Net Zero:
What Progress?
May/Jun 2025
Figures from Berkeley Earth suggest that 2024 was the warmest year on record. The California-based research establishment estimates that global mean surface temperatures last year were 1.62°C above pre-industrial levels. This followed on from a warm 2023, the only other year to have registered temperatures higher than 1.5°C above the 1850-1900 baseline.
A strong El Niño in the South Pacific, which lasted from mid 2023 to mid 2024 is likely to have had a major impact — the two year aberration from trend similar to that seen in the 1870s, a period with a similar super El Niño.
It is also possible, the researchers suggest, that the January 2022 Hunga Tonga eruption was a major contributor to unusual weather in 2023 and 2024. Unlike most volcanoes, the eruption of Hunga Tonga was rich in water vapour and low in sulfur. Usually, a large volcanic eruption can result in a period of cooling because sulfur dioxide particles in the atmosphere reflect sunlight away from the planet, but the Hunga Tonga eruption may have contributed warming instead because of the greenhouse effect caused by its injection of 150m tonnes of water vapour into the stratosphere.
ANTHROPOGENIC CO₂ EMISSIONS 1860-2024
They note that the warming spike observed in 2023 and 2024 has been extreme and represents a larger than expected deviation from the previous warming trend. Over the past 50 years, they point out, global warming has proceeded in an almost linear fashion, consistent with an almost linear increase in total CO₂ emissions. Berkeley Earth further warns that the 2023/24 performance suggests that the past warming rate is no longer a reliable predictor of the future, and perhaps additional factors have created conditions for faster warming in the short-term. At least, with the onset of a mild cooling El Niña at the beginning of this year, the hope is that 2025 may not be as bad.
Separately, the World Meteorological Organization (WMO) issued its Global Annual to Decadal Climate Update in May. It also points to record temperatures in 2024, although a little lower at only 1.55°C above the 1850-1900 baseline. It projects that it is likely that one of the next five years will break the 2024 record, and suggests that there is a 70% chance that the 2025-2029 five-year average will exceed 1.5°C above pre-industrial levels.
This level of temperature increase on a sustained basis is seen a trigger for certain irreversible climate tipping points and is a key tenet of the Paris Agreement, signed at the 2015 United Nations Climate Change Conference (COP21).
As a reminder, the agreement lists a series of commitments:
- To “pursue efforts” to limit global temperature rises to 1.5°C, and to keep them “well below” 2.0°C above those recorded in pre-industrial times;
- To achieve a balance — net zero — between the greenhouse gases that humans put into the atmosphere and the gases that they actively remove, in the second half of this century;
- Each country to set its own emission-reduction targets, reviewed every five years to raise ambitions;
- Richer countries to help poorer nations by providing funding — climate finance — to adapt to climate change and switch to renewable energy.
The +1.5°C aspirational limit is seen as covering a multi-decade average; that the past two years have exceeded it does not necessarily mean that the target has been broached. However, if the linear trend since the start of the century continues, the ten year average temperature anomoly could well hit it by 2034.
Aviation — Net Zero relies on SAF
Aviation is estimated to account for 2.5% of anthropogenic CO₂ output from fossil fuels — roughly a gigatonne of CO₂ expected for 2025 from burning 100bn gallons of jet fuel.
The vast majority of fuel is used on medium and long-haul flights for which there is not (yet) a viable alternative to a fuel with the same hydrochemical chemical formula as fossil sourced jet fuel.
Air traffic will continue to grow, albeit at a lower rate than historically. IATA is suggesting a global annual increase in the number of passengers of around 3.5% over the next 25 years. The 5bn passengers expected in 2025 could double to over 10bn by 2050, and carbon emissions reach 2Gt CO₂ a year.
So, the only solution for the industry to achieve “net zero” is to find a fuel manufactured from sources of carbon (and hydrogen) that have absorbed carbon from the atmosphere: the hope being to create a closed loop — Sustainable Aviation Fuels (SAF).
(For descriptions of the processes to produce SAF see Aviation Strategy Jan/Feb 2024).
The industry’s “pathway” to net zero is partly based on an expected improvement in fuel efficiency from new generation aircraft, a modest improvement in infrastructure and operations (such as air traffic control and airway management), the imposition of carbon offset controls (such as CORSIA and the European ETS) — but 65% of the CO₂ “saved” will need to come from sustainable aviation fuels.
SAF production reached 1m tonnes in 2024 — double that in 2023 but still less than 0.3% of industry fuel requirement. It is expected to double again in the current year to over 2m tonnes. But production is building rapidly.
In the US, the Energy Information Administration (EIA) reports that current SAF capacity stands at 30,000 barrels a day up from 2,000 in early 2024; this in large part is a result of the federal tax incentives and SAF volume mandates from the US Environment Protection Agency (EPA) under its Renewable Fuel Standards Program (RFS). The EIA expects SAF will account for around 2% of the USA’s jet fuel consumption of 1.7m b/d by 2026.
Europe, instead of offering incentives, has imposed mandates on the fuel suppliers. The EU’s ReFuelEU programme came into effect at the beginning of this year and specifies that 2% of the fuel supplied to airports in 2025 must be SAF, that proportion rising to 70% by 2025. It has also introduced anti-tankering rules on all airlines operating to EU airports by requiring airlines to uplift a minimum percentage of their fuel needs at EU airports.
TO NET ZERO
‡ Efficiency=improvements above "business as usual"
According to FuelsEurope (a lobbying group for the fuel refiners and distributors) the current EU capacity of HEFA (the most common bio-SAF) is about 1.5m tonnes a year — more than enough to cover the ReFuelEU 2% mandate for 2025 — and there are firm plans to add refining capacity of an additional 2.4m tonnes/year by 2029.
SAF remains expensive to produce, but FuelsEurope notes that the average SAF premium over conventional jet fuels has fallen from a ratio of over four times to below two in the matter of three years.
IATA is not particularly happy with the position in Europe: it would prefer a few carrots rather the the sticks of imposed regulation.
At the industry body’s AGM in June, Director General Willie Walsh complained that, in Europe, most fuel suppliers have preferred to pass on their cost of complying with the legislation by charging a “compliance fee” to each tonne of fossil jet fuel purchased — and that these fees average twice the premium to conventional jet fuel than suggested by current SAF prices. This pricing behaviour, he suggested, works against the development of a global, liquid, and transparent SAF market as suppliers avoid contracting for the supply of mandated SAF with airlines. In typically blunt fashion he said: “That’s a billion-dollar windfall for fuel suppliers. This is the EU great green scam.”
Climate Finance
IATA had more to complain about at the end of June.
The Global Solidarity Levies Task Force (GSLTF) put out a proposal for a global progressive tax on frequent and premium class air passengers.
The GSLTF is co-led by France, Kenya and Barbados (and in this proposal joined by Spain). It states that it is responsible for designing proposals for solidarity levies on undertaxed sectors that contribute disproportionately more to global carbon emissions, are undertaxed and/or benefit extensively from globalisation. These solidarity levies, it says, can help generate finance for climate and development action. The task force was formed following the 2023 Nairobi Climate Declaration (in the lead up to COP28). By COP30 later in 2025 it aims to “enable governments to bring together a coalition of the willing ready to implement one or more of these levies”.
The group has cited a report from CE Delft that examines the relative merits of imposing levies (taxes) on:
- jet fuel for commercial aviation;
- modular ticket levy (priced by length of haul);
- frequent flyer levy (exponentially priced by annual frequency of flight);
- private jet fuel levy (no brainer!).
The report concludes that a tax on jet fuel “performs best in terms of mobilizing climate finance and promoting climate justice,achieving high CO₂ emission reductions (10% reduction through both demand and supply-side effects), strong revenue potential (€84bn), and limited distributive impacts, though its legal implementation is more complex and challenging. A ticket levy performs slightly less effectively, achieving a 6% reduction in CO₂ emission through demand-side effects and generating €62bn in revenue. However, its legal implementation is more straightforward. The private jet fuel levy, while targeting only 2% of global aviation emissions and generating modest revenues (€6bn), scores well on climate justice and faces fewer legal obstacles compared to a fuel levy on commercial flights”.
Part of the aim of the proposal would be to redistribute the tax raised to countries (particularly those dependent on tourism) which will be hard hit by climate change.
But as IATA points out yet again, the airline industry is a highly competitive and low margin business, and the €84bn potential tax grab equates to three times the forecast net profits for the industry in 2025.
