Carbon Offsetting & Air Travel Part 1: CO2-Emissions Calculations

This research paper evaluates three prominent air travel emissions calculators, focusing on their handling of aircraft models, flight profiles, cargo, occupancy rates, and seat classes. The authors find that results vary significantly, with economy seat emissions differing by a factor of 1.7 between calculators. TRX Travel Analytics is rated as the highest quality due to its use of extensive, regularly updated datasets and carrier-specific information. The paper highlights that while specificity in aircraft models and seat classes can improve accuracy, uncertainties regarding engine types, maintenance, and actual flight behavior remain challenges for all tools.

• Air travel emissions calculations can vary significantly across different tools, with estimates for a single flight's economy seat differing by up to a factor of three.
• In comparative examples for London to Hong Kong and London to New York, economy seat emissions results varied by a factor of 1.7 between the evaluated calculators.
• The TRX Travel Analytics calculator is identified as the best available tool because it utilizes extensive, regularly updated datasets and allows users to identify the most efficient carrier for a specific route.
• Allocating emissions based on seat space (footprint) creates a much larger disparity between classes than allocation based on weight; for example, TRX Travel Analytics showed a spread of over 300% between economy and business class.
• Aircraft fuel efficiency varies significantly by model; for instance, the fuel burn rate per passenger is one-third higher for a B747-400 than for an A320.
• The Virgin Atlantic calculator is noted for shortcomings, including a failure to account for occupancy rates and a lack of transparency regarding the data used for non-Virgin Atlantic routes.
• Atmosfair's calculator is criticized for using outdated data sources and for subtracting only the marginal fuel increase caused by cargo rather than allocating emissions proportionally by weight.
• Significant factors that impact fuel burn but are often missing from calculators include engine type (up to 15% uncertainty), aircraft type differences (40%), maintenance (9%), and tankering practices (10%).

APA

Kollmuss, A., & Lane, J. (2008). Carbon Offsetting & Air Travel Part 1: CO2-Emissions Calculations. Stockholm Environment Institute. https://www.sei.org/mediamanager/documents/Publications/Climate/sei_air_travel_emissions_paper1_27_03_09.pdf

Chicago

Kollmuss, Anja, and Jessica Lane. Carbon Offsetting & Air Travel Part 1: CO2-Emissions Calculations. Stockholm Environment Institute, 2008. https://www.sei.org/mediamanager/documents/Publications/Climate/sei_air_travel_emissions_paper1_27_03_09.pdf.

Wikipedia

{{cite report |last1=Kollmuss |first1=Anja |last2=Lane |first2=Jessica |title=Carbon Offsetting & Air Travel Part 1: CO2-Emissions Calculations |publisher=Stockholm Environment Institute |date=29 May 2008 |url=https://www.sei.org/mediamanager/documents/Publications/Climate/sei_air_travel_emissions_paper1_27_03_09.pdf |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{kollmuss2008carbon, author = {Kollmuss, Anja and Lane, Jessica}, title = {{Carbon Offsetting \& Air Travel Part 1: CO2-Emissions Calculations}}, institution = {Stockholm Environment Institute}, year = {2008}, month = may, url = {https://www.sei.org/mediamanager/documents/Publications/Climate/sei_air_travel_emissions_paper1_27_03_09.pdf}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }