Other blogs in the series "Flying High: Aviation and Net Zero": Part 1 - Airlines: a polluting comfort Part 2 - Sustainable aviation: a difficult process
Airlines are useful, and many of us enjoy flying for holidays, working abroad, or seeing distant family. The aeroplane has become a part of life, like the car or train, an accepted mode of transportation. We are now more aware that air travel is not guilt-free – but how many of us are aware of the extent of its polluting impact? In this blog, the effect of airlines on the environment is explored, as we document how flight has become a major source of concern for climate justice activists and policymakers.
While the Wright Brothers are generally known as the inventors of the modern aeroplane, commercial airlines can be traced back to the early 20th century. Beginning with the United States Postal Service’s airmail service using military aircraft following the First World War, the 1920s saw the emergence of passenger airlines such as KLM, Air France, and Lufthansa, which still exist today. Limited to very few passengers, these flights nevertheless became popular among a wealthy elite of businessmen, journalists, and European colonial administrators, rapidly increasing the speed of travel within and between continents.
Access to aeroplane travel gradually expanded with the size and efficiency of jets, and the second half of the 20th century saw a major expansion in air passenger numbers. Despite remaining a relatively expensive form of travel, 100 million passengers travelled by air in 1960, according to a brief from the Environmental and Energy Study Institute. By 2017, this number had reached over 4.5 billion (this figure includes passengers who fly multiple times separately). Although the absolute greenhouse gas emissions of electricity generation, agriculture, and even road travel outweigh those of commercial aviation, the proportional impact of a single flight is one of the most intensive sources of individual emissions footprints. Higher rates of flying in Europe and North America are an important cause of global emissions inequalities: single flights often outweigh an entire year’s emissions for the average person in many countries of the Global South.
The continuous growth in passenger numbers since the 1970s has not shown signs of slowing in response to the climate crisis. While the outbreak of the COVID pandemic in 2020 led to the largest decline in yearly passenger numbers on record, passenger numbers appear to be quickly recovering according to 2022 data. It is also clear that the aviation industry also sees these passenger declines as temporary: manufacturers Airbus and Boeing project significant profit growth for this year, and wider expert predictions point to a return to the growth trends of the previous half-century.
This future growth is partly linked to projected trends in international development, as air travel becomes cheaper and accessible to billions of new passengers in the Global South. The International Air Transport Association (IATA) estimates that annual air passenger numbers will rise to 8.2 billion by 2037. Predicting the continuation of trends toward Western-style consumer society in much of the world, the body forecasts that Asia contributes more than half of all new passengers over the next 20 years. According to this model, China will become the world's largest aviation market by the mid-2020s, India will replace the UK as the world's third-largest market around this time, while Indonesia will become the fourth-largest passenger market by 2030. Demand for flights, therefore, looks set to grow, as large numbers of first-time passengers add to growth that has historically been a product of a global privileged minority.
Linked in part to growth in passenger numbers is growth in emissions, which has already been severe in recent years. In 2013, the CO2 contribution of commercial aviation was placed at 710 million tonnes, rising over 24% by 2018 to reach 905 million tonnes. If military aviation is also included, the 2018 emissions linked to the sector exceed a billion tons (see figure below). US commercial aviation alone contributed 202.5 million tonnes of CO2 in 2017, or 23.5% of the total CO2 produced by commercial aviation. The ICAO (International Civil Aviation Organization of the United Nations) predicts that aviation emissions will triple by 2050, by which time it is estimated that airline emissions will account for about 25% of global carbon emissions. Despite the size of these numbers, emissions growth has historically outstripped ICAO predictions: between 2013 and 2018, CO2 emissions from commercial aviation increased 70% more than the body had predicted. This makes for troubling reading for those concerned with curbing and reversing the growth of global greenhouse gas production.
Image: Budapest Ferenc Liszt International Airport. Source: Jorge Franganillo, distributed under a CC-BY 2.0 license.
Overall, aviation accounted for 11% of total CO2 emissions from transport in 2015, and 1.5% of global greenhouse gas emissions. In Europe, direct emissions from aviation accounted for 3.8% of total CO2 emissions and 13.9% of emissions from the transport sector, as of 2017. These proportions might appear small, but again, it is the inequality and individual intensity of production of these emissions which presents air travel as a major issue for climate campaigners. As a report by the European Commission highlights, someone on a return flight from Lisbon to New York generates roughly the same level of emissions as the average person in the EU does by heating their home for a whole year. If everyone on Earth were to take one long-haul flight per year, the resultant carbon emissions from the aviation sector would exceed the present yearly total for the entire United States.
Of course, not everyone on Earth is taking a long-haul flight every year, and aviation is a primary issue of climate justice. Frequent fliers have a disproportionate role in the production of aviation emissions: Dan Rutherford of the International Council on Clean Transportation (ICCT) has highlighted the importance of a group of business travellers who fly six or more times per year, and are more likely to fly in the more carbon-inefficient business-class. He estimates that, if everyone flew as much as this group, ‘global oil consumption would increase by 150% and CO2 emissions from fossil fuel use by more than 60%’. While all aviation is carbon-intensive and should not be taken lightly, a small number of wealthy frequent fliers should perhaps then be the primary focus of critique, rather than widening markets of new fliers in the Global South. This problem has been highlighted at its extreme by recent attention to private jet usage among the super-rich, which popularised connected to the names of some famous figures. Taylor Swift, or at least her jet, was found to have emitted almost 1,200 times the average person’s yearly emissions. These flights represent a dramatically larger carbon footprint on a per-passenger basis than the infrequent commercial flights taken by many.
As this cartoon by First Dog on the Moon in The Guardian emphasises, a host of business leaders will also be making similar private jet flights, without the media coverage that a celebrity name brings. Private jets are particularly troublesome because they simply would not fly without an individual’s decision to do so. Again, as dramatic cuts to greenhouse gas emissions become particularly urgent, serious questions must be asked of all flights. But the disproportionate impacts of a small elite of frequent fliers and private jet owners are, at the very least, insulting to the efforts made by many to live more sustainably wherever possible.
Image: two private jets on a runway await passengers. Source: Privatejetexpert, distributed under a CC-BY 4.0 license.
Despite widespread recent coverage of action against aviation activists, neither demand nor emissions show any real signs of slowing down. While a limited number of policy interventions have been discussed by European governments, particularly against frequent fliers, few are any more than ideas at this stage. A second blog in this series will discuss expected efficiency increases in aircraft, highlighting that CO2 from the industry will continue to grow as total demand outpaces gains made by technical improvements. Both policy interventions and demand reduction will be required in the sector to comply with Paris Agreement commitments and avoid the worst effects of climate change.