I hate to admit it: I’m a frequent flier.

I wasn’t always this way. Growing up, we took humble vacations at the Jersey Shore, no air travel required. Fast forward to out-of-state college, and the numbers started to add up real fast. During college, I was also blessed with the opportunity to study abroad on four different continents, a trip of a lifetime that racked up several lifetimes’ worth of emissions.

For years, air travel has been the bane of my climate-conscious existence. Carbon offset programs offered to absolve my guilt…but I wasn’t so sure of this miracle cure. I decided to dive into what carbon offsets are, how they work, and the estimated price tag for my offsets.

Why the concern?

Air travel is a major contributor to carbon emissions. In 2019, planes released 916 million tons of carbon dioxide into the atmosphere, more than the entire country of Germany. Theoretically, every flight you take produces a hefty sum of climate damage. 

A round-trip flight from New York to Miami could release a half a ton of carbon dioxide. For comparison, the average person produces about four tons of carbon dioxide each year. If you’re a frequent flier, air travel probably makes up a significant chunk of your carbon footprint.

What are carbon offsets?

At first glance, carbon offsets sound promising. The name makes it sound like a new technology that can suck our emissions out of the atmosphere. Unfortunately, the real thing is a little more complicated and probably less effective.

Carbon offsets are donations to eco-friendly projects. With the help of a calculator, a person or business can estimate their total emissions and donate a corresponding amount to charity. Each program uses a different calculator based on different equations, but the general idea is that for every ton of carbon dioxide you produce, you donate a set amount. So offsets do not actually take any carbon out of the atmosphere; they’re more of a penance for emitting in the first place. Theoretically, your donation will fund programs that actually reduce future greenhouse gas emissions.

There’s a wide variety of different carbon offset programs, but for simplicity, we’re going to focus on the ones aimed at everyday people looking to atone for their travels. You can buy these online or directly through some airline checkouts.

Different calculators, different numbers

Just Google “carbon flight calculator” and you’ll find a host of websites offering to help. Each of these websites provides a handy-dandy calculator for estimating your flight emissions, and most even feature a big “DONATE” button.

But when I started typing my numbers in, I was bewildered. Different websites were producing vastly different estimates for my carbon emissions, and in turn, how much money I “should” donate. Some were nearly twice as high as others. I did some digging, and found that each website based its calculations on different formulas. It turned out that measuring carbon emissions isn’t so cut-and-dry: the emissions released by a given flight can vary by aircraft and weather. Your “proportion” of the emissions is affected by things like whether a flight is full or what class you sit in. Some calculators try to adjust for these different factors, sometimes in different ways. Many websites publish their formulas, but not all are so transparent.

My numbers

I ended up using three different calculators: those offered by The Good Traveler, MyClimate, and Carbon Footprint Calculator. I tried to choose calculators that would reflect the significant variation in estimates.

ProgramEmissions (kg)Donation ($)
The Good Traveler50,219 581.16
Carbon Footprint Calculator22,708261.42

The Good TravelerCarbon offset program partnering with airports and airlinesInputs: departure airport, arrival airport, layovers, number of travelers, one-way vs. roundtripProduced the highest emissions estimate (50,219 kg), more than twice that of the lowest estimateUses a formula based on 344 lbs. CO2 per 1000 miles of air travel Does not publish its entire formula
MyClimateCarbon offset program for various types of emissionsInputs: departure airport, arrival airport, layovers, number of travelers, one-way vs. roundtrip, classSuggested a donation ($848.00) nearly 1.5 times that of The Good Traveler, despite estimating 0.6 times their total emissionsPublishes entire formula
Carbon Footprint CalculatorPowered by Carbon FootprintProvides estimates for various types of emissionsInputs: departure airport, arrival airport, layovers, number of travelers, one-way vs. roundtrip, classProduced the lowest emissions estimate (22,708 kg)Produced the lowest suggested donation, with options ranging from $261.42–$582.52Lowest suggested donation is equal to about $11.51 per ton of emissions

In all, I had traveled more than 100,000 miles. But the calculators produced wildly different estimates as to how much carbon my flights had emitted, and how much my penance should be. 

Where does my donation go?

It depends on the program and the project. Sustainability projects can range from planting trees to the donation of clean-burning cookstoves. The idea is that trees can absorb carbon dioxide from the atmosphere, or that cookstoves can minimize future emissions from low-income countries. 

The tricky thing is finding a project that’s effective, long-lasting, and equitable. For example, consider a project that would pay rural landowners not to cut down their forests. This might seem like a simple tradeoff, but in countries like Brazil, locals have a lot at stake. Converting forest to pastures can be a lifeline for poor rural families. A farmer can earn US $200 by selling a cow, compared with a few dollars per kilogram of sustainably-sourced rubber from the forest. In this case, carbon offsets need to provide a viable alternative for people with no other source of income. 

Where does the carbon go?

Nowhere. Or to be more specific, it stays in the atmosphere until it’s absorbed by trees, the ocean, or some groundbreaking technology. But theoretically, your donations could help speed up that process.

Are carbon offsets even ethical?

The overall consensus by experts is that it’s better to reduce your emissions in the first place. Making a large donation doesn’t negate the fact that you’ve contributed to climate change. Although it might clear your conscience, it really just shifts the burden to someone else’s plate.

Some people have compared carbon offsets to Middle Age indulgences. In the days before Luther broke with the Catholic church, people could buy indulgences (aka donations) to purchase forgiveness for their sins. Ultimately, it was viewed as a rich person’s express train to heaven.

In a podcast published by the University of Oxford, philosophy professor John Bloome says that preventing future carbon emissions is cheaper than “buying” the cost of past emissions. For example, he explains that a trans-Atlantic flight might generate 1.5 tons of carbon dioxide, an amount that will ultimately cause $85 worth of damage. In contrast, buying an offset for 1.5 tons of future emissions might only cost $10. Why the difference?

Most carbon offset projects take place in developing countries, where costs are often cheaper. Consider the example project of donating eco-friendly cookstoves: building and delivering a cookstove in the Congo might be cheaper than buying and delivering a cookstove in the United States. In this way, projects in developing countries might have a bigger bang for the buck, economically speaking. Alternatively, imagine buying an acre of forestland for preservation: would the total cost be cheaper in Northern California or Brazil?

Some activists believe that this process shifts the burden of fighting the climate crisis from rich countries to poor countries. Furthermore, carbon offsets take advantage of the fact that people in developing countries get paid lower wages and have fewer economic protections than in rich countries. Bloome argues that carbon offsetting is a way of transferring funds from rich countries to poor countries, a point of contention during recent climate talks. 

Birdseye view of intersecting highways, industrial complexes, and warehouses. A plane wing is in foreground.
View from my airplane window

How should I choose my offset?

If you’re thinking about buying a carbon offset, remember that projects should be verified and permanent. In other words, is the program real, and if so, how long will it last for?

Unfortunately, the world of carbon offsets can be murky and misleading. Some projects claim to protect areas that are already preserved; others might not guarantee that the preservation is permanent. For example, with some projects you might pay to protect land this year, only to have it developed next year. Even the Holy See was duped by a plan to plant a “Vatican Forest” in Hungary. Meanwhile, supposedly protected lands in Cambodia lost half their forest cover from 2008 to 2017. Other reports have found that carbon offset programs tend to vastly overestimate the amount of carbon the projects will actually save.

Prospective buyers should also check whether the offsets are purchased in addition to (not instead of) any existing airline requirements. The Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA) set baseline emissions levels using data from 2019 and 2020; the aviation company must pay for any additional emissions. Also, carbon offset projects shouldn’t have leakage, which is when deforestation is prevented in one area only to be diverted somewhere else. 

Some carbon offsets are verified by organizations like The Climate Action Reserve and Gold Standard. These organizations investigate projects to make sure that they’re legitimate.

Overall, projects should be transparent and clear, preferably providing robust evidence to back-up their claims. Just like with any other purchase, you should make sure you trust the product before investing.

Long story short

Until we find long-term solutions to climate change, offsets are a band-aid for individuals looking to prevent future harm to the environment. They’re poorly regulated, so while some projects are doing great work, others might be more misleading.

As for my emissions, I’ll donate the money directly to an organization of my choice, a registered environmental nonprofit that I trust. That way, I can be confident my donation is going to a good cause. There’s no question: my wallet will hurt. But not as much as the emissions I can’t erase.