Using the example of a Chicago family of four that had been minimizing when it came to the daily commute but was planning to fly to Disney World, the researchers found that the trip's emissions equaled nearly two years of commuting pollution.
Naturally, there are all but infinite permutations. But three key factors determine which mode of travel is greenest: what kind of vehicle you'll be using if you drive, how many people are traveling with you, and how far you're going.
Still, green is one thing. But practicality and price are also important. Who wants to spend most of a one-week vacation on a bus?
The researchers suggest an attitude change: The vacation isn't just the destination, it's about getting there, too. Imagine the scenery on the buses that can now get you to the Grand Canyon and Denali National Park in Alaska.
Closer to home, the comparisons get interesting.
A friend recently invited my husband and me to spend the July Fourth weekend in Boston. We'd go on Thursday and come back on Monday.
I checked into options, and here's how they played out:
Driving 350 miles from my home would take about 61/2 hours one way, not counting pit stops. My Prius gets 50 miles per gallon. Factoring in $3 a gallon puts me at $42 for the round trip, and since there are tolls, I'll arbitrarily up that to $80.
Taking a Greyhound from Philadelphia would take 71/2 hours - comparable to driving - and, with 21-day advance purchase, cost $130 round trip for the two of us. Plus, we'd leave the driving, as they say, to someone else.
Amtrak takes six hours and costs - ouch! - $240 for two.
Flying takes as little as 11/4 hours, but I'm going to add getting to the airport two hours ahead of time and call it 31/4 hours. On Expedia.com, the coach fare for two totaled $520.
