Air Travel CO2 Emissions
Distance Calculations
The NETZERO Air Travel Calculator presents estimates of the distances between 300 major airports in the United States, based on the use of an "Arc Length" formula applied to the longitude and latitude of each airport, as reported by the Federal Aviation Administration (FAA). This formula allows us to calculate the distance in statute miles between two points on the globe while compensating for the curvature of the Earth's surface.
Calculating Total Emissions per Flight
To calculate the total emissions, we need an estimate of the emissions per passenger mile. All of the assumptions we have incorporated in our calculator for both the flight categories and emission factors are based on those developed by the World Resources Institute's (WRI) Safe Climate project.
Flight Categories
The WRI defines three categories for airline flights based on their relative travel distance:
- Short Haul flight - less than 452 kilometers (280.9 miles)
- Medium Haul Flight - between 452 kilometers and 1600 kilometers (994.4 miles)
- Long Haul Flight - 1,600 kilometers or more.
Emission Factors
In order to estimate a traveler's individual contribution to emissions, we need to have a standard emission factor that allows us to convert units of distance into CO2 emissions. The WRI has developed separate emission factors for each of the three flight categories:
- Short haul flights - 0.18 kg of CO2 per passenger kilometer
- Medium haul flights - 0.13 kg of CO2 per passenger kilometer
- Long haul flights - 0.11 kg of CO2 per passenger kilometer
Conversion of Miles into Kilometers
The final piece of information needed to complete the calculation is the conversion of Statue Miles into Kilometers (Number of miles X 1.609 kilometers).
Total Emissions
The final calculation of CO2 emissions for is based on:
Total miles converted into kilometers x the appropriate emission factor of CO2 emitted per kilometer of air travel. We then multiply this by 2 for a round trip. The final result is a conversion of these total kilograms of CO2 into metric tons based on the conversion factor of 1,000 kg per metric ton.
Sample Calculation
Here's a sample calculation:
(500 miles x 1.609 km/mile = 804.5 kilometers) x 0.13 Kg. of CO2 per kilometer (medium haul flight) = 104.585 kilograms of CO2 x 2 for a round trip flight = 209.17 Total Kilograms of CO2 / 1,000 = 0.21 metric tons.