Climate Change Committee – recommendations to government – lots on aviation carbon changes and policies needed

Climate Change Committee has published its guidance for the UK government on its Sixth Carbon Budget, for the period 2033 – 37, and how to reach net-zero by 2050.  There is a great deal of detail, many documents, many recommendations – with plenty on aviation. The intention is for UK aviation to be net-zero by 2050, though the CCC note there are not yet proper aviation policies by the UK government to achieve this. International aviation must be included in the Sixth Carbon budget. If the overall aviation CO2 emissions can be reduced enough, it might be possible to have 25% more air passengers in 2050 than in 2018. The amount of low-carbon fuels has been increased from the CCC’s earlier maximum realistic estimates of 5-10%, up to perhaps 25% by 2050, with “just over two-thirds of this coming from biofuels and the remainder from carbon-neutral synthetic jet fuel …” Residual CO2 emissions will need to be removed from the air, and international carbon offsets are not permitted. There is an assumption of 1.4% efficiency improvement per year, or at the most 2.1%. There “should be no net expansion of UK airport capacity unless the sector is on track to sufficiently outperform its net emissions trajectory.”  The role of non-CO2 is recognised, but not included in carbon budgets; its heating effect must not increase after 2050.  And lots more …


You can watch the CCC presentation – on Youtubehere

The main full report

The Sixth Carbon Budget – the road to UK’s Net Zero


The Sixth Carbon Budget – Methodology reporting


Policies for the Sixth Carbon Budget and Net Zero


There are many sector summaries;  The Aviation sector summary is

The Sixth Carbon Budget Aviation

The CCC’s Key Recommendations

Our recommended pathway requires a 78% reduction in UK territorial emissions between 1990 and 2035. In effect, bringing forward the UK’s previous 80% target by nearly 15 years.

The Sixth Carbon Budget can be met through four key steps:

1. Take up of low-carbon solutions. People and businesses will choose to adopt low-carbon solutions, as high carbon options are progressively phased out. By the early 2030s all new cars and vans and all boiler replacements in homes and other buildings are low-carbon – largely electric. By 2040 all new trucks are low-carbon. UK industry shifts to using renewable electricity or hydrogen instead of fossil fuels, or captures its carbon emissions, storing them safely under the sea.

2. Expansion of low-carbon energy supplies. UK electricity production is zero carbon by 2035. Offshore wind becomes the backbone of the whole UK energy system, growing from the Prime Minister’s promised 40GW in 2030 to 100GW or more by 2050. New uses for this clean electricity are found in transport, heating and industry, pushing up electricity demand by a half over the next 15 years, and doubling or even trebling demand by 2050. Low-carbon hydrogen scales-up to be almost as large, in 2050, as electricity production is today. Hydrogen is used as a shipping and transport fuel and in industry, and potentially in some buildings, as a replacement for natural gas for heating.

3. Reducing demand for carbon-intensive activities. The UK wastes fewer resources and reduces its reliance on high-carbon goods. Buildings lose less energy through a national programme to improve insulation across the UK. Diets change, reducing our consumption of high-carbon meat and dairy products by 20% by 2030, with further reductions in later years. There are fewer car miles travelled and demand for flights grows more slowly. These changes bring striking positive benefits for health and well-being.

4. Land and greenhouse gas removals. There is a transformation in agriculture and the use of farmland while maintaining the same levels of food per head produced today. By 2035, 460,000 hectares of new mixed woodland are planted to remove CO2 and deliver wider environmental benefits. 260,000 hectares of farmland shifts to producing energy crops. Woodland rises from 13% of UK land today to 15% by 2035 and 18% by 2050. Peatlands are widely restored and managed sustainably.


The CCC has 4 alternative pathways for the future. These are:

Balanced New Zero Pathway  – their main one
also (depending on more or less innovation, and more or less behaviour change):
– Headwinds
– Tailwinds
– Widespread engagement
– Widespread innovation

Possible future numbers of air passengers (they see 25% more than in 2018 as possible)

Number was about 292 million in 2018.
The CCC see number of Airport terminal passengers by 2050 (assuming net zero carbon emissions, by the various pathways – technology or less demand) as:
365m in   Balanced Net Zero Pathway
365m in   Headwinds
245m in   Widespread Engagement
438m in   Widespread Innovation
245m in   Tailwinds

Some of the content on aviation and recommendations:

From the full report:
Aviation section  P 176 – 181
Non-CO2 impacts   P 372 – 375
Including aviation in the Sixth Carbon Budget   P 418 – 423
Lots of recommendations dotted around from about P 420 onwards. Summary of recommendations from P442.

Some of the recommendations are:   

We advise that IAS emissions should be included in the Sixth Carbon Budget.
The Committee recommends a Sixth Carbon Budget of 965 MtCO2e, including emissions from the UK’s share of international aviation and shipping (IAS).
We therefore conclude that IAS emissions should be included in carbon budgets as early as possible (see section 3), and certainly formally within the scope of the Sixth Carbon Budget and 2050 target. Alongside this, the UK should push for suitably strong international targets and mechanisms to deliver reductions in IAS emissions.
The Committee therefore do not currently recommend inclusion of non-CO2 effects of aviation or shipping within the budgets.
We recommend that engineered CO2 removal is allowed to contribute to meeting UK carbon targets under the Climate Change Act.
Our recommendation is that the Government should not expect or plan to use international credits to meet the Sixth Carbon Budget – the recommended budget should be considered a minimum UK contribution through domestic action.
Any use of international credits (whether purchased by the Government or UK companies) should be additional to the domestic effort of the Sixth Carbon Budget, to support the global effort to reduce emissions.
For now, the Committee’s recommendation on credits within CORSIA is the same as for other credits – they should not be used to meet UK carbon budgets
We recommend that the UK NDC is set to require at least a 68% reduction in emissions from 1990 to 2030 on a basis that excludes emissions from international aviation and international shipping, in line with UN convention. A clear commitment should also be made to tackle IAS emissions:
We therefore recommend that, as a rule, outperformance of carbon budgets is not carried forward to subsequent periods.
Following this advice, the Government must set the Sixth Carbon Budget in law by the end of June 2021. This must be followed, as soon as is practicable, by a set of policies and proposals to meet the budget. We recommend that both these steps are taken without delay, in the first half of 2021.

Recommendations on inclusion of international aviation in the Sixth Carbon Budget (2033 – 37)

They say IAS should be included in the Sixth Carbon Budget and P149  link  :
“Inclusion of IAS is manageable. While the United Nations Framework Convention on Climate Change (UNFCCC) treats emissions from international aviation and international shipping separately from emissions solely within country borders, allocating these emissions to countries presents no fundamentally greater challenges than for other sectors already included in UK emissions targets:
– Emissions are already estimated and reported to the UN and can be included in UK emissions targets on the same basis. The uncertainty attached to estimates of IAS emissions is no higher than for other sectors covered by carbon budgets (Box 10.1).
– While careful policy design is necessary to avoid simply pushing emissions abroad, such considerations also apply to sectors already covered by carbon budgets (e.g. manufacturing and agriculture).
– Inclusion in the UK carbon budgets does not preclude exclusion in communications to the UN, as we recommend for the UK’s 2030 NDC.


On demand management they say:

P 178
“Demand management.
The Balanced Net Zero Pathway does allow for some limited growth in aviation demand over the period to 2050, but considerably less than a ‘business as usual’ baseline. We allow for a 25% in growth by 2050 compared to 2018 levels, whereas the baseline reflects unconstrained growth of around 65% over the same period. We assume that, unlike in the baseline, this occurs without any net increase in UK airport capacity, so that any expansion is balanced by reductions in capacity elsewhere in the UK.”
The “Widespread Innovation” pathway has a greater contribution from technological performance, both in terms of improved efficiency (2.1% per annum) and the contribution of sustainable aviation fuels. By 2050, around a quarter of fuel use is biofuel, with a further quarter carbon-neutral synthetic jet fuel. These technical improvements lead to a lower carbon-intensity and lower cost of aviation, although demand in this scenario is considerably higher, reaching 50% above 2018 levels by 2050 (in line with the Climate Assembly UK’s ‘technological change’ scenario). Emissions in 2050 are 15 MtCO2e, 63% below 2018 levels.
One of the report’s authors, Piers Forster, on demand management:  CCC recommend demand measures such as carbon pricing, fuel levy or VAT. We also say non-CO2 warming should be capped at least at 2050 levels for better. And no net airport expansion without outperformance. And a frequent flier tax – probably the best option and supported by Climate Assembly.

On “sustainable aviation fuels” they say:

[The CCC has previously said 5% or at the most 10% SAF by 2050].
P 176  “Sustainable aviation fuels (SAF) contribute 25% of liquid fuel consumed in 2050, with just over two-thirds of this coming from biofuels* and the remainder from carbon-neutral synthetic jet fuel (produced via direct air capture of CO2 combined with low-carbon hydrogen, with 75% of this synthetic jet fuel assumed to be made in the UK and the rest imported).”
“Biojet. Solid biomass feedstocks are gasified then converted into aviation biofuel, with CCS. Starting from the mid-2020s, this route ramps-up to meet 11% of aviation fuel demand by 2050. In addition, waste fats/oils are converted into biojet, with a transition from biodiesel in the 2030s, with their use alongside limited biojet imports ultimately meeting 6% of aviation demand by 2050.”


One reason for the higher use of biofuels suggested in this report is that electrification of road vehicles has advanced even faster than anticipated. So there is less need to reserve liquid fuels for them, and a higher proportion of biofuels could be used for the aviation sector (not much more biofuel produced overall).

There are also impacts on biodiversity and water quality which have not been possible to quantify. These are detailed in the Methodology Report.

On the non-CO2 impacts of aviation

The CCC separates aviation CO2 and non-CO2 impacts. The latter cause important short term warming. This has previously been ignored by governments. It now has to be taken into account. The aim is no extra non-CO2 heating from aviation by 2050.

On P 374 of

“For consistency with the Net Zero target, under which UK GHG emissions are
reduced to Net Zero to stop contributing to further increases in global temperature
by 2050, UK aviation non-CO2 effects should also target stopping contributing to
further increases in global temperature by this same date. Without the
development of mitigation options for these non-CO2 effects, this would require
year-on-year demand growth to be reduced to essentially zero by or before 2050.”

But because of uncertainties they say

“The Committee therefore do not currently recommend inclusion of non-CO2 effects of aviation or shipping within the budgets.”

On failings in government policy on aviation the CCC say;

P 1667  of

“Although the UK aviation industry has committed to a Net Zero goal for 2050 this is not yet a policy goal for Government. Higher-level strategic gaps include the lack of formal inclusion of international emissions in UK carbon budgets & the Net Zero target, and the need for a sector emissions trajectory to inform demand management and airport capacity policies. Further research is also needed on non-CO2 effects and potential mitigation options.”


The policy recommendations for aviation

P 29 of  are:

  • Formally include International Aviation emissions within UK climate targets when setting the Sixth Carbon Budget.
  • Work with ICAO to set a long-term goal for aviation consistent with the Paris Agreement, strengthen the CORSIA scheme and align CORSIA to this long-term goal.
  • Commit to a Net Zero goal for UK aviation as part of the forthcoming Aviation Decarbonisation Strategy, with UK international aviation reaching Net Zero emissions by 2050 at the latest, and domestic aviation potentially earlier. Plan for residual emissions, after efficiency, low -carbon fuels and demand-side measures, to be offset by verifiable greenhouse gas removals, on a sector net emissions trajectory to Net Zero.
  • There should be no net expansion of UK airport capacity unless the sector is on track to sufficiently outperform its net emissions trajectory and can accommodate the additional demand.
  • Monitor non-CO2 effects of aviation, set a minimum goal of no further warming after 2050, research mitigation options, and consider how best to tackle non-CO2 effects alongside UK climate targets without increasing CO2 emissions.
  • Longer-term, support for sustainable aviation fuel (SAF) should transition to a more bespoke policy, such as a blending mandate. However, near-term construction of commercial SAF facilities in the UK still needs to be supported.
  • Continue innovation and demonstration support for SAF technologies, aircraft efficiency measures, hybrid, full electric and hydrogen aircraft development and airspace modernisation.

The CCC’s comments on annual expected efficiency improvement:

Efficiency improvements. [in their Balanced Net Zero Pathway]. “The fuel efficiency per passenger of aviation is assumed to improve at 1.4% per annum, compared to 0.7% per annum in the baseline. This includes 9% of total aircraft distance in 2050 being flown by hybrid electric aircraft.”   link

Higher efficiencies are assumed in other scenarios, up to 2.1% per year.  P 179 of  link

CCC comments on airport expansion

CCC say UK should: “Commit to a Net Zero goal for UK aviation as part of the forthcoming Aviation Decarbonisation Strategy, [expected early in 2021?] with UK international aviation reaching Net Zero emissions by 2050 at the latest, and domestic aviation potentially earlier.”   P 33 of  link

The Government should assess its airport capacity strategy in the context of Net Zero and any lasting impacts on demand from COVID-19. Investments will need to be demonstrated to make economic sense in a Net Zero world and the transition towards it.

• Unless faster than expected progress is made on aircraft technology and SAF deployment, such that the sector is outperforming its trajectory to Net Zero, current planned additional airport capacity would require capacity restrictions placed on other airports.

• Going forwards, there should be no net expansion of UK airport capacity unless the sector is assessed as being on track to sufficiently outperform a net emissions trajectory that is compatible with achieving Net Zero alongside the rest of the economy, and is able to accommodate the additional demand and still stay on track.

P 35 of link

CCC on the need for carbon capture and storage in future:

P 197 of link

Furthermore, the reliance only on natural removals to offset remaining positive emissions
(e.g. in agriculture) means that staying at Net Zero after 2050 would require ever increasing natural carbon stocks (e.g. in forests and peatlands), requiring a slowly but
ever-increasing area of the UK to be devoted to sequestration. Overall, this supports our message that CCS is essential to achieving Net Zero, at lowest cost, in the UK. The importance of CCS globally further underscores the urgency of progressing CCS plans in the UK.

Engineered greenhouse gas removals, such as Bioenergy with carbon capture and storage (BECCS), Direct Air Capture of CO2 with storage (DACCS) and increased use of Wood in Construction will be required to permanently remove carbon from the atmosphere, in order to offset remaining residual emissions in the UK and achieve Net Zero by 2050. As set out in Chapter 1, our scenarios aim to reduce emissions where decarbonisation solutions exist, and minimise the need for removals.


And there is so much more !

Thread of tweets from the Aviation Environment Federation (AEF):   @the_AEF

9th December 2020

1/12  @theCCCuk report out today on the recommended level of the 6th carbon budget (2033-37) also makes detailed recommendations on the pathway to net zero by 2050 or earlier, including for aviation “one of the most thorny topics”, according to
@ChiefExecCCC #UKCarbonBudget

2/12 From 2033, emissions from international aviation and shipping (IAS) should be formally included in UK climate law, says the CCC. Until now emissions from these sectors have been ‘allowed for’ but not capped. Emissions from flying were, pre-pandemic, rising without penalty.

3/12 Given limits to the options for decarbonising aviation, flying is named as one of the ‘high carbon activities’, alongside meat consumption and driving, where we need to see behaviour change as well as a shift of energy supply and use of ‘greenhouse gas removals’.

4/12 CCC’s recommended ‘balanced pathway’ allows for 25% growth (above 2018 levels) in demand for flying by 2050. Though a reduction in demand growth accounts for the biggest wedge of the anticipated aviation emissions cut to 2050.

5/12 Compared to earlier modelling, CCC has ramped up its assumptions on sustainable aviation fuels which it now assumes to be 25% of total fuels by 2050 (2/3 biofuels, 1/3 synthetic jet fuel produced via direct air capture of CO2).

6/12 23 Mt of CO2 remain from aviation by 2050, which would need to be balanced by carbon removals, says the CCC, though how these would be paid for (whether by airlines or Govt) is not spelled out. Other scenarios in which, for example, demand is lower, are also considered.

7/12 There should be no net increase in airport expansion to limit demand growth, says CCC. This is the strongest line it’s adopted on this issue.

Expansion can only be justified if matched by ‘restrictions’ at other airports or industry outperforms on ambitious pathway assumed.

8/12 “If efficiency or SAF do not develop as expected, further demand management will be required”, CCC says. “Demand management framework will therefore need to be developed and in place by mid-2020s to annually assess, and if required, act as a backstop to control [emissions].”

9/12 Non-CO2 impacts require further assessment, says CCC, before appropriate measures are put in place to tackle them, but “as a minimum goal, there should be no additional non-CO2 warming from aviation after 2050.”

10/12 Finally, what about offsetting? The Government and industry have often argued aviation emissions should be tackled by way of the UN Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA).

11/12 UK should work with  @icao to strengthen CORSIA scheme, says CCC, but as it currently represents “an insufficient contribution to goals of Paris Agreement”, CORSIA credits “should not be used to meet UK carbon budgets.” This is a strong – and v important – recommendation.

12/12 Our press release, focussing on the airport expansion recommendation of
‘s report on the recommended level of the 6th carbon budget, can be read here Right pointing backhand index