Aviation sector plans to address its massive climate impact by offsetting part of its emissions growth. Producing a respectable offset is becoming more and more difficult in a world where we are rapidly approaching our pollution limits. Below are some of the pitfalls the sector will have to avoid if the scheme is to have any positive environmental impact.

After 20 years of postponing action on its soaring emissions, the International Civil Aviation Organization (ICAO) agreed in 2016 to establish an offsetting scheme, Carbon Offsetting and Reduction Scheme (CORSIA) to partly compensate for its emissions growth above 2020 levels. CORSIA will not reduce emissions but allows airlines to emit more as long as the emissions are offset through the purchase of carbon credits from various projects around the world.

There are numerous issues with this approach, starting with the fact that there is no room for offsetting in the “post-Paris” world: in order to even have a chance to meet the Paris Agreement climate goals, all sectors must reduce emissions instead of increasing them and asking others to reduce on their behalf.

Beyond this basic problem, past experiences show how unreliable offsetting can be as a climate tool, from problems related to accounting emissions and verifying the impact of projects to gross human rights violations in the project planning and implementation.

A European Commission study has found that 73% of the potential supply of credits from the UN Clean Development Mechanism (CDM) from 2013 to 2020 are unlikely to deliver “real, measurable and additional” emission reductions. Many of the projects have also been linked to human rights violations, such as the hydro-dam project Barro Blanco in Panama which, after years of pressure by environmental and human rights campaigners was withdrawn from the CDM in 2016.

On the other hand, methodologies used (what type of activities are allowed) can be equally problematic. Take for example the destruction of industrial gases HFC-23 and N2O, unwanted side products of industrial processes with high global warming potential which is considered as eligible and credit producing activity under the CDM. Research has shown that the initial, since revised, methodology used to calculate the baselines for these credits led to perverse incentives to increase pollution in order to be paid to reduce it later.

Programme does not an offset make

ICAO has best practice criteria that current voluntary offset programmes must meet, including that offsets delivered must be additional, quantified, monitored, reported and verified. On the basis of this criteria, ICAO is now developing the future rules for CORSIA.

This week, ICAO has invited offset providers, including the UN’s Clean Development Mechanism (CDM) and voluntary market programmes such as Verified Carbon Standard (VCS) and Gold Standard to a seminar to present their programmes to airlines and governments. While most of the current offset certifiers expect that their programs will be accepted under CORSIA, it is important to realise that no programme is immune to bad offsets, meaning projects that either do not reduce emissions, cause harm to the local communities, or both.

When assessing what offsets should be allowed in CORSIA, it is therefore crucial to be thorough. Suggesting that we just look at a whole program, knowing that in practice individual projects or – one level up – a whole methodology can be flawed, doesn’t make environmental sense.

Learning from the past and looking to the future

The aviation offsetting scheme is being built at a breakneck pace, but there are very real, and complex, difficulties that this measure has to defy. It must be compatible with the Paris Agreement, it must be transparent to show if it’s meeting its objectives, and it should learn from the history of offsetting. Failing this, it will repeat mistakes of the past.

As CORSIA will fall short of even the sector’s own goal of carbon neutral growth from 2020, its ambition will need to be ratcheted up. The revision in 2023 will offer an opportunity to address any challenges that could not be surmounted. Considering the growing complexities related to setting up a robust global offsetting measure, increasing ambition may involve a fundamental rethink of what a market-based measure with environmental integrity looks like. It almost makes an international aviation charge look palatable.