Research Topics

Our laboratory conducts researches mainly on climate change mitigation, using a computer simulation model called “Integrated assessment model” that integrates relevant discipline such as energy, economy, agriculture, land use, and water use into a single platform. We primarily focus on future greenhouse gas emissions, their reduction measures, and economic implications of such climate mitigation policies. Meanwhile, the economic analysis of climate change impacts is also one of the scopes of our studies. Moreover, beyond the climate change issue, to provide solutions to achieve broader sense of sustainable development is the newly focused area in the research area. We cover multi-scale areas spatially temporally. For instance, spatial resolution varies from national (each country of Asia), whole Asia, to the globe and sometimes gridded scale analysis is also carried out (0.5 °x0.5 °). The temporally coverage is near to long-term future such as next decade to entire this century.

Development of global greenhouse gas emissions scenarios and climate change mitigation assessment

The climate change mitigation is the long-term process where continuous efforts to reduce greenhouse gases (GHG) emissions over this century is required. In this study, we attempt to answer to the questions such as how much GHG emissions can be reduce, how much it would cost then, what can be the bottleneck to achieve the goal of emissions reduction, what kind of policy can help to mitigate the social cost and etc. the studies focus from near to long term (e.g. 2030-2100). An economic model incorporates detailed representations in energy system and land-use is a core calculation tool. The ultimate goal is to make policy suggestions based on the scientific knowledge.

Global primary energy supply and energy sources associated with the baseline (top) and other climate policy cases in 2100 (bottom) for SSP1, SSP2 and SSP3.
Global GHG, CO2, CH4, and N2O emissions (from top to bottom) associated with the five mitigation cases for SSP1, SSP2, and SSP3.

Fujimori S., Hasegawa T., Masui T., Takahashi K., Herran D.S., Dai H., Hijioka Y., Kainuma M. (2017) SSP3: AIM implementation of Shared Socioeconomic Pathways. Global Environmental Change, 42, 268-283.

Policy proposals for achieving sustainable development goals

This research targets to present policy proposal or social sustainable development goals, so-called SDGs achievement. SDGs have set targets for development in various fields such as poverty, hunger, public health and economics, climate change and other fields in 2030. Among them, we will deal with environmental matters deeply and we set the targets of development not only for 2030 but also for 2050 and 2100. Studies may need to adjust multi-disciplinary research fields something like to clarify what would happen to the other sectors as a consequence of climate change mitigation implementation.

Effects of climate change and emissions mitigation efforts on food security. a) Global population at risk of hunger and b) global mean dietary energy availability in the baseline scenario under different socio-economic scenarios (SSPs). Ribbons and error bars show the ranges across models. c, d) Changes from the baseline level due to climate change and emissions mitigation efforts under different SSPs and climate change and emissions mitigation scenarios (RCPs) in 2050. Bars shows median level of individual effect across models. Symbols show the combined effects for each model. MAgPIE is excluded due to inelastic food demand. (Hasegawa et all., 2018)

Hasegawa T., Fujimori S., Havlik P., Valin H., et al., (2018) Risk of increased food insecurity under stringent global climate change mitigation policy, Nature Climate Change. Vol.8, pp.699–703.

Calculation of the expensive impact of global warming

Global warming has various effects on the human system. Using economic models mainly, we will calculate expense of the effect on agriculture, water resources, floods, sea level rise. The target area is globe or Asia and we demonstrate the benefits of preventing global warming and aim to contribute to provide impact side information with respect to the climate change policy makers.

Estimated worktime ratio. Estimated yearly average worktime ratio with a resolution of 0.5° × 0.5°. When the worktime ratio is x, the recommended work-rest ratio is x/(1−x). The left-hand and center columns of panels show the values for low-intensity and moderate-intensity work, respectively, performed indoors (without air-conditioning). The right-hand column of panels shows the values for high-intensity work performed outdoors. The median values of 5 GCMs are shown.

Takakura J, Fujimori S, Takahashi K, Hijioka Y, Hasegawa T, Honda Y, et al. (2017) Cost of preventing workplace heat-related illness through worker breaks and the benefit of climate-change mitigation. Environmental Research Letters, 12(6), 064010.

Proposal of low-carbon scenarios for Asian countries

Asian countries emit nearly half of the global GHGs, and the possibility of greenhouse gas reduction in this area is one of the keys of global climate change policies. Meanwhile, Asian countries are not homogenous in the sense that they have individual own political systems, energy systems, GHG compositions, and different priorities in policy making. In recent years, for example, the air pollution in China gets more serious and the challenge in climate change and air pollution mitigations are promoted comprehensively. We will make the proposal of low-carbon strategies for each country considering each country’s situation.

Relationship between Land Use Change and Water, Ecosystem and Agriculture

Land is deeply concerned with the water and food demand/supply, and it is one of the essential resources for human activities. Also, the land use changes have had a major impact on ecosystems such as biodiversity losses. Furthermore, in recent years, there is a serious concern that the significantly large land-use change can be happened due to the implementation of large scale purpose grown biomass energy crops. In this theme, we estimate the detailed distribution of land use in the future and analyze the relationship with agriculture, water, ecosystem, energy and so on.

Changes in the factions of grid cell area occupied by each land-use category in 2100 from the 2005 level for the baseline scenario.

Hasegawa T., Fujimori S., Ito A., Takahashi K., Masui T. (2017) Global land-use allocation model linked to an integrated assessment model. Science of The Total Environment , 580, 787-796.

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