ICAO CORSIA: Decarbonizing Global Aviation

Overview

The Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA) represents the first global market-based measure for an entire industrial sector. Developed by the International Civil Aviation Organization (ICAO), it is a critical pillar in the aviation industry's strategy to achieve net-zero carbon emissions by 2050.

While domestic aviation emissions are covered under the Paris Agreement, international flights fell into a regulatory gap. ICAO developed CORSIA to fill this gap, aiming for carbon-neutral growth from a baseline of 85% of 2019 emissions levels.

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What is CORSIA and Why Was It Developed?

CORSIA is a global scheme designed to address the growth in CO₂ emissions from international flights. The scheme works on an offsetting principle: rather than capping total emissions, it requires airlines to compensate for any increase in emissions above the baseline by purchasing high-quality carbon credits or using approved lower-emission fuels.

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Types of CORSIA Eligible Fuels (CEF)

CORSIA incentivizes the shift away from traditional kerosene through two primary categories of fuels. To be eligible, these fuels must meet strict sustainability criteria and be certified by approved bodies:

1. CORSIA Sustainable Aviation Fuel (SAF): Renewable or waste-derived fuels produced from feedstocks such as used cooking oil, agricultural residues, or municipal waste. They can reduce lifecycle emissions by up to 80% compared to fossil jet fuel.
2. CORSIA Lower Carbon Aviation Fuel (LCAF): Fossil-based aviation fuels produced with significantly lower carbon footprints (at least a 10% reduction) through technologies like Carbon Capture and Storage (CCS) during the refining process.

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How CORSIA Reduces GHG Emissions

CORSIA acts as a gap-filler while the industry develops long-term technological solutions like electric or hydrogen aircraft. It reduces emissions through:

• Emissions Capping: By requiring offsets for growth above 85% of 2019 levels, it effectively stabilizes the net impact of international aviation.
• Economic Incentives: By putting a price on carbon growth, it makes Sustainable Aviation Fuels (SAF) more economically competitive compared to traditional fuels.
• Funding Global Climate Projects: The purchase of CORSIA Eligible Emissions Units directs billions of dollars into green projects globally — such as reforestation and renewable energy — particularly in developing nations.

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Key Challenges in Implementation

• Regulatory Complexity: Implementation requires countries to transpose ICAO rules into national law. As of 2026, many nations still lack the domestic enforcement mechanisms needed to make the scheme truly binding.
• Supply of High-Integrity Credits: There is a bottleneck in the supply of carbon credits that meet the rigorous Article 6 requirements of the Paris Agreement, which prevent double-counting of emission reductions.
• Regional Fragmentation: Some regions, like the EU, have their own Emissions Trading Systems (ETS). Aligning these regional cap-and-trade systems with the global CORSIA offsetting system creates administrative and legal friction for international airlines.

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Risks Involved

• Double Counting: A significant risk is that a country might claim an emission reduction for its own climate goals while an airline simultaneously uses it as a CORSIA offset — resulting in no net benefit to the atmosphere.
• Greenwashing Concerns: Critics argue that CORSIA relies too heavily on offsets rather than forcing airlines to reduce emissions at the source. If the quality of offsets is low, the scheme risks becoming a paper exercise rather than a genuine climate solution.
• Economic Volatility: The price of carbon credits and SAF is highly sensitive to geopolitical events. Energy market shifts can significantly increase the cost of compliance for airlines, potentially leading to higher ticket prices or reduced participation in voluntary phases.

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CORSIA at a Glance