2024-10-27-IMF-目的地净零排放_迫切需要对航空和航运征收全球碳税（英）_51页_2mb

Summary of "Destination Net Zero: The Urgent Need for a Global Carbon Tax on Aviation and Shipping"

Core Content

This IMF Staff Climate Note emphasizes the urgent need for a global carbon tax on international aviation and shipping to support the transition to net-zero emissions and enhance climate mitigation efforts. The sectors are significant contributors to global CO₂ emissions, and their decarbonization is critical for achieving the Paris Agreement's temperature goals.

Main Points

• Emissions Contribution:
  In 2023, international aviation and maritime emitted 610 and 850 million tonnes (Mt) of CO₂, respectively, accounting for about 1.5 and 2 percent of global fossil fuel emissions. Combined, these sectors contribute more emissions than all but four countries.

• Emissions Growth:
  Without mitigation, emissions from these sectors are expected to grow rapidly, reaching 15–25 percent of global CO₂ emissions by 2030 and potentially 40 percent under a 1.5°C scenario by the same year. This growth is particularly concerning as countries decarbonize in line with the Paris Agreement.

• Need for Carbon Pricing:
  Carbon pricing (either through carbon taxes or ETSs) is essential to provide a price signal that incentivizes efficiency, technological development, and the adoption of low-carbon fuels. It also offers a significant revenue stream—up to $200 billion annually by 2035, which could triple current global climate finance.

• Sector Differences:

  • Fuel Intensity: Fuel costs make up 20% of airline ticket prices but only 3–5% of shipped product prices, meaning carbon pricing will have a larger impact on air travel demand than on maritime freight.
  • Product Type: Aviation is a consumer good with a high proportion of leisure travel, while maritime is an intermediate input dominated by cargo.
  • Tax Base Mobility: Maritime has high mobility due to long voyages and refueling at low-cost ports, while aviation has more limited mobility.

• Current Policies:

  • Aviation: CORSIA (Carbon Offsetting and Reduction Scheme for International Aviation) is currently voluntary but will become mandatory for most flights in 2027. It allows operators to offset emissions above 85% of 2019 levels.
  • Maritime: The IMO has focused on energy efficiency standards and is considering emissions pricing. However, these measures are not cost-effective due to lack of incentives beyond compliance.

• Mitigation Opportunities:

  • Short-term: Efficiency improvements in new and existing vessels, better maintenance, and operational practices.
  • Long-term: Adoption of zero-emission fuels such as hydrogen, ammonia, methanol, and biofuels. However, these fuels face challenges in production costs, storage, and infrastructure.

• Policy Options:

  • Carbon Tax: Simple, provides long-term price certainty, and can be cost-effective in promoting emission reductions and zero-emission fuel adoption.
  • ETS (Emissions Trading System): Offers flexibility but requires more administrative and compliance capacity.
  • Feebates: Provide a sliding scale of fees and rebates based on emissions relative to a pivot point, reducing price impacts and offering some revenue.
  • TPS (Tradable Performance Standards): Similar to feebates but does not generate revenue.
  • Offsets: Can reduce mitigation costs but are not always additional and face uncertainty in future prices.

• Revenue and Allocation:
  A global carbon tax could generate substantial revenue, which could be used for international climate finance, R&D, or national budgets. Revenue allocation remains a political challenge, especially for small island and vulnerable states.

• Administrative Feasibility:
  ICAO and IMO have established data collection systems for emissions and fuel use, which are necessary for implementing pricing mechanisms. However, enforcement and coordination across member states are still required.

Key Design Issues

• Price Signal: A robust and credible carbon price trajectory is essential to drive investment in low-carbon technologies.
• Revenue Allocation: Determining how to distribute carbon tax revenues among countries and purposes (e.g., climate finance, R&D) is a major political challenge.
• Compensation Mechanisms: Vulnerable states may require compensation to offset increased transport costs, which could be achieved through rebates or targeted support.
• Implementation Challenges: Both carbon taxes and ETSs require international coordination and agreement among 193 ICAO and 175 IMO member states.

Conclusion

A global carbon tax on international aviation and shipping fuels is a viable and cost-effective instrument for achieving net-zero emissions and generating substantial revenue for climate action. While there are political and administrative challenges, the ICAO and IMO have laid the groundwork for implementing such a policy. The note suggests that a carbon tax, with a clear and credible price trajectory, is preferable to other mechanisms due to its simplicity, price certainty, and revenue potential.