Global Climate Change and Food Production in Japan

Carbon dioxide levels in the atmosphere have increased from about 280 to 356ppmv since the pre-industrial period. An IPCC report estimated that the increase in global average surface temperature at equilibrium resulting from a doubling CO2 would be likely to be between 1.5 and 4.5°C, with a best estimate of 2.5°C. Such climate change is expected to have great impact on crop production. Crop model simulations under the condition of current cultivars and cropping systems indicates that a 2xCO2 climate would substantially increase crop yield and its stability in northern and north-central Japan, and that, in south-central and south-western Japan, it will decrease the yield and its stability to a marked extent. By aggregating these regional impacts over the whole country, national crop production is concluded that would not change significantly from the current level. However, the variability of yield is likely to increase, reflecting increased high-temperature-induced spikelet sterility in south-central and south-western Japan. Adjustment of agricultural practice, such as advancing the planting date and application of supplemental irrigation, is necessary to adapt to climatic changes projected from the GCMs. The yields of crops could increase by introducing adjustment of agriculture practices under the predicted warm climate; however Kyushu where higher temperature could result in heat stresses on crops, it is expected that the yield reduction 2xCO2 climate could not be recovered by supplemental irrigation and advancing the planting date.