International aviation emissions have crossed a regulatory threshold that many airlines had postponed planning for since 2020. Newly released data from the International Civil Aviation Organisation confirms that emissions from international flights in 2024 have exceeded 85 percent of 2019 levels, triggering offsetting obligations under the Carbon Offsetting and Reduction Scheme for International Aviation.
The Sectoral Growth Factor for 2024 has been set at 0.15948315, a technical but consequential figure that determines how much emissions growth airlines must compensate with eligible carbon credits.
The positive SGF marks the first formal reactivation of CORSIA compliance since the pandemic collapse in air traffic effectively suspended offset demand. Under the scheme’s design, airlines are required to offset only emissions growth above a baseline tied to pre pandemic activity. As long as global emissions remained below that level, compliance costs were largely theoretical. That dynamic has now shifted, and for carriers operating international routes in participating states, carbon credit procurement is no longer optional.
CORSIA entered its First Phase in January 2024, covering the period through 2026. Participation at this stage remains voluntary at the state level, but more than 120 countries have opted in, including all major aviation markets such as the European Union, the United Kingdom, the United States, Japan, Brazil, and the United Arab Emirates. For airlines based in or operating between these jurisdictions, offsetting requirements now apply to a portion of their international emissions, calculated using the sector wide growth factor rather than individual airline performance.
The regulatory scope will expand significantly in the Second Phase from 2027 to 2035, when participation becomes mandatory for nearly all ICAO member states, excluding only least developed countries, landlocked developing nations, and small island states. This transition effectively brings the vast majority of internationally operating airlines under a single global carbon compliance framework, a rarity in a sector historically resistant to binding climate regulation.
Compliance under CORSIA hinges on the purchase and cancellation of ICAO eligible emissions units. Approved credits must meet specific environmental integrity criteria and can be sourced through recognized carbon registries, aviation focused marketplaces, or structured long term contracts tied to projects such as forestry based REDD+ programs, biogas deployment, methane abatement, or renewable energy. While this flexibility is intended to contain costs, it also exposes airlines to the volatility and credibility debates that continue to shape global carbon markets.
Market participants note that the reactivation of CORSIA comes at a time when scrutiny of offset quality is intensifying. Airlines face the dual risk of rising credit prices as demand returns and reputational exposure if purchased credits are later challenged on additionality or permanence grounds. As Alexey Zotov, General Manager of ACGC S.a.r.l., part of the ACN Group, has pointed out, airlines will be obliged to purchase credits through recognized channels, but the strategic choice of instruments and counterparties is becoming as important as compliance itself.
CORSIA was never intended to deliver absolute emissions reductions from aviation. Its stated purpose is to stabilize net emissions at baseline levels while longer term solutions mature. That limitation is becoming more visible as air traffic rebounds and offset volumes scale up. Industry data consistently shows that efficiency gains and fleet renewal alone cannot counteract demand growth, placing greater emphasis on fuel based solutions.
Sustainable Aviation Fuel remains the sector’s primary lever for structural decarbonization, but global SAF supply remains limited and costly relative to conventional jet fuel. As a result, airlines are increasingly evaluating integrated strategies that combine near term carbon credit procurement with longer term SAF offtake agreements. This approach reflects both regulatory reality and investor pressure, as reliance on offsets alone is unlikely to satisfy future climate disclosure and transition plan expectations.
