Assessment of Projected Impacts of Large-scale Anthropogenic Climatic Changes on Natural Ecosystems, Agriculture, and Social Systems of Japan

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Research effort was concentrated on the elucidation of projected impacts of anthropogenic climatic warming due to increasing CO_2 on natural vegetation and agriculture of Japan. Effects of the detonation of atomic bombs (Hiroshima and Nagasaki) and accident of the Chernobyl's atomic pile were also studied using global and local models of atmospheric diffusion. The results can be summarized as follows :1. Thermal environment of ponded shallow water was studied to make clear possible effects of climatic warming of heat balance and temperature of paddy fields. It was expected that climatic warming should cause a temperature rise of about 3-4ﾟC over the Japan. Evaporation from water surface should increase by 4-6 percent per ﾟC with the rise of water temperature.2. Crop-weather models were used to investigate effects of increased CO_2 level and projected climatic changes on crop yield (rice, maize, and wheat). Rice yield is expected to decrease due to heat stress in a warmed climate. The introduction of advanced agriculture practices is needed to mitigate such bad effects of warmed climate. Although the yield of maize and wheat crops would be lowered by decrease in rain fall during the growing period, such bad effects can be compensated by application of irrigation water.3. The migration of climatically suitable area with projected climatic warming was studied for several tree species. It was found that the suitable area for silver fir and Japanese oak may decrease by 50-60 percent compared with that at present, and that the area of laurel forest zone was not very sensitive to climatic warming.4. Atmospheric diffusion models were used to estimate the area of radioactive contamination due to the detonation of atomic bombs and the accident of the Chernobyl's atomic pile. The results were in good agreement with the spatial distribution of radioactivity measured after the detonation of atomic bombs.