We all know that air travel has impacts on the environment and a number of companies now include offsetting their air travel carbon impacts as one of their green business practices. However this is not as easy as it seems. Carbon emissions are not the only impact from air travel and different offset calculators use differing methodology to determine how much should be offset. Aside from this, the level of your personal emissions also varies depending on flight distance, the type of plane and whether you are flying business or economy. This article will help you understand some of the different factors that contribute to your personal air travel carbon emissions.
Aeroplanes burn fossil fuels to operate which release CO2 into the atmosphere. There are different opinions on how much air travel contributes to global CO2 emissions with figures ranging from 2% to 10%. Not only are CO2 emissions an issue but aeroplanes also release water vapour, nitrogen oxides and methane. The environmental impact 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 determining the impacts of air travel. Radiative forcing is the rate at which a given atmospheric gas alters radiation that is entering the atmosphere.
Not all emissions calculators include the radiative forcing factor in their calculations which underestimates the environmental impact of the flight. To make it even more complicated there are differing opinions as to what the radiative forcing factor should be set to. The Intergovernmental Panel on Climate Change (IPCC) recommend a radiative forcing factor of 2.7 and this seems to be most commonly used. So for a more accurate assessment of your flights impacts, you want to choose a calculator that includes radiative forcing but the story does not stop there.
There are a range of other variables that affect your individual emissions. First is the distance traveled and whether this is long or short. 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. The type of plane will also impact the level of emissions from the flight as newer model aeroplanes tend to be more fuel efficient.
As for the emissions each passenger is responsible for, this will vary depending on whether the flight is full and whether the person is traveling economy or business. If the flight is not fully occupied, each person will have to offset a higher level of emissions to offset the whole impact of the flight and if you are traveling in business class, you are taking up more space and will be responsible for a greater percentage of the emissions.
As you can see calculating the emissions to offset air travel is not as straight forward as it first seems, in spite of this an understanding of the factors that contribute to your personal emission levels from air travel gives you a better idea how your travel decisions impact the environment.