The aviation industry is currently on a path to becoming climate-neutral and various stakeholders such as airlines, airports, and regulatory bodies are setting targets to achieve this goal. The purpose of this chapter is to explain aviation's contribution to climate change and the existing efforts of the industry to reduce and mitigate climate impact. The chapter covers recent evidence suggesting that our changing climate is beginning to impact the industry, largely in a negative manner. Therefore, the industry will need to plan and adapt to its changing environment while developing new technologies and approaches. The challenges and opportunities of alternative aircraft fuel and energy source are presented, along with modifications to infrastructure that will accelerate the transition to a carbon and climate-neutral industry.
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In 2019, the aviation industry contributed 2.1% of all human-induced carbon dioxide emissions and approximately 12% of all carbon emissions from the transport sector (ATAG, 2020). As the aviation industry begins its recovery in the post-pandemic world, it’s contribution to carbon emissions and climate change will increase relative to other transport modes. This is in part, due to the rapid expansion of aviation expected in the post-pandemic period which will see more passenger carriage and aircraft operations. It is also due to higher power and energy requirements of aircraft operations which makes it difficult to transition to alternative energy sources that are able to deliver the payload and range performance achievable with existing fossil fuel sources. At the same time, the rapid electrification of surface transport modes such as cars and heavy goods vehicles reduces their contribution to climate change, resulting in a proportional increase in the climate impact of aviation. However, the aviation industry has had a successful history of developing new technologies and operational practices to drive efficiency and reduce environmental impact. During periods of high fossil-fuel prices, airlines have placed greater emphasis on introducing technology and developing practices to reduce fuel burn, helping to reduce operational cost and emissions. According to Schafer and Waitz (2014), aircraft fuel burn reduced by 70% between 1960 and 2000.
Although improvements to aircraft, engines and operational procedures have enabled aviation to become relatively more efficient and environmentally friendly, the continued rate of development is unlikely to fast enough to meet decarbonisation targets. Instead, alternative fuel and energy sources provides the best hope for radical improvements. The most promising of these technologies is electric-battery aircraft and hydrogen-powered aircraft. However, these sources have their own challenges particularly in terms of airport infrastructure developments and logistics to accommodate new aircraft.
From a commercial perspective, there are also pressures for the industry to become greener. In the last decade, investors and shareholders have been demanding more sustainable practices by airlines and airports, and passengers are becoming more environmentally conscious when travelling. In some countries, there has been evidence of declining air travel demand. In the first three quarters of 2019 average monthly demand for domestic air travel in Sweden fell by 8.7% compared to 2018 (Gossling et al. 2020).
Aviation’s contribution to climate change is not just limited to carbon dioxide emissions. Aircraft engines also emit oxides of nitrogen (NOx) which have a net warming impact, in the short-term, due to the formation of atmospheric ozone (Lee, 2018). In addition, water vapour and soot emissions from engines may form condensation trails (contrails) depending on atmospheric conditions. These line-shaped clouds reflect incoming solar radiation (cooling effect) but also trap outgoing radiation (warming effect). The net effect is that of warming and contributes to climate change; an effect which is further enhanced if contrails evolve into long-lasting cirrus clouds.
Furthermore, the period of aviation’s growth and expansion over the last half century has coincided with a period of rapid climate change with average surface temperatures increasing by 0.2oC per decade (Allen et al., 2019). The associated extreme weather events, sea-level rises and changes to other weather phenomenon has and will continue to impact aviation operations. For example, coastal airports may need to build sea defences and airlines may need to plan for more frequent and severe in-flight turbulence. Therefore, not only does aviation impact to climate change, but a changing climate also impacts the aviation industry. Thus, climate change is a significant component for the operational and commercial sustainability of the industry.
The objectives of this chapter are to: