Policy clash: Can projected aviation growth be reconciled with the UK Government's 60% carbon-reduction target?

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Transport Policy 14 (2007) 103–110 www.elsevier.com/locate/tranpol

Policy clash: Can projected aviation growth be reconciled with the UK Government’s 60% carbon-reduction target? Alice Bows, Kevin L. Anderson Tyndall Centre for Climate Change, MACE, P.O. Box 88, University of Manchester, Manchester M60 1QD, UK Available online 22 November 2006

Abstract In 2004, the UK’s aviation industry emitted an estimated 9.8 MtC; a figure that, without direct intervention, is projected to rise to 16–21 MtC by 2030 according to the UK Government. As the UK’s 60% carbon-reduction target approaches, so aviation is likely to become a dominant carbon-emitting sector. This paper calculates the proportion of carbon emissions resulting from the Government’s projected aviation growth in relation to a contracting carbon budget. It concludes that the Government must urgently address today’s very high levels of growth in emissions within the industry, and ensure future growth can be reconciled with the Government’s own carbon targets. r 2006 Elsevier Ltd. All rights reserved. Keywords: Aviation; Carbon dioxide; Energy policy; White paper

1. Introduction Carbon dioxide emissions from the aviation industries of all EU member states are growing rapidly, including from those nations where the sector is considered to be mature (Bows et al., 2005). The UK’s aviation industry, the EU’s largest and arguably most mature, is the fastest growing source of carbon dioxide emissions of any sector in the UK economy (Anderson et al., 2005). As the UK is a typical Annex 11 country, such emissions growth within this relatively mature sector is particularly worrying.2 From a Corresponding author. Tel.: +44 161 306 3737.

E-mail address: [email protected] (A. Bows). Annex 1 nations are the industrialised countries that were members of the Organisation for Economic Co-operation and Development (OECD) in 1992, plus countries with economies in transition (the EIT Parties), including the Russian Federation, the Baltic States, and several Central and Eastern European States. Despite the UK’s aviation sector being the largest of any EU25 nation, it is of a sufficiently similar scale and growth rate to permit informed analogies to be made. 2 Even outside the EU and in some respects the OECD, the UK exemplifies the implications of very high emissions growth from aviation on meeting climate change objectives. In China, for instance, whilst the economy is growing at approximately 10% per annum, aviation passenger growth recently reached 24% in 1 year. Whilst this measure is in passenger numbers, even assuming very high load factors and efficient aircraft, aviation will still be subject to a very high emissions growth rate. 1

0967-070X/$ - see front matter r 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.tranpol.2006.10.002

policy-forming perspective, aviation is highly problematic in its impact on the climate. Complications arise from, for example, the apportioning of aviation emissions released during international flights between nations, and individual nations taxing fuel at the expense of their competitive advantage. In relation to propulsion, jet engines are a mature technology, and consequently the efficiency of the current fleet is not set to change substantially within the foreseeable future. Exacerbating this absence of a stepchange in fuel efficiency is the long design life of aircraft, effectively locking society into current technology for at least the next 30–50 years.3 The size of the potential impact of aircraft on the climate is also surrounded by uncertainty. Carbon dioxide emissions from the industry are well understood, and therefore easy to compare with other sectors. However, aviation’s full contribution to climate change has, potentially, a much greater impact than that of the carbon dioxide emissions alone; nitrous oxides, soot and water vapour, released at different altitudes in the atmosphere, cause additional warming. Combined with the production of condensation trails (contrails), under certain atmospheric conditions, and 3 The new Airbus A380 is likely to have a lifetime of around 30 years, with very similar designs being constructed for, at least, the next two decades.

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the likely consequent formation of cirrus clouds, aviation’s instantaneous warming impact is estimated to be between 2 and 4 times that of the carbon dioxide emitted (IPCC, 1999). Uncertainties both in the appropriateness of an ‘uplift factor’ (Forster et al., 2006) and the atmospheric chemistry behind it have reinforced wider international reluctance to tackle the problem of aviation and climate change. Within this paper, UK Government projections for aviation emissions over the coming 45 years are compared with the UK’s contribution to stabilising atmospheric carbon dioxide concentrations at 550 parts per million by volume (ppmv)—in line with the UK Government’s own 60% carbon4-reduction target. To put this into context, current atmospheric concentrations of carbon dioxide are 380 ppmv, and those in pre-industrial times were 280 ppmv. In addition, comparisons are also made with a target of 450 ppmv. The 450 ppmv level is, according to recent results disseminated at the Department for the Environment, Food and Rural Affairs (DEFRA) climate change conference, more likely to avoid so-called ‘dangerous climate change’, than the commonly referred to figure of 550 ppmv (Jones et al., 2006; Elzen and Meinshausen, 2006). No attempt has been made to ‘uplift’ the carbon dioxide emissions from aviation to account for contrails and other gases within this paper, a position that is in keeping with that of the EU Commission (COMM, 2005). It is clear from the results however, even in the absence of any ‘uplift factor’, that under a contracting carbon dioxide budget, the proportion of carbon dioxide emissions predicted by the Government to be released by this one sector will have profound consequences for all other sectors of the economy.

2. The impact of aviation growth from today to 2050 2.1. Carbon-reduction policy in the UK With the publication of the 2003 Energy White Paper (DTI, 2003), so the UK Government explicitly endorsed a target of reducing UK carbon dioxide emissions by 60% by 2050. The choice of 60% essentially reflected an acceptance of the earlier analysis contained in the Royal Commission on Environmental Pollution (RCEP) 22nd report, ‘Energy—The Changing Climate’ (RCEP, 2002). The RCEP argued that a 60–90% reduction in carbon dioxide emissions is required of industrialised nations by 2050 if ‘dangerous climate change’ is to be avoided. The RCEP’s target was calculated on the basis that all nations progress towards an equal per-capita carbon dioxide emissions level by 2050, in accordance with a ‘contraction and conver4 ‘Carbon-reduction target’ refers to the carbon dioxide target, but measured in Million tonnes of Carbon, rather than in a measurement of carbon dioxide. To convert carbon dioxide to carbon, simply divide by 3.67. Similarly for ‘carbon-budget’.

gence’ climate policy regime developed by the Global Commons Institute (GCI), (Meyer, 2000). Contraction and convergence is an international framework for apportioning equitably a contracting global carbon dioxide emissions budget. Within this framework, the world’s nations work together to set and achieve a global annual emissions target—contraction. In addition, nations converge towards equal per-capita emissions by an expressly defined year—convergence. By simultaneously ‘contracting and converging’, such a policy requires all nations to impose targets from the outset (Cameron and Evans, 2003). Although it can be argued that some countries should be permitted to emit more than others for a range of reasons, such as a cold environment, historical emissions or the existence of a well-developed transport network, proponents of ‘contraction and convergence’ consider making allowances for such differences will interminably delay climate negotiations. As stabilising the atmospheric carbon dioxide concentration at 450 or 550 ppmv5 demands a reduction strategy that is initiated as a matter of urgency, proponents of ‘contraction and convergence’ consider that the simplicity of the concept gives it an important practical appeal. To support the ‘contraction and convergence’ regime, the GCI produced a model—CCOptions—to apportion national emissions according to a chosen carbon dioxide stabilisation level and convergence date. Both the original version of the CCOptions model, from which it would appear the Energy White Paper 60% carbon-reduction target arose, and a more recent version, which aims to be consistent with the latest Hadley Centre climate models incorporating carboncycle feedbacks, are used within this analysis. In analysing the Energy White Paper, the RCEP report (RCEP, 2002) and the GCI’s contraction and convergence regime, it is evident that the underlying basis of the 60% target is a stabilisation of the atmospheric carbon dioxide concentration at 550 ppmv. However, the UK Government have not openly adopted ‘contraction and convergence’ as their official emissions policy. According to work recently undertaken within the Tyndall Centre (Bows et al., 2006), the inclusion within the ‘contraction and convergence’ regime of data from the most recent Hadley Centre model (i.e. biogeochemical feedbacks), suggests that the carbon-reduction target necessary to stabilise atmospheric carbon dioxide concentrations at 550 ppmv is nearer to 65% than 60%. Stabilising carbon dioxide concentrations at the lower level of 450 ppmv is commonly referred to by the IPCC and the RCEP and would correspond approximately to an 80% rather than a 60% reduction. Current research suggests lower stabilisation levels than 550 ppmv are likely to be necessary if unacceptable major disruption to the climate is to be avoided (Elzen and Meinshausen, 2006). Moreover, DEFRA acknowledge that the latest science tends to 5

Carbon dioxide has a lifetime in the atmosphere of around 100 years. Reaching 450 or 550 ppmv requires there to be a strict limit on the amount of carbon dioxide emissions released over the next 100 years.

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suggest a carbon dioxide concentration of 450 ppmv6 rather than 550 ppmv relates to a temperature increase of 2 1C (DEFRA, 2006). Due to the political emphasis on stabilising carbon dioxide at 550 ppmv, and the scientific evidence pointing towards the lower 450 ppmv target, both levels are investigated here. 2.2. Growth within the aviation industry Since 1960, global air passenger traffic (expressed as revenue passenger-kms) has increased by nearly 9% per year—2.4 times the growth rate of global mean Gross Domestic Product (IPCC, 1999). By 1997, growth in global air passenger traffic had slowed to approximately 5% per year as the industry matured in some parts of the world; however, according to the IPCC, this 5% per year figure is now expected to continue until 2015. Across Europe, growth since the 1980s has often exceeded the global mean figure, with the UK experiencing a 6.6% annual rate of growth in total domestic and international traffic between 1985 and 1998 (ATAG, 2000) and 8% between 2003 and 2004 (CAA, 2004; DfT, 2005). The programme of airport expansion considered necessary by the UK Government to meet their own projected growth in demand (DfT, 2004b) has stimulated ongoing debate on the appropriate scale of the aviation industry. According to the White Paper, ‘‘all the evidence suggests that the growth in popularity and importance of air travel is set to continue over the next 30 years’’. In 2003, some 200 million passengers passed through UK airports, a figure that is predicted to rise to between 400 and 600 million by 2030 (DfT, 2004b), if sufficient capacity is provided. This implies an annual rate of increase in passenger traffic of between 2.6% and 4.2%.7 Similar rates of increase are also forecast Europe-wide; the Air Transport Action Group (ATAG) predicts increases of around 4% per year for European passenger traffic, and 4.4% per year for international air transport to and from European nations up to 2015 (ATAG, 2000). Furthermore, Airbus predict the aviation industry across Europe growing at 5.2% per year until 2023 (Airbus, 2005) and Boeing forecasts European aviation growth at 4.3% per year over a similar period (Boeing, 2005). Implications of such growth for carbon dioxide emissions and climate change are far reaching. Technological improvements in engine performance, airframe design and air traffic management are unlikely to offer reductions in emissions per seat kilometre flown for the global fleet of more than 1.4% per annum (IPCC, 1999).8 However, even with very conservative Government 6 It should be noted that even the 450 ppmv target only provides an approximate 50:50 chance of not exceeding the 2 1C figure. 7 In fact, as growth within the UK’s aviation industry is currently around 8%, this would imply much lower levels of growth at some point between 2004 and 2030 to average at between 2.6% and 4.2% per year. 8 The ACARE target is to improve the fuel efficiency per passengerkilometre of a new plane in the year 2020 by 50% compared with a new plane in 2000 (ACARE, 2002). The DfT incorporated these improvements

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and industry projections of aviation growth,9 such improvements still leave a 1.2–2.8% increase in emissions from the aviation industry each year. Given the long lifetime of new aircraft—in the region of 30 years—the Government’s current ‘predict and provide’ approach to aviation leaves the UK wedded to a future of increasing emissions from the sector. The impact of a growing aviation industry within a nation attempting to significantly reduce its carbon dioxide emissions are demonstrated in Table 1, where projections of the aviation carbon dioxide emissions generated by the Department for Transport (DfT) are summarised. The first two columns contain data taken from the DfT’s ‘Aviation and the Environment: Using Economic Instrument’s’ paper published in March 2003 (DfT, 2003). The high capacity case assumes new runways at Heathrow, Gatwick, Stansted, Manchester, Birmingham and Edinburgh. The low capacity case assumes no new runways. In both cases the assumed fuel efficiency improvements over the fleet may be underestimates according to the White Paper. The next three columns present the DfT’s revised projections as produced for the Aviation White Paper (DfT, 2004a). The ‘worst case’ projection assumes limited fuel efficiency improvements, limited fleet renewal, and no economic instruments. This projection is based on the ‘high capacity’ case developed within the Economic Instruments paper (DfT, 2003), but with three, rather than two, additional runways built in the South East of England, as well as, so-called, unconstrained capacity in the regions.10 The ‘central case’ figures are again based on the ‘high capacity’ case, but incorporating fleet fuel efficiency improvements envisaged by the IPCC (1999) and by the Advisory Council for Aeronautics Research in Europe (ACARE).11 Finally, the ‘best case’ estimates use economic instruments to produce an additional 10% fleet fuel efficiency saving from 2020 onwards, with a 5% fleet fuel efficiency saving in 2010. All of the results shown in Table 1 indicate that emissions from the aviation industry are expected to grow rapidly between now and at least 2040. Such emissions growth will have a profound effect on the UK as it

(footnote continued) and calculated how they would translate across the entire fleet, which results in an approximate 1% improvement per year. Their method is outlined in paragraph 3.56 of the Aviation and Global Warming paper (DfT, 2004a). 9 Aviation within the UK grew in terms of passenger numbers by 8% per year between 2003 and 2004. 10 Capacity is inherently constrained in such forecasts by, for example, by existing landing charges, car park fees, etc. 11 ACARE assume 50% fuel efficiency improvement between 2000 and 2020 for a new aircraft. To incorporate this over a time-span out to 2050 and over the entire fleet, the DfT assume a 15% improvement between 2000 and 2030, with a further 25% occurring between 2030 and 2050. The remaining 10% is already factored into the original DfT figures and arises from assumed improvement in operational measures in aviation. The ACARE targets are laid out in Aviation (2005).

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Table 1 Government projections of carbon dioxide emissions from the UK’s aviation sector. The difference in 2000 figures is based on the differing ways of accounting for carbon dioxide emissions from aircraft.a The figures from both papers incorporate freight as well as passenger transportb Year

DfT Low capacity

High capacity

Worst case

Central case

Best case

8.8 10.8 14.9 17.7 18.2 17.4

8.8 10.3 13.4 15.9 16.4 15.7

UK Aviation White Paperc

Economic instruments paper

Million tonnes of carbon (MtC) 2000 2010 2020 2030 2040 2050

7.1a

18.3

7.1

20.8

8.8 11.4 16.5 20.9 25.1 29.1

a

The 2000 figures differ due to different methods of estimating the emissions, one by SERAS and one by NETCEN, with the principal difference lying in the calculation of carbon dioxide emission from domestic aviation [D.9 (DfT, 2003)]. The conversion from million tonnes of carbon dioxide to carbon was done by dividing the figures by 3.67. b Table D6 in the Economic Instruments paper (DfT, 2003) illustrates that both freight and passenger transport is included. c This data includes both passenger and cargo flights as discussed in paragraph 3.53 of Aviation and Global Warming: (DfT, 2004a).

attempts to significantly reduce its emissions from the economy as a whole.

2.3. Aviation growth in relation to the UK’s contraction emissions profile To examine the impact on the UK economy of the UK Government’s predicted growth in aviation-induced carbon dioxide, a comparison is made between contracted profiles of emissions designed to stabilise carbon dioxide concentrations at 550 and 450 ppmv (relating to the 2 1C temperature figure) and the DfT’s latest projections for carbon dioxide emissions from aviation over the next 50 years (taken from Table 1). In Section 2.1, reference was made to a more recent version of the CCOptions model that attempts to reproduce emission profiles generated by later versions of the Hadley Centre’s General Circulation Model, in which a more ‘detailed’ representation of climatic biogeochemical feedbacks is included (i.e. an improved representation of the carbon-cycle).12 Fig. 1 compares the UK Government’s aviation projections with stabilisation profiles generated by both the old and new versions of the CCOptions model, and for both 450 and 550 ppmv. 12 The atmospheric concentration of carbon dioxide depends not only on the quantity of carbon dioxide emitted into the atmosphere (natural and anthropogenic), but also on, for example, changes in land use and the strength of carbon sinks within the ocean and biosphere. As the atmospheric concentration of carbon dioxide increases (at least within reasonable bounds), so there is a net increase in the take-up of carbon dioxide from the atmosphere by vegetation (carbon fertilisation). Changes in temperature and rainfall induced by increased carbon dioxide affect the geographical distribution of vegetation and hence its ability to store carbon dioxide (Hadley, 2002). The complicated and interactive nature of these effects leads to uncertainties with regard to the size and sign each of the carbon-cycle feedbacks (Cox et al., 2006; Cranmer et al., 2001).

Fig. 1. DfT projections of aviation’s emissions for the UK in relation to contraction and convergence profiles for 450 and 550 ppmv, each with a convergence date of 2050. The contraction and convergence profiles were generated using both a version of CCOptions consistent with the UK Government’s 60% carbon-reduction target and a version incorporating biogeochemical feedback results.

The solid black line was produced for 550 ppmv by the older version of the CCOptions model and achieves the UK Government’s 60% target, but does not incorporate any results based on biogeochemical feedbacks. The solid grey curve illustrates the resulting profile if the newer version of the CCOptions model, incorporating biogeochemical feedbacks, is used. Similarly, the two dashed lines illustrate outputs from the old and new CCOptions model for 450 ppmv. All the profiles set a convergence date of 2050, as assumed in the UK’s 60% target. Also included in the figure is the DfT’s ‘worst’, ‘central’ and ‘best’ case projections for carbon dioxide emissions generated by the UK’s domestic and international aviation industry.

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The contraction profiles for 550 ppmv in Fig. 1 show from where the UK’s 60% target is derived: between 2000 and 2050, using the older version of CCOptions, carbon dioxide emissions reduce from around 150 Million tonnes of Carbon (MtC) to approximately 65 MtC—around 60% lower than current levels. To stabilise carbon dioxide concentrations at 450 ppmv, the emissions reduction required using this older model version are in the region of 80%, with a final 2050 emission budget of 32 MtC. The resulting percentage cuts required for 550 and 450 ppmv stabilisation using the newer version of CCOptions would be 65% and 85%, respectively. Turning to the aviation projections illustrated within Fig. 1, the results show that under the DfT’s ‘worst’ case projection, carbon dioxide emissions from the aviation industry are accounting for between 93% and 112% of the total carbon budget for the 450 ppmv profiles by 2050. This is particularly worrying as recent scientific research (Elzen and Meinshausen, 2006) indicates that stabilising carbon dioxide concentrations at levels probably lower than 450 ppmv, will be necessary if there is to be a reasonable likelihood of avoiding the so-called ‘dangerous climate change’. In other words, it will be virtually impossible to reconcile such levels of growth in aviation with a 450 ppmv stabilisation level unless dramatic changes are made to the way aircraft consume fuel, or indeed to the nature of the fuel source itself. However, with current aircraft design locking the sector into using kerosene for 30–50 years, such changes are difficult to envisage. Furthermore, even under the DfT’s ‘best’ case projection, between 50% and 60% of the UK’s contracting 2050 carbon budget under the 450 ppmv regime will be taken up by the aviation industry. Such a disproportionate allocation of emissions to one sector will inevitably have significant consequences for all other carbon dioxide-emitting sectors of the economy. It should also be stated that the global carbon budget data within the CCOptions model does not include international aviation. If such data was included, then the cuts necessary to achieve the desired stabilisation level would be larger, therefore the results here are likely to be an underestimate of the true scale of the problem. Considering now the 550 ppmv profiles, even within the DfT’s ‘best’ case projection, aviation emissions represent between 25% and 27% of the contracting carbon budget by 2050, and between 45% and 51% for the UK Government’s ‘worst’ case projection. In 2004, aviation accounted for 7% of the UK’s carbon budget.13 The likely shift from a 7% share to these much higher proportions would indicate that other sectors need to substantially decarbonise to compensate for air travel, either through reductions in demand or a move towards a low-carbon energy supply. 13 Value calculated from the domestic and international aviation emissions data including freight transport compiled for the UNFCCC by NETCEN and the total carbon dioxide emissions for 2004 calculated using the Digest of UK Energy Statistics (DTI, 2005).

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To summarise, the UK Government’s projections predict the aviation industry accounting for between 25% and 51% of the UK’s 2050 carbon budget if 550 ppmv is the stabilisation target, and between 50% and 112% of the UK’s 2050 carbon budget for 450 ppmv. Whilst it may be argued that the Hadley Centre model generates slightly larger carbon-cycle feedbacks than other similar models (Zeng et al., 2004), the projections nevertheless clearly highlight the substantial contradictions between the UK Government’s Energy White Paper targets for carbon dioxide emissions and the same Government’s desire to facilitate airport expansion.

3. Discussion 3.1. Implications for the UK economy The 60% target was originally chosen to contribute to stabilising global carbon dioxide concentrations at 550 ppmv, the level at which it was believed represented the threshold between acceptable and dangerous climate change. International aviation, unlike domestic aviation, is currently excluded from the UK’s 60% target, despite the omissions essentially negating the objective of the target (Anderson et al., 2005). By quantifying the aviation industry’s carbon dioxide emissions in relation to the UK’s total carbon budget, this paper clearly demonstrates that including aviation in the target has dramatic consequences for other key sectors of the economy, many of which also have increasing emissions. Household energy consumption is currently growing at approximately 1% per year [(DTI, 2005) and earlier copies], whilst private road transport emissions have recently increased at 1% per year. However, in the short–medium term, behavioural, technical and modal opportunities exist for reversing the emission trends of other sectors. For example, within private road transport by combining an increase in shortdistance commuting by public transport, a marginal increase in the load factors of cars and improving their fuel efficiency so that the best available today becomes the mean of tomorrow. In contrast, explicitly facilitating growth in aviation, where no short- to medium-term alternatives to using kerosene or step changes in fuel efficiency improvements are envisaged, will undoubtedly seriously constrain the emission space available in other sectors. Furthermore, recent science suggests that the stabilisation level more closely associated with avoiding dangerous climate change is likely to be 450 ppmv or lower. Preliminary research conducted by the Tyndall Centre (Bows et al., 2005) into the potential impacts of continuing current levels of growth in the UK’s aviation industry on other sectors of the economy indicates that under the 450 ppmv stabilisation profile, all other sectors of the economy will need to significantly, possibly completely, decarbonise by 2050 if the respective carbon-reduction target is not to be exceeded.

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3.2. Additional measures for mitigating carbon dioxide emissions from aviation Whilst incremental improvements in engine performance, airframe design and air traffic management are gradually reducing the ‘relative’ emissions from the industry, more radical suggestions are being made to significantly reduce emissions growth. For example, significantly increasing load factors on planes from the European average of 60% to closer to 90% could cut relative emissions for European carriers by up to a third, but would require a radical shift in the relationship between companies, more sophisticated and integrated ticketing arrangements and perhaps greater flexibility from the passenger. The acceptance of a slower form of flight, such as non-jet aircraft, turbo-props and perhaps even airships for freight may offer reduction opportunities, but inevitably require both substantial new infrastructure and cultural change. The introduction of the higher capacity and more efficient A380 aircraft design will reduce emissions per passenger if the load factor is high. However, if the industry intends to fly these larger aircraft as often as their smaller counterparts, they will be facilitating further growth in passenger numbers, and this is likely to result in an increase in emissions. There is a considerable body of research investigating the prospective fuel efficiencies of the aviation sector (Green, 1992; IPCC, 1999; Little, 2000; RCEP, 2002). As carbon dioxide emissions are proportional to fuel use, such fuel efficiencies, along with longer term technology options, need to be accounted for in emissions projections. Relevant to the UK specifically is the review of environmentallyrelated technology options undertaken for the Aviation White Paper (Little, 2000). This work concurs with the RCEP (2002) and the IPCC (1999) in stating that aircraft designs up to 2030 are thought likely to be based around conventional airframe configurations, integrating best practice technology. Although the Little report concludes that fuel efficiency improvements for new planes of 2% per year could be obtained in principle, up until 2030, the DfT are more conservative in their ‘central’ case emissions projection (DfT, 2004a) in which they assume that ACARE’s fuel efficiency provides a more realistic estimate.8 Regarding alternative fuels, biofuels such as methanol, ethanol and biogas have substantial safety implications for use with jet aircraft. By contrast, Fischer-Tropsch14 kerosene produced from either biomass or coal with carbon capture and storage has potential to increase the sector’s low-carbon energy use without significantly impacting safety (Saynor et al., 2003). However, initially at least, renewable and low-carbon fuels are likely to be used for road transport or electricity generation in preference to aviation and, nevertheless, are subject to 14 Fischer-Tropsch is a chemical process for making oil from biomass or coal.

very substantial sustainability concerns in terms of large scale production. The use of hydrogen offers an opportunity for eliminating carbon dioxide and further reducing NOx from aircraft (Ponater et al., 2003). However, its widespread use presents major design problems for aircraft in terms of airframes and engine design (Saynor et al., 2003) and would entail global changes in supply, ground handling, and storage. Hydrogen fuelled aircraft would also emit water vapour with consequent warming, unless such aircraft were flown at altitudes chosen to minimise the effects of contrail formation in particular. The RCEP takes the view that the environmental benefits of using hydrogen rather than kerosene for fuelling aircraft engines are uncertain, and that for many decades, hydrogen can be discounted as a way to reduce the climate change impacts of air travel (RCEP, 2002). Consequently, kerosene-type fuels are considered by many to be the only viable option for aircraft within the next 50 years (IPCC, 1999). Radically alternative airframe designs have been investigated as a means of improving the efficiency of aircraft. One example, the blended-wing body (BWB) airframe, also known as the ‘Flying Wing’ (RCEP, 2002), could carry over 600 passengers. The BWB has the body partly or wholly contained within the wing, so that the interior of the wing in the central part of the aircraft becomes a wide passenger cabin. The BWB could, so its proponents claim, be significantly lighter and experience very much lower drag than the conventional swept wing-fuselage airframe design. Its fuel usage would therefore be reduced, perhaps by as much as 30%, further reducing aircraft take-off weight (RCEP, 2002; Liebeck et al., 1998). Because of the lower weight and drag, this type of aircraft could have a lower cruise altitude and an extended optimal range (RCEP, 2002). Nevertheless, given the long service lives of aircraft, it is likely to be many decades before BWB aircraft make a significant contribution to air travel. Furthermore, it is likely that two-thirds of all the aircraft that will be flying in 2030 are already in use today (RCEP, 2002). 3.3. Aviation and the European Emissions Trading Scheme Incorporating international aviation into the European Emissions Trading Scheme (ETS) is seen by many as a key step towards a consistent and sector-wide effort to combating climate change. However, as all of the EU nations are industrialised, they too will be looking to significantly reduce their carbon dioxide emissions from all of their sectors year-on-year. The EU Commission intends to include international aviation in the EU ETS by or before 2012 (COMM, 2005). The Commission is also intending for the scheme to include all flights taking off from EU nations, as opposed to a scheme incorporating just intra-EU flights in the first instance; the latter being preferred generally by the aviation industry (Bows et al., 2006). However, given the logistics of incorporating this

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Table 2 How the emissions cap within the EU ETS may affect the price of carbon permits No emission cap reduction

Small emission cap reduction

Large emission cap reduction

Extra allowance for aviation (at a level similar to the total value of aviation emissions)

Little or no change in permit price

Small increase in permit price

Large increase in permit price

No extra allowance for aviation

Moderate increase in permit price

Big increase in permit price

Very large increase in permit price

international sector within the current EU ETS, it is highly unlikely that trading between the aviation industry and other sectors will begin prior to 2010. In the meantime, it is likely the EU member states will broadly follow the UK example and also significantly increase their emissions from aviation. Carbon dioxide emissions from the UK’s aviation industry increased by 11% between 2003 and 2004 according to the latest figure submitted to the UNFCCC by the National Environment Technology Centre (NETCEN).15 This equates to the aviation industry emitting 9.8 MtC in 2004. Growing this 9.8 MtC figure at rates similar to the annual average experienced between 1993 and 2000, results in a near doubling of emissions from the UK’s aviation industry by 2012 (18 MtC). That is to say, the aviation industry will be likely emitting in the region of a quarter of UK’s 2050 carbon budget by 2012 and around 12% of the 2012 total under a contracting budget aiming to stabilise carbon dioxide concentrations at 550 ppmv. Furthermore, this scenario suggests that the UK Government forecasts presented in Table 1 are significantly underestimating aviation’s likely contribution to future carbon dioxide emissions. Although the aviation industry within the UK is the largest in Europe, and therefore emissions from this sector are a larger proportion of the nation’s total than many other EU nations, work carried out by the Tyndall Centre (Bows et al., 2005) suggests that the picture in Europe, in terms of rapidly growing emissions within the aviation industry and a reducing carbon cap, is not dissimilar. At present there is considerable uncertainty surrounding the cap under which the EU ETS will operate. For example, will the cap be raised when the aviation industry is included, and if so, by how much? Will there be a reduction in the cap year on year, and if so, what will the rate of change be? Table 2 qualitatively illustrates these issues and their likely impact on the cost of carbon. The inclusion of aviation’s emissions in the EU ETS and the impact on permit prices is further complicated by the 15 NETCEN estimate the emissions associated with the UK’s aviation industry by employing a methodology that takes into account aircraft movements, distances travelled, deliveries of aviation spirit and turbine fuel and the consumption of aviation turbine fuel by the military. The data therefore includes both passenger and freight aircraft. The methodology and uncertainties associated with this data are discussed in (Watterson et al., 2004).

industry’s very substantial growth. Again, taking the UK as an example, if by 2012 the UK’s aviation industry is emitting in the region of 18 MtC, and given only 40% of UK emissions are subject to trading within the EU ETS, then assuming the cap remains unchanged, as a minimum, the UK’s aviation industry will account for 28% of the UK’s emissions within the scheme by 2012. If an extra allowance is made for aviation it will be even more difficult for the EU as a whole to significantly reduce its carbon dioxide emissions. If no allowance is made however, and given the huge proportion of emissions that are likely to be attributable to the aviation industry, the price of permits is very likely to rise substantially. 4. Conclusions The Kyoto agreement, and indeed all other national and international climate change targets, omit those emissions arising from international aviation. The analysis presented in this paper, conducted for a typical Annex 1 nation with a ‘mature’ aviation industry, demonstrates that effective climate change targets must include, urgently, emissions from aviation. Although there are a variety of technical options available to the industry for improving aircraft fuel efficiency and decarbonising the fuel source, the benefits will be incremental and unlikely to significantly impact aircraft fleets before 2030. In the absence of explicit polices to curb aviation growth, global emissions from this sector will continue to grow rapidly as passenger demand outstrips substantially improvements in both fuel efficiency and carbon intensity. To address the issue of growth, EU policymakers are currently debating the inclusion of aviation emissions within the EU’s emissions trading scheme, a position recently supported by the UK Government (DEFRA, 2006). Given that it is unlikely emissions will be included prior to 2010–2012, the current very high emissions growth rates will result in the aviation industry being increasingly responsible for a large proportion of the EU’s total carbon budget. By analysing the effect of a contracting carbon dioxide budget in relation to growing carbon dioxide emissions from a typical ‘mature’ aviation industry, this paper illustrates conflicts between the UK’s current climate and aviation policies. Analysing the UK Government’s own projections of both emissions from aviation and those from

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other non-aviation sectors, demonstrates how aviation could increasingly become a dominant emissions source. Exacerbating the already substantial disjuncture between climate change and aviation policy are the additional warming effects of aviation on the climate arising from contrails, cirrus clouds and impacts on other greenhouse gases. These additional effects have, historically, been equated to an increase in the potential impact of aviation on the climate by between 2 and 4 times (IPCC, 1999). Combining these additional effects with the UK Government’s likely underestimate of aviation’s carbon dioxide emissions, leads to the conclusion that aviation growth can not be reconciled with the Government’s explicit commitment to make its contribution to avoiding ‘dangerous climate change’. The UK Government, and those across Europe, must therefore urgently address the very high levels of growth currently experienced within the industry, and consider additional carbon-reduction measures16 if future growth in the industry is to be reconciled with the carbon-reduction targets to which they have all committed. References ACARE, 2002. Strategic Research Agenda Volume 2: The Challenge of the Environment, from /http://www.acare4europe.com/docs/ es-volume1-2/volume2-03-environment.pdfS. Airbus, 2005. Global market forecast, from /http://www.airbus.com/en/ myairbus/global_market_forcast.htmlS. Anderson, K., Shackley, S., Mander, S., Bows, A., 2005. Decarbonising the UK: Energy for a Climate Conscious Future. The Tyndall Centre. ATAG, 2000. European Air Traffic Forecasts 1985–2015. IATA. Aviation, 2005. A strategy towards sustainable development of UK aviation. AOA, S., BATA, NATS. Boeing, 2005. Current market outlook, from /www.boeing.com/commercial/ cmo/2-1.htmlS. Bows, A., Anderson, K., Upham, P., 2005. Growth Scenarios for EU & UK Aviation: Contradictions with Climate Policy. Tyndall Centre. Bows, A., Anderson, K., Upham, P., 2006. Contraction & convergence: UK carbon emissions and the implications for UK air traffic. Tyndall Centre Technical Report, vol. 40, Tyndall Centre for Climate Change Research, Norwich. CAA, 2004. Main Outputs of UK Airports. CAA. Cameron, J., Evans, A., 2003. What happens after Kyoto? More of the same or ‘Contraction & Convergence’? New Economy 10 (3), 128–131. COMM, 2005. Reducing the climate change impact of aviation. Commission of the European Communities 459. Cox, P.M., Huntingford, C., Jones, C.D., 2006. Conditions for sink-tosource transitions and runaway feedbacks from the land carbon-cycle. In: Schellnhuber, H.J., Cramer, W., Nakicenovic, N., Wigley, T., Yohe, G. (Eds.), Avoiding Dangerous Climate Change. Cambridge University Press, Cambridge. 16 For example, in the short-term, a fuel and carbon tax to be applied to fuel consumed in domestic and European flights (currently there is no tax on aviation fuel as a consequence of the 1944 Chicago agreement). However, it is legally possible to apply a fuel and carbon tax to domestic and European flights. In the medium-term, some form of carbon allowance either in the form of a personal carbon quota or in constrained air-miles. In the longer-term, the 1944 Chicago agreement could be renegotiated in light of international efforts to tackle climate change. Supplementary instruments could for instance be a moratorium on airport expansion, increased passenger duty linked to the seat-kilometre fuel efficiency of the plane.

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