The Carbon Market's Credibility Crisis: How Forest Credits Became Forests of Doubt

Barbara Haya was staring at satellite imagery at 2:17 in the morning when she noticed something that didn't add up. The forest block in Peru — certified as a protected carbon offset project — showed the same deforestation pattern as the unprotected land beside it. Trees were vanishing at nearly identical rates on both sides of an invisible boundary. The offset project, which had sold millions of dollars in credits to airlines and technology companies seeking carbon neutrality, was supposed to be preventing this exact outcome.

'I kept checking my data,' Haya, director of the Berkeley Carbon Trading Project, told me. 'I thought I had the wrong coordinates.' She didn't. What she had found was a microcosm of a much larger problem: the voluntary carbon market, worth nearly $2 billion annually and growing, is built substantially on credits that aren't delivering the climate benefits they promise.

This isn't a story about fraud, though fraud exists in these markets. It's more troubling than that. It's a story about how well-intentioned systems, designed to channel private capital toward forest conservation, have created an elaborate architecture of accounting that often fails basic scientific scrutiny. And it matters enormously, because voluntary carbon markets are supposed to be one of our primary tools for reaching net-zero emissions by mid-century.

What the Satellites Revealed

The premise behind forest carbon credits seems elegantly simple. A project developer identifies a forest at risk of being cut down, secures funding to protect it, and sells credits representing the carbon dioxide that would have been released had the trees been felled. Companies buy these credits to offset their own emissions. Forests survive. The atmosphere benefits. Everyone wins.

The thing is, this logic depends on a counterfactual — what would have happened without the project — that is inherently impossible to observe directly. Project developers must estimate how much deforestation would have occurred in the absence of their intervention. And here is where the architecture wobbles.

Thales West, the Cambridge University researcher who led the Science study, describes the methodology gap in stark terms. Project developers were setting their baseline deforestation estimates by looking at nearby areas with high historical clearing rates, even when the project forests themselves faced minimal threat. They were measuring what happened somewhere else and claiming credit for preventing it where they stood.

This finding didn't emerge in isolation. A Guardian investigation in January 2023, working with Die Zeit and SourceMaterial, examined Verra-certified projects specifically and found that more than 90 percent of rainforest offset credits were likely 'phantom credits' that did not represent genuine carbon reductions. Verra, the largest carbon standard in the voluntary market, certified these projects.

The Uncomfortable Data

The voluntary carbon market was supposed to solve a fundamental problem in climate economics: how to put a price on nature's services. Forests sequester carbon, but that service has historically been invisible to markets. Carbon credits were meant to make forests worth more alive than dead.

The market has attracted enormous corporate investment. Microsoft, Delta Air Lines, Salesforce, and dozens of other major companies have purchased forest carbon credits as part of their climate strategies. Shell alone has committed to spending $100 million annually on nature-based carbon credits. These are not naive buyers; they employ sustainability teams and consultants who examine the credentials of offset projects.

But the problem is structural, not about due diligence. Carbon credit methodologies were developed by the same organisations that derive revenue from certifying projects — a conflict of interest that critics say has consistently favoured more generous crediting approaches. Verra, Gold Standard, and the American Carbon Registry all operate on fees paid by project developers seeking certification.

Haya's research at Berkeley has shown that the problem varies enormously by project type. Renewable energy credits, while facing their own issues of additionality, generally perform better than forest credits. But forest credits account for approximately 40 percent of all voluntary market transactions by value — and they carry the worst integrity record.

The Industry's Response

The carbon market industry has not been deaf to these criticisms. In January 2023, the Integrity Council for the Voluntary Carbon Market — an independent governance body established with backing from major banks and investors — published its Core Carbon Principles, a new benchmark meant to separate high-quality credits from the rest.

Verra, meanwhile, announced in November 2023 that it would retire its existing forestry methodology and develop a new approach incorporating dynamic baselines and more rigorous monitoring. David Antonioli, Verra's then-CEO, acknowledged that the existing system needed improvement while defending the organization's overall track record.

Some major buyers have responded by pulling back. Nestlé announced in early 2024 that it would no longer use carbon credits to meet its climate targets, focusing instead on direct emissions reductions. EasyJet, one of the aviation industry's largest offset purchasers, has shifted entirely to carbon removal credits rather than avoidance credits.

But the scientific community remains divided on whether reforms will be sufficient. Grayson Badgley, a forest carbon researcher at Black Rock Forest and Columbia University, has argued that the fundamental problem isn't just methodology — it's the market structure itself.

The Deeper Tension

Here is what this means for the broader climate finance architecture. The voluntary carbon market was supposed to demonstrate that private capital could flow to conservation at scale without mandatory regulation. It was proof of concept for market-based environmentalism. Its credibility crisis threatens more than individual projects; it threatens the idea that voluntary mechanisms can play a meaningful role in addressing climate change.

The alternatives are not obviously better. Mandatory carbon pricing through taxes or cap-and-trade systems faces intense political opposition in most major economies. Public conservation funding, while more reliable in its outcomes, cannot scale to the $100 billion annually that forest preservation is estimated to require. The voluntary market, for all its flaws, has channelled real money to real forests.

Haya, despite her damning research, doesn't advocate for abandoning carbon markets entirely. She believes in a reformed version — one with conservative baselines, independent verification, and a fundamental shift in who bears the risk of overestimation. Currently, if a project overcredits, the buyers never know. In her proposed system, buffer pools and insurance mechanisms would force project developers to share that risk.

What We Still Don't Know

The deepest uncertainty isn't about past credits but future ones. Article 6 of the Paris Agreement, finalized at COP26 in Glasgow, establishes a framework for international carbon trading between countries. If voluntary markets can't get the accounting right, what happens when sovereign nations begin trading credits against their nationally determined contributions?

The World Bank estimates that robust carbon markets could reduce the cost of implementing national climate pledges by 50 percent. That estimate depends on the credits being real. If they're not — if we build international climate architecture on the same foundation that voluntary markets have shown to be unstable — the consequences extend far beyond corporate greenwashing.

Haya returned to that Peruvian project several times in subsequent years. The forest is still there — degraded at the edges, but standing. Whether the carbon credits it sold made any difference to that outcome remains, like so much in this field, genuinely unknowable. 'We're asking the market to quantify something that can't be precisely quantified,' she said. 'And then we're treating those quantities as if they're money.'

The question that haunts the carbon market's critics and defenders alike is whether better methodology can solve what may be a philosophical problem. Forests exist in the present. Deforestation happens in real time. But carbon credits trade in a currency of counterfactuals — futures that didn't happen, measured against futures that might. The science of attribution keeps improving. Whether it can ever improve enough remains the open question that no amount of satellite imagery can answer.