Masako Ikefuji

Optimal Emission Tax with Endogenous Location Choice of Duopolistic Firms

This paper explores optimal environmental tax policy under which duopoly firms strategically choose the location of their plants in a simple three-stage game. We examine how the relationship between the optimal emission tax and the choice of location of duopoly firms affects the welfare of the home country. We characterize the relationship between the optimal emission tax and the fixed cost, depending on the degree of environmental damage from production. Finally, we show the existence of asymmetric equilibrium in which either firm chooses relocation of its plant even if the duopoly firms are identical ex ante.

Conformism and Structural Change

We study structural change in a simple, two-sector endogenous growth model and show that the presence of commodity-specific consumption externalities can be a source of structural change. When the degrees of consumption externalities are different between different goods, the two sectors grow at different rates, whereas the aggregate economy exhibits balanced growth in the sense that capital stock and expenditure grow at the same constant rate. Under the more restrictive condition such that the degrees of consumption externalities are the same, structural change does not occur. We also show that the dependence of the benchmark consumption levels on the past consumption is crucial for the divergent patterns of structural change across countries.

Internal vs. External Habit Formation in a Growing Economy with Overlapping Generations

This paper explores the roles of internal and external habit formation in a simple model of endogenous growth with overlapping generations. Unlike the representative agent settings in which the distinction between internal and external habits may not yield significant qualitative differences in working of the model economy, we show that the internal and external habit persistence in overlapping generations economies may have qualitatively different effects on the steady-state characterization as well as on the dynamic behavior of the economy. We also confirm that in an overlapping generations framework, whether the habits in the utility function takes subtractive or multiplicative forms may be critical both for long-run growth and for transitional dynamics.

Adaptation for Mitigation

This paper develops a dynamic model consisting of two regions (North and South), in which the accumulation of human capital is negatively influenced by the global stock of pollution. By characterizing the equilibrium strategy of each region, we show that the regions’ best responses can be strategic complements through a dynamic complementarity effect. The model is used to analyze the impact of adaptation assistance from North to South. It is shown that North’s unilateral assistance to South (thus enhancing South’s adaptation capacity) can facilitate pollution mitigation in both regions, especially when the assistance is targeted at human capital protection.

Expected Utility and Catastrophic Risk

An expected utility based cost-benefit analysis is in general fragile to its distributional assumptions. We derive necessary and sufficient conditions on the utility function of the expected utility model to avoid this. The conditions ensure that expected (marginal) utility remains finite also under heavy-tailed distributional assumptions. Our results are context-free and are relevant to many fields encountering catastrophic risk analysis, such as, perhaps most noticeably, insurance and risk management.

The effect of health benefits on climate change mitigation policies

This paper studies the interplay between climate, health, and the economy in a stylized world with eleven heterogeneous regions, with special emphasis on USA, Europe, China, India, and Africa. We introduce health impacts into a simple economic integrated assessment model where both the local cooling effect of SO2 and the global warming effect of CO2 are endogenous, and investigate how these factors affect the equilibrium path. Regions do not respond in the same way to climate change. In particular, emission abatement rates and health costs depend on the economic and geographical characteristics of each region. Two policy scenarios are considered, Nash and Optimal, for which we present both global and regional results. Results for Africa and China are highlighted.

Scrap Value Functions in Dynamic Decision Problems

We introduce an accurate, easily implementable, and fast algorithm to compute optimal decisions in discrete-time long-horizon welfaremaximizing problems. The algorithm is useful when interest is only in the decisions up to period T, where T is small. It relies on a flexible parametrization of the relationship between state variables and optimal total time-discounted welfare through scrap value functions. We demonstrate that this relationship depends on the boundedness, half-boundedness, or unboundedness of the utility function, and on whether a state variable increases or decreases welfare. We propose functional forms for this relationship for large classes of utility functions and explain how to identify the parameters.

Climate Change, Economic Growth, and Health

This paper studies the interplay between climate, health, and the economy in a stylized world with four heterogeneous regions, labeled ‘West’ (cold and rich), ‘China’ (cold and poor), ‘India’ (warm and poor), and ‘Africa’ (warm and very poor). We introduce health impacts into a simple integrated assessment model where both the local cooling effect of aerosols as well as the global warming effect of CO2 are endogenous, and investigate how those factors affect the equilibrium path. We show how some of the important aspects of the equilibrium, including emission abatement rates, health costs, and economic growth, depend on the economic and geographical characteristics of each region.

Environment and Growth

This paper examines the implications of the mutual causality between environmental quality and economic growth. While economic growth deteriorates the environment through increasing amounts of pollution, the deteriorated environment in turn limits the possibility of further economic growth. In a less developed country, this link, which we call “limits to growth,” emerges as the “poverty-environment trap,” which explains the persistent international inequality both in terms of income and environment. This link also threatens the sustainability of the world’s economic growth, particularly when the emission of greenhouse gases raises the risk of natural disasters. Stronger environmental policies are required to overcome this link. While there is a trade-off between the environment and growth in the short run, we show that an appropriate policy can improve both in the long run.

The impact of natural disasters on economic growth

This paper studies the impact of natural disasters on economic growth in an endogenous growth model. Production with the use of fossil fuels as input brings about air pollution, which can be one of the causes of climate change. Climate change may be accompanied by natural disasters that causes serious damage to physical capital stock. We assumed that when more polluting inputs are used, the risk of natural disaster is greater, which results in more damage to capital stock. We examine the social planner’s problem taking the risk of natural disasters into account. We show that a steady state exists and that it is saddle path stable. In addition, optimal growth with natural disasters is positive but lower than that without pollution and natural disasters.