Select Committee on Environmental Audit Ninth Report


112. Between July 2003 and September 2004, our predecessor Committee produced no fewer than four very critical reports on the Government's aviation policy. Among the key criticisms made by the Committee were that:

DfT's plan for a large expansion of aviation was incompatible with the Government's very demanding target for 60% carbon reductions by 2050especially when taking into account the wider global warming contribution of aviation (previously accepted by the Treasury as equivalent to 2.5 times the weight in emissions simply of CO2 );

the 2003 Future of Aviation White Paper was based on a "predict and provide" model, of a kind seen not to work in the case of roads; and

the Department had significantly overstated the environmental benefits to the UK that would accrue from airport expansion (for instance, by including the benefits to foreign tourists).

In the last of these reports on aviation, the Committee left the matter thus:

The growth of aviation remains of immense concern to us in terms of the enormous local environmental quality of life and landscape impacts, the huge forecast increase in carbon emissions, and the need to develop more sustainable lifestyles. There remain fundamental and apparently irreconcilable differences between the DfT and ourselves, and we fully expect to return to these issues on future occasions.[163]

113. In framing the terms of reference for this inquiry we announced that, because the Committee had explored aviation in some detail in the last Parliament, this inquiry would focus mainly on the other forms of transport (road, rail, and the maritime sector).  However, we made it clear that "the Committee is also interested in assessing what has changed with regard to aviation emissions since the last EAC inquiry into that subject."[164] Having received written evidence on aviation from, among other bodies, the Tyndall Centre, Aviation Environment Federation (AEF), British Airports Authority (BAA), and Manchester Airports Group (MAG), we decided to take oral evidence from BAA and MAG, along with British Airways (BA) and Easyjet, as well as devoting some time to this issue with Friends of the Earth and, finally, the Secretary of State. Our conclusion is that, sadly, little has changed for the better since EAC's last report on aviation. Progress on introducing financial mechanisms to reduce the growth in emissions from flying is slow, and both the Government and the industry are as intransigent as ever. We urge the Department to widen the terms of its current progress review of the 2003 Future of Aviation White Paper into a fundamental rethink of its airport expansion policy.

114. The Government is right when it acknowledges that flying is a big contributor of carbon emissions and therefore to climate change, in addition to its negative contribution to air quality and noise pollution.[165] But what this means is that while the aviation industry can be allowed to thrive and even to grow, this can only take place within strict limits. We note the proposal of the Aviation Environment Federation, that demand for flights be managed to ensure that emissions from UK aviation remain constant in absolute terms, by limiting growth in passenger numbers to no more than the rate at which the industry improves its fuel (hence carbon) efficiency, currently some 1-2% a year. Aside from simply ensuring that aviation emissions remained manageable within a declining carbon budget, this would naturally provide the most effective incentive to the industry to make fuel efficiency innovations, since this would be the only way in which it was allowed to grow. While we have not examined the practicality of designing a mechanism (such as through a rise in Air Passenger Duty) to manage demand to such a specific rate of growth, and while we have some doubts as to whether the industry's claimed fuel efficiency rates will apply to the overall average of all planes in service, we would support such a proposal if it could be guaranteed to prevent an absolute rise in emissions. The Department should implement demand management measures straightaway; but to develop its use of such policies, it should commission and publish research on demand management policies which would generate predictable levels of passenger numbers and emissions outcomes.

Growth in aviation within a declining carbon budget

115. The Tyndall Centre referred us to research it published in February 2006,[166] giving the most authoritative demonstration yet of how the Government's airport expansion policy is on a collision course with its Climate Change Programme. Based on a recommendation from the Royal Commission on Environmental Pollution, the Government has set a target for total UK CO2 emissions to stand at around 65MtC by 2050, a reduction of 60% from 1990 levels. Even taking DfT's own "best case" projections for carbon emissions from UK aviation in 2050[167]some 15.7MtC, a projection even lower than the "central case" about which our predecessor Committee was sceptical[168]this means that by mid-century aviation will be taking up some 24% of the economy's entire capacity to emit carbon. And this is without even applying an "uplift factor" to quantify, in Millions of tonnes Carbon equivalent (MtCe), the extra radiative forcing of emissions released at altitude.

116. Under DfT's "best case" projections, then, aviation will grow from around 5% of the UK's carbon emissions today to 24% in 2050 (in neither case counting radiative forcing, which would increase these proportions). In other words, even under the Government's own and most optimistic projections, every other sector of the economy would have to cut its share of UK emissions, while that of aviation would be assisted to almost quintuple.[169] Given that these are both "best case" figures and do not take into account radiative forcing, this is likely to be a very substantial understatement of the actual figure to which the Government's current expansion policies are leading. Power companies, manufacturers, retailers, households, motorists and hauliers are already going to have to make significant efforts to decarbonise their lives and livelihoods. If the Government continues in its policy of allowing just this one industry to grow, it will either cause severe pain to all other sectors or provoke so much opposition as to fatally undermine its 2050 target. If their joint PSA target is to mean anything, the Department for Transport must work with the Department for Environment, Food and Rural Affairs to construct a new approach to aviation which constrains its future growth.

117. In one of our sessions, we referred to findings from a previous Tyndall Centre report,[170] which on the basis of its own projections for aviation growth, and applying an uplift factor of 2.7, argued that, unless constrained by Government action, aviation would take up over 100% of the UK's carbon budget in 2050. Joe Irvin, BAA's Director of Public Affairs, responded:

Mr Irvin: Not to be taken by surprise, I have a copy of the report of the Tyndall Centre so obviously I am aware of it. It would be alarming if all of it were true. Obviously, a lot of interesting work has gone into it, but it depends on the assumptions that you make. It makes some very contentious assumptions, rather like The Da Vinci Code.

Emily Thornberry: Do you say it is the same as The Da Vinci Code? Can we quote you on that?

Mr Irvin: No, but, in the same way, if one makes certain assumptions one can perhaps go in the wrong direction. […][171]

He then criticised it, on the basis that its forecasts for passenger growth were higher than the Government's, that there were issues with the way in which it applied uplift factors to account for radiative forcing, and that a reference to runway capacity was substantially inaccurate. While we would take issue with much of what he said, we might here simply observe that none of his criticisms applies to our arguments from the 2006 Tyndall Centre report above.

Aviation and the EU ETS

118. The Government's preferred policy on dealing with emissions from aviation is to include it within "a well-designed emissions trading regime, because it allows a specific emissions limit to be set and achieves that limit in the most cost effective way."[172] In practice this means including flights to destinations within the UK and throughout Europe within the EU Emissions Trading Scheme (ETS), with departures to long haul destinations being left for the foreseeable future, pending ongoing discussions within the International Civil Aviation Organization (ICAO).[173]

119. Under the ETS, overall limits on CO2 emissions are set by National Allocation Plans. High-emitting companies are compelled to participate, and allocated a certain number of allowances, each representing a tonne of CO2; they can either buy permits to allow them to emit in excess of their initial allocation, or sell allowances if they have reduced their emissions. Phase I of the ETS will run to 2008, with Phase II running until 2012. Overall allowances will be reduced in each Phase, bringing downward pressure on all emissions. The European Commission now aims to produce a legislative proposal and impact assessment on the inclusion of aviation in the EU ETS by the end of 2006.[174]

120. As we understand it, including aviation in the ETS is intended both to constrain (though not to stop, still less to reverse) the absolute growth in carbon emissions from aviation itself, and to increase the reduction in emissions from other sectors, thus helping the ETS to achieve significant absolute reductions in emissions from the EU overall. By purchasing carbon credits, airlines will a) incur costs that will be passed on to customers, hence proportionately depressing demand; b) become incentivised to seek fuel efficiencies, to make the most efficient use of their carbon credits; and c) to enable their continued growth in emissions, increase the demand for emissions credits and raise the price of carbon, effectively tightening the emissions cap on all industries.

121. However, a great many complications and uncertainties remain in the way of turning this model into reality. For instance, a report published earlier this year by DfT and Defra concluded that adding aviation to the ETS (using an assumed allocation base year of 2008), "will not have a discernible impact on average annual prices of carbon instruments"[175]implying that inclusion would have little effect on either dampening demand for flights or increasing the downward pressure on other sectors. Conversely, manufacturing groups have been expressing concern that inclusion of aviation could have a very significant and unfair impact on themboth in that the Government is committed to a policy which supports the expansion in absolute emissions from aviation, and that airlines may be able to outbid other industries for carbon credits through being better able to simply pass costs onto customers. As Friends of the Earth explained in our recent inquiry into Pre-Budget 2005:

Mr Juniper: […] There are concerns being expressed, for example, by cement, steel and aluminium companies […] because they fear that the purchase of credits by the aviation sector could mean that they would have to go to China in order to remain in business and that the aviation companies […] can pass on the cost very quickly to their customers. If you want to fly from Stansted, you can only fly from Stansted. If you want to buy cement, you can buy it from England but you can also buy it from China. So they see this as being potentially quite a negative impact on those other sectors which are included in the ETS […][176]

Such concerns led the Aviation Environment Federation to suggest to us that pre-emptive opposition from such industries might lead to the terms on which aviation enters the ETS the emissions cap it is givenbeing watered down.[177] The AEF also expressed scepticism about the idea that one of the effects of inclusion would be to drive on carbon efficiency improvements within aviation: "We have a gut feeling that if and when aviation emissions are part of any ETS all these supply-side efficiency gains will be smartly attributed to an "ETS effect". We believe that the technology and operational gains identified as possible […] would in all likelihood, happen anyway."[178]

122. While we acknowledge the significant potential benefits of including aviation within the EU ETS, there remain very considerable uncertainties to be resolved before we can have confidence that such benefits would actually be realised. This underlines the need for the Government to step up still further its negotiations with European partners - and to take much bolder action unilaterally in the meantime.

123. On the timing of inclusion of aviation in the ETS, in 2004 our predecessor Committee expressed its astonishment "at the lack of essential research to underpin the incorporation of aviation in the EU Emissions Trading System (ETS)", and concluded: "In view of the timescales involved in developing and ratifying EU directives, we suspect it may soon be too late to achieve the Government's professed intention of incorporating aviation in the second phase of the EU ETS from 2008."[179]

124. None of the evidence we have heard in our inquiry has given us any reason to alter this view. We noted that the Secretary of State would not give an opinion on when he thought it would happen, but merely confirmed that it was still the Government's "ambition […] to try and secure that entry from 2008 or as soon as possible thereafter."[180] Indeed, the Secretary of State himself drew attention to ongoing opposition to the inclusion of aviation in the ETS from European airlines and governments:

Mr Alexander: […] In terms of where we are in those negotiations, the evidence from the public statements of Lufthansa, even in the last 48 hours, evidences that the argument is not yet won within the aviation community. It is also no secret that some of our international partners are less than convinced of the merits even of a European scheme, never mind a wider scheme given the global nature of air travel.[181]

Furthermore, we also learned that the Government has not even begun to talk to the UK aviation industry about what level of carbon allocations it should receive within the ETS.[182] While we commend the very significant leadership which the Government has shown in raising this issue up the European agenda, the evidence we have received suggests that inclusion of aviation within the ETS is still several years away.

125. This highlights the need for the Government to start actively preparing a "Plan B" for dealing with CO2 from UK aviation. CCP 2006 states that: "The Government has made it clear that it reserves the right to act alone or bilaterally if progress at an international level proves too slow."[183] However, when we pressed the Secretary of State on what this alternative plan was, and when the Government would decide it was time to adopt it, he claimed that even to hint at what and when it might be would undermine the Government's efforts to persuade other EU governments to agree on inclusion of aviation in the ETS.[184] His argument was essentially that simply outlining an alternative would be to give the impression that the UK was not serious about the ETS, and give other States an excuse to raise objections to it themselves. We fundamentally reject this argument, and are concerned that it may simply be a cover for the fact that the Government does not have, in the end, any substantial idea for a "Plan B". Indeed, we would argue that to publish proposals and a timetable for UK action (to be taken if the ETS route were taking too long) would actually increase the pressure on all parties to agree to an early inclusion of aviation in the ETS. The Department should publish such a timetable and set of proposals as soon as possible.

Flying and taxation

126. It is scandalous that governments around the world have failed to grasp the nettle of taxing aviation fuel. It is equally scandalous that no Member State within the EU charges VAT on international air tickets. While this would require co-ordination across the EU, individual States are free to impose VAT on domestic tickets. Beyond this, in 2001, the Government made reforms to Air Passenger Duty (APD) which had the effect of cutting the tax on most short-haul flights from £10 to £5 - a cut which meant that, even while passenger numbers went up by 35% from 2000 to 2004, with emissions rising by 10%, APD revenue went down by 8%.[185] And Budget 2006 froze APD for the fifth year running (since it was reformed in 2001, when its main effect was the cut referred to above), with its only reform being to cut the tax on economy flights to Croatia by £15.[186]

127. In previous reports, EAC has consistently called for Air Passenger Duty to be raised. The Government has consistently insisted that APD is a blunt instrument and "not an environmental tax", given that it does not differentiate between flights in terms of their carbon emissions per passenger. In our report on Pre-Budget 2005, we recommended that APD be reformed in a way that ensured aviation paid more of its external environmental costs. Since then there has been further public discussionfor instance, from the Liberal Democratsof reforming APD to levy it per plane rather than per passenger. We asked Friends of the Earth about this, who told us:

Mr Dyer: It makes sense because it would hopefully encourage airlines to fill the planes better, whereas very often they have up to a quarter of empty seats. […] The other thing I would hope it would do would be to encompass freight flights as well, which are entirely untaxed at the moment. Obviously they pay no air passenger duty and they benefit from tax-free fuel, which is somewhat unfortunate when they burn magnitudes more fuel and carbon compared to surface transport for a lot of freight which does not need to go by air.

128. However, FoE were in addition very clear that the most important contribution could be made simply by raising the levels of APD, regardless of how it was charged:

Mr Bullock: […] It is caricatured as being a blunt instrument, but that is a smokescreen, in my view. It is blunt and they do not like it because it is effective. If you run it through the Department for Transport's own models, if [set at a level simply] to stop the fall of aviation's cost, then that runs through their models and massively affects the demand projections for 2030 to the point that you do not actually need the new runways that they claim are necessary at the moment. There are not so many problems. APD does not need to be reformed before it can be increased, basically, although it could be worthwhile having reform.[187]

129. Speaking to members of the Swedish government, we learned that Sweden has recently introduced a policy of differential landing fees. Landing fees can be used to financially penalise less carbon efficient aircraft relative to more modern and carbon efficient aircraft. Appearing before the Committee, the Secretary of State acknowledged the potential for landing fees to be used in this way, and appeared to outline a Departmental preference for this above a reformed version of Air Passenger Duty, but seemed to rule out any action in this direction for the foreseeable future:

As my predecessor has said, APD seems to us a fairly blunt instrument. On a previous occasion it has been suggested that if you were interested in terms of incentives to the industry to effect the kinds of changes we want to see, given the changes that have taken place in airline technology and the fact that the fleet coming into Heathrow tends to be a younger and therefore more fuel efficient fleet than other airports across the world, one of the things that could be considered would be whether you can incentivise the right kind of aircraft to be landing in terms of your landing charges at Heathrow. We are not actively participating in that discussion at the moment because my main focus is on making sure that we see the progress we want to see in terms of aviation in the ETS.[188]

130. The Government has no excuses for not raising Air Passenger Duty. When we have recommended this in the past, the response has been that APD is a "blunt instrument" that does not differentiate between the relative carbon-efficiency of different flights. Our response to this is that APD could be levied per flight, rather than per passenger. Above all, however, whether reformed or not, APD should be raised so as to slow the growth of aviation and stabilise its absolute level of emissions.

131. At the same time, we welcome the Secretary of State's acknowledgement of the potential role that differential landing fees could play, and urge him to introduce them. They could be used to complement a reformed and increased APD, in that they could specifically target the fuel efficiency of different models of aircraft.

132. On our trip to the Netherlands, we met officials at the Ministry of Transport and the Ministry of Environment, who gave us details of a recently-imposed aviation tax levied specifically on domestic flights. We discussed the possibility of another State concluding a bilateral agreement with the Dutch government, expanding such a tax to cover both internal flights within each country and international flights between them. While no such an agreement was actually being talked of, they agreed that it would be allowed by international regulations. The Government has the power to increase taxes on domestic flights: it should do so, and as soon as possible. It should further work to conclude bilateral agreements with European partners to levy additional taxes on flights between them. Revenue generated as a result could be put towards investment in improving rail services, including high speed rail links, and to accelerating the development and introduction of more energy efficient aircraft designs.

133. In this inquiry we heard from BAA that airport vehicles are allowed to run on "red diesel"—taxed at 6.44p a litre[189]—because they do not run on public roads, even though airports are major sources of both carbon emissions and air pollution.[190] (Although BAA told us they "have a fast-moving programme of change to get away from fossil fuel-based vehicle fleets to renewable energy fleets",[191] the use of red diesel naturally means there is less financial incentive for airports to invest in low carbon vehiclesfully electric vehicles would be particularly suited to this role, given the short distances and low speeds involvedwhich would also improve local air quality.) This anomaly should be ended forthwith.

Consumer information and carbon offsetting

134. One of the Department's four carbon reduction priorities is "encouraging people to be more aware of the environmental impact of the journeys they make and encourag[ing] them to make more environmentally friendly journeys."[192] As part of this, the Department has helped to introduce the fuel efficiency labelling of new cars in car showrooms. There is, however, nothing equivalent to this in respect of aviation. That this is particularly needed is illustrated by the Department's own research which has shown that only one in eight air travellers associate flying with its impacts on climate change.[193]

135. The Government should study how best to raise public awareness of the climate change impacts of flying, and of the undesirability - and ultimately impossibility - of ongoing increases in flights within a declining carbon budget. As part of this, the Department should force airlines which operate services from and within the UK prominently to display (eg, on all their adverts, tickets, and webpages) a fuel efficiency label, similar to that for new cars, based on the average fuel efficiency of their entire fleet which flies out of UK airports. Additionally, wherever airlines advertise the routes which they operate from the UK, they should be compelled to state the relevant carbon emissions per passenger—according to a nationally-set methodology for calculating them - alongside the fare.

136. Carbon offsetting is one means of both raising awareness of the climate change impacts of aviation, and of helping to reduce them. Offsetting is an attempt effectively to cancel out a calculable amount of carbon one is responsible for emitting (eg, from a specific plane journey), by paying a fee which goes towards a carbon reduction project. This sometimes involves planting trees, but increasingly now means funding a low carbon energy project in a developing economy.

137. We welcome the Government's new commitment to offset all its air travel through the new Government Carbon Offsetting Fund. Equally, we share its enthusiasm for voluntary offsetting schemes. At the same time, we fully recognise that offsetting is not the solution to the global warming problems caused by growth in aviation, which fundamentally requires a stabilisation of its absolute emissions. Also, we retain concerns as to the potential for offsetting schemes to be subject to fraud. Given that offsetting payments are relatively cheap, help to tackle climate change, and can be used to improve the lives of deprived communities in the developing world, the Government should make them a compulsory charge on all airline tickets. It is important, however, that this is accompanied by rigorous auditing of the projects funded as a result. Moreover, the public should not be encouraged to think that offsetting implied that growth in aviation emissions was environmentally tenable.

138. Given that in CCP 2006 the Government went out of its way to praise "recent airline initiatives, allowing customers to voluntarily calculate and offset emissions from their flights"[194] as a contribution to the UK Climate Change Programme, we feel it only right to report our observations on the scheme operated by British Airways through Climate Care. In our recent experience of flying with British Airways, we found that at "no point in the passenger experience from booking to landing was it ever mentioned […] as an option by anyone involved in that process."[195] Indeed, Dr Andrew Sentance of BA confirmed that take-up of the scheme had been low: "We have offset between 1000 and 2000 tonnes of CO2 with Climate Care in the past year."[196] Considering that, according to BA's own website, a single fully loaded jumbo jet will account for 1574 tonnes CO2 on one return flight between Heathrow and Sydneybased on a load of 410 passengers, each calculated to emit 3.85 tonnes CO2 and paying an offsetting charge of £28.83this is not very impressive.[197] What seems just as unimpressive is that, if one goes direct to Climate Care's own website, the figure it gives per passenger on the same flight is 5.61 tonnes CO2, at a charge of £42.11.[198] The difference is due to the different methodology which BA use to calculate emissions from flights.

Latest research on radiative forcing

139. One of the things which has changed since EAC's last report on aviation is the state of scientific research on the extent of radiative forcing from aviation's non-CO2 contributions to global warming. As DfT explained to us:

The original and previously most widely supported work relating to the non-CO2 impacts of aviation is that of the IPCC in 1999, which suggested a reference factor of 2.7. […] The multiplier of 2.5 was used in a March 2003 joint report by HMT and DfT on 'Aviation and Economic Instruments' to estimate the climate change related external costs of aviation.

More recent research: Trade-Off in 2000[199] updates the estimate of carbon dioxide forcing to the year 2000 and improves the accuracy of the impact assessment, resulting in a factor of 1.9. […]

In order to reflect the most recent and robust scientific evidence currently available, Government has therefore decided to recognise the more recent TradeOff work and use a multiplier of 2. The multiplier of 2 has been adopted for the Government Carbon Offsetting Fund.

This decision will be kept under review as further scientific evidence becomes available. […][200]

140. We would simply observe that in neither the original IPCC report nor the more recent TRADEOFF paper do the multipliers take the possible effects of aviation-induced cirrus clouds into account (essentially, because the science is still too uncertain to quantify them with adequate confidence).[201] For this reason, we welcome the Government's commitment to keep its assessment of the radiative forcing (RF) of aviation under review, as further scientific evidence becomes available. This is particularly welcome, given that the paper it relies upon states that, depending on the results of further study into the effects of cirrus clouds, "It is possible that the total aviation RF could be twice as large as the total RF given here." In its current progress review of the Future of Aviation White Paper, the Department should clearly state how it proposes to alter its aviation policies, should further research indicate that the effects of cirrus clouds are indeed so large.

163   Environmental Audit Committee, Aviation: Sustainability and the Government's second response, para 6 Back

164   "Reducing Carbon Emissions from Transport", Environmental Audit Committee press release, 19 January 2006  Back

165   Cm 6764, p 70 Back

166   A. Bows, K. Anderson, and P. Upham, "Contraction and Convergence: UK Carbon Emissions and the Implications for UK Air Traffic", Tyndall Centre for Climate Change, February 2006  Back

167   DfT, Aviation and Global Warming, January 2004,, para 3.57. The Department in this context defines "UK aviation" as encompassing both domestic and international departures. Back

168   Environmental Audit Committee, Pre-Budget Report 2003: Aviation Follow-up, para 42  Back

169   For reference, if aviation emissions in absolute terms were kept at their current levels through to 2050, then aviation's share of the UK carbon budget would still rise, given the cuts made by all other sectors. To put it another way, if aviation does not join in the carbon reduction process, it will still force all other sectors to make steeper cuts, even if its emissions do not grow at all in absolute terms. Given the projected improvements to fuel efficiency which the industry forecasts, fixing emissions at their current levels would still allow for a substantial increase in passenger numbers. This questions still further the need for an aggressive airport expansion plan. It also suggests that there is actually significant room for both an expansion of aviation and an enforcement of some level of absolute reductions in aviation emissions at some point by 2050. Back

170   A. Bows, P. Upham, K. Anderson, "Growth Scenarios for EU and UK Aviation: contradictions with climate policy", Report by Tyndall Centre for Climate Change (North) for Friends of the Earth, April 2005,  Back

171   Qq 566 -7 Back

172   Cm 6764, p 71 Back

173   The Government says it "is also continuing to press for the development and implementation, through the International Civil Aviation Organization, of emissions trading at the international level." Cm 6764, p 71 Back

174   Cm 6887, para 6.38, p 132 Back

175   Ev 236 Back

176   Oral evidence taken before the Environmental Audit Committee on 1 February 2006, HC (2005-06) 882, Q 18 Back

177   Ev236 Back

178   Ev230 Back

179   Environmental Audit Committee, Pre-Budget Report 2003: Aviation Follow-up, para 36 Back

180   Q703  Back

181   Q703  Back

182   Q573 [Mr Dowds] Back

183   Cm 6764, p 72 Back

184   Q 710 Back

185   Environmental Audit Committee, Pre-Budget 2005: Tax, economic analysis, and climate change, para 17 Back

186   That is, it reclassified Croatia as a destination to which the EU rates of Air Passenger Duty, rather than the more expensive long-haul rates, should apply. Back

187   Q603 [Mr Dyer, Mr Bullock] Back

188   Q705 Back

189   Rate given for "Marked gas oil and ultra low sulphur diesel not for road fuel use". HM Revenue & Customs, "Current Hydrocarbon Oil duty rates", viewed 13 July 2006, Back

190   Q546 [Mr Dowds] Back

191   Q546 [Mr Dowds] Back

192   Q646 Back

193   DfT, Attitudes to Air Travel, 2002,,p 15 Back

194   Cm 6764, p 72 Back

195   Q530 [Mr Hurd] Back

196   Q 531 Back

197  Back

198  Back

199   Sausen R., Isaksen I., Grewe V., Hauglustaine D., Lee D. S., Myhre G., Köhler M. O., Pitari G., Schumann U., Stordal F. and Zerefos C. (2005) "Aviation radiative forcing in 2000: and update on IPCC (1999)", Meteorologische Zeitschrift 114, 555 - 561 Back

200   Ev221-2 Back

201   Sausen, R., et al, (2005), p 559 Back

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