I’m a very climate-conscious person. I’ve dedicated a lot of adult life to trying to protect and build more green spaces while reducing reliance on fossil fuels.

Yes, there’s a glaring contradiction in my way of life: I’ve flown a lot.

I don’t own a car. I bike, walk, and take public transportation. I even write about sustainable travel and urban planning.

But when I want to visit family in Latin America, friends in Spain, or take the trip of a lifetime, I get on a plane. It’s simply the only way to get to these places.

This led me down a rabbit hole of reading and researching about sustainable flying. I wanted to know if there were more sustainable or eco-friendly airlines.

Sadly, it’s clear that “eco-friendly” and “airline” are incompatible, and will be for decades.

And I don’t mean that in a way like, “Nothing’s perfect.” Airlines and their “sustainability” initiatives are tinkering around the edges of one of the most environmentally destructive things we can do.

So in this article, I’m going to walk through:

• how much pollution flying actually produces
• why aviation is so hard to decarbonize
• and what travelers like you and me can realistically do to reduce their impact

The real answer to sustainable flying may not be choosing a greener airline. It may be rethinking how often we fly in the first place.

If you want to go deeper on this, I really enjoyed Christopher de Bellaigue’s book Flying Green: On the Frontiers of New Aviation. It’s less than 150 pages.

TL;DR: The Truth About “Sustainable Airlines”

• There are no sustainable airlines. Flying is bad for the environment, period.
• According to this stat from the European Union: “Someone flying from Lisbon to New York and back generates roughly the same level of emissions as the average person in the EU does by heating their home for a whole year.”
• Yes, aviation produces only about 2.5% of global CO₂ emissions, according to the International Energy Agency.
• That may not sound bad, but consider that a small minority of frequent flyers drive most aviation emissions. Research suggests 1% of people are responsible for more than half of aviation emissions worldwide.
• The “sustainable” measures for airlines, like sustainable aviation fuel (SAF), more efficient aircraft, and investments in new technologies are very far away from getting the industry even close to environmentally-friendly.
• Airlines are investing in improvements like more efficient aircraft and sustainable aviation fuel (SAF). SAF deserves its own article, and it’s an improvement, but far from sustainable.
• But SAF currently makes up well under 1% of global jet fuel use, meaning its impact is still extremely limited. Getting this to a substantial number is really tough and has many downsides.
• Even the “greenest” airlines are only reducing emissions at the margins.

“The most sustainable flight is the one you don’t take.” – Wayne (Plane?) Gretzky??

The most effective way to reduce aviation emissions is still simple: fly less.

That doesn’t mean never flying. Travel can be one of life’s great joys, and experiencing different parts of the world can deepen our motivation to protect it.

And let’s not blame this all on individuals like us. When I say “fly less,” I mean we must fight for better options. France, for example, has banned specific domestic flights where a train journey of under 2.5 hours exists. That only works because of their high-speed train network.

If we want truly sustainable travel, the bigger solutions likely lie beyond airlines themselves—things like better trains, fewer short-haul flights, and choosing fewer but longer trips.

What’s So Unsustainable About Flying?

It uses a lot of jet fuel, especially to get off the ground and land. (Which is why short flights, per passenger mile, are even worse.)

While a car’s efficiency is measured in miles per gallon, a plane’s efficiency is often better understood in gallons per second.

A large long-haul jet, like a Boeing 747 or 777, burns about a gallon of fuel per second. This is some napkin math, but over a 5-hour international flight, that’s approximately 18,000 gallons.

Consider that your typical car gas tank is 12-18 gallons. That’s a thousand tanks of gas to get from New York to LA.

It turns out that lifting a giant machine off the ground and carrying it across the world uses a lot of energy.

This is Poised to Get Worse As More People Fly

But there’s an important reason aviation’s share of emissions looks small.

Most people on Earth never fly.

Flying is still largely concentrated among wealthier people in wealthier countries.

Results from surveys on flying showed that in 2018, before the pandemic, only ~11% of the world’s population flew in a given year.

The same survey estimated that 1% of people are responsible for more than half of global aviation emissions. Shoot, I’m in that 1% for sure.

That means aviation’s climate impact is highly concentrated among a relatively small number of travelers.

Let’s just say it like it is. Flying is mostly for people who live in rich, developed countries.

So as more countries develop economically, more people will likely fly.

Why Aviation Won’t Be Sustainable Anytime Soon

If airlines know flying is bad for the climate, why don’t they just switch to cleaner technology?

We don’t have it. This is a physics problem more than anything else. Let’s start with electric planes.

Electric planes don’t, and won’t, work for long distances

Electric planes may grab headlines and attract the enthusiasm of Silicon Valley types, but these just don’t make sense.

Batteries are far heavier than jet fuel for the amount of energy they store. That means a battery-powered plane capable of flying across the Atlantic would be so heavy that it couldn’t carry enough passengers to make sense.

Because of this, the electric aircraft experiments you’ll see are for short routes, think flights of a few hundred miles or less.

I wonder if we had some kind of invention that moved fast, maybe even underground, fully-electric, and that dropped us off right in the city center. Like a train, but high-speed. Oh that’s right, high-speed rail has existed for over 50 years. Just build that.

Look at France. Because of its high-speed rail, they have gotten rid of various short, domestic flights.

Hydrogen Planes Are Far Away

Hydrogen is another technology often mentioned as the future of aviation.

In theory, hydrogen could power aircraft with zero carbon emissions at the tailpipe. But in practice, it introduces a whole new set of engineering challenges.

It seems more plausible, but far away. As answered by MIT Climate, “Every airport would need a steady supply of hydrogen to refuel the jets that fly through, just as they must have huge quantities of jet fuel now. He estimates that each of those airports would need lots of extra energy—the equivalent of a small nuclear reactor’s worth—to create all that hydrogen. Barrett says governments probably would need to fund much of this work, because the aviation industry would hesitate to take on something so costly that won’t have an immediate payoff.”

So there are real logistical challenges, but the physics are better.

Some companies—including Airbus—are exploring hydrogen-powered aircraft, but most experts believe widespread commercial adoption is decades away, if it happens at all.

Sustainable Aviation Fuel Has to Be the Biggest Greenwashing Campaign in the Industry

All right, I might ruffle some feathers with this one. I even saw a freaking ad in New York about an airline bragging about using “sustainable aviation fuel.”

SAF is made from sources like used cooking oil, agricultural waste, or other biological materials.

Anything that’s carbon-based, they find a way to make it fuel.

The theory for why this is better is obvious: itself of fossil fuels, you use other materials. The other upside is you can use this right now in the airplanes.

Problem #1: There’s Not Enough Cooking Oil

Cooking oil is a great idea. As an avid composter, I don’t want the cooking oil. Put it in the planes.

But do you have enough cooking oil lying around to fill up the tank of a plane? I sure don’t. I’m not even sure every McDonald’s nearby could get us from New York to LA.

Today, well under 1% of global aviation fuel supply comes from SAF, meaning almost every flight you take is still powered almost entirely by fossil fuel.

Sure, that’s a step, but without a scalable source of carbon for SAF, it’s not going to make a real dent.

Problem #2: Land-Use and the “Ethanol Mistake”

If you’re around my age, you remember when ethanol was touted as “renewable energy.”

The U.S. poured billions into corn-based ethanol, only for studies to later show that the land-use changes, plowing up prairies and using massive amounts of fertilizer, made it more carbon-intensive than gasoline in many cases.

We traded food security and biodiversity for a fuel that didn’t even solve the emissions problem.

Relying on SAF to scale the aviation industry faces the exact same trap. To produce enough “bio-fuel” to power the global fleet, we would need to dedicate millions of acres of land to energy crops rather than food or natural forests.

Given all of this, the claims that airlines are transitioning to sustainable aviation fuel is really a pipe dream. Is it good that they’re snagging up all the cooking oil they can? Sure. But that’s not going to make the aviation industry sustainable.

Are Some Airlines More Sustainable Than Others?

Even if there’s no such thing as a truly sustainable airline, some airlines are less polluting than others.

Most fancy-sounding press releases from airlines trying to make themselves sound better for the environment tend to rotate between a few points.

• Invest in newer aircraft
• Commit to using more sustainable aviation fuel
• Set long-term climate targets, such as “net-zero by 2040 or 2050”
• Invest in future technologies like hydrogen aircraft or carbon capture

These efforts are often presented as evidence that an airline is becoming greener.

And to be fair, some of them do reduce emissions. But in most cases, they improve efficiency at the margins rather than fundamentally changing the impact of flying.

Let’s look at what these initiatives actually mean.

Newer Aircraft Are More Fuel Efficient

One of the most meaningful ways airlines can reduce emissions is simply by operating newer planes.

Newer planes are more efficient.

According to a 2020 report by the International Council on Clean Transportation, newer aircraft are 40% more efficient now than in 1960. This is no doubt a good thing. And since fuel is expensive, the industry has every incentive to be more efficient.

So if you want to be on a less damaging flight, take the one with the newer aircraft.

Sustainable Aviation Fuel (SAF)

We’ve already talked about this. If an airline says they’re sustainable because of SAF, see if you can find what percentage of SAF they use, and where the carbon materials come from. You’ll quickly find out it’s not really sustainable at all.

“Net-Zero by 2040 or 2050”

Many airlines now advertise long-term climate goals such as “net-zero emissions by 2050.”

At first glance, this sounds like airlines are planning to eliminate their emissions entirely.

Net-zero doesn’t mean airlines will stop emitting carbon. Instead, it means they plan to balance their emissions with carbon removal or offsets.

Most airline net-zero plans rely on a mix of:

• sustainable aviation fuel
• more efficient aircraft
• operational improvements
• carbon offsets or future carbon removal technologies

Offsets typically fund projects like forest conservation or renewable energy projects that supposedly reduce emissions somewhere else.

However, offsets are widely debated. They often overestimate the climate benefits they deliver, and they don’t eliminate the emissions from the flight itself.

Investments in Future Technology

Airlines also frequently announce investments in technologies that could make flying cleaner in the future.

These include things like:

• hydrogen-powered aircraft
• electric regional planes
• carbon capture technologies
• advanced sustainable fuels

As I mentioned, hydrogen-powered seems possible. Electric regional planes seem like a way to not lose out to high-speed rail. We’ve covered fuels.

Carbon capture is an example of a dumb technology. Even after decades of investment from the fossil fuel industry, carbon capture still takes an obscene amount of energy and space to operate, negating the benefits. It’s greenwashing.

And while these airline companies can tout their investments in technologies, they’re also the prime beneficiaries of the research. Sort of how the pharmaceutical industry knows it’s an ultimately profitable idea for them to fund medical research, the aviation industry knows that better and more tech is in their interest. Do they deserve a pat on the back for this? I don’t think so, no.

When I step back, I think the picture is clear.

Whatever genuine efforts exist to improve efficiency are just going on the edges of the problem.

So the “most sustainable airline” is really just the least bad option in a carbon-intensive industry.

How to Fly More Sustainably (If You Have to Fly)

I haven’t stopped flying. What I have done is try to limit my flights to the ones that will bring me the most joy.

Travel can be one of the most meaningful experiences in life. It’s through travel that I’ve become so much more passionate about creating a better world.

When I was flying a lot, I began to hate it. The crammed seats, TSA, and lackluster food options. But when I limit my flights to when it’s going to bring me way more joy and excitement, that’s when I know the tradeoff is worth it.

Fly Less Often

This is the biggest one.

The most effective way to reduce aviation emissions is simply to take fewer flights.

As I share in this article, I limit myself to six flights per year.

I take fewer trips, but I might stay longer.

I say no to the work flight. I choose long-distance trains and even buses if I really want to go to the event.

Avoid Short Flights When Possible

Short flights are particularly inefficient.

A large share of an airplane’s fuel burn happens during takeoff and climb, which means shorter flights often produce higher emissions per mile than longer ones.

Because of that, I’ve started following a personal rule: no flights under four hours.

I’ll admit that’s a little hardcore in the United States, where our trains aren’t very good outside the Northeast.

It means I’ve found myself on long-distance Amtrak trains or obscure regional buses, experiencing the world in a different way. I’ve even gotten used to taking Greyhound. It’s not that bad.

But in many parts of the world, especially Europe and parts of Asia, trains can easily replace short flights.

If you live in the U.S. and think it’s hopeless, there’s a tool called Busbud that’s pretty good for showing you the options.

Choose Direct Flights

If I do fly, I always try to fly direct.

Connecting flights add extra takeoffs and landings, which increases fuel burn. A direct flight may travel a slightly longer distance in some cases, but avoiding an extra takeoff generally reduces emissions.

For example, when I went to Sacramento this year, I took a direct flight from New York to San Francisco, then I took the Amtrak up to Sacramento. It was about the same time total as the layover and $150 less.

Advocate for Better Travel Options

At the same time, we shouldn’t put the entire burden of climate responsibility on individual travelers.

If we could eliminate every flight that’s possible with a train, that would cut a big chunk of emissions from flying.

In many places, especially the United States, flying is often the only practical option for traveling between cities.

If you want to take a train from Boston to New York, it’s easy. But try getting from Chicago to Nashville or Dallas to Atlanta without flying, your options are Greyhound and Flix buses.

That’s not a failure of individuals. It’s a failure of infrastructure.

If we want more sustainable travel, we need to demand better alternatives. That means investing in things like:

• modern passenger rail
• high-speed rail between major cities
• reliable regional trains and buses
• transit connections to airports and train stations

Countries that have made these investments already show what’s possible. In parts of Europe and Asia, high-speed rail has replaced millions of short-haul flights.

A Concrete Example of This

For example, I’m a member of the Rail Passengers Association, which advocates and lobbies in D.C. for better passenger rail in the United States.

I donate $15/month. While that alone won’t transform American transportation overnight, collective pressure like that is part of how big infrastructure changes happen.

Because the real path to sustainable travel probably isn’t just greener airplanes. It’s a movement that demands more sustainable travel options.