Sustainable travel: What works, what doesn’t

If you’re planning on stopping at grandma’s this holiday season and/or sneaking in a getaway, you’re not alone. Between now and the end of the year, nearly half of Americans will travel, and the total number of trips is on the rise. The planet-warming potential of those journeys can be huge: Due to travel, shopping, tree-lighting, and other merriment over the Christmas holiday alone accounts for about 5.5% of each person’s annual emissions.

Curbing the impact of a lot of seasonal spending can be fairly cut-and-dry (buy less), but the path toward reducing the environmental imprint of travel, specifically, is murky. While the impact of each trip does vary based on the mode of transport we choose and the distance we travel, some aspects are out of our control—say, the model of airplane you’re boarding, if a train is electric or diesel, or if sustainable aviation fuel ever really gets off the ground.

In the meantime, though, no one’s getting grounded for their emissions, and there are some ways to make each voyage gentler on the Earth. So we decided to fact-check commonly touted “eco” travel tips to help you figure out how best to reach loved ones—or perhaps a sandy beach—with the planet in mind. We rated each piece of advice on a (admittedly unscientific) scale of 0 to 5 🧳s, with 0 being “probably no help at all,” 2.5 being “sometimes true,” and 5 being “works for everyone, every time.”

Buying carbon offsets: ½ 
When buying plane tickets, you may have noticed an option to purchase carbon offsets to help zero out the emissions of your flight. These funds are great in theory: They direct money toward carbon-reduction efforts like forest preservation. But in practice they’re deeply flawed: Investigations and analysis have consistently found that these programs often drastically overstate (even fabricate) their emissions benefits. Crucially, offsets have also become a form of climate delay. They were created as a short-term solution to buy time for the airline industry to bring down emissions, explains Sola Zheng, a senior researcher at the International Council on Clean Transportation who studies the environmental impacts of commercial aviation.

Packing lighter: 🧳🧳
It seems like easy math: Reduce the weight of your bags and reduce the amount of fuel a plane burns to get and stay aloft. While this is technically true, an emptier duffel doesn’t make a major difference in a flight’s overall efficiency, says Zheng. Passenger weight, which includes both the persons and their luggage, only accounts for, at most, one-fifth a plane’s heft. “The weight that you’re transporting affects the amount of fuel that you need to burn, but the scale of that is quite small,” Zheng says. On road trips, however, how much you load up the trunk can directly impact how much gas you burn: An extra 100 pounds in your vehicle could cut fuel economy by up to 2%, simply because it takes more energy to get moving.

Avoiding layovers: 🧳🧳1/2
Nonstop flights generally have lower emissions than connecting journeys, Zheng says. Additional flights mean additional rounds of takeoff and landing, the most fuel-intensive parts of the trip, and the routes may be circuitous. For international flights, direct is “almost always better,” Zheng says, and layovers abroad may involve major detours. This is an imperfect rule, though: In some instances a direct flight can also follow a path that generates more greenhouse gases than two connecting ones. Zheng estimates that some flights can spike their emissions by 50%, if they, for instance, veer off the most fuel-efficient route due to air traffic or are using older, less efficient aircraft. The best tactic for wading through all this is checking emissions estimates, such as those provided by Google Flights (more on that in a second).

Taking the train: 🧳🧳1/2
Riding the rails is only better than flying in certain circumstances. In places where electric, high-speed rail is the norm, like in Asia and Europe, a train is most often the greenest way to go. In the U.S., however, it only comes out ahead if you’re on the Northeast Corridor, which runs between Boston and Washington, D.C.—and is the only all-electric route in the Amtrak system. According to the U.S. Department of Transportation, a rail trip from Boston to New York produces 25.3 kilograms of CO2 emissions per person, compared to 141.1 kilos in the air, 135 kilos in a car, and 26.7 kilos on the bus. Beyond that route, U.S. train trips longer than around 1,200 miles begin to inch closer to flight emissions, Zheng says. For example, the longer (and diesel-burning) ride from Washington, D.C., to Orlando, Fla., produces 224.2 kilograms of CO2 per person, compared to 246.6 on a plane, 137 in a car, or 111.1 on a bus.

Driving instead of flying: 🧳🧳🧳
There are almost too many variables (gas versus electric, distance, weather, the weight of the car) to deliver a hard-and-fast ruling on driving versus flying, but if there’s one thing that hits close to universal truth it’s that carpooling is king. On long drives, like a cross-country road trip, the number of passengers pulls down each person’s total emissions contribution; without several people in the car, a solo flight will generally net fewer emissions per person. For shorter trips, though, “it’s very hard to find cases where it would be better to fly,” Zheng says. That’s because on quick hops the fuel-intensive takeoff and landing make up a relatively large portion of travel time. 

Booking ‘greener’ accommodations: 🧳🧳🧳1/2
If you’re not headed for a relative’s sofa bed or guest room, you can look for a more sustainable place to stay. Hotels use more energy and water compared with most residential and commercial buildings, and contribute about 1% of global carbon emissions. In fact, full-service hotels use around three times the energy and around twice the water of multifamily buildings. Over the last decade, establishments have increasingly turned to renewables and worked to improve energy efficiency. You can hunt down these spots by checking for certifications: LEED, Green Seal, and GreenKeys don’t have financial ties to the industry.

Flying coach: 🧳🧳🧳🧳
While springing for an upgrade doesn’t immediately make an airliner’s emissions go up, it does impact how much of a trip’s total footprint dotted-lines back to an individual person. First and business class passengers emit from 2.6 to 4.3 times more carbon dioxide per mile flown than folks traveling in economy. That’s because premium seats take up more room than coach seats, Zheng says, so the share of emissions per person is higher. File this one under theoretical, but still valid.

Checking emissions estimates: 🧳🧳🧳🧳1/2 
The emissions estimate tool on Google Flights takes a fair amount of guesswork out of choosing a best-for-the-planet itinerary, Zheng says—and similar tools on Booking.com, Expedia, and Skyscanner work off the same model. It’s best to think of the estimates from these tools as indicators as opposed to comprehensive analyses. The data, for example, don’t account for warming factors beyond CO2 emissions, such as contrails (the long wisps of clouds left by aircraft exhaust that trap heat in the atmosphere), or the amount of fuel burned when taxiing around crowded airports. (Zheng and her colleagues at the International Council on Clean Transportation are working with Google on improvements to address these issues.) Still, these tools are important because they help passengers send a crucial message to the industry about what customers want, Zheng says.