Some information on this page was taken from the American Forests webpage.
The measurement of a single passenger’s portion of a jet aircraft’s contribution to climate change is subject to a great many variables based on the number of seats, the number of passengers, and the type and efficiency of the aircraft’s engines, as well as the distance traveled. Shorter trips use considerably more miles-per-gallon-per-seat. The fuel efficiency is lower on shorter trips than on longer distance flights because take-off and landing use much more fuel than flying at altitude.
The Federal Aviation Administration estimates an average of 48 miles-per-gallon-per-seat. This figure takes into account non-revenue passenger miles such as those incurred while taxiing and in holding patterns.
Jet fuel and gasoline for cars create about the same amount of CO2 emissions per gallon (around 20 lbs per gallon).
Cars have fuel efficiencies anywhere between 10 mpg (a large SUV) to 60 mpg (a hybrid engine car like the Honda Insight). That means, if you travel alone in your SUV, you’ll create more emissions than if you had taken an airplane. If you drive to your destination with your whole family in your small Honda, the emissions per person will be much lower than if your whole family had taken the plane.
This does not take into account the issue of marginal versus average carbon emissions. In other words, you could argue that the plane flies anyway, no matter if you are on it or not. Looked at it from this angle, adding one more person to the plane will only very marginally increase the amount of fuel the plane uses. From this view, it is always better to fly than to drive, because you’ll avoid the emissions from your car.
Yet this argument is flawed. Planes only fly because there are people who want to get to places. During the Y2K scare around the turn of this century, hundreds of flights were canceled, because people chose not to fly. The consumer drives the supply.
The question of which is the more environmental choice — traveling by car or by plane — has no easy answer.
Even so, here are some simple suggestions for you to consider:
If you can avoid traveling for business by using video and phone conferencing, do it.
If you have the option of taking the train instead of the plane or car, take the train.
If you can choose between local vacations and vacations somewhere far away in the tropics, stay local.
New York is 2,462 miles from Los Angeles. There are 128,100 Btus of energy in one gallon of kerosene-type jet fuel, and it requires 3,999 Btus of energy to move one passenger one mile in a commercial jet. (Calculated from: Oak Ridge National Laboratory, Center for Transportation Analysis, Transportation Energy Data Book: Edition 20, Nov 2000.)