JP

Markets versus Regulation: The Efficiency and Distributional Impacts of U.S. Climate Policy Proposals

Regulatory measures have proven the favored approach to climate change mitigation in the U.S., while market-based policies have gained little traction. Using a model that resolves the U.S. economy by region, income category, and sector-specific technology deployment opportunities, this paper studies the magnitude and distribution of economic impacts under regulatory versus market-based approaches. We quantify heterogeneity in the national response to regulatory policies, including a fuel economy standard and a clean or renewable electricity standard, and compare these to a cap-and-trade system targeting carbon dioxide or all greenhouse gases. We find that the regulatory policies substantially exceed the cost of a cap-and-trade system at the national level. We further show that the regulatory policies yield large cost disparities across regions and income groups, which are exaggerated by the difficulty of implementing revenue recycling provisions under regulatory policy designs.

Non-nuclear, Low-carbon, or Both? The Case of Taiwan

The Fukushima nuclear accident in Japan has renewed debates on the safety of nuclear power, possibly hurting the role of nuclear power in efforts to limit CO2 emissions. I develop a dynamic economy-wide model of Taiwan with a detailed set of technology options in the power sector to examine the implications of adopting different carbon and nuclear power policies on CO2 emissions and the economy. Without a carbon mitigation policy, limiting nuclear power has a small economic cost for Taiwan, but CO2 emissions may increase by around 4.5% by 2050 when nuclear is replaced by fossil-based generation. With a low-carbon target of a 50% reduction from year 2000 levels by 2050, the costs of cutting CO2 emissions are greatly reduced if both carbon sequestration and nuclear expansion were viable. This study finds that converting Taiwan's industrial structure into a less energy-intensive one is crucial to carry out the non-nuclear and low-carbon environment.

Quantifying Regional Economic Impacts of CO2 Intensity Targets in China

To address rising energy use and CO2 emissions, China's leadership has enacted energy and CO2 intensity targets under the Twelfth Five-Year Plan (2011–2015), which are defined at both the national and provincial levels. We develop a computable general equilibrium (CGE) model with global coverage that disaggregates China's 30 provinces and includes energy system detail, and apply it to assess the impact of the current binding provincial CO2 emissions intensity targets. We compare the impact of the provincial targets approach to a single target for China that achieves the same reduction in CO2 emissions intensity at the national level. The national target assumes trading of emissions allowances across provinces, resulting in the least-cost reductions nationwide. We find that the national target results in about 20% lower welfare loss in China relative to the provincial targets approach. Given that the regional distribution of impacts has been an important consideration in the target-setting process, we focus on the changes in provincial-level CO2 emissions intensity, CO2 emissions, energy consumption, and economic welfare. We observe significant heterogeneity across provinces in terms of the energy system response as well as the magnitude of welfare impacts. We further model the current policy of fixed end-use electricity prices in China and find that national welfare losses increase. Assumptions about capital mobility have a substantial impact on national welfare loss, while changing assumptions about the future availability of domestic natural gas resources does not have a large effect.

The role of China in mitigating climate change

We explore short- and long-term implications of several energy scenarios of China's role in efforts to mitigate global climate risk. The focus is on the impacts on China's energy system and GDP growth, and on global climate indicators such as greenhouse gas concentrations, radiative forcing, and global temperature change. We employ the MIT Integrated Global System Model (IGSM) framework and its economic component, the MIT Emissions Prediction and Policy Analysis (EPPA) model. We demonstrate that China's commitments for 2020, made during the UN climate meetings in Copenhagen and Cancun, are reachable at very modest cost. Alternative actions by China in the next 10 years do not yield any substantial changes in GHG concentrations or temperature due to inertia in the climate system. Consideration of the longer-term climate implications of the Copenhagen-type of commitments requires an assumption about policies after 2020, and the effects differ drastically depending on the case. Meeting a 2 °C target is problematic unless radical GHG emission reductions are assumed in the short-term. Participation or non-participation of China in global climate architecture can lead by 2100 to a 200–280 ppm difference in atmospheric GHG concentration, which can result in a 1.1 °C to 1.3 °C change by the end of the century. We conclude that it is essential to engage China in GHG emissions mitigation policies, and alternative actions lead to substantial differences in climate, energy, and economic outcomes. Potential channels for engaging China can be air pollution control and involvement in sectoral trading with established emissions trading systems in developed countries.

Absolute vs. intensity-based emission caps

Cap-and-trade systems limit emissions to some pre-specified absolute quantity. Intensity-based limits, that restrict emissions to some pre-specified rate relative to input or output, are much more widely used in environmental regulation and have gained attention recently within the context of greenhouse gas (GHG) emissions trading. In this paper we provide a non-technical introduction to the differences between these two forms of emission limits. Our aim is not to advocate either form, but to elucidate the properties of each in a world where future emissions and GDP are not known with certainty. We argue that the two forms have identical effects in a world where future emissions and economic output (i.e. GDP) are known with certainty, and show that outcomes for marginal costs, abatement, emissions and welfare diverge only because of the variance of actual future GDP relative to its forecast expectation.

A modeling study on the climate impacts of black carbon aerosols

A three-dimensional interactive aerosol-climate model has been developed and used to study the climatic impact of black carbon (BC) aerosols. When compared with the model's natural variability, significant global-scale changes caused by BC aerosols occurred in surface latent and sensible heat flux, surface net long-wave radiative flux, planetary boundary layer height, convective precipitation (all negative), and low-cloud coverage (positive), all closely related to the hydrological cycle. The most significant regional change caused by BC revealed in this study is in precipitation that occurs in the tropics (shift of precipitation center in the ITCZ) and in the middle and high latitudes of the Northern Hemisphere (change in snow depth). Influenced by BC caused changes in cloud cover and surface albedo, the interactive model provides smaller positive all-sky forcing at the top of atmosphere (TOA) and larger negative forcing at the surface than the offline diagnostics (the direct forcings). The actual solar radiative forcings by BC derived from the interactive model also exhibit significant interannual variations that are up to 4 times as large as their means. Based on the revealed changes in cloud radiative forcing by BC, a non-Twomey-Albrecht indirect forcing by BC that alters radiative budgets by changing cloud cover via thermodynamics rather than microphysics is also defined. It has been demonstrated that with an absolute amount more than 2 times higher than that of the TOA forcing, the surface forcing by BC is a very important factor in analyzing the climatic impact of BC. The result of this study suggests that with a constant annual emission of 14 TgC, BC aerosols do not cause a significant change in global-mean surface temperature. The calculated surface temperature change is determined by a subtle balance among changes in surface energy budget as well as in the hydrological cycle, all caused by BC forcing and often compensate each other. The result of this study shows that the influences of BC aerosols on climate and environment are more significant in regional scale than in global scale. Important feedbacks between BC radiative effects and climate dynamics revealed in this study suggest the importance of using interactive aerosol-climate models to address the issues related to the climate impacts of aerosols.

An Issue of Permanence: Assessing the Effectiveness of Temporary Carbon Storage

In this paper, we present a method to quantify the effectiveness of carbon mitigation options taking into account the `permanence' of the emissions reduction. While the issue of permanence is most commonly associated with a `leaky' carbon sequestration reservoir, we argue that this is an issue that applies to just about all carbon mitigation options. The appropriate formulation of this problem is to ask `what is the value of temporary storage?' Valuing temporary storage can be represented as a familiar economic problem, with explicitly stated assumptions about carbon prices and the discount rate. To illustrate the methodology, we calculate the sequestration effectiveness for injecting CO2 at various depths in the ocean. Analysis is performed for three limiting carbon price assumptions: constant carbon prices (assumes constant marginal damages), carbon prices rise at the discount rate (assumes efficient allocation of a cumulative emissions cap without a backstop technology), and carbon prices first rise at the discount rate but become constant after a given time (assumes introduction of a backstop technology). Our results show that the value of relatively deep ocean carbon sequestration can be nearly equivalent to permanent sequestration if marginal damages (i.e., carbon prices) remain constant or if there is a backstop technology that caps the abatement cost in the not too distant future. On the other hand, if climate damages are such as to require a fixed cumulative emissions limit and there is no backstop, then a storage option with even very slow leakage has limited value relative to a permanent storage option.

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