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What Your Flight History Reveals About Your Carbon Footprint

What Your Flight History Reveals About Your Carbon Footprint

Farah Stockman

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Credit…David Rothenberg

Farah Stockman

Last year, the pandemic made me miss Thanksgiving at my sister’s house in Minnesota. This year, I would have walked through fire to get to her sweet potato pie.

When I went to book my plane tickets, I was forced to confront something unexpected: guilt. Alongside price and departure time, a new column of data popped up on Google Flights — the carbon emissions associated with each ticket. According to Google, a nonstop JetBlue flight from Boston to Minneapolis produces an estimated 288 kilograms (0.288 metric tons) of carbon dioxide per passenger. Sun Country — ever the bargain airline — costs the planet only an estimated 204 kilograms.

Aviation makes up less than 3 percent of global carbon emissions. But for frequent fliers, it’s the biggest slice of our so-called personal carbon footprint. In 2018, just 1 percent of the world’s population accounted for more than half of aviation-related carbon emissions. Almost 90 percent of the global population did not fly at all that year. About half of all Americans didn’t take a single flight in 2017. But a small group of “super-emitters” took six trips or more and were responsible for about two-thirds of flights.

That math has led a growing number of people, especially in Europe, to swear off flying altogether and push others to do the same. Flight shame, or flygskam as they call it in Sweden, is spreading.

The website FlightFree, which is dedicated to persuading people to give up air travel, includes the testimonials of Americans who’ve pledged to stay on the ground. A state lawmaker from Vermont, a reverend from Massachusetts and even a former pilot are all quoted about why they think it is no longer fair to fly. One California woman who had always dreamed of visiting New Zealand said she was now resigned to the idea that she’d never go — “unless I can find a boat to take me.”

The most powerful tool that FlightFree uses to stoke climate guilt is its emissions calculator, which estimates that a generic flight from Boston to Minneapolis emits 0.7 metric tons of CO₂ equivalent per passenger — more than twice as much as the amount estimated by Google. The site goes on to say that that amount is enough to melt two square meters of Arctic sea ice. Giving up on my trip to Minnesota for Thanksgiving, I’m told, would be a climate sacrifice equivalent to forgoing meat for 1.2 years.

But guilt and shame have their limits. If fighting climate change starts to mean giving up the chance to see family over the holidays, most Americans won’t get on board.

The most impressive thing about Google’s algorithm is that it incites the right amount of climate guilt without a word about Arctic ice. Flights with significantly higher emissions than the average get a warning label. Flights with significantly lower emissions get a green badge. Other than that, the numbers speak for themselves.

People can factor them into their decision when they book a flight, or ignore the numbers altogether. It turns out, though, that guilt can be persuasive: Those who can see the carbon emissions of each flight are more likely to avoid flights with higher emissions.

That’s what Google engineers in Zurich hoped would happen when they pioneered this project in 2019, the year that “flygskam” took off as a phrase in English-speaking countries. They designed the algorithm to factor in the fuel efficiency of each aircraft’s engine as well as the number of passengers that can fit on board that kind of plane. (Flying economy and flying nonstop tend to decrease your emissions.)

Picking the most fuel-efficient tickets can sharply reduce your carbon footprint without much sacrifice. One working paper by the International Council on Clean Transportation, subtitled “The Case for Emissions Disclosure,” found that choosing the least-polluting itinerary on a route could emit 63 percent less CO₂ than the most-polluting option, and 22 percent less than the average flight.

For a while, users had to dig around to find Google’s carbon emissions information. But last month, just before the climate summit in Glasgow, Google put CO₂ emissions directly into the search results for all to see. The company intends to share its model with other travel platforms, hoping to make carbon emissions estimates more standard and thus more credible in the eyes of the public, James Byers, a senior product manager for Google, told me.

Currently, carbon footprint estimates for flights are all over the map. For instance, Kayak, another travel site that allows customers to search for low-emitting flights, frequently comes up with estimates that are vastly different from Google’s. (Kayak’s estimates come a German nonprofit called Atmosfair, which uses a different methodology.)

Google engineers hope that climate guilt will drive consumer preferences and incentivize companies to invest in aircraft that are more fuel efficient. That could speed the development of electric planes and greener jet fuels. That’s a wonderful vision. I hope it works.

But carbon calculators have a dark side, too. The concept of a personal carbon footprint has been promoted by BP, the fossil fuel giant largely responsible for the notorious Deepwater Horizon oil spill.

A special climate-conscious part of BP’s website is a one-stop shop for climate guilt. It has a carbon footprint calculator that estimates that a generic flight from Boston to Minneapolis would put 0.62 metric tons of carbon emissions in the air, more than twice Google’s estimate for the JetBlue flight. Then it graciously offers to take my money to offset those emissions by buying solar panels in India, fuel-efficient cookstoves in Mexico and wind turbines in China. My climate sin of visiting my sister would be absolved for the low price of $2.80.

Paying to offset carbon emissions isn’t a bad thing. But it’s tough to trust that those offsets are permanent and real, particularly when they are promoted by an oil company — even one that says it aims to be carbon neutral by 2050.

The real downside of climate guilt and carbon calculators is the way they shift the burden of responsibility to individuals, who must make extraordinary sacrifices, away from the fossil fuel industry, which has been accused of blocking the far more consequential systemic change we need.

Michael Mann, a climate scientist and the author of the new book “The New Climate War: The Fight to Take Back Our Planet,” argues that BP started one of the first carbon calculators — and promoted itself as being “Beyond Petroleum” — possibly to deflect attention from its own role in the climate crisis. “Whether this reflected a genuine embrace of green energy or a cynical ‘green wash’ gambit, we’ll never know,” he writes. But if all of us are guilty, then no one can single out the fossil fuel industry for blame.