For those who fly—which is only a little more than 10% of the population—the emissions associated with air travel make up a big chunk of individual climate impact. As many of us turn our eyes towards summer vacation, that can cast a cloud over planning that jaunt to Hawaii or Europe. Perhaps there’s hope? As you book your flight, the airline offers you a carbon offset, a small add-on fee to cancel out the emissions from your trip.
Seems like a great deal? Not so fast. Let’s talk about it.
What are carbon offsets?
In the simplest terms, carbon offsets are a mechanism to balance out the emissions from one thing by investing in efforts to reduce emissions elsewhere. Some airlines and companies buy these directly, explains Robert Mendelsohn, an environmental economist at Yale University who specializes in assessing the monetary value of ecosystems and emissions, but there’s also the voluntary market. That’s what lets individuals buy offsets (often also called credits) through online marketplaces.
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Each credit promises to offset one metric ton of carbon dioxide. For instance, a round-trip journey from L.A. to New York produces about 1.4 metric tons of carbon dioxide equivalent emissions (CO2e) per passenger. (You’ll notice that this number is higher than the estimates you’ll see on Google Flights, which don’t include non-CO2 warming factors like contrails.) Terrapass, a website that sells offsets, says they can balance out burning all that jet fuel for just $16.
The offset programs these sites sell generally fall into one of two buckets: avoidance projects and removal projects. Avoidance includes, for example, making energy improvements to buildings. Think switching from fossil fuels to renewables or going from gas water heaters to solar ones. Removal projects, however, are probably what springs most to mind when people think of offsets; they center on sequestering carbon through things like forestry projects that aim to sock carbon away in the form of biomass.
Some offset projects also attempt dual benefits of reducing emissions and supporting local communities. These tend to be smaller in scale, like programs that help people switch from gas cookstoves to electric ones or forestry projects that help communities access timber and fruit.
Do they work?
Most offset programs simply don’t add up. A 2023 investigation by The Guardian and an analysis from the university ETH Zurich both found that the vast majority are “likely junk” and/or don’t reduce emissions to the degree they say they do. “Research has shown most of these carbon offsets are not working. They’re failing,” says Anuradha Mittal, founder of nonprofit The Oakland Institute and an expert on human rights issues and conservation policies.
There are lots of ways to think about what would make a “good” offset, but criteria developed at MIT’s Sloan School are particularly helpful. A legit offset project as one that is “additional, verifiable, immediate, and durable.” The challenges of hitting all four checkboxes are myriad. A couple examples: More than one company can claim to reduce their emissions through the same offset project, in what is known as “double counting.” It’s also possible to overestimate a program’s potential; that’s certainly true of forestry, where the effects aren’t necessarily immediate.
“If you’re actually paying for real mitigation, it is going to cost more than if you’re paying for fake mitigation.”
Robert Mendelsohn, environmental economist, Yale University
Forestry projects in particular have a real problem when it comes to durability. A 2022 report by the Global Forest Coalition dinged them on several counts. They can, for instance, fail due to poor management or deforestation. “Carbon dioxide stored in trees will sooner or later be released back into the atmosphere,” the authors wrote, “including through fires and pests, which are now more frequent and extreme due to climate change.”
Poorly managed projects can also lead to social harm. A 2023 analysis by Carbon Brief showed that more than 70% of programs hurt local communities and Indigenous peoples. The companies behind such projects tend to prioritize making the effort successful (or at least seem so) over collaborating with community members in shaping the programs. One project in Uganda, for instance, leased more than 10,000 acres, which resulted in evictions and food insecurity for locals.
Yale’s Mendelsohn does point out that some projects can be legit––ones, for example, that help replace gas guzzlers with electric cars—but they’re often sold too cheaply to be effective. This is especially true for airline offsets or individual markets, which typically ask $20 or less per metric ton. U.N. estimates say the actual cost of forestry projects are between $50 and $200 per metric ton. “If you’re actually paying for real mitigation, it is going to cost more than if you’re paying for fake mitigation,” Mendelsohn says. “That’s all the administrative cost is of creating a fake market. It’s expensive but it’s cheaper than actually doing something.”
So what are you supposed to do?
Don’t fret, no one’s getting grounded, but experts recommend actions other than buying credits to address individual aviation emissions. “Unfortunately, there’s no shortcut to deal with our climate crisis without changing our lifestyle,” says Mittal.
Fly less. According to a 2021 analysis, frequent fliers account for the majority of airline emissions: In the U.S. just 12% of people take two-thirds of all flights. Being cognizant of the impact of air travel is a good step, because that can help you be choosy about when it’s worth it to fly versus making connections or having experiences in other ways.
Skip the upgrades. Sit in economy. Per-person emissions are about two to three times higher in upper classes, simply because those seats take more space and gobble up more resources.
Compensate. Living a climate-conscious existence is about picking your spots. If you fly, it might make sense to make other changes in your day-to-day. Logging more miles in an EV or simply driving less adds up. Consider, for example, that the 1.4 metric tons of CO2e emitted jetting back and forth from L.A. to New York are equivalent to driving about 3,500 miles in a gas-powered car—or about a quarter of the average American’s annual mileage.
Get engaged. Mittal says that the most impactful thing anyone can do is to vote for candidates that prioritize climate policies and advocate for measures that reduce emissions. This could mean pushing for big changes like greener schools, or perhaps EV and e-bike incentives, investment in public transit, or taxes that would put more onus on private flyers.