Beyond the envelope: Rethinking is required to achieve essential greater ambition in aviation emissions mitigation

Beyond the envelope: Rethinking is required to achieve essential greater ambition in aviation emissions mitigation | Chris Lyle

Wed 12 Feb 2020 – All measures towards aviation emissions mitigation should be supported and progress in ICAO’s basket of measures – aircraft technology, operational procedures, sustainable fuels and implementation of the CORSIA global market-based measure – will add to the impact. But, all together, they are still critically inadequate in terms of both substance and shortness of time frame. The timeline is critical if aviation’s requisite contribution to the Paris targets is to be achieved and even given the most optimistic scenario, aviation will fall well short. Thus, beyond stretching the envelope of the past and current mechanisms there is a pressing need for a serious re-evaluation of the whole approach to mitigation of aviation GHG emissions. New paradigms are required, believes Chris Lyle (right), with thinking outside two boxes, that of aviation and that of methodology.


As to the first box, one elemental weakness in the treatment of international aviation emissions through ICAO (while domestic flights and airport-related emissions fall under other UNFCCC commitments) is that there is no directly identifiable national commitment, only a global ‘sector-determined’ contribution. Not only is potential action diluted, international aviation is treated in a silo and not in the context of differing national circumstances and the relative contribution of aviation to the economy – notably for cases where tourism is critical.


ICAO’s aspirational goal of carbon-neutral growth, established in 2010, is now outmoded. Its basket will contribute pro rata less than any of the first Nationally Determined Contributions (NDCs) to which 184 Parties have committed under the Paris Agreement. Therefore, the international aviation sector, with its separate treatment, is predicted to take a substantially increasing share of the global carbon emissions budget. International aviation should be included in NDCs in order to encourage increased national commitment, both through CORSIA implementation and preferably through additional mitigation measures.


As to thinking outside the second box, that of methodology, additional market-based measures (MBMs), and maybe even some forms of demand management such as economic or explicit rationing, will be necessary if aviation is to make its contribution to the 2°C and 1.5°C targets. Efforts to bring aviation into line with other sectors through the application of VAT and fuel taxes on international flights will continue to be constrained by international comity and law. Ideally, a framework would be established whereby increasingly stringent demand management criteria would apply the lesser the effectiveness of other measures.


At the same time, means must be found whereby the more concerned nations and communities may take more ambitious mitigation action while not being held back by deniers and rearguards. Leaders must be allowed to lead.


In this era of big data and cybernetics, there are new options for MBMs. Consideration towards placing responsibility directly on passengers is reportedly being given by the UK’s Committee on Climate Change, and initiatives in this direction include a ‘Climate Friendly Travel’ programme by SUNx and ‘Transforming the future of travel for everyone’ by Travalyst, elaboration of whose technology search platforms by Wisekey and SkyScanner respectively have inspired the following conjecture.



Giving passengers emissions ownership


A fundamental catalyst might be an emissions levy applied by a country, not as at present on air carriers, but rather on nationals of that country and/or those others whose primary residence for tax purposes is in that country.


Aviation may represent “only” 2.4% of global CO2 emissions at present – if growing and almost certainly much greater in terms of all GHGs plus contrails – but a considerably higher percentage of the carbon footprint of the vast majority of individuals who take even a single flight. Charging the passenger directly would raise consciousness of emissions concerns and enable international aviation emissions to be included in a national regulatory regime, independently or in co-operation with other countries as desired.


Such an approach would make an important contribution in this nascent era of carbon budgeting and trading amongst and for individuals. The concept of a ‘carbon card’ is already in operation in several European countries, if at present on a voluntary basis.


A key advantage of applying a levy directly on nationality or residence of passengers rather than on all passengers via air carriers is that this is beyond the reach of the Chicago Convention and air services agreements, and would dismantle third-party objections regarding the ‘exclusivity’ provision of CORSIA. In the case of international travel it would be in effect a form of duty on imported emissions, a concept which is already under consideration in a wider perspective by a number of countries.


In the context of the UNFCCC, this would be a form of Common But Differentiated Responsibilities (CBDR) given that the vast majority of originating international passengers are from developed countries (China is at the top of the country rankings but it could well decide to include air transport emissions as a negative factor in its burgeoning social credit system). Further, there could be alignment with certain provisions of CORSIA, for example exemptions could apply for flight stages to and from LDCs, LLDCs and SIDS. There might also be partial exemptions or a discounted levy for flight stages using electric or hybrid electric aircraft, or those using verified sustainable aviation fuel (SAF). Ultimately, the levy could be based on the actual emissions of the flights.


Emission amounts might initially be based on an existing internationally recognised source such as ICAO’s carbon calculator but would preferably be related to aircraft type and seat density by class of travel. While setting and application of the levy would be the responsibility of individual States, commonality of the calculator with other countries would clearly be beneficial.


Revenues could be hypothecated towards investment in assured SAFs such as synthetics and biofuels from waste, on the understanding that aviation would be given priority in the use of such fuels. The calculated volume of the emissions, along with the related levy, would be separately identified in the ticket purchasing process, both to motivate/educate the passenger and to enable comparative options, which might include surface travel and other travel and tourism components at some point in time. The emissions and payment would be filed by the air carrier with tax authorities (as already with, for example, the UK’s Air Passenger Duty) and the individual passenger would be given access to his or her portfolio. To further motivate passengers and reduce their costs, their own portfolio might perhaps in full or part be aggregated at financial year-end and credited against income taxes. Corporate or group purchases would be debited to the individual passenger with reimbursement by the purchaser a matter of internal arrangement.


The levy would apply to any flight booked in the home country, either those flights originating from that country or, to counter booking transfers to other country sources, connecting through it, including all air carriers used and connections made. It would cover scheduled, non-scheduled and business aircraft flights.


For purely domestic flights without a connection to an international journey, to avoid discrimination all passengers would be subject to the levy but only nationals and tax residents would have a centralised file and benefit from any tax break.


While some might consider discriminatory an effect whereby neighbouring passengers on an international flight may be subject to a levy or not depending on their nationality or place of residence, there are numerous other precedents for such differentiation in taxation and trade. Given today’s fare-setting algorithms, neighbouring passengers may well in any event have paid significantly different prices for their tickets as a result of application of a variety of criteria.


As with current fares, there may be ‘leakage’ loopholes that could be exploited. For example, a passenger might travel to a neighbouring country to buy an onward ticket or have someone else in that country purchase the onward ticket for them. The situation applies today in Canada whereby some passengers travel across the nearby US border to take advantage of the more competitive low fares in that country, but it has not become a critical issue. The need to add a connection in the journey is a dissuader and the sum of separate fares for consecutive parts of a journey is generally more expensive than a through fare.


Another loophole could be purchasing outbound and return tickets separately at origin and destination respectively. But again, the price of two one-way tickets is generally significantly more expensive than a round trip and the levy may well be less than the difference in fares. In any event, even with current technology the traveller could be linked directly with his or her nationality and residence even when travel originates in another country.


There are of course privacy issues with such an approach, but airline industry and immigration/customs authorities are already moving towards simply swiping a passport or other ID together with taking a photograph, and ultimately solely to facial recognition. The ID is already frequently required in the booking process prior to check-in, for visa or other travel authorization purposes. Like it or not, ‘big brother’ is already playing a growing role in our lives, notably in the commercial shopping arena. The approach outlined here may seem complex but the technology and data are already at hand, and given that control would fall within the management and jurisdiction of an individual State, it is likely to be less complex than CORSIA.


While the above is clearly just a concept and relates only to passenger traffic and not to freight, hopefully it is one illustration of the kind of brainstorming and action that is required – and soon – on aviation emissions mitigation in the light of increasing and overarching global greenhouse gas emissions exigencies.



Chris Lyle is Chief Executive of Canadian-based Air Transport Economics, a Fellow of the Royal Aeronautical Society and a veteran of British Airways, the UN Economic Commission for Africa, ICAO and the UN World Tourism Organization. He has been actively involved in aviation emissions mitigation policy since before the adoption of the 1997 Kyoto Protocol. He can be reached at


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