ICAO 9951

Offsetting Emissions from the Aviation Sector

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Organization: ICAO
Publication Date: 1 January 2011
Status: active
Page Count: 40



In general terms an offset is a "compensating equivalent". As an activity, offsetting is the "cancelling out" or "neutralizing" of emissions from a sector like aviation with emissions reductions achieved in a different activity or location that have been rigorously quantified and verified.

Offsetting can occur in either a regulatory or a non-regulatory context. In a non-regulatory context, offsetting is an idealistically or politically motivated action. In a regulatory context, offsetting is an action by companies or nations to achieve compliance with a mandatory emissions commitment.

In a regulatory context, it is only when credits are acquired from outside the emissions trading scheme or linked schemes and used to meet commitments/obligations under the scheme that the activity is referred to as offsetting. On the other hand, if a regulated emitter acquires compliance units (allowances or credits) from another regulated emitter within the same emissions trading scheme, or from a linked scheme, this is referred to simply as emissions trading.


Within the aviation sector, the only offsetting that is currently taking place is non-regulated voluntarily passenger-based offsetting. The airlines' roles are limited to offering an opportunity for the passengers to offset emissions caused by their travel.

Several concerns related to offsetting activities are discussed in this report. The most important relate to difficulties airline passengers have navigating on websites, limited participation, lack of transparency about the credits being offered, including the general absence of rigorous verification requirements.

On the positive side, buying offsets mitigates GHG emissions. Airline consumers are being educated about the effects of air travel on climate change, the development of carbon markets is encouraged, and the need for improved standards and verification requirements for the generation of offset credits is becoming more accepted.


Despite the rapid ongoing growth of voluntary offsetting by air passengers, the potential for this type of voluntary approach for mitigating the effects of aviation emissions on global climate change is likely limited. Despite what appears to be widespread support, the willingness to actually purchase credits on a voluntary basis has been weak.

Nevertheless, steps might be taken to increase demand and quality of non-regulatory offsetting. For example, ensuring offset credits meet internationally accepted rigorous standards for quantification and verification, and improving systems for tracking credits to ensure they are used only once, should be pursued.

Offsetting in a regulatory context may be an important tool in the future. If there is a decision to regulate emissions from aviation that allows for emissions trading and emission sources not covered by a regulated system that can reduce emissions at a cost less than reducing emissions from aviation itself, an offsetting mechanism is likely to be part of the scheme.

This report concludes with a discussion of opportunities to use offsetting in the future. At the passenger level, it is possible to draw on current voluntary experience. However, there is also the possibility of using offsetting at a global sectoral level, either in a regulated emissions trading system or through an emissions charge. Offsetting can also be applied at an air carrier level rather than at the passenger level. These options offer some interesting possibilities for the future.

Document History

ICAO 9951
January 1, 2011
Offsetting Emissions from the Aviation Sector
EXECUTIVE SUMMARY THE UNDERSTANDING OF OFFSETTING In general terms an offset is a "compensating equivalent". As an activity, offsetting is the "cancelling out" or "neutralizing" of emissions from a...