In Barbara Kingsolver's book, "Flight Behavior," a hard-working, blue-collar mom is approached by an environmentalist who reads her a "sustainability pledge." He wants her to consider what she can do to lower her carbon footprint.

By the end of the pledge, he is squirming, as well he should.

"Fly less," he says.

The woman squints up at him. "Fly less?"

She hasn't flown in her entire life. Her concept of a night out is a burger at McDonald's. In this singular interaction, Kingsolver pinpoints the uncomfortable truth for many of us who eat organic foods, drive a Prius and even install a solar panel or two. Often the biggest footprint, and the least questioned, is our travel habits.

Traveling involves a lot more fossil fuels than we use at home. The United States is responsible for nearly half of worldwide carbon dioxide emissions from aircraft.

According to, the method of travel matters less than how full is the vehicle. A big car with one person in it uses more carbon per person, per mile than most full planes. Taking a train is about half the emissions as a plane - if both are full.

But wait, you may be asking. Whose car? Your full Honda Accord gets twice the mileage of a full SUV. And all airlines do not have the same carbon footprint, nor do all airports, or all roads.

What materials are used to make them? What ecosystems do they interrupt? Which is worse, a 10-square-mile airport or 1,000 miles of four-lane highway?

It is impossible to accurately gauge one's own footprint for any given trip. I throw up my hands. There must be a better way.

Let's work from known principles. Use trains and buses because they are significantly lower energy users than cars when full.

Carpool. When we must travel alone, use fuel-efficient vehicles.

Travel less - or travel differently.

Travel slowly (think sailboats!) and closer to home. Or, travel for a purpose other than pleasure, and then enjoy the trip.

As my friend Emily says: "We're spending all that money anyway - why not have it go to something real?"

There are countless opportunities to be useful all over the world and the traveler loses none of the pleasures: sun, fun, beauty, local interaction, education, food.

Understanding and appreciating far-away places, we hope, improves international relations, and there is nothing like a physical visit. But it does not automatically follow that world travel is the best way to become a global citizen. We risk the charge of hypocrisy when we visit places that struggle mightily with climate change or other forms of pollution without making a sustained effort to reduce our thirst for pleasure travel.

As a wise woman named Marge once said: "The first rule of hole is to stop digging." This means we are not to continue digging and find ways to throw the dirt back into the hole, which seems to me what buying carbon credits is all about.

Here's another uncomfortable way to look at it: It is well-known that we are using fossil fuels at a rate that is creating global climate change. We are borrowing, as it were, from our grandchildren who will pay the price for our use and overuse.

This truth becomes much more real if you think of it this way: Every trip you take is one less trip that will be available for your grandchildren. Overindulge too much today, and there will be nothing left for them.

Is this accurate? I can't claim to know the future. But I can imagine scenarios wherein collapsing infrastructure and overwhelming debt make travel much less likely than it is today.

The most efficient and honest way to channel us toward travel habits more in line with our finite atmosphere is to price fossil fuels at their source. A steadily rising price on fossil fuels allows us to make decisions based on reality - the actual cost of the fuel, including its cost to planet and ourselves living on that planet.

Well over half of the fossil fuels are already priced in their home countries. The U.S. is lagging embarrassingly behind. The playing field needs to be leveled.

Only when carbon is priced will we fully face what we are losing in return for our travel. The choice remains ours - and if travel is precious enough, we can keep doing it.

Many of us, however, will make alternative choices.

Katya Gordon is a volunteer for the Citizens' Climate Lobby and a resident of Two Harbors.