Yasuaki Hijioka

• Doctor of Engineering
• National Institute for Environmental Studies

Although the risk of heatstroke is already severe in Japan, it is expected to increase due to climate change. Researchers have mainly focused on future increases in heatstroke morbidity and mortality to project the risk of heatstroke in Japan. However, the economic burden of heatstroke remains unclear. This study evaluated ambulance transport costs...

Millions of students in Japan participate in school sports club activities, where thousands of heat illness cases occur every year. With future climate change, there is concern about the increased health risks posed to students in sports club activities by the worsening heat environment. However, few studies have quantitatively assessed the heat il...

The automobile sector faces major challenges in reducing greenhouse gas (GHG) emissions, with the shift to electric mobility raising concerns about resource sustainability. Although circular economy (CE) strategies are suggested as complementary solutions, their long-term effectiveness is questioned due to rapid vehicle electrification. This study...

The incineration of waste for power generation, the utilisation of cogeneration, and the application of heating represent promising approaches to the decarbonisation of a future carbon-neutral society. Nevertheless, given the context of global carbon neutrality promotion and growing interest from countries in the potential of waste as a substitute...

A substantial body of systematic literature reviews has focused on the topic of industrial decarbonization. However, the decarbonization of industrial heating systems has been hampered by the continued reliance on fossil fuels for industrial heating. Remarkably, at the temperature level of industrial processes, the provision of relatively low-carbo...

With higher temperatures expected in the future due to global climate change, addressing health risks such as heat illness is increasingly important. In Japan, thousands of heat illness cases occur annually during school sports club activities. The risk may vary by sport, location, and region, but how heat safety thresholds (HSTs) should be adjuste...

Heatstroke is a serious health concern in Japan. To reduce heatstroke risk, the government of Japan implemented the “Heatstroke Alert” nationwide in 2021, employing the wet bulb globe temperature (WBGT) as a criterion. Although the WBGT is a useful meteorological indicator for assessing the risk of heatstroke, other important meteorological indicat...

Millions of students in Japan participate in school sports club activities, where thousands of heat illness cases occur every year. With future climate change, there is concern about the increased health risks posed to students in sports club activities by the worsening heat environment. However, few quantitative evaluations of the impact of heat o...

Climate change adaptation options need to be prioritized so that decision-makers make the appropriate choice among multiple options using decision analysis methods. Although different decision analysis methods are applied in different sectors, the status and challenges of applying the methods in various sectors have not been investigated to date be...

With higher temperatures expected in the future due to global climate change, addressing health risks such as heat illness is increasingly important. In Japan, thousands of heat illness cases occur annually during school sports club activities. The risk may vary by sport, location, and region, but how heat safety thresholds (HSTs) should be adjuste...

The heat-related health impacts of extremely high temperatures have become increasingly severe worldwide. Quantitative information on these impacts is necessary to plan and implement adaptation measures. The present study aimed to predict the number of heatstroke ambulance calls (HAC) and ambulance occupancy rate of patients with heatstroke (AORPH)...

Objectives To verify the appropriateness of applying uniform heat safety thresholds (HSTs) in sports club activities at Japanese junior high and high schools, and to propose the flexible application of HSTs according to the conditions of the activity. Methods A case-crossover study was conducted using 2011–2019 heat illness incident data from Japa...

Information on the variation in photovoltaic (PV) power generation is essential for resource assessment. This work investigated the interannual variability of the nationwide electric power supply from PV systems in Japan. Objectives of this study were twofold: One was the quantification of the annual variability of the nationwide PV power supply. T...

What will be the aggregated cost of climate change in achieving the Paris Agreement, including mitigation, adaptation, and residual impacts? Several studies estimated the aggregated cost but did not always consider the critical issues. Some do not address non-market values such as biodiversity and human health, and most do not address differentiati...

Background: Relatively little attention has been paid to the potential effects of rising temperatures on changes in human behavior that lead to health and social consequences, including aggression. This study investigated the association between ambient temperature and aggression using assault death data from Seoul, South Korea (1991-2020). Methods...

One of the negative consequences of increased air temperatures due to global warming is the associated increase in heat-related mortality and morbidity. Studies that focused on future predictions of heat-related morbidity do not consider the effect of long-term heat adaptation measures, nor do they use evidence-based methods. Therefore, this study...

Thermal safety guidelines with upper thresholds aim to protect athletes' health, yet evidence based sport-specific thresholds remain unestablished. Experimenting with athletes in severely hot conditions raises ethical concerns, so we used a thermo-physiological model to validate the thresholds of guidelines for outdoor sports. First, the reproducib...

Background: The health effects of heat are well documented; however, limited information is available regarding the health risks of hot nights. Hot nights have become more common, increasing at a faster rate than hot days, making it urgent to understand the characteristics of the hot night risk. Objectives: We estimated the effects of hot nights...

To reduce heatstroke cases, the Japanese government launched “Heatstroke Alert” in 2020. In this initiative, an alert is issued when the daily maximum wet bulb globe temperature (WBGT) is expected to reach or exceed 33 °C. However, heatstroke incidents at a daily maximum of WBGT of 33 °C can vary by regions and by age groups. In this study, we anal...

Under the Climate Change Adaptation Act, Local Climate Change Adaptation Centers (LCCACs) enhance climate change adaptation at the local level in Japan by gathering, analyzing, and disseminating essential information on climate change and its impacts on their communities. Although no literature has yet investigated the obstacles encountered by LCCA...

Objectives: To validate the upper thresholds of the thermal safety guidelines for multiple outdoor sports in terms of heat illness risk. Methods: The reproducibility of the joint system thermoregulation model (JOS-3) of core temperature has been validated for 18 sports experiments (n=213) and 11 general exercise experiments (n=121) using the Bland–...

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 explic...

Background Climate change and its subsequent effects on temperature have raised global public health concerns. Although numerous epidemiological studies have shown the adverse health effects of temperature, the association remains unclear for children aged below five years old and those in tropical climate regions. Methods We conducted a two-stage...

Planning adaptations to climate change require an understanding of how climate-related impacts cascade across sectors of society. Equally important is the need to engage stakeholders in discussions of climate-related impacts, risks, vulnerabilities, and adaptation issues. The impact chain (IC) approach, which emerged about a decade ago, can be used...

The evaluation of the representation of the surface downward shortwave flux (DSF) from atmospheric reanalysis data products is required to obtain reliable information for the resource assessment of surface solar energy. The representation of the DSF from the Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2), reana...

This study analyzed the association between heatstroke incidence and daily maximum wet bulb globe temperature (WBGT) for all 47 prefectures in Japan by age group and severity using time-series analysis, controlling for confounders, such as seasonality and long-term trends. With the obtained association, the relative risk between the reference WBGT...

Background Environmental factors have been associated with adverse health effects in epidemiological studies. The main exposure variable is usually determined via prior knowledge or statistical methods. It may be challenging when evidence is scarce to support prior knowledge, or to address collinearity issues using statistical methods. This study a...

Climate change and anthropogenic activities are affecting the hydrological conditions of rivers and may have altered nutrient and suspended sediments released into coastal seas. However, testing this hypothesis is difficult, confounded by the lack of observational data and the unavailability of globally accepted suspended sediment concentration (SS...

There are concerns about the impact of climate change on Olympic Games, especially endurance events, such as marathons. In recent competitions, many marathon runners dropped out of their races due to extreme heat, and it is expected that more areas will be unable to host the Games due to climate change. Here, we show the feasibility of the Olympic...

Climate change has the potential to cause forest range shifts at a broad scale and consequently can alter crucial forest functions, including carbon sequestration. However, global-scale projections of future forest range shifts remain challenging because our knowledge of the physiological responses of plants to climatic stress is limited to particu...

In recent years, there has been concern about the increase in flood risks due to climate change, and the revision of flood control plans towards climate change has become a severe challenge. In this study, in order to understand the changes in the risk that have already occurred, we quantitatively analyzed the trends of changes in heavy rainfall le...

The incidence of heatstroke is affected by various meteorological variables. However, previous studies in Japan have mainly investigated and adopted a single temperature metric or composite index for their analyses. Herein, we conducted a time series study through multivariate analysis of different weather conditions simultaneously, in order to ana...

Water quality monitoring programs have been widely implemented worldwide to monitor and assess water quality and to understand its trends. However, water quality analysis based on point-source field observations is difficult to perform at large spatial and temporal scales. In this paper, a fully automated Google Earth Engine (GEE) application algor...

There are concerns about the impact of climate change on Olympic Games, especially endurance events, such as marathons. In recent competitions, many marathon runners dropped out of their races due to extreme heat, and it is expected that more areas will be unable to host the Olympic Games due to climate change. Here, we show the feasibility of the...

Tracking progress toward the Sustainable Development Goals (SDGs) requires monitoring of various social-ecological indicators over space and time, including the ratio of land consumption rate to population growth rate (LCRPGR), an indicator of land-use efficiency (SDG 11.3.1). In this study, we analyzed state-of-the-art Earth observation data (1975...

Climate change is expected to increase the frequency, intensity and spatial extent of extreme climate events, and thus is a key concern for food production. However, food insecurity is usually analysed under a mean climate change state. Here we combine crop modelling and climate scenarios to estimate the effects of extreme climate events on future...

Process-based models are powerful tools for simulating the economic impacts of climate change, but they are computationally expensive. In order to project climate-change impacts under various scenarios, produce probabilistic ensembles, conduct online coupled simulations, or explore pathways by numerical optimization, the computational and implement...

With the intensifying challenges of global environmental change, sustainability, and biodiversity conservation, the monitoring of the world's remaining forests has become more important than ever. Today, Earth observation technologies, particularly remote sensing, are at the forefront of forest cover monitoring worldwide. Given the current conceptu...

Climate change impact assessment studies often use future projections of only a few global climate models (GCMs) due to limited research resources. Here we develop a novel method to select a small subset of GCMs that widely capture the uncertainty range of large ensemble. By applying this method, we select a subset of five GCM projections from the...

気候変動にともない，西日本を中心に問題となっている竹林の拡大が，より高緯度，高標高域でも深刻化することが懸念されている。本研究では，日本と中国におけるマダケ属の分布情報と気候データを用い，マダケ属の潜在生育域を日本全土で推定する統計モデルを構築した。さらに現在と将来の潜在生育域の変化から，気候変動によって竹林の拡大リスクが増大する地域を推定した。その結果，東北地方から北海道の低地を中心に生育確率の上昇が予測された。西日本でも，広い範囲で現在より生育確率が上昇する傾向がみられた。気候変動による拡大リスクの変化を考慮しつつ，竹林の新規植栽や管理のあり方を検討する必要がある。

In order to project climate-change impacts under a wide-range of scenarios or conduct on-line coupled simulations, the computational and implementation cost of economic impact calculations should be reduced. To do so, in this study, we developed various emulators that mimic simulation outputs, namely economic models coupled with bio/physical proces...

This study investigated the effects of a drink supplement containing Momordica charantia extract from bitter melon on physical fitness and levels of stress hormones during a four week exercise training program in a hot environment. Ten male tennis players were orally administrated in a four week (100 ml, 6 times a day), and the pre and post supplem...

Synergies and trade-offs exist between climate mitigation actions and target indicators of the Sustainable Development Goals (SDGs). Some studies have assessed such relationships, but the degree of such interaction remains poorly understood. Here, we show the SDG implications associated with CO 2 emissions reductions. We developed ‘marginal SDG-emi...

The conceptualization of the Shared Socioeconomic Pathways (SSPs) framework represented a major leap in scenario development in the context of global environmental change and sustainability, providing significant advances from the previous scenario frameworks—especially the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emission...

Coastal areas provide important services and functions for social and economic activities. Damage due to sea level rise (SLR) is one of the serious problems anticipated and caused by climate change. In this study, we assess the global economic impact of inundation due to SLR by using a computable general equilibrium (CGE) model that incorporates de...

Human life comes to a standstill as many countries shut themselves off from the work due to the novel coronavirus disease pandemic (COVID-19) that hit the world severely in the first quarter of 2020. All types of industries, vehicle movement, and people's activity suddenly halted, perhaps for the first time in modern history. For a long time, it ha...

More than half of the world’s population currently live in urban areas and are particularly at risk from the combined effects of the urban heat island phenomenon and heat increases due to climate change. Here, by using remotely sensed surface temperature data and social-ecological indicators, focusing on the hot dry season, and applying the risk fr...

Solar radiation is an essential parameter for ecological, agricultural, and other models. However, the availability of large-scale radiation data is usually limited. The Mountain Microclimate Simulation Model (MTCLIM) can resolve such data insufficiency by estimating missing daily shortwave solar radiation data using simple climatological and topog...

Pine wilt disease (PWD) is one of the most serious conifer diseases, with further expansion expected under ongoing climate change. Sustainable forest management and effective pest control of pine forests therefore requires rigorous exploration of potential PWD risk areas under current and future climate conditions. To predict potential PWD risk are...

Climate change mitigation efforts to reduce greenhouse gas (GHG) emissions have associated costs, but there are also potential benefits from improved air quality, such as public health improvements and the associated cost savings. A multidisciplinary modeling approach can better assess the co-benefits from climate mitigation for human health and pr...

Climate change, air pollution, and the rapidly aging population are important public health challenges. An understanding of air pollution impacts is imperative for preventing air-pollution-related deaths and illnesses, particularly in vulnerable subgroups such as the increasing population of older adults. To assess the effects of short-term air-pol...

Limiting the magnitude of climate change via stringent greenhouse gas (GHG) mitigation is necessary to prevent further biodiversity loss. However, some strategies to mitigate GHG emission involve greater land-based mitigation efforts, which may cause biodiversity loss from land-use changes. Here we estimate how climate and land-based mitigation eff...

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

There are great uncertainties in the projected economic impacts of climate change¹, arising from uncertainties in the climate response², the climate change mitigation pathway³ and the socioeconomic development pathway⁴. Although the relative contributions of these factors are important for climate change related decision-making, they are poorly und...

Agricultural land abandonment is a growing problem in Japan due to various factors, but more especially the declining trend of farmer population. • Residential and urban land abandonment is also another issue, especially in municipalities and regional cities whose population has been decreasing. • Considering that land abandonment can result in var...

The shape and size of planning units (PUs) at the initial stage of regional systematic conservation planning (SCP) can strongly affect the final portfolio. In previous studies, the influence of PU shape and size has typically been considered for single study sites that include mainly natural land cover types. The impacts of PU shape and size in are...

Land abandonment, e.g. agricultural land abandonment, can result in various social and ecological impacts. It would thus be helpful if the extent and spatial pattern of future land abandonment could be projected. However, the trajectory of future land abandonment generally depends on various factors, including biophysical conditions and future chan...

Background: Previous studies show that escalations in ambient temperature are among the risk factors for acute kidney injury (AKI). However, it has not been adequately studied in our location, Seoul, South Korea. In this study, we aimed to examine the association between ambient temperatures and AKI morbidity using emergency department (ED) visit...

While Southeast Asia’s forests play important roles in biodiversity conservation and global carbon (C) balance, the region is also a deforestation hotspot. Here, we consider the five shared socioeconomic pathways (SSPs) to portray a range of plausible futures for the region’s forests, employing a state-of-the-art land change modelling procedure and...

In sharp contrast with the global trend in population growth, certain developed countries are expected to experience rapid national population declines. Considering future land use scenarios that include depopulation is necessary to evaluate changes in ecosystem services that affect human well‐being and to facilitate comprehensive strategies for ba...

Changes in the environmental heat stress need to be properly evaluated to manage the risk of heat-related illnesses, particularly in the context of climate change. The wet bulb globe temperature (WBGT) is a useful index for evaluating heat stress and anticipating conditions related to heat-related illness in the present climate, but projecting the...

Process-based simulations of global-scale economic impact of climate change are computationally costly. This limits the number of scenarios that can be explored in the assessment. To overcome this difficulty, in this study, we developed and tested the emulators which mimic the behavior of the simulators with much lower computational cost. The devel...

Full- text available through the IPCC website: https://www.ipcc.ch/sr15/

Changes in agricultural yields due to climate change will affect land use, agricultural production volume, and food prices as well as macroeconomic indicators, such as GDP, which is important as it enables one to compare climate change impacts across multiple sectors. This study considered five key uncertainty factors and estimated macroeconomic im...

Climate change increases workers' exposure to heat stress. To prevent heat-related illnesses, according to occupational-health recommendations, labor capacity must be reduced. However, this preventive measure is expected to be costly, and the costs are likely to rise as the scale and scope of climate change impacts increase over time. Shifting the...

Quality of life (QOL), although a complex and amorphous concept, is a term that warrants attention, especially in discussions on issues that touch on the impacts of climate change and variability. Based on the principles of RepOrting standards for Systematic Evidence Synthesis, we present a systematic review aimed at gaining insights into the conce...

Changes in agricultural yields due to climate change will affect land use, agricultural production volume, and food prices as well as macroeconomic indicators, such as GDP which is important as it enables one to compare the climate change impacts across multiple sectors. This study considered five key uncertainty factors and estimated macroeconomic...

Myanmar is one of the mangrove‐richest countries in the world, providing valuable ecosystem services to people. However, due to deforestation driven primarily by agricultural expansion, Myanmar's mangrove forest cover has declined dramatically over the past few decades, while what remains is still under pressure. To support management planning, acc...

Replacing rainfed cropping systems with irrigated systems has been deemed an effective agricultural adaptation measure in response to climate change. However, few agricultural impact assessments have considered changes in the water availability because of climate change and water use competition among crops. Here we assessed future global crop prod...

Waste management is becoming a crucial issue in modern society owing to rapid urbanization and the increasing generation of municipal solid waste (MSW). This paper evaluates the carbon footprint of the waste management sector to identify direct and indirect carbon emissions, waste recycling carbon emission using a hybrid life cycle assessment and i...

We investigated dam behaviour during high-flow events and their robustness against perturbations in meteorological conditions using the H08 global hydrological model. Differences in these behaviours were examined by comparing simulation runs, with and without dams and using multiple meteorological datasets, at a case-study site, Fort Peck Dam on th...

Energy demand associated with space heating and cooling is expected to be affected by climate change. There are several global projections of space heating and cooling use that take into consideration climate change, but a comprehensive uncertainty of socioeconomic and climate conditions, including a 1.5 °C global mean temperature change, has never...

We investigate how uncertainties in key parameters in the carbon cycle and climate system propagate to the costs of climate change mitigation and adaptation needed to achieve the 2 and 1.5 °C targets by 2100 using a stochastic version of the simple climate model for optimization (SCM4OPT), an integrated assessment model. For the 2 °C target, we fin...

Hydropower generation plays a key role in mitigating GHG emissions from the overall power supply. Although the maximum achievable hydropower generation (MAHG) will be affected by climate change, it is seldom incorporated in integrated assessment models. In this study, we first used the H08 global hydrological model to project MAHG under two physica...