Today, we’ve sent a critical letter to the Science Based Target initiative (SBTi). SBTi aims to help companies to set science-based emission reduction targets in line with the latest climate science. Businesses around the globe use the work of SBTi to officially validate their climate targets, and communicate those to the outside world, to politicians and consumers.

However, we are deeply concerned about SBTi’s latest work on aviation. In February 2023, they released a new technical report for an interim pathway for aviation, based on a 1.5 target. Airlines use such pathways created by SBTi to set their emission reduction targets. But instead of a pathway truly based on science, we believe it is a flawed scenario that helps the aviation industry to sustain its growth path while blowing up the carbon budget. The letter is signed by 28 organisations including Transport & Environment, Greenpeace, Stay Grounded and other organisations from all over the world that work on reducing aviation’s impact on the climate.

These are our main concerns with the SBTi’s aviation pathway:

  • It tells the industry that it only needs to start with steep emission reduction after 2030. But by that time, we will have run out of carbon budget, so it makes reaching the target of 1.5 degrees highly implausible.
  • It does not take the non-CO2 effects of aviation into account.
  • It allows the aviation industry to take a bigger part of the carbon budget than it has today. This is not a science based decision, but a political one. 
  • It is based on relative emission targets, instead of absolute ones. While it is important that planes become more energy efficient, if the number of flights increases at the same time, emissions can still rise. We therefore need absolute emission reduction targets.  
  • It does not differentiate between emerging economies and early industrialised economies, while the latter have already used up the largest part of the carbon budget.
  • Lastly, SBTi only looks at targets. Because of this, an airline that lobbies against climate measures that are necessary to reach the target 1.5 degrees maximum, can still be SBTi-certified.

With this pathway, the SBTi does not “drive ambitious climate action in the private sector”, but facilitates greenwashing and unambitious target setting, and in doing so, hampers real climate action.

We urge SBTi to revoke the interim technical report for the 1.5°C Sector Pathway for Aviation and to develop pathways for aviation that are truly science based and aligned with what is needed to reach 1.5C.



Read the full letter here:


Dear Mr Amaral,

In February 2023, SBTI released a new technical report for an interim pathway for aviation, based on a 1.5 target. With this letter, we – NGOs working to reduce aviation’s impact on the climate – want to express our great concern with this pathway. Instead of a science based pathway, we believe it is a flawed scientific scenario that helps the aviation industry to sustain its growth path while blowing up the carbon budget.

The new scenario is flawed

The new pathway is based on a combination of the IEA Net Zero Roadmap and the ‘Breakthrough’ scenario from the International Council of Clean Transportation’s Aviation Vision 2050 report. According to ICCT, Breakthrough is consistent with a 1.75°C, not a 1.5 °C future. They note: “For a 1.5°C pathway to be maintained without increasing aviation’s share of a global carbon budget, an additional 50% reduction in cumulative emissions (11 Gt of CO2) […] would be required. This is equivalent to achieving net-zero emissions by 2030 — two decades sooner than planned in existing net-zero commitments.”

SBTi used this ICCT scenario as a basis for their 1.5 pathway, on the assumption that airlines should be allowed to almost double their share of a global carbon budget. It is striking that the 1.5 scenario for the coming decade is the same as the below 2 degrees scenario. This new SBTI 1.5 aviation scenario effectively permits ‘moderate’ aviation growth until 2030-2035. To accommodate this continued growth, the pathway takes the high-risk approach of delaying steep aviation emissions reductions until after 2030. This blows up the carbon budget, and makes reaching the target of 1.5 degrees highly implausible.

This obviously goes against the need for rapid emissions reductions, which are necessary to avoid near-term catastrophic climate tipping points. This approach is not aligned with what the IPCC says is necessary: “Without immediate and deep emissions reductions across all sectors, limiting global warming to 1.5°C is beyond reach”. It adds: “Doing less in one sector needs to be compensated by further reductions in other sectors if warming is to be limited. (high confidence).

To allow for the growth of aviation, the SBTi pathway relies on highly unrealistic assumptions about the scale up of biofuels, e-fuels and hydrogen. It also relies on the hope that hydrogen planes will enter into service in 2035. According to the scenarios upon which this SBTi scenario is based, it is assumed that biofuels will account for 17%-18% of aviation fuels. Next to the many negative consequences arising from production of biofuels this stands in striking contrast with the 0,05% that was achieved in 2020, after more than a decade of missed biofuel targets. The EU only targets 6% for 2030, which means it is almost certain that 17-18% will not be achieved. ICCT estimates that there is a sufficient resource base of 5.5% of projected EU jet fuel in 2030. Furthermore, if biofuels or the energy needed for e-fuels is diverted from more efficient uses in other sectors, it could actually lead to an increase in emissions. This is not an unrealistic possibility, as the amount of energy needed to fuel aeroplanes is huge: “the estimated electricity used to generate aviation fuels rises from zero in 2020 to 25EJ in 2050, almost equaling global production of hydro, wind, solar, and geothermal power in 2019”.

According to ICCT, to realise this unprecedented growth of fuel substitutes, “early, aggressive, and sustained government interventions” are necessary – such as a fuel tax. Nonetheless, the SBTi does not check whether companies that aim to be validated lobby against these government policies. Hence, the scenario places the responsibility for reaching the targets for a large part beyond the scope of the companies, while airlines that receive validation are even allowed to lobby against the government interventions that are necessary. To make it even worse, whilst this scenario will require steep emissions reductions from 2032, it has no mechanism for ‘binding’ companies to these steeper emissions reductions at that moment. Hence companies are able to greenwash themselves in these critical years to come with the use of this pathway, and leave the accreditation process in 2032 or lobby then for an adjusted pathway.

The new SBTi scenario can and will be used by the industry to defend its growth path. For airlines in early industrialised economies that have lower growth possibilities than airlines in emerging economies, targets for the period until 2030 will be easily met as there is no steep reduction in emissions required. The pathway does not differentiate between country emission pathways that require faster action for early industrialised economies like the Netherlands. This is necessary for reasons of equity and climate justice – which is an essential component of the Paris Agreement – and to include historical responsibility. This pathway will allow airlines in mature economies to even grow absolute emissions in the coming years – which is not a fair distribution.

SBTi’s scenarios should also be based upon absolute emissions

SBTI’s pathways for aviation are based upon emissions intensity, whereas it is absolute emissions that heat the climate. It allows for airlines and airports to focus on relative efficiency, while they could still be increasing their absolute emissions as a result of growth. This is a dangerous distraction, and not aligned with the need for rapid absolute emissions reductions.

The scenario contravenes demand management

By accepting the growth path of the industry, it contravenes necessary demand-side changes. According to the IPCC: The indicative potential of demand-side strategies across all sectors to reduce emissions is 40-70% by 2050 (high confidence).

According to IPCC, demand management is necessary in aviation: “there has been a growing awareness of the need for demand management solutions combined with new technologies […] (high confidence). There is a growing need for systemic infrastructure changes that enable behavioural modifications and reductions in demand for transport services that can in turn reduce energy demand.”

“[m]itigation strategies can be classified as Avoid-Shift-Improve (ASI) options, that reflect opportunities for socio-cultural, infrastructural, and technological change. The greatest Avoid potential comes from reducing long-haul aviation…”. Specifically, “[s]ocio-cultural factors such as avoid[ing] long-haul flights and shifting to train wherever possible can contribute between 10% and 40% to aviation GHG emissions reduction by 2050”.

However, the unrealistic SBTi pathway will enable the industry to lobby against such necessary demand-side strategies, since it allows for growth.

The pathway excludes the non-CO2 impacts of aviation

The pathway excludes the non-CO2 impacts of aviation, whereas the total climate impact of aviation is about three times greater than the impact of CO2 alone. Measures to reduce CO2 emissions do not necessarily translate into the same level of reductions of non-CO2 impacts. This means that aviation’s (overall) climate impact would take a different trajectory than shown in the SBTi interim pathway.

SBTi does not measure quality of plans

As SBTi does not measure the quality of the plans that have been made, nor checks whether those plans are realistic to deliver targets, it is possible for airlines and airports to set unrealistic targets that are not backed up by appropriate plans, and still use the SBTi’s accreditation in their marketing. To give an example: Heathrow Airport is planning to build a third runway which would generate an additional 9 million tonnes of emissions each year. Nevertheless, it still secured accreditation from SBTi. It is also striking that Dutch airline KLM has not actually developed the plans yet to reach their reduction target, yet still received its SBTi validation for the ‘well below 2 degrees’ scenario, and uses the SBTi scenario as a defence in a current greenwashing court case that is brought forward by Fossielvrij NL – one of the signatories of this letter. As the 1.5 scenario is built upon unrealistic technological developments, and “early and sustained government intervention triggers”, it allows even more for unsubstantiated and unrealistic plan making.


We believe this pathway does not meet SBTi’s own criteria for scenarios approved for science-based target setting: it is not plausible, consistent nor responsible. It appears to be constructed based on political assessments on what is feasible for the aviation industry, rather than being based on what is necessary to reach 1.5. It allows for airlines and airports to expand, for investors and banks to finance expansion and policy makers to allow for expansion – on the basis of an unrealistic, unscientific and inequitable scenario. With this pathway, the SBTi does not “drive ambitious climate action in the private sector”, but facilitates greenwashing and unambitious target setting, and in doing so, hampers real climate action.

We urge you to revoke the interim technical report for the 1.5°C Sector Pathway for Aviation and to develop pathways for aviation that are truly science based and aligned with what is needed to reach 1.5C.

Kind regards,

Hiske Arts
Fossielvrij NL

Supported by

Reclame Fossielvrij
Stay Grounded
Transport and Environment
Natuur en Milieu
Milieudefensie | Friends of the Earth Netherlands
Ecologistas en Acción
Safe Landing
CBalance (Fair Travel)
Flight Free UK
No Airport Expansion!
Bristol Airport Action Network (BAAN)
Group for Action on Leeds Bradford Airport UK
Centre for Citizens Conserving Environment & Management (CECIC)
AbibiNsroma Foundation
350 Seattle
Alofa Tuvalu
Attac France
Flight Free Australia
Pensons l’Aéronautique pour Demain (PAD)
South-West Essex Fight the Flights
GACC (Gatwick Area Conservation Campaign)
International Climate Safe Travel Institute
De Reclamejagers / The Add Hunters