Pressure for aviation to have to include its non-CO2 climate impacts of its emissions
The lack of scientific clarity on the impact of its non-CO2 effects is a risk for commercial aviation, as it starts to take steps to address the problem of its carbon emissions and their climate impact. There is an aspirational target by the ICAO for the commercial air travel sector to reach “net-zero CO2 emissions by 2050”. The exact meaning of net-zero is never clear, or how genuinely the emissions will be removed. But that ignores the other problem aviation has, which is the non-CO2 impacts of its emissions at high altitude. These are various gases, including nitrogen oxides (NOx) and also contrails. Studies indicate that these may double, or even triple, the climate warming impact of the plane’s CO2 alone. The science is complicated, and the impacts are different at different times of day, in different weather conditions, in different places, and different durations of effects. However, it is convenient for the industry to continue hiding behind claims that the science is uncertain, as the reality would be a real handicap for their future plans. Tim Johnson, of the Aviation Environment Federation (AEF) said though ICAO has refused to address non-CO2 impacts yet, this will become imperative between now and 2050 (at the very latest).
Lack of clarity on aviation’s non-CO2 effects ‘creates risk’ in net-zero push
By Lewis Harper (Flight Global)
20 October 2022
The lack of scientific clarity on the impact of non-CO2 effects is a risk for commercial aviation as it seeks to address its environmental footprint, according to speakers at the Aviation Carbon 2022 conference in London on 17 October.
Citing the now widely adopted target for commercial aviation to reach net-zero CO2 emissions by 2050 – which was rubber-stamped at a governmental level during the recent ICAO assembly via agreement on a long-term aspirational goal (LTAG) – speakers cautioned that factors such as nitrogen oxides (NOx) and contrails might eventually draw more focus, should scientists suggest with confidence that they have a significant warming impact.
“When we look at these [net-zero] roadmaps we’re mostly focusing on the CO2 effect and largely leaving out the non-CO2 effects,” says Siyi Hao, a sustainable aviation specialist at consultancy Roland Berger.
He describes this as a “potential risk for our planning”, despite there being good reason for the lack of commitment on the issue so far, given that “we don’t really have a perfect scientific understanding of it”. That is because achieving better scientific understanding might heighten the sustainability hurdles for aviation.
“We speak to the leading academics in the world, and our understanding so far is that when we take into consideration all the non-CO2 effects and look at the global warming potential of aviation… it could get as high as three times CO2 alone,” Hao suggests.
Tim Johnson, director of UK-based NGO the Aviation Environment Federation, reminded delegates at the conference that the Paris Agreement created a goal around limiting the rise in global temperatures – of which CO2 emissions are just one contributing factor when it comes to aviation.
Johnson says that during the recent ICAO assembly, his federation was sufficiently concerned to argue, unsuccessfully, that the UN body should launch a process aimed at assessing non-CO2 effects ahead of its next gathering.
“We didn’t necessarily want [the LTAG] to recognise non-CO2, but it is really clear that Paris is a temperature-based goal and that non-CO2 impacts from aviation have temperature implications,” Johnson says.
“Between now and 2050, we have to figure that out.”
Regarding specific factors, Hao notes that NOx has a “significantly higher global warming potential compared to CO2”, but that it does not linger in the air for as long.
He further describes contrails as a “very strange animal” that can have a warming or cooling effect depending on a number of factors.
Ultimately, “the science is still far from perfect” on non-CO2 effects, Hao says.
Indeed, among the challenges in countering non-CO2 effects from aviation, studies have pointed out that doing so often involves increased fuel usage – and therefore higher CO2 emissions.
Some studies suggest that the use of sustainable aviation fuels could reduce NOx emissions versus conventional jet fuel, but that transformational reductions in non-CO2 effects are most likely to be achieved with electric propulsion or the use of hydrogen fuel cells.
Aircraft engines that burn conventional jet fuel are known to emit CO2, NOx, water vapour, hydrocarbons, carbon monoxide, sulphur gases, and soot and metal particles.
Voluntary Carbon Markets and Offsetting
From the Climate Change Committee
This report looks at the evidence on the risks and opportunities presented by voluntary carbon markets and ‘offsetting’ to progress to Net Zero in the UK and beyond. Voluntary carbon markets are markets where carbon credits are purchased, usually by organisations, for voluntary use rather than to comply with legally binding emissions reduction obligations. Voluntary carbon markets are growing, driven in part by demand from businesses looking to ‘offset’ their emissions.
2. Key messages
High-integrity carbon credits purchased by businesses can play a small but important role in supporting the transition to Net Zero. But before growing voluntary carbon markets, Government must put in place stronger guidance, regulation and standards to ensure purchase of carbon credits is not used as a substitute for direct business emissions reduction, and to improve the integrity and transparency of carbon credits. In the absence of these measures, there is a real risk that voluntary carbon markets slow progress towards Net Zero or damage other priorities such as climate adaptation and biodiversity.
We make three broad recommendations:
1. Encourage businesses to support high integrity nature-based and biological solutions and engineered removals, while focussing on achieving direct business emissions reduction.
2. Continue efforts to protect and raise the integrity of carbon credit projects, in the UK and globally, and to ensure voluntary carbon markets are resulting in lower overall global emissions and positive wider impacts.
3. Support the modest but useful role voluntary carbon markets can play in the UK Net Zero pathway, in tandem with other measures.
3. Supporting information, charts and data
Voluntary Carbon Markets and Offsetting – Charts and data (XLSX • 305KB)
Climate Change Committee recommendations to government on voluntary carbon markets and offsetting
The Climate Change Committee (CCC) has a new report, called “Voluntary Carbon Markets and Offsetting”. It looks at the evidence on the risks and opportunities presented by voluntary carbon markets and ‘offsetting’, in relation to progress to “Net Zero” in the UK and beyond. The role of voluntary carbon markets can only be limited. The CCC says that before growing voluntary carbon markets, Government must put in place stronger guidance, regulation and standards to ensure purchase of carbon credits is not used as a substitute for vital direct business emissions reduction – also to improve the integrity and transparency of carbon credits. In the absence of these measures, there is a real risk that voluntary carbon markets slow progress towards Net Zero or damage other priorities such as climate adaptation and biodiversity. The CCC recommends that business should use measures with high integrity, but focus on actually cutting their direct emissions. Voluntary carbon markets should result in lower overall CO2 emissions. They say carbon credit standards should better consider biodiversity and other ecosystem services, especially in biodiversity priority areas. Climate and nature should both be protected together.