Increasingly companies are looking to offset the impacts of air travel when implementing green business practices. However there are many factors that affect the level of your personal (or company) emissions. Here I outline the different factors that affect your level of emissions and experiment with four different air travel carbon calculators.
Factors that Affect your Personal Level of Emissions
Radiative Forcing: As well as CO2 from buring aeroplane fuel, aeroplanes also release water vapour, nitrogen oxides and methane into the atmosphere. The environmental impacts of these is greater when released at high altitude than what it would be at ground level. While these impacts are not entirely understood, it is generally agreed that a radiative forcing factor should be used when calculating the impacts of air travel (although there are differing opinions on what the radiative forcing factor should be set to). Radiative forcing is the rate at which a given atmospheric gas alters radiation that is entering the atmosphere. Treehugger has a great article on radiative forcing here.
Short or Long Distance: Short distance flights are less fuel efficient overall due to the fuel consumed during takeoff and landing but they also generate less condensation trails (water vapour) due to the shorter time spent at high altitude which also have an environmental impact.
Type of Plane: Newer planes tend to be more fuel efficient than older models.
Occupancy of the Flight: Calculators work by determining the overall level of emissions for the flight and dividing this by the number of passengers. If the flight is not full each person is responsible for a greater percentage of emissions. Some calculators use historical trends to determine this.
Business or Economy: Business class seats take up more space so each person in business class is responsible for a greater level of emissions.
Air Travel Emissions Calculator Examples
I thought I would put the calculators to the test by considering the emissions of a flight I took a few months ago. The flight was a one way direct flight from Singapore to Brisbane flying economy class. Although there are a huge number of calculators available, I selected these four from doing what a lot of people do when wanting to offset emissions – a google search on “air travel emission calculators”
International Civil Aviation Organisation (ICAO) – Carbon Emissions Calculator
The ICAO calculator has you enter your origin and destination, whether you are flying economy or premium class and whether the trip is one way or return.
The result was a distance travelled of 6,143 km generating 479.41 kg of CO2.
To understand the calculator a link is provided to a 15 page document which explains the methodology and data sources. The calculator is not linked to carbon offsets scheme.
The Choose Climate calculator uses a map where you choose your origin and destination. There are no place names on the map so accurately picking these is a challenge. The calculator also lets you choose between economy or business class, one way or return and lets you change the occupancy figure for the aircraft.
The result was a distance travelled of 7,466 km generating 273 kg of CO2.
The site gives some details of their calculations but not a full methodolgoy and it is not linked to a carbon offset scheme.
The Terrapass calculator has you enter your origin and destination, whether the flight is direct, one way or return and what class you are travelling. The calculator also asks for the airline.
The result was a distance travelled of 3,814 miles (6,138 km) generating 1,1001 lbs (454 kg) of CO2. To offset this through Terrapass costs $11.90.
The CO2 balance calculator has you enter your origin, destination and whether the flight is one way or return.
The result was a carbon total of 1.44 tons (1,440 kg) which can be offset through the website (the price depends onthe project you choose to invest in). The website has some notes explaining its methodology.
Choosing a Calculator
In the end end choosing an emissions calculator will be a matter of personal choice. However the more robust calculators include radiative forcing and provide details on their methodolgy. Out of four calculators tested, ICAO and Terrapass provided the most detail on their calculations and also came up with similar results.
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