SRESシナリオ別に見たCO₂排出の健康被害係数の開発

抄録

Objective. Global warming is exerting a damaging effect on human health. This damage is not only influenced by future climate conditions, but also projected economic development and population growth. That being said, there are no health damage factors related to CO₂ emissions which take into account future socioeconomic scenarios in life cycle impact assessment (LCIA). Thus the purpose of this research is to calculate human health damage factors based on special report on emission scenarios (SRESs) developed by IPCC.
Materials and Methods. The procedure used to calculate the SRES-based damage factors is as follows. First, a framework was developed to calculate damage factors based on multiple parameters: rise in temperature, relative risk increase, mortality rate increase, rise in number of deaths, and disability-adjusted life year (DALY) increase. Secondly, these parameters were calculated for each individual SRES based on the relationship among the parameters and CO₂ emissions, GDP, and population values of each scenario. Finally, the damage factor for each SRES was calculated by multiplying all the parameters that had been calculated based on the CO₂ emission, GDP and population data in the corresponding scenarios.
Results and Discussion. Using this method, the human health damage factors for four SRESs (A1B, A2, B1, and B2) were calculated. The damage factors consisted of six different items: malaria, diarrhea, cardiovascular disease, malnutrition, coastal flooding, and inland flooding. The calculated results by scenario were 2.0×10^-7, 6.2×10^-7, 2.1×10^-7 and 4.2×10^-7 DALY/kg-CO₂, respectively. The damage caused by malnutrition is the greatest, followed by diarrhea. The projected future mortality rate and DALY per death based on future GDP per capita contributed significantly to the differences among the four damage factors, while the difference of temperature rise among scenarios depended on future CO₂ emission is not influential to the damage factors.
Conclusions. The human health damage factors related to CO₂ emissions for four SRESs were estimated. As a result of differences between future socioeconomic scenarios, the largest amount of damage per CO₂ emission unit was 3 times greater than the smallest amount. Therefore, sensitive analysis is highly recommended when seeking to compare damage caused by global warming and other impact categories.