2021-09-30-未来能源研究所-碳定价与二氧化碳排放弹性（英）_127页_3mb

Summary of "Carbon Pricing and the Elasticity of CO₂ Emissions"

Core Content

This working paper investigates the impact of carbon pricing on CO₂ emissions across five sectors in a panel of 39 countries from 1990 to 2016. The authors construct a new dataset of sector-level carbon prices and use a synthetic control factor model to estimate the effects of carbon pricing on emissions growth, elasticity, and potential future emission reductions. The paper also explores whether carbon pricing alone is sufficient to meet international climate targets, such as those outlined in the Paris Agreement.

Main Authors

• Ryan Rafaty: Political scientist and postdoctoral researcher at Climate Econometrics, Nuffield College, Oxford. His research focuses on the design and performance of climate change mitigation policies.
• Geoffroy Dolphin: Postdoctoral fellow at Resources for the Future (RFF) and PhD graduate from the University of Cambridge Judge Business School. His research spans political economy, energy economics, and climate policy.
• Felix Pretis: Assistant Professor at the University of Victoria and co-director of the Climate Econometrics project. He is also a James Martin Research Fellow at the Oxford Martin School.

About RFF

Resources for the Future (RFF) is a nonprofit research institution in Washington, DC, dedicated to improving environmental, energy, and natural resource decisions through economic research and policy engagement. Working papers from RFF are for discussion and have not undergone formal peer review.

Key Findings

1. Impact of Carbon Pricing Introduction

• The introduction of carbon pricing has led to a statistically significant 1.5 percentage point reduction in aggregate CO₂ emissions growth relative to counterfactuals.
• The electricity and heat sector showed the largest reduction, with a 2.5 percentage point decrease.
• The effect is attributed to policy introduction rather than the price level itself, suggesting that the mere implementation of carbon pricing can reduce emissions.

2. Elasticity of Emissions with Respect to Carbon Price

• The (semi)elasticity of CO₂ emissions is small and imprecisely estimated, with a median estimate of -0.03 percent per $1/tCO₂.
• The manufacturing sector showed a more significant elasticity effect, with a median estimate of -0.16 percent per $1/tCO₂.
• The authors argue that the introduction effect (policy implementation) often overshadows the price effect, leading to overestimation of emission reductions in previous studies.

3. Sufficiency of Carbon Pricing for Emission Reduction Targets

• Carbon pricing at current levels is unlikely to be sufficient to achieve the emission reductions required by the Paris Agreement.
• The study suggests that achieving the necessary reductions would require global carbon pricing with near 100% emission coverage and prices exceeding $250/tCO₂.
• Even with such high prices, the paper acknowledges that carbon pricing alone may not be enough without complementary policies.

Methodology

• The authors use a synthetic control factor model, two-way fixed effects (TWFE), and interactive fixed effects (IFE) to estimate the treatment effects and elasticities.
• They construct a novel dataset of emissions-weighted carbon prices across five sectors for 39 countries that implemented carbon pricing and 164 that did not.
• The dataset includes emissions data from 1975 to 2016.
• To address endogeneity, they use fixed weights in the emissions-weighted carbon price series and allow for a multifactor error structure.

Challenges and Limitations

• The lack of standardized carbon price data across countries and sectors has hindered cross-country empirical assessments.
• The identification challenges in estimating the causal effect of carbon pricing are significant due to the complexity of policy implementation and economic responses.
• Previous studies have often focused on statistical significance rather than economic significance, and have not adequately differentiated between introduction and price effects.

Policy Implications

• Carbon pricing is an important tool for reducing emissions, but its effectiveness is limited at current price levels.
• The introduction effect is a key driver of emission reductions, and should not be ignored in future studies.
• The paper emphasizes the need for complementary policies to achieve the emission reductions required for climate targets.
• The results support the idea that introducing carbon pricing in non-covered sectors could lead to substantial emission reductions.

Conclusion

• The study concludes that while carbon pricing can reduce emissions, it is not sufficient on its own to meet the ambitious targets of the Paris Agreement.
• A linear specification of the relationship between carbon price and emissions is appropriate for the data considered, as nonlinear relationships are not detectable in the short sample.
• The authors advocate for more comprehensive and standardized data collection and for more nuanced empirical approaches that differentiate between policy introduction and price effects.