Research

Abstract: Changes in the global economy and climate system have significant consequences for local and regional economies and ecosystems. To evaluate the impacts of changing global conditions on regional sustainability, we adopt the weak sustainability plus (WS+) framework, which examines both a comprehensive sustainability measure, inclusive wealth (weak sustainability, WS) and the quality of critical natural capitals (strong sustainability, SS). To assess and project global impacts on sustainability at a subnational scale, we develop a dynamic regional food, energy, and water systems (DR-FEWS) integrated assessment framework. The framework links global market, stewardship, and climate conditions to the regional economy, local land use, and environmental qualities (e.g., GHG emissions and water quality). We apply this integrated framework to the U.S. Midwest region and analyze its FEWS sustainability across a range of plausible scenarios developed through regional stakeholders’ participation. The results reveal that the region is weakly sustainable under all five scenarios examined, with a growth in produced capital offsetting a decline in natural capital. However, the WS+ test indicates that only two of five scenarios meet the necessary criteria in the 2030s and 2040s, with the regional water quality target not met for other scenarios. Lastly, two high environmental stewardship scenarios achieve a decoupling of economic development and environmental degradation. Our work proposes a novel, comprehensive framework that integrates economic, land use, and sustainability assessment models to examine subnational sustainability, thereby advancing sustainability science.

Abstract: Circular economy solutions within the food system aim to keep valuable materials in economic circulation (out of landfills) and to enhance food security and the environmental sustainability of food systems. Widely embraced waste hierarchies invariably give a priority to waste prevention. Prevention policies can be formulated as carrots, e.g., waste abatement subsidies, or sticks, e.g., waste disposal taxes, and applied at one or more segments along the food supply chain. We develop a general equilibrium model of the U.S. Midwest that endogenizes food waste decisions at key supply chain links. Existing economic models of circular food systems often fail to endogenize the amount of food that is wasted and seldom apply multiple policies at different food supply chain stages. Our results identify how carrots and sticks differ: with a consumer food waste tax, 88% of GHG emissions reduction derives from reduced food demand (and thus supply); with consumer waste abatement subsidies, 28% derives from decreased landfill deposits and 64% from reduced food supply. While both strategies are generally found to be effective in reducing GHG emissions, the abatement cost reduction approach induces greater food waste reduction. Our results also suggest that policies aimed at consumers can have four times greater impacts than those applied upstream, yet induce negative upstream spillovers. Lastly, as their combinations typically generate additive effects, carrots and sticks can complement one another, further informing an optimal policy suite that reduces food waste, while mitigating unintended consequences (e.g., rebound effects or consumption reduction).

Abstract: Climate policy is far from certain in the United States. Clean energy tax credits have undergone repeated cycles of short-term renewal and expiration, while changes in the political leadership tend to significantly shift the government's environmental policies. Given that, the investigation into the uncertainty of climate policy and its economic and environmental impacts in the U.S. is of great importance.. I develop a dynamic stochastic model of the U.S. economy with a focus on the energy sectors, explicitly incorporating the uncertainty and varying stringency of the government's climate policies. The simulation results highlight that, in the face of policy uncertainty, the investment decisions can be preempted or delayed depending on the current policy stringency, and a deterministic model can over-predict CO2 emissions, 8-12% more than when a stochastic model is used. The examination of policy timing scenarios reveals that achieving lower emissions in 2050 requires enacting stricter policies close to the target year, whereas minimizing the cumulative emissions is accomplished by earlier adoption of policies, though possibly repealed later. The analysis further suggests that scenarios with earlier policy adoption are associated with up to 37% lower abatement costs than those with later policy adoption. Lastly, subsidies become less cost-effective in reducing CO2 emissions around 2041 as technological progress begins to plateau. The study is particularly relevant for policy analysis in democratic countries, including the U.S., where political transitions and subsequent policy shifts are inevitable. The research would also provide insights into pathways to meet the U.S. mid-century climate goal and mitigate global climate change.

Abstract: This paper aims to inform the policy plans toward decarbonization of the electricity sector by providing a quantitative analysis of different policy scenarios and their impacts on the US regional economy. The study develops a neoclassical growth model for the US economy incorporating state-level heterogeneities in energy sectors and economic interactions between states. Primarily, the suggested model intends to analyze how different states experience the national-scale energy transition process. The results would inform future transition policies. As a preliminary analysis, I examined two distinct states, California and Wyoming. Wyoming suffers a substantially larger drop in the state gross output and welfare than California does when the constraint of a carbon-free electricity target is introduced. The economic impacts are observed via several channels, including the resource extraction sector, fossil-fuel electric power sector, and trade of those products.