There Is No Sustainable Way to Fly

Despite what airlines promise, carbon offsets and sustainable fuels won’t negate the heavy environmental cost of air travel.

Last month, just weeks after climate activist Greta Thunberg was named Time’s Person of the Year, JetBlue announced that it would go carbon neutral on all its domestic flights by the end of the summer, becoming the first major airline in the world to make such a commitment. News coverage of the announcement highlighted the airline’s intention to “use an alternative fuel source for flights leaving from San Francisco” along with “direct flight paths, new planes and other technologies.”


In other words, the company was hoping to innovate its way out of the aviation industry’s massive impact on the environment.

But a closer look revealed that there was no magic bullet behind this seemingly bold initiative. The fine print of JetBlue’s press release reveals that the airline doesn’t plan to reach this ambitious goal by decreasing the amount of carbon its planes spew into the air, but by making up for that carbon somewhere else. The airline will reach net zero emissions by funding “offsets,” or projects such as wind turbines and tree plantings that decrease global emissions overall.

Fly a plane here, plant a tree there—that’s the plan, for the most part.

JetBlue isn’t alone in offering such carbon offsets as an antidote to customer anxieties about air travel, and neither is it the only airline seeking to develop green aviation technology such as biofuels and electric jet engines; just last week the British aviation industry announced a similar plan to achieve net zero emissions by 2050. These policies promise to help the aviation industry go green without having to cancel a single flight, but the solutions they offer are too little and too late. The only sustainable way to fly, at least for now, is to fly less.

“The problem we face with air travel is that at present there aren’t good low-carbon alternatives,” said Peter Miller, a regional director at the National Resources Defense Council who focuses on clean energy advocacy. “There are a lot of technologies that are on the drawing board or just getting off the drawing board, but they’re not here yet, so the question is what we should do in the interim.”


On a global scale, cars are a far larger contributor to climate change than planes: air travel still only accounts for around 10 percent of global emissions from transportation, compared to 60 percent from automobiles. As a result, the gradual increase in electric vehicle ownership and gasoline fuel economy could help put a big dent in carbon emissions over the next few decades.

But our climate challenge isn’t as simple as carbon quantity: these statistics disguise the uniquely devastating short-term impact that air travel has on the atmosphere. Jet engines emit not only carbon dioxide but also sulphates, nitrous gases, and icy vapor streams called contrails, all of which trap heat in the atmosphere. Furthermore, they emit these greenhouse gases directly into the atmosphere at high altitudes, which research suggests could contribute to a disproportionate amount of short-term warming.

Recent climate forecasts say we must cut greenhouse gas emissions in half over the next ten years in order to stave off global catastrophe, but the aviation industry has thus far been moving in the opposite direction. One recent estimate found that emissions from air travel had risen more than 1.5 times faster than previously predicted, and the fuel inefficiency of American carriers was partially to blame. Worse still, the number of annual airline passengers is currently projected to double by 2037, which means that any path toward a livable future will have to involve finding a sustainable way to fly. But the solutions that major airlines like JetBlue have embraced thus far are nowhere near guaranteed to counteract the damage that commercial aviation is doing to the planet.


Take offsetts, for instance. Even before JetBlue pledged to go carbon-neutral by funding such carbon-reducing projects, airlines including United and Delta already gave customers the option to purchase offset credits for their flight, paying a little extra to assuage their flying guilt.

These measures might sound like climate-forward action on the airlines’ part, but in many places such offsets will soon become far more common. Next year will begin the first phase of the United Nation’s aviation emissions plan, CORSIA, which requires airlines in signatory countries to commit to keeping their emissions at 2020 levels by purchasing offsets or using sustainable fuels. The plan will remain voluntary until 2027.

But Jessica Green, a professor at the University of Toronto who studies climate governance, said there’s no way to know for sure how much an offset is actually helping stop climate change, especially when an airline like JetBlue doesn’t reveal what kind of offsets it buys.

“Offsets vary a lot in quality,” Green said, “and a lot of times they’re purchased through aggregators of credits, which makes it harder to know where the project actually came from or what it’s actually doing. When you click the button it’s like, ‘oh, this is two tons of carbon,’ and you have no idea whether it was a wind farm in Malawi or methane capture in Brazil.”

A recent ProPublica investigation into reforestation projects in South America, for instance, found that the projects were completed behind schedule and delivered far less than their expected carbon benefit.


“It’s not de facto problematic, but given that we know there’s a lot of iffy projects out there, the less transparency we have about where these offsets come from, the less of a service it does,” Green said. “It also creates this mentality that you can just click a button and then you’ve been absolved of your sins.”

Sustainable fuels like the ones JetBlue will use in San Francisco are a similarly insufficient solution. The airline plans to adopt Neste biofuels, made from recycled organic material, which emit up to 80 percent less carbon than traditional fuel. Multiple European airlines including Germany’s Lufthansa have already tested these fuels on short-haul flights over the past few years, and major carriers like United are also planning to buy millions of barrels of waste-produced biofuel, and the U.S. Department of Energy is funding experiments in producing cheap fuel from fats and greases. But Miller says the infrastructure to make these fuels affordable on a large scale does not exist yet, and could take decades to develop.

“The U.S. airline industry is taking clear actions to grow more sustainable while also continuing to serve the needs of our customers,” said Carter Yang, spokesperson for Airlines for America, the lobbying group representing the country’s biggest airlines. “We’re continuously investing in more fuel-efficient planes, developing sustainable aviation fuel and implementing more efficient procedures in the air and on the ground,” Yang added, would help U.S. airlines meet CORSIA’s targets.


It’s equally unclear how much electric airplanes could do to mitigate the adverse impact of the aviation industry. Right now, the most advanced electric batteries from companies like Rolls Royce, Pipistrel, and startup ZER0 (dubbed the “Tesla of the skies”) can’t power flights of longer than a few hundred miles, and it’s unlikely that they ever will—an average jet engine is more than fifty times as powerful as the best lithium-ion battery, and the battery is much more expensive.

If the cost of such batteries ever comes down, electric planes might be able to replace many short-term flights. Norway, for instance, has pledged to take all its domestic flights electric by 2040. But passengers might traverse such short distances just as easily on transportation methods like trains and buses, which are cheaper, better-tested, and also environmentally friendly. There’s also the matter of where the electricity for these batteries comes from: if you juice them with electricity that comes from burning coal, you aren’t helping.

The best way to reduce air travel emissions in the immediate future, then, might be for people to simply fly less. Achieving that on a large scale might sound impossible—we can’t just demand that millions of people cancel their vacations—but it looks a bit easier once you realize that airline passengers are a far smaller group than car owners or users of electricity. Despite the rapid recent expansion of the aviation industry in China and Southeast Asia, some estimates suggest that more than 80 percent of the world’s population has never boarded a plane. Furthermore, a small group of frequent fliers generates a disproportionate share of emissions: the 12 percent of Americans who took six or more flights in 2017 were responsible for at least two-thirds of air travel emissions in that year, probably even more.

“JetBlue’s commitment to reduce their emissions is valuable,” Miller said, “and we have to support the decisions of companies to do more than they’re required to do. But it’s not a substitute for societal action, or national action, or international action to achieve emissions reductions.” Motherboard reached out to JetBlue and the other airlines mentioned in this story, but they did not respond to requests for comment.

In the absence of revolutionary technology that will drastically reduce the environmental impact of commercial flights, the best way for policymakers to make flying sustainable may be to discourage this frequent flying, especially when the trips are for business meetings and academic conferences that might just as easily be accomplished with a Skype call. Green said governments could accomplish this by subsidizing train travel instead of new airports, or by instituting what she calls a “runway tax”—charging consumers or airlines themselves an extra few hundred dollars to take off or land at an airport. Such taxes are always easier for corporations to absorb than individual consumers, but as Thunberg herself has pointed out, the international community has all but refused to touch the aviation industry—the Paris climate agreement, for instance, featured not a single binding resolution regarding air travel.

In the absence of any such regulation, Green said, the major airlines are still seeking to position themselves as climate-conscious, but on their terms.

“I think the airline industry, especially with this normative shift about flight-shaming, sees the writing on the wall,” she said. “I think they view initiatives like this as kind of a preemptive way to buy themselves some more time.”