Many airlines offer passengers the opportunity to offset a flight’s carbon emissions with carbon credit schemes—but a new study suggests there are few solid checks on such programs. Photo via iStock/kyoshino

Carbon Credits

Do Forest Carbon Credits Work and Actually Help the Environment?

BU environmental ecologist and alum scientist team up for study of forest carbon credits and recommend ways to boost schemes’ potential to offset emissions

It takes a lot of fuel to get an airplane up in the sky and keep it there—which means a lot of emissions. In fact, the airline industry produces more greenhouse gases than many major countries. Most airlines know this isn’t a good look, so they are pushing for cleaner fuels—and offering passengers the chance to help them offset a flight’s carbon emissions. Book a trip with a big carrier and you might be asked if you want to invest in forest preservation, saving enough trees to soak up your jet-setting’s environmental emissions.

But is that really helping the planet or is it just a way for corporations to look better? A new study coled by researchers at Boston University and the nonprofit Clean Air Task Force has found some of these efforts, known as forest carbon credit schemes, might not be doing much good. After examining the standards-governing programs, which are typically certified by governments or independent regulators, they concluded there could be more solid checks to help ensure that they’re delivering any climate benefits. Writing in the journal Earth’s Future, the researchers recommend a series of new guidelines and improvements to “the carbon market system that would promote reliably high-quality forest carbon credits.”

“There’s been a lot of appetite for these credits so corporations can meet their sustainability goals, but some of the credits that have been sold have been found to be dubious at best,” says Lucy Hutyra, a BU College of Arts & Sciences Distinguished Professor and chair of Earth and environment. “This paper is not about, the system is broken, let’s just scrap it; it’s looking at what works well, what doesn’t, and how we can improve it.”

Weak Guidelines Mean Climate Benefits Not Guaranteed

There are a few different types of carbon credit schemes—some are voluntary, while some are regulated compliance markets. The expensive ones involve using industrial technology to capture carbon dioxide and store it underground; the cheaper ones may pay landowners to preserve forests and wetlands. If a company expects to exceed its planned or legally mandated carbon emissions—or is just striving to prove its green credentials—it can offset them by buying credits. Each credit is a promise to reduce or remove carbon dioxide in one place for every ton of it pumped out in another. But the credits are controversial and have plenty of detractors: a 2024 Reuters story called carbon offsets “scandal-ridden”; the Guardian has reported that “more than 90 percent of rainforest carbon offsets by [the] biggest certifier are worthless.” Done right though, they have huge potential, experts say.

“About half of our fossil fuel CO2 emissions don’t stay in the atmosphere; they go into a combination of the land and the ocean. The land carbon sink is an amazing thing,” says Hutyra. “A miracle has been happening for decades across the globe: the planet is not feeling the full brunt of our energy habits—it would be warmer than it is today if it was.”

For their study, Hutyra and her colleagues examined voluntary forest credit markets in North America, focusing on the standards, or protocols, that govern how they’re run and certified. For example, most schemes require that the carbon will be stored for a set period and will have a risk protocol to mitigate against potential threats to that: What happens if, say, a forest is ravaged by fire or disease? The researchers—a team of 12 scientists with expertise spanning forest and soil carbon science, wildfire risk and prevention, ecosystem modeling, and human impacts on forests—then assessed the robustness of 20 protocols, giving each a likely effectiveness score.

“Overall median protocol scores ranged between very weak and satisfactory,” they concluded in their paper. The only standard to get a satisfactory score was one that hasn’t even been applied in the real world yet. Nothing hit a “median score of robust or higher.”

“Our results show that the protocols used to generate credits are a critical weak link in the forest carbon market system,” says BU alum Rebecca Sanders-DeMott (GRS’17), the Clean Air Task Force’s director of ecosystem carbon science. She and Hutyra were colead authors on the paper. “Without significant improvements, the integrity of the forest carbon market will remain at risk.”

Better Quality Carbon Credits

According to Hutyra, the management of risk is one of the biggest areas for enhancement. To insure against disaster, a forest carbon credit scheme will set aside buffer zones—reserve pools of land in case the primary preservation land is damaged. “In the current system, the buffer pool risks are very conservative, very low estimates of risk,” says Hutyra. Plus, they don’t always take into account different levels of danger or how they might evolve over time. “The wildfire risk in one part of California could be really quite different than another part,” she says. Hutyra offers two easy fixes: bigger buffer zones and area-specific risk maps.

In addition to improvements to risk reduction, the researchers list four other areas for change, from better monitoring to an overhaul of the general market structure. The paper gives 22 specific changes, split evenly by changes that should be relatively easy to implement—such as requiring “risk reassessments at least every 5 years”—and those that will require bigger leaps forward.

Among the more involved recommendations are two related to what the researchers call “leakage.” A carbon credit might preserve forest in one spot, but it doesn’t stop someone building a mall in another; that causes leakage, because “the net effect is no actual change in the land carbon sink, in real emissions to the atmosphere,” says Hutyra. She says fixing that requires a better system for calculating leakage at national and global levels, alongside ways of incentivizing climate positive land use changes.

Restore Confidence in Carbon Markets, Mitigate Climate Change Impacts

Beyond advancing the science and pushing for change, there was a personal bonus to the project for Sanders-DeMott and Hutyra. During her biology PhD program at BU, Sanders-DeMott took classes with Hutyra, who also served on her PhD committee.

“Rebecca has grown in ways where her expertise far outweighs mine,” says Hutyra, pointing to Sanders-DeMott’s professional experience in connecting the science to what matters to policymakers and decision-makers. “I no doubt have learned as much from Rebecca in this process as I contributed. It’s been really fun, and it’s also the power of alumni, community, and relationships in science.”

Sanders-DeMott says the project encapsulated much of what her time at BU taught her about being a scientist and having an impact on the world.

“Lucy is brilliant, so knowledgeable about forest carbon science, and a pleasure to work with. It was an honor to collaborate on a project that extends expertise I developed as a student at Boston University into a topic with direct policy relevance,” she says. “This project is a great model of connecting cutting-edge science to policy and practice that I hope feels as fulfilling to all involved as it has been for me.”

The next step for the research team is to get the word out about their findings and recommendations. In addition to the scientific paper, the Clean Air Task Force is publishing an everyday language report, hosting webinars, and conducting targeted outreach with the groups managing carbon credit protocols. Although Hutyra recognizes there’s currently less federal appetite for tackling climate change, she’s hopeful the team’s research can have a positive impact, noting that other countries and many US states are still pursuing climate goals. The study recommendations also provide a useful way for companies to make sure they’re buying effective credits.

Sanders-DeMott agrees that while federal oversight of the voluntary carbon credits market would be helpful, it’s not essential.

“Global energy demand is rising, and while decarbonizing our energy systems is critical, it will take time—decades, in fact. Meanwhile, the impacts of climate change are already being felt and are accelerating,” she says. “Forests, which have long served as vital carbon sinks, are under increasing threat.

“By taking these recommendations seriously, carbon market actors can help restore confidence in carbon markets and unlock the full potential of forests to mitigate the worst effects of climate change, buying us time as we scale the technologies we need to ensure a high-energy, zero-emissions future.”

This research was funded by the Clean Air Task Force.