by 2100. The improvement of productivity cannot offset the GDP shrink caused by demographic changes. Furthermore, the population aging and decline accelerate the wealth concentration in urban areas. The Theil index, calculated using the economic projection results, shows increasing trends in all the scenarios. Tokyo's presence in Japan's economy will continue to increase throughout this century. Meanwhile, Kanagawa and Saitama, which belong to the top five prefectures in terms of economic production, may lose their positions. The Tohoku region, already suffering from population decline, will face severe economic stagnation. Our findings suggest that the depressing future is inevitable unless Japan overcomes the population aging and decline.
Keita Honjo; Kei Gomi; Yuko Kanamori; Kiyoshi Takahashi; Keisuke Matsuhashi. Long-term projections of economic growth in the 47 prefectures of Japan: An application of Japan shared socioeconomic pathways. Heliyon 2021, 7, e06412 .
AMA StyleKeita Honjo, Kei Gomi, Yuko Kanamori, Kiyoshi Takahashi, Keisuke Matsuhashi. Long-term projections of economic growth in the 47 prefectures of Japan: An application of Japan shared socioeconomic pathways. Heliyon. 2021; 7 (3):e06412.
Chicago/Turabian StyleKeita Honjo; Kei Gomi; Yuko Kanamori; Kiyoshi Takahashi; Keisuke Matsuhashi. 2021. "Long-term projections of economic growth in the 47 prefectures of Japan: An application of Japan shared socioeconomic pathways." Heliyon 7, no. 3: e06412.
We conducted a detailed estimation of direct and indirect CO2 emissions related to multi-person households in 49 Japanese cities. Direct energy consumption was decomposed into energy use in order to consider the relationship with regional conditions. The results showed that CO2 emissions from direct energy consumption were almost as large as indirect CO2 emissions induced by consuming products and services, suggesting that lifestyle improvements are important for both energy savings and reducing CO2 emissions relating to product and service consumption. In addition, CO2 emissions from direct energy consumption varied widely between cities, making them susceptible to regional conditions. We also calculated CO2 emissions from direct energy consumption and examined the regional conditions for individual forms of energy use. CO2 emissions were higher in cold regions and lower in larger cities. In Japan, large cities are often located in relatively warm areas, so we conducted an analysis to distinguish the effects of climatic conditions from those of urbanization. This analysis allowed us to clarify the effects of regional conditions on factors such as heating/cooling and the ratio of detached houses to apartments.
Yujiro Hirano; Tomohiko Ihara; Masayuki Hara; Keita Honjo. Estimation of Direct and Indirect Household CO2 Emissions in 49 Japanese Cities with Consideration of Regional Conditions. Sustainability 2020, 12, 4678 .
AMA StyleYujiro Hirano, Tomohiko Ihara, Masayuki Hara, Keita Honjo. Estimation of Direct and Indirect Household CO2 Emissions in 49 Japanese Cities with Consideration of Regional Conditions. Sustainability. 2020; 12 (11):4678.
Chicago/Turabian StyleYujiro Hirano; Tomohiko Ihara; Masayuki Hara; Keita Honjo. 2020. "Estimation of Direct and Indirect Household CO2 Emissions in 49 Japanese Cities with Consideration of Regional Conditions." Sustainability 12, no. 11: 4678.
Under the session “Quantifcation of the population”, the following sentence Population curves of Japan SSP1 and Japan SSP2 are close, because the diference between high fertility and medium setting is not remarkable by NIPSSR.
He Chen; Keisuke Matsuhashi; Kiyoshi Takahashi; Shinichiro Fujimori; Keita Honjo; Kei Gomi. Correction to: Adapting global shared socio-economic pathways for national scenarios in Japan. Sustainability Science 2020, 15, 1007 -1008.
AMA StyleHe Chen, Keisuke Matsuhashi, Kiyoshi Takahashi, Shinichiro Fujimori, Keita Honjo, Kei Gomi. Correction to: Adapting global shared socio-economic pathways for national scenarios in Japan. Sustainability Science. 2020; 15 (3):1007-1008.
Chicago/Turabian StyleHe Chen; Keisuke Matsuhashi; Kiyoshi Takahashi; Shinichiro Fujimori; Keita Honjo; Kei Gomi. 2020. "Correction to: Adapting global shared socio-economic pathways for national scenarios in Japan." Sustainability Science 15, no. 3: 1007-1008.
Nature-based tourism (NBT) is vulnerable to a rapid increase in visitors because natural resources are often open access. Market failure caused by over-exploitation of natural resources is an example of social dilemmas in common-pool resource systems. Game theory, which describes people’s decision making under conflicts, has been applied to the analysis of social dilemmas in NBT. However, previous studies use non-cooperative games assuming individualistic players and discuss the emergence of social dilemmas only in a limited situation. Here, we demonstrate, by developing a two-player non-cooperative game of wildlife viewing, that the traditional game-theoretic approach fails to find social dilemmas. By analysing the competition between tour operators (players) with different social value orientations (SVOs), we found that concentration of tours becomes a Pareto-inefficient Nash equilibrium (PINE) when both players are competitive. Whether the wildlife-viewing market is a Prisoner’s dilemma depends on players’ SVOs. Furthermore, we found that fair punishment on competitive players promotes rather than suppresses the emergence of PINE. Our results suggest that the diversity of SVOs is an essential factor in understanding social dilemmas in NBT.
Keita Honjo; Takahiro Kubo. Social Dilemmas in Nature-Based Tourism Depend on Social Value Orientations. Scientific Reports 2020, 10, 3730 -10.
AMA StyleKeita Honjo, Takahiro Kubo. Social Dilemmas in Nature-Based Tourism Depend on Social Value Orientations. Scientific Reports. 2020; 10 (1):3730-10.
Chicago/Turabian StyleKeita Honjo; Takahiro Kubo. 2020. "Social Dilemmas in Nature-Based Tourism Depend on Social Value Orientations." Scientific Reports 10, no. 1: 3730-10.
After the severe nuclear disaster in Fukushima, which was triggered by the Great East Japan earthquake in March 2011, nuclear power plants in Japan were temporarily shut down for mandatory inspections. To prevent large-scale blackouts, the Japanese government requested companies and households to reduce electricity consumption in summer and winter. It is reported that the domestic electricity demand had a structural decrease because of the electricity conservation effect (ECE). However, quantitative analysis of the ECE is not sufficient, and especially time variation of the ECE remains unclear. Understanding the ECE is important because Japan’s NDC (nationally determined contribution) assumes the reduction of CO2 emissions through aggressive energy conservation. In this study, we develop a time series model of monthly electricity demand in Japan and estimate time variation of the ECE. Moreover, we evaluate the impact of electricity conservation on CO2 emissions from power plants. The dynamic linear model is used to separate the ECE from the effects of other irrelevant factors (e.g. air temperature, economic production, and electricity price). Our result clearly shows that consumers’ electricity conservation behavior after the earthquake was not temporary but became established as a habit. Between March 2011 and March 2016, the ECE on industrial electricity demand ranged from 3.9% to 5.4%, and the ECE on residential electricity demand ranged from 1.6% to 7.6%. The ECE on the total electricity demand was estimated at 3.2%–6.0%. We found a seasonal pattern that the residential ECE in summer is higher than that in winter. The emissions increase from the shutdown of nuclear power plants was mitigated by electricity conservation. The emissions reduction effect was estimated at 0.82 MtCO2–2.26 MtCO2 (−4.5% on average compared to the zero-ECE case). The time-varying ECE is necessary for predicting Japan’s electricity demand and CO2 emissions after the earthquake.
Keita Honjo; Hiroto Shiraki; Shuichi Ashina. Dynamic linear modeling of monthly electricity demand in Japan: Time variation of electricity conservation effect. PLOS ONE 2018, 13, e0196331 .
AMA StyleKeita Honjo, Hiroto Shiraki, Shuichi Ashina. Dynamic linear modeling of monthly electricity demand in Japan: Time variation of electricity conservation effect. PLOS ONE. 2018; 13 (4):e0196331.
Chicago/Turabian StyleKeita Honjo; Hiroto Shiraki; Shuichi Ashina. 2018. "Dynamic linear modeling of monthly electricity demand in Japan: Time variation of electricity conservation effect." PLOS ONE 13, no. 4: e0196331.
Understanding the hourly electricity profile and the electricity consumption by each appliance is essential for encouraging energy-saving measures in the household sector. There are two methods for identifying energy consumption for households in existing studies: the engineering and the statistical methods. Both methods have strengths and limitations. In this study, we developed a hybrid method based on the statistical method by combining following three steps using knowledge of the engineering method; externalizing the electricity consumption for the refrigerator, adding the number of at-home-and-awake members as explanatory variables, and restricting appliance usage hours. The proposed hybrid method could adequately reproduce the total hourly electricity consumption and seasonal variation compared to the engineering method, and could decompose major appliances, some of which that were not disaggregated by the statistical method. For the quantitative analysis of the model improvement, we calculated Root Mean Squared Error (RMSE) and Mean Absolute Error (MAE) for each method with direct metering data. For most of appliances, RMSE and MAE of hybrid model were improved from 11% to 71% compared to the existing methods. The collection of more samples to increase the accuracy of the estimation and application to areas of low statistical data availability are future steps
Hiroto Shiraki; Shogo Nakamura; Shuichi Ashina; Keita Honjo. Estimating the hourly electricity profile of Japanese households – Coupling of engineering and statistical methods. Energy 2016, 114, 478 -491.
AMA StyleHiroto Shiraki, Shogo Nakamura, Shuichi Ashina, Keita Honjo. Estimating the hourly electricity profile of Japanese households – Coupling of engineering and statistical methods. Energy. 2016; 114 ():478-491.
Chicago/Turabian StyleHiroto Shiraki; Shogo Nakamura; Shuichi Ashina; Keita Honjo. 2016. "Estimating the hourly electricity profile of Japanese households – Coupling of engineering and statistical methods." Energy 114, no. : 478-491.
Rapid reduction of anthropogenic greenhouse gas emissions is required to mitigate disastrous impacts of climate change. The Kyoto Protocol introduced international emissions trading (IET) to accelerate the reduction of carbon dioxide (CO2) emissions. The IET controls CO2 emissions through the allocation of marketable emission permits to sovereign countries. The costs for acquiring additional permits provide buyers with an incentive to reduce their CO2 emissions. However, permit price has declined to a low level during the first commitment period (CP1). The downward trend in permit price is attributed to deficiencies of the Kyoto Protocol: weak compliance enforcement, the generous allocation of permits to transition economies (hot air), and the withdrawal of the US. These deficiencies created a buyer’s market dominated by price-making buyers. In this paper, I develop a coalitional game of the IET, and demonstrate that permit buyers have dominant bargaining power. In my model, called cooperative emissions trading (CET) game, a buyer purchases permits from sellers only if the buyer forms a coalition with the sellers. Permit price is determined by bargaining among the coalition members. I evaluated the demand-side and supply-side bargaining power (DBP and SBP) using Shapley value, and obtained the following results: (1) Permit price is given by the product of the buyer’s willingness-to-pay and the SBP (= 1 − DBP). (2) The DBP is greater than or equal to the SBP. These results indicate that buyers can suppress permit price to low levels through bargaining. The deficiencies of the Kyoto Protocol enhance the DBP, and contribute to the demand-side dominance in the international permit market.
Keita Honjo. Cooperative Emissions Trading Game: International Permit Market Dominated by Buyers. PLOS ONE 2015, 10, e0132272 .
AMA StyleKeita Honjo. Cooperative Emissions Trading Game: International Permit Market Dominated by Buyers. PLOS ONE. 2015; 10 (8):e0132272.
Chicago/Turabian StyleKeita Honjo. 2015. "Cooperative Emissions Trading Game: International Permit Market Dominated by Buyers." PLOS ONE 10, no. 8: e0132272.
Many governmental and non-governmental organizations have distributed insecticide-treated nets (ITNs) to malaria endemic areas, which contributed to the reduction of malaria deaths. However, some people in malaria endemic areas used ITNs for alternative purposes such as fishery and agriculture. It is unclear why people threatened by malaria misuse ITNs. Here we develop a N-player mosquito net game, and theoretically show that the misuse of ITNs might be underpinned by individual and social rationality. In the mosquito net game, each player uses ITNs for malaria prevention or alternative purposes. The proper ITN use decreases the probability of malaria infection, while the improper ITN use increases the player's labor productivity. Each player's expected payoff is influenced by other players' strategies. We found that the misuse of ITNs can be a Pareto efficient Nash equilibrium. The maximum number of players using ITNs for malaria prevention is limited by insecticidal effectiveness of ITNs and extra income from ITN misuse. Furthermore, we found that players in a low-income community are attracted to the misuse of ITNs even if the probability of malaria infection is high. Introduction of a tax on ITN misuse was shown to be effective to motivate the players to use ITNs for malaria prevention. Our results demonstrate that understanding decision making of people in malaria endemic areas is essential to design more effective malaria control programs. © 2013 Elsevier Ltd. All rights reserved
Keita Honjo; Akiko Satake. N-player mosquito net game: Individual and social rationality in the misuse of insecticide-treated nets. Journal of Theoretical Biology 2014, 342, 39 -46.
AMA StyleKeita Honjo, Akiko Satake. N-player mosquito net game: Individual and social rationality in the misuse of insecticide-treated nets. Journal of Theoretical Biology. 2014; 342 ():39-46.
Chicago/Turabian StyleKeita Honjo; Akiko Satake. 2014. "N-player mosquito net game: Individual and social rationality in the misuse of insecticide-treated nets." Journal of Theoretical Biology 342, no. : 39-46.
An understanding of the factors affecting household CO2 emissions is necessary for effective climate policies aimed at reducing emissions. We developed an empirical model of household CO2 emissions in the 47 prefectures of Japan and conducted a sensitivity analysis to evaluate the impacts of demographic, meteorological, and economic changes on emissions. Emissions are projected to increase with demographic changes by 2030, and to decrease with temperature increases during the twenty‐first century. Carbon taxes on energy sources are projected have a limited effect on the reduction of emissions in the short term. The closure of nuclear power plants is projected to lead to a substantial increase in emissions.
Keita Honjo; Masahiko Fujii. Impacts of demographic, meteorological, and economic changes on household CO 2 emissions in the 47 prefectures of Japan. Regional Science Policy & Practice 2013, 6, 13 -30.
AMA StyleKeita Honjo, Masahiko Fujii. Impacts of demographic, meteorological, and economic changes on household CO 2 emissions in the 47 prefectures of Japan. Regional Science Policy & Practice. 2013; 6 (1):13-30.
Chicago/Turabian StyleKeita Honjo; Masahiko Fujii. 2013. "Impacts of demographic, meteorological, and economic changes on household CO 2 emissions in the 47 prefectures of Japan." Regional Science Policy & Practice 6, no. 1: 13-30.
SUMMARYInsecticide-treated nets (ITNs) are a major tool to control malaria. Over recent years increased ITN coverage has been associated with decreased malaria transmission. However, ITN ‘misuse’ has been increasingly reported and whether this emergent behaviour poses a threat to successful malaria control and elimination is an open question. Here, we use a game theory mathematical model to understand the possible roles of poverty and malaria infection protection by individual and emerging ‘community effects’ on the ‘misuse’ of malaria bednets. We compare model predictions with data from our studies in Lake Victoria Islands (LVI), Kenya and Aneityum, Vanuatu. Our model shows that alternative ITN use is likely to emerge in impoverished populations and could be exacerbated if ITNs become ineffective or when large ‘community effects’ emerge. Our model predicted patterns of ITN use similar to the observed in LVI, where ‘misuse’ is common and the high ITN use in Aneityum, more than 20 years after malaria elimination in 1990. We think that observed differences in ITN use may be shaped by different degrees of economic and social development, and educational components of the Aneityum elimination, where traditional cooperative attitudes were strengthened with the malaria elimination intervention and post-elimination surveillance.
Keita Honjo; Luis Fernando Chaves; Akiko Satake; Akira Kaneko; Noboru Minakawa. When they don't bite, we smell money: understanding malaria bednet misuse. Parasitology 2013, 140, 580 -586.
AMA StyleKeita Honjo, Luis Fernando Chaves, Akiko Satake, Akira Kaneko, Noboru Minakawa. When they don't bite, we smell money: understanding malaria bednet misuse. Parasitology. 2013; 140 (5):580-586.
Chicago/Turabian StyleKeita Honjo; Luis Fernando Chaves; Akiko Satake; Akira Kaneko; Noboru Minakawa. 2013. "When they don't bite, we smell money: understanding malaria bednet misuse." Parasitology 140, no. 5: 580-586.