Impact assessment of climate change on rice production in Asia in comprehensive consideration of process/parameter uncertainty in general circulation models

We assessed the impact of climate change on rice production in Asia in comprehensive consideration of the process/parameter uncertainty in general circulation models (GCMs). After inputting future climate scenarios based on the projections of GCMs for three Special Report on Emissions Scenarios (SRES) (18 GCMs for A1B, 14 GCMs for A2, and 17 GCMs for B1) into a crop model, we calculated the average change in production (ACP), the standard deviation of the change in production (SDCP), and the probability of a production decrease (PPD) for each SRES scenario, taking into account the effect of CO2 fertilization. In the 2020s, PPD values were high for all SRES scenarios because the negative impacts of climate change were larger than the positive effects of CO2 fertilization in almost all climate scenarios in the near future. This suggests that it will be necessary to take immediate adaptive actions, regardless of the emission scenario, in the near future. In the 2080s, there were large differences in ACP, SDCP, and PPD among the SRES scenarios. The scenario with the highest atmospheric CO2 concentration, A2, showed a notable decrease in production and a high PPD in the 2080s compared with the other scenarios, despite having the largest CO2 fertilization effect. In addition, A2 had the largest SDCP among the SRES scenarios. On the other hand, the scenario with the lowest atmospheric CO2 concentration, B1, showed a small decrease in production, and a much smaller SDCP and a much lower PPD, than in the case of A2. These results for the 2080s suggest that a reduction in CO2 emissions in the long term has great potential not only to mitigate decreases in rice production, but also to reduce the uncertainty in these changes.