Policy measures to promote mid-summer drainage in paddy fields for a reduction in methane gas emissions: the application of a dynamic, spatial computable general equilibrium model

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.

Economic and Environmental Effects of Public Transport Subsidy Policies: a Spatial CGE Model of Beijing

Public transport plays an important role in the environment. This study established a Spatial Computable General Equilibrium (SCGE) model to examine the economic and environmental effects of public transport subsidy policies. The model includes firms, consumers, and traffic modules in one framework. Statistical data from Beijing were used in calibration to obtain benchmark equilibrium. Based on the equilibrium, simulations compared citywide social welfare, jobs-housing spatial population distribution, and environmental outputs under four subsidy policies: fare subsidy, cash grants, road expansion, and public transport speedup. Based on the results regarding the effects of public transport policies, conclusions can be drawn about which policies will have greater overall social influence and should therefore be used.

REGIONAL FLOOD IMPACTS AND ADAPTATION IN A FEDERAL SETTING: A SPATIAL COMPUTABLE GENERAL EQUILIBRIUM ANALYSIS FOR SWITZERLAND

Climate change, a growing population and inappropriate land use may lead to a significant increase in the frequency, intensity and the duration of water-related extreme events. We aim (1) to gain a better understanding of the direct and indirect economic impacts of floods, (2) to analyze the issue of efficient flood adaption as well as the issue of financing adaptation in a federalist system, where local and national governmental authorities interplay in the provision of local public good adaptation. Our numerical thought experiments are based on a dynamic, spatial differentiated Ramsey type Computable General Equilibrium Model. Regions are determined by exposure and vulnerability to floods and are not identical with territorial units. Our results indicate: (1) general equilibrium effects caused by flood damages in vulnerable regions lead in regions of low vulnerability also to considerable welfare and GDP losses. (2) Providing local public good adaptation can at low economic costs significantly reduce negative impacts on welfare, GDP as well as the allocation of resources between regions and sectors. (3) Funding adaptation by imposing a regional land tax should be preferred to a national output tax or a combination of both with transfers from national to regional governments.