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Why Gatwick expansion adds to the aviation carbon headache

In July, Gatwick Airport published its master plan setting out its intention to progress detailed design and development work to bring the existing standby runway into regular use alongside the main runway, while continuing to safeguard land for an additional runway to the south.

Growth projections underpinning the master plan suggest that use of the standby runway could see passenger numbers grow to 70 million passengers per annum (mppa) by 2032/33, a 53% increase on the 45.7 million passengers who used the airport in 2017/18. Aircraft movements are set to grow at a slower rate due to an estimated 10% increase in the average number of passengers per plane, but by 2032/33 they could reach 390,000 movements per annum, around 39% more than the airport handled last year. While the airport says it has no immediate plans to seek permission for an additional runway, the master plan suggests that if it’s built, the airport’s capacity could eventually reach 95 million passengers per annum.

What about the carbon implications of using Gatwick’s standby runway?

But what about the carbon implications of using Gatwick’s standby runway? At first glance it’s hard to find the complete answer. The master plan does point to an increase in the airport’s emissions from 0.77MtCO2 in 2017 to 0.95MtCO2 in 2028, but this assessment is limited in both scope and duration: the analysis shows the emissions that Gatwick is directly responsible for (such as fuel used by vehicles at the airport, and the electricity purchased), as well as indirect emissions from passenger journeys to and from the airport and staff commuting. Aircraft emissions are also included in this calculation, but crucially, only for the landing and take-off cycle, capturing the flights emissions below an altitude of 3,000 feet only. The majority of in-flight emissions, those produced in the climb and cruise phases, are excluded. It also fails to look beyond 2028 which limits its relevance when it comes to analysing how expansion could impact the UK’s ability to reach net zero emissions by 2050.

Department for Transport’s 2017 UK Aviation Forecasts for air passengers, aircraft movements and CO2 emissions at UK airports, provide better evidence for the likely carbon impacts of expansion out to 2050. Unlike Gatwick’s estimate, the DfT forecasts calculate the emissions for the entire flight and attribute them to UK airports on the basis of all departing flights. In a 2050 scenario where Heathrow builds and operates a third runway, Gatwick Airport (without using its standby runway), is assumed to handle 52 mppa, served by 297,000 aircraft movements annually, and generating 2.7MtCO2.

Assuming Gatwick’s standby runway continues to serve a similar range of destinations with the same aircraft fleet mix, and extrapolating the data from the DfT’s scenario and applying it to an increased passenger throughput of 70mppa, this would equate to 3.63MtCO2 in 2050, an increase of nearly 1MtCO2. This may prove to be a conservative figure if Gatwick develops a wider range of long-haul destinations than assumed by the DfT model, or if its passenger numbers increase beyond 70mppa between 2033 and 2050. It is also dependant on delivery of a large number of modelling assumptions including the application of a carbon price that reaches £221 per tCO2 by 2050 (substantially higher than the carbon prices that apply to aviation today, or that are likely to apply in the coming years) and a 48% improvement in aircraft efficiency between 2016 and 2050.

In relation to the Climate Change Act’s original 80% reduction target, the Committee on Climate Change (CCC) consistently advised Government that it should plan for UK aviation emissions in 2050 to be no higher than they were in 2005 (when the sector emitted 37.5Mt CO2). CCC is now expected to write to the Secretary of State this autumn setting out its recommendations for the aviation sector consistent with delivering the newly legislated net zero target. Based on the CCC’s modelling scenarios, there is a strong suggestion that the sector may need to limit its emissions to somewhere between 22-30MtCO2 by 2050, balanced by carbon removals, if the UK is to reach net zero greenhouse gas emissions across the economy. However, with the addition of a third runway at Heathrow, the DfT forecasts show that emissions will not even meet the current 37.5Mt planning assumption and will rise to around 40Mt by 2050. As this forecast assumes other airports will only grow to the levels determined by their existing terminal and runway capacities, the prospect of an additional 1MtCO2 from use of Gatwick’s standby runway, plus any increases from proposed airport developments elsewhere, will heighten the scale of the problem. This will threaten the UK’s ability to meet its climate target, reinforcing AEF’s argument, set out in our response to the Government’s recent aviation strategy consultation, that further runways should be ruled out on climate grounds.