Wednesday, May 11, 2011

25 Days to Green Travel: Day Six

4 Principles for Choosing Green Transportation

Thousands of websites have launched carbon emissions calculators, but often these sites only lead to more questions like: How do you choose the most eco-friendly route? Does a bus, plane, train, boat/ship, or car emit less carbon? And why do some sites say that flying produces fewer carbon emissions than driving?
These are all valid questions and honestly, when I started researching carbon footprints I was astounded by the widely varying results I got from different carbon footprint calculators. Thus, to help you choose the most environmentally-friendly form of transport I’ve put together 4 principles for choosing green transportation.
These principles rest on the basic assumption that you cannot realistically walk or bike to your destination.
1. Test an Emissions / Carbon Footprint Calculator
The first step to choosing an option for green transportation is to do some basic research. There are numerous carbon calculators available online and Climate Outreach and Information Network has put together a list of the best carbon calculators. In the transportation/travel category they rank the following as top air and land travel calculators:
Top 5 Air Travel Calculators
(author note: I can’t find the actual calculator on this website)
Top 5 Land Travel Calculators
I personally like Choose Climate because it allows you to enter the type of ticket and plane, but it’s not the prettiest of the calculators.
Or if you like visuals you might like this calculator by the UK’s Transport Direct. However, when considering this calculator read the next three principles.
2. Be a Skeptic
Let’s face it, there’s money to be made in the world of “green.” And many of the organizations that offer carbon calculators offer them for just that purpose – $$$. Moreover, while calculating carbon emissions should be an exact science, no one seems to have perfected it yet (from Climate Outreach and Information Network):
We found massive variation in the calculators’ emissions estimates. For a return flight to Tokyo, the highest estimate was 15.66T ( and the lowest was 1.71T ( One is nine time more than the other! This means users need to be very careful which website they choose to calculate their emissions from air travel.
One of the reasons this variation occurs is because calculators differ in their assumptions of size of plane, number of passengers, coach/first class, number of stops, and one-way or return flight. Because of the possible ulterior motives and the lack of precision in calculators, don’t immediately make your transportation decision on the results of a single calculator.
3. Consider the Impact of Flying High
Another piece of the puzzle to consider is the difference in carbon emissions on the ground versus in the air. Planes fly higher in the atmosphere, thus their emissions are much harsher on the environment. Oxford University estimates that “the full climate impact of aviation is deemed to be between 2 and 4 times greater than CO2 alone.”

According to Grist:
Apparently to attempt an accurate whole measurement of air travel’s climate impact, one needs to account for “radiative forcing”: how the released gases, including nitrogen oxides and water vapor, alter the radiation entering our atmosphere. The science of radiative forcing is quite complex and in flux, what with the variety of flights and the changes in weather and the uncertainties of science and so forth, hence airplane emissions are often calculated by multiplying the carbon emissions with a set number. The Nobel Prize-winning IPCC sets a multiplier of 2.7.
4. Use Common Sense

The bottom line is, use your best judgment. A train is going to be better than a bus which will be better than a car which will be better than a plane. And the more people that fit into these vehicles the better. You also need to think about what makes sense for your location. Going from Washington, D.C. to New York City via Amtrak is reasonable for most people (in terms of the time the trip takes), but going from Washington, D.C. to San Francisco on a train isn’t realistic for many folks. In the end, you have to weigh your personal wants and needs against your impact on the environment.

4 Principles for Choosing Green Transportation is the fifth post in Go Green Travel Green’s 25 Days to Green Travel series. You can see the complete list of articles in the 25 Days to Green Travel Index.
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