Question from Linda of Eureka, CA:

Here’s a question that my brother and I have been ruminating about. I don’t know the price of jet fuel, but what makes the most sense: to take my parents on a road trip from Seattle, WA down to Eureka, CA (about 1000 miles roundtrip), or to fly them, which makes the lesser carbon footprint? Of course, if I drove them, my Prius gets about 60 miles to the gallon.

Answer from faircompanies:

With all the low-cost airlines these days, more and more of us are making our short-distance travel by plane instead of the car or train (though not as common an alternative for Americans as it is for Europeans). Obviously, the train, or bus, are much better alternatives to air travel, but if you’re choosing between a plane and a car, it’s not always so obvious.

To calculate your carbon footprint, here’s a site that will determine your CO2 usage for plane or car trips. Let’s start by calculating the estimated footprint for your proposed roadtrip.

First of all we need to determine your gas mileage for your Prius, which seems to be a controversial topic. While the EPA ranks the Prius as #1 in gas mileage with 60mpg in the city and 51mpg on highways, many Prius owners have reported their mileage as being closer to 43mpg. For this exercise, we’ll use the EPA’s 51mpg highway number.

I entered your info into the calculator and it determined that for a 587 mile trip (one way from Seattle to Eureka), you would be emitting .10 tons of CO2.

Now for the plane trip. Since there is no option to enter Eureka as an airport, I chose another trip that is roughly the same distance. Atlanta to Washington DC is a 639 mile trip (just 42 miles more than from Seattle to Eureka). For this trip, the calculator spit out: .10 tons of CO2.

So it appears that the two trips are very similar, but since these are costs calculated for one person, when you add your parents to the equation, I’m assuming the economies of scale would favor the roadtrip. 

The reasoning behind this is that while your parents extra weight would affect the fuel efficiency of your hybrid, we can’t assume that the plane would be flying with empty seats if your parents didn’t buy tickets so their added presence could have a bigger effect on fuel expenditure (given that the more people who buy tickets, the more planes that are put in the air).

Obviously, this carbon calculator isn’t exact- there are other variables like fuel usage for travel from home to the airport, plane loads, highway traffic, etc- but I did find a European climate awareness site that gives out a more general rule of thumb: “If you have to choose between plane and car, try not to use the plane for less than 1000 km [621 miles]. Landing and take-off are very heavy on fuel. Over short distances this leads to very high emissions of CO2 per passenger km.”

By choosing the roadtrip perhaps you can slightly reduce your carbon use, but overall, the choice between a car and a plane will never have a true winner; the only way we can really impact energy consumption is when we can opt out of these two gas guzzlers for cleaner alternatives like buses, trains and bicycles.