Planes, Trains, or Automobiles: Which is Greenest?

Liz Biscevic — Moral Compass

As a traveler, you want to go out into the world and see as many places as possible, but you also don’t want to add to your carbon footprint. We break down the five most popular modes of travel to find out which is best for the environment.


Flying has a particularly bad reputation among environmentalists nowadays, and it’s easy to understand why. Aviation is an industry reliant on fossil fuels and contributes around 2.5 percent of total carbon emissions. By 2050, international flights alone are expected to account for 22 percent of overall carbon emissions  as other industries shrink their carbon footprints. Though some aircraft manufacturers are exploring fuel-efficient technology, until a battery exists that produces as much power as jet fuel, long flights on commercial electric planes are still wishful thinking.

The problem is, there is no environmentally efficient alternative that can transport over 8 million people every day. Smithsonian magazine breaks down a comparison of flying versus driving that complicates the argument against air travel: A Boeing 747 burns 5 gallons of jet fuel per mile of flight. For a 4,000-mile flight, that’s 20,000 gallons of fuel—obviously an atrocity to our ozone layer. But when you divide that number by the 400 passengers on board, that’s only 50 gallons of fuel per person. When you compare that to driving a Honda Civic—which, on average, gets around 30 miles per gallon without traffic—a driver would still need 133 gallons of fuel to make it to 4,000 miles. Even with two people in the car, air travel still seems to be more efficient.

When it comes to flying, the deciding factor should be distance. Flying economy is more carbon efficient than driving distances over 100 miles, but not as efficient as taking a train or bus or carpooling.

Another big factor is how you fly. Though flying economy isn’t as comfy as first class, it’s much better for the environment. Not only do first-class seats take up twice as much space as economy, but the energy to service those customers—providing power for bigger TV screens and gourmet meals—is greater as well. When possible, opt for budget airlines that don’t offer first-class travel. More seats is better for the environment.

Avoid layovers if possible because the combustion needed to get the plane off the ground burns more fuel than when it’s coasting in the air. If you’re traveling a long distance and a direct flight isn’t available, choose the most direct path to your destination. The shorter the flight, the less fuel it burns.


According to the Transportation Energy Data Book, trains emit around 1.61 megajoules of energy per passenger-kilometer (1 passenger-kilometer is one passenger transported 1 kilometer), and they can transport hundreds of people at once.

When compared to flying, not only do trains produce less emissions, but those emissions aren’t released directly into the upper atmosphere. Some trains today also use renewable energy—like solar or wind—which offsets your carbon footprint. Though this trend is mostly in Europe, American transit companies are slowly getting onboard.

Travel by train doesn’t only benefit the environment. Inexpensive local trains in many countries provide tourists opportunities to stop in lesser-known cities to experience the true culture of the region without the tourist traps. Taking the train could allow you to meet a new travel companion for a day trip, or a local with great regional tips. Also, your Instagram followers are over shots of clouds from planes. Imagine the scenic photos you’ll take from a train’s ground-level window seat.


In most cases, taking the bus is considered an environmentally safe mode of travel, especially compared to flying. Many buses today utilize renewable energy sources, and, according to a report by the Union of Concerned Scientists, can cut your carbon emissions in half compared to taking a flight or driving even an electric car.

But distance matters. When you’re in it for the long haul—like more than 1,000 miles—flying coach would be the better the option, as the amount of fuel emitted per passenger is lower.


When it comes to the environmental impact of driving, the answer is more complicated than it may seem. For example, if your journey is less than 500 miles—like a trip up the coast from Southern to Northern California—and you have the choice to drive or fly, it comes down to how many people are in the car. If it’s just you, the more sustainable option is to fly. If you’re traveling with a group of friends or family, driving in one vehicle is the greener choice.

According to the Union of Concerned Scientists report: “Carbon from cars and trucks adds up, especially when those vehicles travel long distances and are only partially occupied. If you’re traveling alone or with one other person, you’re usually better off flying direct in coach than getting behind the wheel of a passenger vehicle. This is especially true for trips of more than 500 miles.” That’s because when you calculate the amount of gas used per person for long distances, a plane is more efficient because it’s transporting significantly more people.

If you’re traveling with family or friends, you can rent electric or hybrid cars easily through any of the major companies or see if car-sharing companies car2go or Zipcar–which offer eco-friendly models in some locations—are operational in your destination. If you’re solo traveling in Europe, try out BlaBlaCar—a carpool app that lets you connect with drivers who are headed to similar destinations. BlaBlaCar lets drivers set their price, and it’s usually just chipping in for gas since the drivers are headed in the same direction anyway. Plus, it’s a great way to meet new people. Traffic is a gas guzzler, so try to find roads free of gridlock or drive during off hours.

Cruises and Boats

Cruises have been on the rise since the late 1960s, for some good reasons. Most cruises offer tourists the chance to visit multiple destinations in one go, with food, drink, entertainment, and on-shore excursions often included in the price. Despite the perks, recent studies have shown cruise liners have a more negative environmental impact than planes, mostly because of fuel consumption boating from place to place, energy producing the on-board luxury experiences, and wastewater contaminating the oceans. Ships produce more than a billion gallons of sewage each year, and all of that gray water from showers and laundry, blackwater from toilets, and oily bilge water from machinery go directly into the ocean.

However, modern ferries and transportation boats meant for short distances are being made with the environment in mind. Today, they’re manufactured with light metals to be as hydrodynamic as possible, allowing them to use less fuel, and are coated with nontoxic paint that prevents rusting, extending their longevity. Most ferries use, or are aiming to use, biodiesel fuel, instead of typical gas, which cuts down on pollution. Compared to flying and driving, taking a ferry or a boat when traveling from coast to coast and island to island could be your greenest bet. Just go to your nearest port and get onboard.

So, what’s the verdict?

It all comes down to distance and how many people are traveling together. As a solo traveler visiting a destination up to 500 miles away, your most eco-conscious options are buses and trains, with flying economy as a runner up. Two or more people traveling within the 500-mile cutoff would do well to travel by bus or train, or failing that, driving, to maximize fuel efficiency. If your vacation involves several coastal spots or islands, explore by boat when possible. Unless you’re traveling in a large group and can charter a bus or van, traveling over 1,000 miles is best done by train or plane.

Flying first class and taking a cruise are definitively the worst for the environment, so save the luxury for an environmentally friendly spa when you reach your destination.

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