This weekend is Memorial Day weekend - which typically kicks off the summer vacation season. But the price of fuel - and the fact that people are increasingly scrutinizing their own carbon footprints - could change how they travel this year. Christy George reports.
The classic American car trip — kids and suitcases crammed in the back, and off to see a national park — may not happen this year.
It's not just the price of gas.
More and more, people in the Pacific Northwest are making the connection that burning fossil fuels like oil contributes to climate change.
Transportation alone accounts for a whopping one-third of all greenhouse gas emissions.
And the biggest piece of that - nine percent - comes from automobiles.
But here in the Pacific Northwest, people have already changed their driving habits.
Clark Derry-Williams is an environmental economist with the Sightlines Institute in Seattle.
He was crunching numbers, and noticed that gasoline consumption in Oregon, Washington and British Columbia went down ten percent over the past ten years.
Clark Derry-Williams: "And that's kind of a surprise because historically gas consumption goes up and up and up in fact because fuel consumption has levelled out but the population continues to grow - on average, we're using 10% less gasoline than we used to."
Clark Derry-Williams says Northwesterners are buying more fuel-efficient cars, taking more public transportation and moving out of the suburbs and into Portland, Seattle and Vancouver.
In fact, the decrease in driving here is significant enough that it's even slightly reduced gas consumption nationally.
But the impact goes beyond gasoline.
Clark Derry-Williams: "If you are only looking at what comes out of your tailpipe, the tailpipe of your car, you're really missing a big portion of the impact of your driving."
He looks at the entire lifecycle of planes, trains and automobiles - and counts all the carbon dioxide emissions - from mining iron ore and smelting it into steel, manufacturing cars and planes, extracting oil, refining it into gas or jet fuel, when you travel, how full the vehicle is - and so on.
Even though cars emit the most greenhouse gases, it turns out driving - especially in a fuel-efficient car - is greener than flying.
That's because planes emit their gases at high altitudes—where they pack a bigger punch.
Clark Derry-Williams: "It's not just the CO2 emissions from the fuel. It's also that when an airplane is flying high up in the sky, it's putting certain kinds of emissions up in a place where they can make a difference."
Commercial aircraft fly high to get above the weather and avoid turbulence, but that has minuses when it comes to contrails—those streaks of white that airplanes leave in the sky.
Clark Derry-Williams: "Contrails, at some times of the year and certain altitudes, can turn into cirrus clouds, and those have a tendency to trap heat that otherwise would escape into space."
The effect is worse at night and in the winter.
Airlines have improved fuel efficiency in recent years, but not enough to counteract the growing number of planes and flights.
Still — most Americans just keep on truckin'.
Kim Solem: "The travel industry is growing, in every sense of the word. Recreational travel is growing, business travel is growing."
Kim Solem is in charge of corporate social responsibility for the Bellevue Washington-based online travel company Expedia.
She says people have more disposable income in emerging travel markets like India and China, while Americans keep finding new reasons to travel - ironically sometimes in search of eco-vacations.
Kim Solem: "…and we're seeing growing cultural exposure & awareness not to neccessarily go lie on the beach but to go see turtles nesting and to go do a Habitat for Humanity volunteer program."
Still, Solem says, many travelers are developing a conscience.
To expunge their guilt, Expedia offers its customers carbon offsets, green hotels and hybrid rental cars.
Others just don't fly much.
Kim Stanley Robinson: "Any trip I take by airplane puts a huge ding in my carbon footprint."
Science fiction writer Kim Stanley Robinson is the author of a popular trilogy about climate change. And he was one of the first to reconsider the ethics of adventure travel in a piece for Outside magazine a few years ago.
He revised his own travel plans after hiking in Antarctica, the Alps and the Himalayas.
Kim Stanley Robinson: "I began to realize I was always comparing them back to Sierra Nevada, and always the Sierra Nevada was the best. All the other mountain ranges were too big or too cold or too dangerous or too full of mosquitoes or one thing or another. So I came to a little realization: why keep going all over the world when you've got what you want right in your backyard?"
Now, he counts his carbon like calories, and sticks to his own bioregion.
Kim Stanley Robinson: "'Is that plane trip really worth it?' the more you ask yourself about these issues, you get to a state the Dalai Lama calls mindful consumption."
Clark Derry-Williams: "People ask us, if you can choose a way to travel, what should it be? Should I drive a car? Buy a Prius?"
If you can't stay home, says Clark Derry-Williams.
Trains or busses are the best choice.
But if you just have to fly, fly in daytime between December and February and choose a middle seat on a packed plane.
A full plane is more fuel-efficient and it's going with or without you.
Trade in that Hummer for a hybrid.
And try biking - or hiking - to work.