Monday, 13 July 2018 was a day for the record books. On that day the Swedish company FlightRadar24 tracked 205,468 flights occurring around the world, making it aviation’s busiest day in history. It would be a herculean task to determine the total carbon footprint of all those flights put together, but a basic back-of-envelope calculation yields some jaw-dropping figures. Consider that even a one-way short-haul flight in Canada (such as the average 1-hour trip between Ottawa and Toronto) generates about 4718 kilograms of carbon dioxide (CO2) — about as much as a typical passenger vehicle does in a whole year.
If the Ottawa to Toronto route is representative of the global average in terms of distance travelled, aircraft type, and occupancy, then the aviation sector would have consumed the equivalent of over 2.2 million barrels of oil on that single day! By way of comparison, that’s enough energy to power nearly 105,000 North American homes for a whole year! It is so much CO2 that it would require 1.1 million acres of forest a full year to remove it all from the atmosphere. That’s one big day of air travel!
Of course, it’s quite possible that many of the flights tracked were not as damaging, since the tracking software sometimes includes non-commercial small aircraft. But even if we cut that estimate in half, the energy used would still be equivalent to the amount of oil coming out of North Dakota’s Bakken oil fields every day. The point is that any way you look at it, the aviation industry is an unmitigated climate change nightmare. Studies show that global flight emissions alone account for about 2% of all anthropogenic emissions globally. Yet that’s just direct aircraft emissions of CO2. Planes also emit nitrous oxides, water vapour, sulfates, and soot — which also impact the climate.
The Intergovernmental Panel on Climate Change (IPCC) found that in 1992, aviation was responsible for 3.5% of all “anthropogenic radiative forcing” (in other words, 3.5% of human-caused climate change), which was expected to climb to 5% by 2050. But that figure doesn’t even account for the sector’s broader supply chain, which would have to factor in all the energy that goes into building, maintaining, and energizing airports and runways; producing, refining, storing, and transporting jet fuel; and of course, feeding all those hundreds of thousands of daily travellers.
There are no good global estimates of emissions from the entire aviation supply chain out there. However, one study of the life-cycle emissions for the aviation sector in the US found that an equivalent of 30% of aircraft emissions are generated through indirect categories such as jet fuel production, airport and runway construction, aircraft manufacturing, and so on. If the same is true in global terms, then the aviation sector is responsible for about 4.6% of anthropogenic radiative forcing.
According to the International Civil Aviation Organization (ICAO), there were more than 4 billion air passengers last year. Of course, not everyone in the world flies. In fact, most of the world (80%) has never been on an airplane. And of the remaining 20%, some travel frequently and some travel about once a year. One educated guess is that 6% of the world’s population flies in a given year (as distinct passengers) — so, about 446 million people in 2016. The aviation sector thus has a population akin to that of Indonesia and Nigeria combined, being responsible for about 4.6% of anthropogenic warming.
All of this raises an important question: Why is it that while the world’s biggest oil companies and, more recently, the world’s largest livestock producers, occasionally get lambasted in the media for their willful ignorance on climate change, the world’s biggest airlines do not? While it’s true that there is a growing popular understanding that flying is a “climate negative” behaviour, there is very little sense of how significant the sector is as a contributor to anthropogenic climate change.
More worryingly is how significant it will be according to projections of growing air travel. According to the International Air Transport Association (IATA), air travel is expected to double over the next two decades. So how is the aviation industry avoiding being held to account for climate change? See part 2 of this blog for the answers.
Ryan Katz-Rosene is an Assistant Professor at the School of Political Studies, with affiliation to the Institute of Environment, and research interests in contemporary environmental debates. He is the president of the Environmental Studies Association of Canada, and a coordinator of the International Political Economy Network. Off campus he helps manage his family’s regenerative farm near Wakefield, Québec. Twitter @ryankatzrosene and web ryankatzrosene.ca
 According to ICAO, the average aircraft on that route burns 1866 kg (493 gallons) of aviation fuel during the trip. According to the Energy Information Administration (EIA), jet fuel emits 9.57 kg of CO2 per gallon. So, the average Ottawa–Toronto flight emits 4718 kg of CO2 (4.718 Metric Tons).
 These conversion factors all come from the EPA’s “Greenhouse Gas Equivalencies Calculator” — using a value of 969,398 Metric Tons (Mt) of CO2 (4.718 Mt x 205,468).
 According to the ICAO, the international component of the sector emitted 448 Mt CO2 from direct fuel consumption in 2010. The ICAO also notes that international aviation accounts for 65% of global aviation fuel consumption, meaning that another 241 Mt CO2 is emitted from domestic aviation. Together, 689 Mt CO2 is equivalent to 1.4% of global anthropogenic emissions in 2010 according to the IPCC. According to IATA, air transport accounted for 2% of anthropogenic emissions in 2017 (about 859 Mt of CO2).
 In reality, those two countries combined only produce about 2.3% of global emissions.