For realizing a decarbonized society, an urgent need exists for tracking changes in automobile-related CO₂ emissions during the COVID-19 pandemic and for ascertaining factors underlying these changes. Nevertheless, assessing detailed changes in Japan using conventional data and methods has been difficult. This study used behavioral survey data obtained during the pandemic to estimate automobile-related CO₂ emissions by city. We identified factors affecting changes over time. Results have indicated that the factors changed during the pandemic. Although self-curfew at the beginning of the pandemic led to decreased automobile-related CO₂ emissions, increased rates of teleworking during the infection’s spread led to increased emissions later in the pandemic. Furthermore, from mid-term to long-term perspectives, increased automobile-related CO₂ emissions have been observed in many cities during the pandemic. Environmental burdens increased nationwide because of the COVID-19 pandemic and teleworking effects, which cannot be overlooked in future city planning for decarbonization.

 We conducted a social survey to understand changes in teleworking frequency and commuting behavior, estimated the CO₂ emissions reduction, and roughly evaluated and compared the CO₂ emissions associated with ICT use, taking regional characteristics into account.

 The target regions were Tokyo (23 wards), which has a high rate of dependence on railroads for commuting transportation, and Tochigi, which has a high rate of dependence on automobiles. April-June and November 2020 were selected as the most frequent teleworking periods. Respondents were asked about their weekly work and commuting status, respectively. We obtained valid responses from Tokyo (n = 1032) and Tochigi Prefecture (n = 506).

 The estimated annual per capita reduction due to teleworking are 60 kg-CO₂ in Tokyo and 233 kg-CO₂ in Tochigi in an evaluation that included both public transportation and automobiles emissions. The estimated annual per capita reduction in Tochigi were 226 kg-CO₂, while in Tokyo were only 4 kg-CO₂, in an evaluation that included automobiles emissions only. The results indicate that teleworking may increase CO₂ emissions in Tokyo, where there are many train users, depending on the time spent using videoconferencing.

 This study aims to estimate the available dwelling stocks (type, structure, construction age, energy saving level, w/wo insulation reform) in Shiga Prefecture in the period from 1970 to 2050, and to analyze energy saving policies for dwelling towards the realization of the net zero CO₂ society.

 In 2050 of enhanced countermeasure (enhanced-CM) case, the share of available dwelling stock built after 2021 to available dwelling srocks is only 44%. The stock average of final energy consumption level is 0.81(current level =1), even if all measures are assumed to be introduced; improvement and mandatory compliance with the energy efficiency standards for new-built dwelling, acceleration of rate of insulation reform with 4-fold for detached house and with 6-fold for apartment. Adding self-consumption of total volume of solar power generation to the above, it achieves 0.63.The reduction rate of cumulative energy consumption after 2021 in the enhanced-CM case remains at 5.5% compared to that of the stagnation-CM case.

 There is an inseparable relationship between the SDGs' goals, including a synergistic relationship and a trade-off relationship. This study aims to clarify the nexus structure of the SDGs with respect to the extension of healthy life expectancy. In addition, using the constructed network structure, we estimate healthy life expectancy based on the SSP scenarios and indicate which goals prioritize extending healthy life expectancy. The results show that social area such as Goal 1 are efficient for extending healthy life expectancy, but they also have many trade-offs and require careful policy choices. On the other hand, environmental area, such as Goal 13, do not significantly impact the primary effect but may have a stronger influence on the secondary outcome because they have the most synergistic relationships and fewer trade-offs. The future projection results also show a decrease in healthy life expectancy, even in the SSP1 scenario. Therefore, the results indicate that improving goals 13 and 15 is particularly important to increase healthy life expectancy. In summary, to increase healthy life expectancy and achieve the SDGs, it is essential to promote policies that achieve environmental area in parallel with social area.

 To clarify the relationship among subjective factors of QoL as a basic study for evaluating the impact of climate change on QoL in the future, a questionnaire survey was conducted throughout Japan, and 11, 880 samples were obtained. The results showed that satisfaction with economic status and personal relationships had a significant impact on satisfaction with living, while there was a certain impact on that by satisfaction with regional conditions as convenience of living and local environment and culture. Positive emotions had a particularly large effect on subjective well-being, but there was also a direct effect of satisfaction with living. The classification of regions by the level of satisfaction with regional conditions revealed characteristic clusters, such as regions with low average temperatures and low satisfaction with regional climate. While there were no regional differences in subjective well-being, there were large regional differences in satisfaction with living, suggesting the need for evaluation tailored to regional characteristics.

 The Basic Plan on Water Cycle is a significant plan that specifies the appropriate conservation and use of groundwater. However, the definition of "watershed" in the plan is still an issue. In addition, the significance of the water cycle in man-made systems such as water supply and sewage systems, which have a hydrological continuity with river water, is not mentioned. In this paper, we propose the concept of a "water cycle sphere" that encompasses a river basin, a water supply area, and a sewerage system area, and is considered as a planning area for water cycle planning. Furthermore, the hydrological continuity of the water cycle between artificial and natural systems will be discussed. The case of the Tama River will be presented as an example of how tap water in an urban area becomes reclaimed water after use and becomes an important water resource for maintaining the flow rate of the urban river, and the significance of the water cycle will be presented.

 An electricity demand-side management model was developed in a small-scale wastewater treatment plant (WWTP) that uses the oxidation ditch (OD) method to support an electricity load shifting by a WWTP. The model makes it possible to estimate the annual power consumption depending on the operation plan with a 30-minute resolution. We set introduction measures of photovoltaic (PV) system at the WWTP site under the condition that the ratio of PV power generation to electricity consumption by the WWTP on an annual total volume basis would be the same value. In contrast to operation plan A that replicates the current operation, plan B was designed to allocate electricity demand in OD reaction tank during the daytime, taking into account the PV generation time zone. As a result, the annual self-sufficiency rate of plan B, based on the electricity supply-demand balance at 30- minute resolution, increased from 46% to 57%, and the self-consumption rate from 44% to 54% compared to plan A.

 This study conducted an experiment focusing on improving the water leakage detection model's generalization performance (the capability to recognize sounds as leakage or not) through the use of AI. Convolutional neural networks were used to create a leak detection model using actual leak sounds collected at 10 sites for each of ductile cast iron pipes (metal pipes) and rigid polyvinyl chloride pipes (non-metal pipes). Recurrence plots were used to develop the model and apply to their testing. In the data preprocessing, band pass filtering and noise reduction process, utilizing actual field pseudo sound data such as transformer and sewer flow sounds, were applied. The generalization performance is then evaluated if it has improved. Through the experiment, it was made clear that the accuracy increased for the low accuracy points by applying both processes. Furthermore, it was confirmed that this pre-processing approach, in addition to the leak detection model, is superior to a leak surveyor's examination of the acoustic data.

 This paper clarifies consumers’ preference on the next generation vehicle such as a fuel cell vehicle (FCV) and a battery electrical vehicle (BEV) in local cities. Main findings are as follows: i) Consumers’ knowledge on FCV and BEV is limited especially regarding lifecycle. ii) A preference on FCV is listed in order of “purchase price”, “fuel price”, “installation of hydrogen refueling station” and “cruising distance” in terms of degree of importance for purchase whereas BEV is listed in order of “fuel price”, “purchase price”, “cruising distance” and “installation of rapid charging station.” These differences reflect distinctive features of FCV and BEV. iii) Consumers who never prefer FCV and BEV in any cases account for 40.3%. The most popular reason for it is that “every performance of FCV and BEV should exceed the existing gasoline-powered vehicle.” It implies that it is essential to improve conditions based on the above-mentioned degree of importance.

 This paper clarifies a possibility of citizen science (participatory monitoring) in climate change issues via questionnaire to nationwide environmental NGOs. Main findings are as follows: i) the NGOs that can be expected to be "leaders" of citizen science are limited to 13.1%. It can be said that the base of citizen science in Japan is not widespread. ii) A popular area of citizen science for participation is observation of familiar flora and fauna, and extrinsic motivation such as some kind of contribution to the local community and non-monetary intrinsic motivation will be effective for most environmental NGOs to participate. iii) The significant determinants of experiences of participation is a situation of establishment of the organizations, range of activities etc. Also, the experience is a significant determinant of future intention.

 Utilization of small wind turbines in local areas may facilitate renewable energy owing to their higher efficiency in low-wind speed conditions and lower noise emission. When local governments consider applying wind turbines to their region, official wind potential maps can be used to estimate power generation. However, information on wind potential, which is important to decide if one introduces a wind turbine or not, generally considers the usage of larger turbines and cannot be applied to small wind turbines. Additionally, such conventional wind maps have targeted the whole country and resulted in the low-resolution of such maps. With this regard, when local governments introduce small wind turbines, they need to calculate wind conditions and potential by themselves, which is challenging for the local governments in terms of cost, time, and other resources. Here in this study, a simple assessment of wind speed and direction in Shinchi, Fukushima was performed using free-GIS software (QGIS). The assessment was performed under the assumption that the small wind turbines were introduced dispersedly in the town. Calculations were conducted with a varied number of measuring points to evaluate calculation reliability, which was improved with an increase in its number. Results gave detailed information on wind and power potential depending on the place and time in various scales (hour, day, and month), which demonstrated the effectiveness of localized assessment and application possibilities in other local regions.

 In this study, seven household models were set up and were evaluated the possibility of power supply and demand adjustment, CO₂ emissions, and costs for each household regarding the effects of introducing and linking PV, BT, and EV. To compare the pre-introduction and post-introduction case, 5 cases were set up: “pre-introduction case”, “PV-only introduction case (PV only)”, “PV and BT introduction case (PV, BT)”, “PV and EV introduction but without V2B (PV, EV)”, and “PV and EV introduction with V2B (V2B)”. As a result, it was found that "V2H" followed by "PV, EV" had a large reduction effect on CO₂ emissions. In addition, the effect on the entire city was evaluated by conducting an extended estimation based on the number of households by type for the city of Kitakyushu. As a result, it was found that the introduction of V2H has the effect of reducing the CO₂ emissions of the residential sector in the entire city by approximately 25%.

 Intergenerational justice regarding the negative impacts caused by the present generation on future generations draws attention. This study investigated 960 Japanese reactions to information on unprecedented hot days that future generations will experience through an Internet questionnaire survey. While the provision of the information increased their intention to take action, approximately 60% of the respondents could not imagine future generations experiencing 400 unprecedented hot days. The result suggested a possibility that pre-formed attitudes were more influential. As a result of analyzing respondents' attributes and 27 attitudes toward climate actions, those who did not trust the information and those who tended to neglect the future opposed climate actions. It was considered that providing future climate change information would strengthen just the behavior intention of existing practitioners. Further studies should be undertaken.

 With the progression of climate change, there are concerns about the effects of heat on sporting events, including the Summer Olympic Games. In this study, we evaluated the heat impacts and adaptation measures for the Summer Olympic Games under climate change in cities worldwide, focusing on nine outdoor sports for which heat guidelines with explicit upper thresholds are specified. The results show that the number of possible host cities of the Summer Olympic Games at present will decrease by up to 40% by the end of the 21st century, with particularly significant decreases in Asia and North America. On the other hand, the decrease of the possible host cities could be reduced to less than 10% by combining adaptation measures such as changing the timing of the Summer Olympic Games and holding the Summer Olympic Games in multiple cities in a country. The results of this study show that the effects of heat are more significant than in the previous study that focused only on a single event (marathon), suggesting that an integrated evaluation of multiple sports is important to assess the feasibility of a multi-sport event such as the Summer Olympics Games.

 Fish have dark and white muscles, but they are reluctant to use their white muscles, which accumulate fatigue during swimming. Therefore, in river maintenance, it is necessary to create low velocity area where fish can move freely and to secure area where they can rest. In this study, investigation of the effect of the riverbed grain size on the fish swimming behavior was conducted. The effects of four different grain sizes (1.2 to 10 mm) and four different velocity normalized by the body length (2 to 10 (1/s)) were investigated using Nipponocypris temminckii with 60mm body length. As a result, it was found that fish rested by pressing their abdomens against the bottom in between swimming, and fish turned upstream direction to minimize the projected area of the body to minimize the water resistance. It was also found that the frequency of resting did not change with velocity and grain size, but the resting time per rest increases.

 Conventional visual methods of monitoring blinking fireflies at night are taking considerable effort and it is difficult to accurately count the number of fireflies. To solve these problems, a firefly monitoring system was developed using the specific software that automatically detects fireflies in images captured by network cameras and single-lens reflex cameras and counts the number of individuals. In this study, we evaluated the detection accuracy of the software through laboratory experiments using Luciola cruciata, and the system was applied to habitats of Luciola parvula, in an attempt to understand the status of firefly occurrence and to verify the applicability of the system. As a result, the system showed the potential to improve a survey accuracy and reduce field survey effort in firefly monitoring.

 The purpose of this study was to determine the effects of local- and geographical-scale environmental factors on the distribution of Procambrus Clarkii to suggest a measure for expansion of this invasive species in the lotus root fields of Naruto City, Tokushima Prefecture. Field surveys were conducted for three times at each lotus field during June - July 2022. The analysis showed a significant relationship between water depth and vegetation cover of lotus fields in June, and percentage of concreted ridges in lotus fields in early July. The percentage of concreted ridges showed a weak negative relationship with the crayfish density in all three surveys, and no relationship was found between the population of American crayfish and geographical factors throughout the three surveys. These suggest that crayfish density is influenced by local environmental factors. Water management with keeping shallower depth during early developmental stage of lotus, and concreting ridges of lotus field might be potential measures on expanding the distribution of invasive crayfish.

 During a disaster, the carbon stock in wood product used in dwellings is emitted as CO₂, and a tremendous amount of disaster debris also emits greenhouse gases during disasters. However, there have been few studies on GHG emissions from disaster debris. The objective of this study is to develop a method for estimating GHG emissions from disaster waste resulting from the demolition of houses damaged by natural disasters. A model for estimating carbon stock release from housing damage was developed, and evaluated CO₂ emissions from house demolition caused by housing damage using the 2016 Kumamoto earthquake as a case study. As a result, CO₂ emissions from house demolition in the 2016 Kumamoto earthquake were estimated to be 1.062 Million t-CO₂. In addition, it was indicated that annual GHG emissions increase by 8% to 16% on a 2017 basis due to CO₂ emissions from disaster debris.

 It was found that milage data from the vehicle inspection certificate data for light motor vehicles were also available. By using the annual mileage of light motor vehicles for passengers and passenger cars by municipality nationwide obtained from the vehicle inspection certihicate data, the CO₂ emissions per capita of private passenger cars were estimated with higher reliability than before, and it was shown that CO₂ emissions are high in eastern Hokkaido, Ibaraki and Fukushima, among other regions. It also analysed the differences in the amount of light motor vehilcles and passenger cars travelled by municipality, etc., and attempted to use this information to examine decarbonisation measures by municipality as an example of measures toward decarbonised societies. The study showed that the diffusion of electric vehicles through home recharging is considered easier in island areas and inland municipalities in western Japan, where the annual milages is short and the share of light motor vehicles for passenger is high.

 This study focused on carbon dioxide enrichment, one of the key technologies for controlling the complex environment of horticulture, which plays an important role in food production, and quantified the spatial supply and demand balance of carbon dioxide obtained by utilizing underutilized resources available in the region. The analysis showed that the use of carbon dioxide, an essential technology for sustainable horticulture, could be a production center for sustainable horticulture in the context of technological advances in the supply sector. In addition, the study found that there are many areas of oversupply of carbon dioxide, which is essential for future food production, and that this study provides the basic tool for building a robust and sustainable supply chain.

 Local governments are facing tight budgets and a shortage of waste disposal leaders, and it is foreseeable that the continuation of the existing general waste disposal system will be difficult in local areas. Even under such severe circumstances, it is important to consider a stable and efficient waste treatment system from a different perspective, as society demands that global warming countermeasures be strengthened in conjunction with the development of waste treatment facilities. In this study, as one of the solutions to such regional issues, we clarified the effects of different methods of relay transportation and relay facility construction on the feasibility of wide-area waste management. As a result, it was clarified that although the construction of relay facilities is effective from the viewpoint of reducing transportation costs, it does not necessarily result in a reduction of project costs for the entire region when the construction and inspection/repair costs of relay facilities are combined, and that it is necessary to consider the appropriate number of relay stations.

 In Osaka Plain, due to its topographical conditions various types of local winds are generated and inflow. The winds are expected to be effectively used as a measure against urban heat island of the plain. Such airflow as nocturnal drainage or mountain wind, flowing down along the Yodo River in a southwesterly direction, may mitigate nighttime urban heat island phenomenon in the plain. In this study, numerical simulation of the airflow was carried out using the WRF to examine structures and generation mechanisms of the airflow. It was found that the airflow is not land breeze caused by land and sea temperature differences, but an accumulation of katabatic winds formed on mountain slopes is the Yodo River basin.