Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA)

Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA)
Name	Carbon Offsetting and Reduction Scheme for International Aviation
Type	Multilateral environmental agreement
Context	International Civil Aviation Organization
Date signed	2016
Location signed	Montreal
Parties	ICAO member states
Language	English, French, Spanish

Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA) is a global market-based measure adopted to address aviation greenhouse gas emissions from international aviation under the auspices of the International Civil Aviation Organization. The scheme aims to stabilize net carbon dioxide emissions from international flights by requiring airlines to obtain and surrender emissions units through offsetting and approved reduction programmes. It represents a negotiated compromise among ICAO member states, airlines, environmental NGOs, and industry stakeholders.

Overview

CORSIA was adopted by the International Civil Aviation Organization at the ICAO 39th Assembly in 2016 and is implemented through standards and recommended practices overseen by ICAO's ICAO Council and the Committee on Aviation Environmental Protection. Its principal objective is to cap net CO2 emissions from international aviation at 2020 levels by requiring offsetting for growth above that baseline. The scheme interacts with other international instruments such as the Kyoto Protocol, the Paris Agreement, and regional measures including the European Union Emission Trading Scheme and national frameworks like the Carbon Pricing initiatives of United Kingdom and Canada.

Background and development

The development of CORSIA followed decades of aviation environmental negotiation, including early voluntary measures advanced by the International Air Transport Association and technical work by ICAO's Committee on Aviation Environmental Protection. Growing scientific evidence from the Intergovernmental Panel on Climate Change and policy pressure from the European Union and United States prompted multilateral talks. Key milestones include the ICAO Assembly resolution of 2013, ICAO's 2016 decision at the ICAO 39th Assembly, and subsequent adoption of implementation elements by the ICAO Council and member states like China, India, Brazil, and Australia. Industry partners such as Airbus, Boeing, and airline alliances including Star Alliance, Oneworld, and SkyTeam engaged in technical consultations, while civil society organizations like Greenpeace, the World Wildlife Fund, and Transport & Environment pushed for stronger measures.

Structure and mechanisms

CORSIA's core mechanism requires participating airlines to monitor emissions from international routes and offset emissions growth above a 2020 baseline by purchasing eligible emissions units from approved programmes. The scheme defines eligible units through a CORSIA Eligible Emissions Units framework developed with inputs from United Nations Framework Convention on Climate Change experts and verification bodies like Verified Carbon Standard and Gold Standard. Implementation phases include a pilot (2021–2023), a first phase (2024–2026), and a second phase (2027–2035), with participation initially voluntary and later mandatory for many ICAO member states. Financial and market mechanisms involve carbon markets such as the Clean Development Mechanism, carbon offsets, and bilateral agreements between states and airlines, while technical pathways include sustainable aviation fuel development supported by manufacturers and research institutions like NASA and the European Commission.

Monitoring, reporting and verification

MRV under CORSIA requires airlines to use standardized monitoring methodologies endorsed by ICAO's Technical Advisory Body. Operators submit emissions reports to their state authority for validation and verification by independent auditors similar to processes used under the Greenhouse Gas Protocol and the United Nations Framework Convention on Climate Change. ICAO maintains a centralized emissions unit registry and transaction logging comparable to registries used by the Clean Development Mechanism and voluntary standards overseen by ISO frameworks. The process emphasizes third‑party verification, chain-of-custody rules for units, and corrective actions overseen by ICAO compliance mechanisms.

Participation and implementation

Participation modalities allow states to opt into the pilot and first phases, with many European Union member states, Australia, Japan, and several African Union members among early participants; major states such as United States and China have varied stances linked to domestic policy. Implementation requires national aeronautical authorities to incorporate CORSIA MRV requirements into national regulations and to establish designated authorities for emission reporting and unit acceptance. Airlines including legacy carriers like Lufthansa, Air France–KLM, and Delta Air Lines announced compliance strategies involving offset procurement, investment in sustainable aviation fuel, and fleet renewal with manufacturers such as Bombardier and Embraer.

Criticisms and controversies

CORSIA has attracted criticism from environmental organizations, scientists, and some states for its reliance on offsets rather than direct emission reductions, echoing debates seen in the contexts of the Kyoto Protocol and Paris Agreement market mechanisms. NGOs like Friends of the Earth International and researchers affiliated with the Intergovernmental Panel on Climate Change have questioned the environmental integrity of certain eligible units and the robustness of verification, paralleling controversies over the Clean Development Mechanism and historical forest carbon projects. Other critiques focus on baseline setting (using 2020), exemptions for certain states, potential double-counting with national inventories under the UNFCCC, and the pace of deployment for sustainable aviation fuel and low-emission aircraft technologies promoted by Airbus and Boeing.

Impact and outcomes

Since adoption, CORSIA has influenced airline corporate strategies, carbon market demand, and research investment in sustainable aviation fuel and efficiency technologies. Early monitoring data and ICAO reports show variable uptake among states and fluctuating offset prices in markets influenced by entities like Gold Standard and Verified Carbon Standard. Analysts from institutions such as the International Energy Agency and Organisation for Economic Co-operation and Development have modelled scenarios where CORSIA contributes to emissions stabilization but is insufficient alone to achieve broader net-zero emissions targets without accelerated fuel and technology shifts. Ongoing reviews by ICAO, engagement from major manufacturers and airlines, and pressures from international fora like the United Nations and G20 continue to shape CORSIA's trajectory.

Category:Climate change policy