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UK Aviation CO2 Emissions Forecast

21st April, 2008

Position statement

The government published forecasts for carbon dioxide (CO2) emissions in Nov 2007. The forecasts are in the document UK air passenger demand and carbon dioxide forecasts, which was published at the same time as the Heathrow expansion consultation documents. The method of estimating CO2 emissions is described in detail in the report and a summary and commentary has been written by the AEF (7 page Word document).

Method of calculation

The most important determinants of emissions are number of passengers and fuel efficiency. AEF has carried out simple estimates of CO2 growth in emissions using the DfT’s passenger forecasts and fuel efficiency and also forecasts of improvements in operating efficiency. The result is a reasonable alignment with the DfT estimates for CO2 growth, given that there are factors such as an increasing average length of trips and freight not included in the AEF calculations. Taking the DfT forecasts for passengers, fuel efficiency and operational improvements as given, the DfT’s forecasts appear reasonable.

Passenger forecasts

The method by which passenger forecasts are estimated are described separately in our paper UK Air Passenger Demand Forecasts together with AEF’s comments on the forecasts. As described in that paper, we consider the general approach to forecasting passengers up to 2030 to be sound, but note with concern that the forecasts imply no significant action to constrain demand, for example, realistic taxes on pollution or constraints in capacity in order to meet climate objectives.

From 2030 to 2050, we consider that the passenger forecasts are extremely dubious, as they assume a sudden abandonment of ‘predict and provide’ policies up to 2030, confirmed in the 2003 White Paper. To illustrate the effect of this covert policy shift, AEF has re-calculated the demand on the assumption of continuing with of ‘predict and provide’ up to 2050. The effect is to increase demand in 2040 by 6.7% over the DfT figure and to increase demand in 2050 by 14.8%. (These increases assume, notwithstanding the above comments, that the 2030 forecast is valid.)

It should be emphasised that AEF by no means supports such ‘predict and provide’ policies – these calculations are simply intended to demonstrate the effect of a continuing with such a policy up to 2050.

Fuel efficiency

The aviation industry and its supporters claim that great improvements have been made over the year and that even greater improvements may be achieved in future. However, the DfT assumes much more modest increases in increases in fuel efficiency. An improvement of 29.7% between 2005 and 2030 is taken, corresponding to an annual (compound) improvement of 1.05%. The AEF considers these forecasts are reasonable and that the government is right not to be swayed by highly optimistic or ‘aspirational’ forecasts from the industry. Given that there are no ‘forcing’ measures even on the horizon (due to the intransigence of ICAO and national governments), a rate of around 1% pa is reasonable.

Operational efficiency

The DfT assumes that there will be 9% improvement in operational efficiency between 2006 and 2019, this being the mid-point of a 6% to 12% range. This is largely due to more efficient routing and air traffic control. This is partly being addressed through EuroControl’s SESAR programme. Early discussions on the environmental implications indicate that getting close to a 10% gain is very unlikely, ie 9% is optimistic.

Total aviation CO2 forecasts

The resulting forecasts for CO2 emissions for UK aviation are:

Year Annual emissions
million tonnes CO2
2005 37.5
2010 42.0
2020 50.0
2030 58.9
2040 61.1
2050 60.3

AEF considers that the DfT forecasts up to 2030 are reasonable. However, this is subject to the important caveat that passenger forecasts are basically ‘predict and provide’ and assume no significant action to constrain demand, for example, realistic taxes on pollution or constraints in order to meet climate objectives.

After 2030 we consider the CO2 forecasts are invalid because of the unjustified assumption of a change from ‘predict and provide’. As noted above, we estimate that passenger demand would be 6.7% higher than the DfT forecast in 2040 and 14.8% higher in 2050.

To a good approximation, CO2 forecasts would be increased in proportion to the passenger forecasts. AEF revised estimates are thus 65.2 mt CO2 in 2040 and 69.2 mt in 2050.

It should be emphasised that AEF by no means supports such a ‘predict and provide’ policy – these CO2 estimates are intended to demonstrate the effect of a continuing with such a policy up to 2050.

Sensitivity analysis

The above figures are the government’s best estimates or ‘central’ case; the DfT also gives a ‘low’ and a ‘high’ forecast a sensitivity tests.

The ‘low’ forecast of CO2 that is 7% below central at 2030 and the ‘high’ forecast that is 6.5% above central. This is a long timescale and there uncertainties in forecasting passenger demand, fuel efficiency, price of oil, action on climate, etc. For these reasons, we consider that the sensitivity tests give a spurious and very misleading impression of the reliability of the forecasts.

CO2 forecasts by sector

Source 2005 2030
Heathrow 18.2 24.9
Gatwick 4.8 5.4
Stansted 1.4 3.3
Luton 0.6 0.9
London City 0.2 0.3
Other UK 9.1 18.2
Ground 1.4 2.2
Freight only flights 0.6 2.4
Uk total 37.5 58.9

The AEF has no particular view on the validity of the individual figures. However, it should be noted that emissions from individual airports will be greatly affected by planning decisions.