WORKING PAPER 2019-16 CO2 emissions from commercial aviation, 2018 Authors: Brandon Graver, Ph.D., Kevin Zhang, Dan Rutherford, Ph.D. Date: September 2019 Keywords: aviation; aircraft; fuel efficiency; carbon dioxide Using historical data from OAG transport-related CO emissions. SUMMARY 2 Aviation Worldwide Limited, national On a national level, flights depart- Greenhouse gas emissions from governments, international agencies, ing airports in the United States and commercial aviation are rapidly in- and the Piano aircraft emissions mod- its territories emitted almost one- creasing, as is interest among fliers elling software, this paper details a quarter (24%) of global passenger in reducing their carbon footprints. global, transparent, and geographi- transport-related CO2, and two-thirds Under a business-as-usual trajecto- cally allocated CO2 inventory for of those emissions came from do- ry, the United Nations’ International commercial aviation. Our estimates mestic flights. The top five countries Civil Aviation Organization (ICAO) of total global carbon emissions, for passenger aviation-related car- expects aviation emissions to roughly and the operations estimated in this bon emissions were rounded out by triple by 2050, at which time aircraft study in terms of revenue passenger China, the United Kingdom, Japan, might account for 25% of the global kilometers (RPKs) and freight tonne and Germany. CO2 emissions from carbon budget. kilometers (FTKs), agree well with aviation were distributed unequally aggregate industry estimates. across nations; less developed coun- Although ICAO and the International tries that contain half of the world’s Air Transport Association (IATA) Nearly 39 million flights from 2018 were population accounted for only 10% publish annual summary statistics analyzed, and 38 million of these were of all emissions. of aircraft operations and econom- flown by passenger aircraft. Total CO2 ics, respectively, relatively little data emissions from all commercial opera- This paper also apportions 2018 is available about fuel burn, fuel ef- tions, including passenger movement, emissions by aircraft class and stage ficiency, and carbon emissions at belly freight, and dedicated freight, length. Passenger movement in nar- the regional and national levels. totaled 918 million metric tons (MMT) rowbody aircraft was linked to 43% Policymakers cannot determine the of aviation CO , and passenger emis- in 2018. That is 2.4% of global CO2 2 precise amount of carbon emissions emissions from fossil fuel use and a sions were roughly equally divided associated with flights departing 32% increase over the past five years. between short-, medium-, and long- from individual countries, nor can Further, this emissions growth rate is haul operations. The carbon intensity they distinguish the proportion 70% higher than assumed under cur- of flights averaged between 75 and of emissions from passenger- rent ICAO projections. 95 grams (g) of CO2 per RPK, rising and-freight and all-freight op- to almost 160 g CO2/RPK for regional erations, or from domestic and The data shows that passenger flights less than 500 kilometers. international flights. transport accounted for 747 MMT, or 81%, of total emissions from com- To better understand carbon emis- mercial aviation in 2018. Globally, BACKGROUND sions associated with commercial two-thirds of all flights were do- Greenhouse gas emissions from com- aviation, this paper develops a mestic, and these accounted for mercial aviation are rapidly increasing. bottom-up, global aviation CO2 in- approximately one-third of global If the global aviation sector were ventory for calendar year 2018. RPKs and 40% of global passenger treated as a nation, it would have been Acknowledgments: We thank Sola Zheng for her assistance in preparing the data file and graphics associated with this paper, and Dale Hall, Jennifer Callahan, Joe Schultz, Annie Petsonk, and Bill Hemmings for providing constructive feedback on an initial draft. This work was conducted with generous support from the Aspen Global Change Institute. © INTERNATIONAL COUNCIL ON CLEAN TRANSPORTATION, 2019 WWW.THEICCT.ORG CO2 EMISSIONS FROM COMMERCIAL AVIATION, 2018 the sixth-largest source of carbon di- largely unavailable, though, is ad- all aviation CO2 in 2018, are both be- 3 oxide (CO2) emissions from energy ditional texture about the data, yond the scope of this work. The consumption in 2015, emitting more including details of emissions based non-CO2 climate impacts of com- than Germany (Air Transport Action on where flights originate, emissions mercial aviation linked to emissions Group [ATAG], 2019; Olivier, Janssens- from domestic versus international of nitrogen oxides, black carbon, Maenhout, Muntean, & Peters, 2016). travel, and the proportion of emis- and aviation-induced cloudiness The International Civil Aviation sions from passenger-and-freight were likewise not quantified.4 Organization (ICAO), the United and all-freight operations. To help, Nations organization with author- this paper details ICCT’s compila- GLOBAL AIRPORTS DATABASE ity over global aviation, expects CO tion of a new data set and uses that 2 We created a Global Airports emissions from international aviation data to analyze the geographic Database, a database with geograph- to approximately triple by 2050 if cur- distribution of CO emissions from 2 ic information for all of the airports rent trends hold (ICAO, 2019a). If other commercial aviation. It also relates included in the Airline Operations sectors decarbonize in line with the emissions to operational variables Database. For each airport, the city, Paris Agreement’s climate ambitions, like aircraft class and stage length. country/territory, latitude, and lon- aviation could account for one-quarter gitude were recorded from Great of the global carbon budget by mid- METHODOLOGY Circle Mapper.5 Based on the coun- century (Pidcock & Yeo, 2016). Multiple publicly available data try/territory information, each airport In 2009, the International Air sources were acquired and merged was assigned to one of ICAO’s sta- Transport Association (IATA), the to quantify commercial fuel con- tistical regions and subregions. global trade association for cargo sumption using Piano 5, an aircraft (See Appendix A for more informa- and passenger air carriers, set three performance and design software tion on the countries and territories 2 in each ICAO statistical region and goals for reducing CO2 emissions from Lissys Ltd. The data obtained from aviation: (1) an average improve- concerned airline operations, air- subregion.) ment in fuel efficiency of 1.5% per ports, and demand, as detailed year from 2009 to 2020; (2) a limit on below. From that we modeled fuel DEMAND ESTIMATION net aviation CO emissions after 2020 2 burn and estimated CO 2 emissions, We quantified the revenue pas- (i.e., carbon-neutral growth); and (3) and then validated the results. senger kilometers (RPKs) for every a 50% reduction in net aviation CO2 airline-aircraft-route combination emissions by 2050, relative to 2005 AIRLINE OPERATIONS using the number of departures from levels (IATA, 2018a). According to DATABASE the Airline Operations Database; the industry estimates, global CO emis- 2 Global airline operations data for cal- flight distance, itself calculated using sions from the airline industry were endar year 2018 was sourced from airport latitudes and longitudes from 862 million metric tonnes (MMT) in OAG Aviation Worldwide Limited the Global Airports Database; the 2017, and fuel efficiency has improved (OAG). The OAG dataset contained the number of seats for the particular by 2.3% per year since 2009 (ATAG, following variables for passenger and airline-aircraft combination; and the 2019).1 For 2018, IATA (2019) esti- cargo airlines: air carrier, departure passenger load factor associated mated 905 MMT of CO from global 2 airport, arrival airport, aircraft type, with the airline or ICAO route group. aviation, an increase of 5.2% from its and departures (number of flights). 2017 estimate of 860 MMT of CO . Total mass transported, in revenue 2 Operations data for cargo carriers tonne kilometers (RTKs), was quan- DHL, FedEx, and UPS was not avail- The values that groups like IATA tified for both passenger and cargo and ATAG provide annually only able from OAG due to restrictions put give the public a single data point in place by the companies. To com- pensate, we utilized alternate data 3 General aviation, which includes business with respect to fuel burn, fuel effi- jets and smaller turboprop aircraft, is ciency, and carbon emissions. ICAO sources to identify the fuel burn asso- estimated to account for about 2% of total aviation CO (GAMA & IBAC, n.d.). (2019b) provides RPK and FTK data ciated with these carriers’ operations 2 (Deutsche Post DHL Group, 2019; U.S. Data on military jet fuel use is very sparse. by country and geographic region, According to one estimate by Qinetiq, in and breaks down global scheduled Department of Transportation [DOT], 2002, military aircraft accounted for 61 MMT CO , or 11% of global jet fuel use at the services into domestic and inter- 2019). All of these sources were 2 combined to create our new Airline time and 6.7% of 2018 commercial jet fuel national operations. What remains use (Eyers et al., 2004). Operations Database. 4 Though considerable uncertainty persists, 1 Measured in terms of revenue tonne the non-CO2 climate impacts of aviation, kilometers (RTKs) transported per liter of General and military aviation, which as measured by their contribution to fuel. Compounded annually, RTKs have likely accounted for 10% or less of historical radiative forcing, are believed to increased by 6.4% since 2009, while fuel be comparable to those of CO2 alone. See use has increased by 4% over the same Lee et al. (2009). time period. See ATAG (2019). 2 http://www.lissys.demon.co.uk/index2.html. 5 http://www.gcmap.com 2 INTERNATIONAL COUNCIL ON CLEAN TRANSPORTATION WORKING PAPER 2019-16 CO2 EMISSIONS FROM COMMERCIAL AVIATION, 2018 operations. For passenger aircraft, (2014). Changes in aircraft weight for passenger mass and checked RPKs were converted to RTKs by as- due to varying seat configurations baggage (ICAO, 2019c).