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Climate Change and Aviation

Mike Lewinski
Image Credit: Mike Lewinski via Flickr

Key aviation and climate change facts

  • Aviation is one of the most energy and carbon intensive forms of transport, whether measured per passenger km or per hour travelling.
  • Emissions from the aviation industry are forecast to grow both in real terms and as a proportion of the national total. In the UK, the share of emissions taken up by aviation is predicted to grow from around 6% today to 25% by 2050, even if the sector is successfully capped at level of 37.5 MtCO2 (equivalent to UK aviation emissions in 2005) which has been recommended by the Committee on Climate Change.
  • Globally, while only a small proportion of the world’s population account for the 2.1 billion passenger trips made annually (some 3900 billion passenger kms per year), aviation is already responsible for 2-2.5% of global man-made CO2 emissions today, and expected to grow to between 4 and 15% by 2050 (as cited in this report).
  • Aviation contributes towards climate change through a range of ‘non-CO2’ impacts which occur at altitude. The most recent evidence indicates that these non-CO2 effects could double the warming impact of aviation, making the industry’s contribution to global climate change far more significant than current estimates suggest..
  • London Heathrow is responsible for more CO2 emissions from international, scheduled passenger flights than any other airport globally (see page 41 of this report by aviation expert David Southgate, 2012 figures).
  • Technology improvements in aircraft efficiency have been unable to keep pace with growth in the overall level of flying. While historic technology improvements look impressive, official UK forecasts predict annual fleet efficiency improvements of less than one percent between now and 2050.
  • In the UK, where the aviation market is relatively mature, demand for aviation is still expected to grow by around 1-3% annually to 2050, while global growth rates are 4-5% per annum, easily outstripping  ICAO’s’s ‘aspirational’ target of annual 2% efficiency gains until 2050.

Challenges and our work on climate change

Unlike many other sectors that are shifting to renewable power, there are few commercially scalable options for ‘decarbonising’ aircraft in the near future. Biofuels, still touted by industry as one of the main solutions, is predicted in Government forecasts to only make up 2.5% of aviation fuel for flights using UK airports by 2050. Two challenges to the take up of biofuels for aviation are producing biofuels which are sustainable and whether the limited supply of bioenergy that is available can be used more efficiently in other sectors. More information on biofuels can be found here.

In addition, the non-CO2 impacts of aviation such as water vapour and nitrogen oxides have a unique climate impact when released at altitude. Water vapour emitted by planes can contribute to the formation of contrails which have a net warming effect, and, where these are persistent, can contribute to the presence of additional cirrus clouds.

A UN report in 2007 (page 9 here) included estimates of the warming and cooling impacts of all aviation emissions to date using a Radiative Forcing Index (RFI). When summed, these estimates – which remain the most recent figures quoted by the UN IPCC – suggested that aviation emissions have a warming effect 1.9 times that of CO2 alone, excluding the impact of cirrus clouds. Yet scientists say that more work is required to identify a metric that is better suited to future policy measures.

Climate change is a global problem and AEF has been at the forefront of campaigning for international action on aviation emissions as a leading member of the International Coalition for Sustainable Aviation. We continue to maintain pressure on the UN’s aviation agency, the International Civil Aviation Organisation (ICAO), to agree an effective mechanism for limiting aviation emissions, and we participate in ICAO’s work programme addressing the issue. We have actively supported action at the EU level in the interim, including the extension of the EU ETS to cover airlines.

At a UK level we helped secure wording in the 2008 Climate Change Act requiring aviation emissions to be accounted for, and we continue to campaign for aviation policy to effectively support climate change policy and legislation.