Rice production is affected by climate change, while climate change is simultaneously accelerated by methane gas (CH₄) emissions from paddy fields. The rice sector must take suitable mitigation measures, such as prolonging mid-summer drainage (MSD) before the rice flowering period. To propose a mitigation policy, this study aims to demonstrate the environmental and economic effects of MSD in Japanese paddy fields by using a dynamic, spatial computable general equilibrium (CGE) model and crop model; the study also considers environmental subsidies with a carbon tax scheme to promote MSD measures. The results demonstrate that climate change under the 8.5 representative concentration pathway (RCP) scenario will reduce rice prices and rice farmers’ nominal income due to bumper harvests until the 2050s. Promoting MSD in paddy fields can prevent a decrease in farmers’ nominal income and effectively reduce CH₄ emissions if all farmers adopt this measure. However, some farmers can potentially increase their own yield by avoiding MSD under high rice prices, which would be maintained through other farmers’ participation. A strong motivation exists for some farmers to gain a “free ride,” and an environmental subsidy with a carbon tax can help motivate farmers to adopt MSD. Therefore, the policy mix of prolonging MSD and environmental subsidies can increase all farmers’ incomes by preventing “free rides” and decrease greenhouse gas emissions with a slight decrease in Japan’s GDP.

中文翻译：

---

减少稻田中仲夏排水以减少甲烷排放的政策措施：动态，空间可计算的一般均衡模型的应用

稻米生产受气候变化的影响，而甲烷（CH ₄）从稻田的排放。稻米部门必须采取适当的缓解措施，例如在稻米开花期之前延长仲夏排水时间（MSD）。为了提出缓解措施，本研究旨在通过使用动态，空间可计算的一般平衡（CGE）模型和作物模型来证明日本稻田MSD的环境和经济影响；该研究还考虑了通过碳税计划来促进MSD措施的环境补贴。结果表明，到2050年代，由于丰收，气候变化在8.5有代表性的集中路径（RCP）情景下将降低稻米价格和稻农的名义收入。在稻田中推广MSD可以防止农民的名义收入减少并有效减少CH ₄如果所有农民都采用此措施，则排放量将减少 但是，一些农民可以通过避免在稻米价格高企的情况下避免MSD来增加自己的产量，而稻米价格的上涨将通过其他农民的参与来维持。有些农民获得“搭便车”的强烈动机，而征收碳税的环境补贴可以帮助激励农民采用MSD。因此，延长MSD和环境补贴的政策组合可以通过防止“搭便车”来增加所有农民的收入，并减少温室气体排放，同时日本GDP略有下降。