Wendover’s Carbon-Offset Problem Has an Accounting Problem of Its Own
Wendover Productions gets the central danger of carbon offsets right: companies can purchase credits for environmental benefits that would have happened anyway. But its 2022 documentary makes several mistakes in presenting the evidence. It misreads the central figures in its Indian cookstove experiment, treats a conservation sanctuary's history as proof that its forest faced no future logging risk, and moves between different carbon-credit systems without adequately distinguishing their rules.
These weaknesses do not rescue the carbon-offset industry. They expose a more important problem: an investigation about unreliable carbon accounting must apply the same precision to its own evidence.
The Indian cookstove experiment is misrepresented
The documentary presents a controlled experiment in India's Koppal district as evidence that improved cookstoves reduced household wood consumption by only 15%.
Its numbers are wrong in a consequential way.
The 2016 study by Aung and colleagues involved 187 households in one village. Researchers randomly assigned 96 households to receive improved stoves and 91 to remain with traditional stoves. Only 166 households completed the follow-up.
The study reported median daily wood consumption of 4.2 kilograms before the intervention and 3.6 kilograms afterwards. Crucially, these were measurements across all households, not separate averages for the intervention and control groups.
The actual comparison found no statistically significant difference between the groups. The intervention's effect was statistically insignificant under both the intention-to-treat analysis (p = 0.74) and the per-protocol analysis (p = 0.95).
The documentary turns an overall before-and-after difference into a treatment-versus-control comparison. That is not a minor presentation error. It misrepresents what the experiment actually measured.
There is another qualification. The researchers found that 40% of intervention households continued using traditional stoves alongside their improved equipment. The documentary describes this as almost half of the entire sample, when it was 40% of the intervention households.
The study's actual conclusion remains damaging to the project: the improved stoves did not demonstrate a statistically significant reduction in fuelwood consumption compared with traditional stoves.
But the distinction matters. A failed intervention is not the same thing as a measured 15% treatment effect.
The wider cookstove problem is considerably better established than this documentary's example suggests. In January 2024, researchers Annelise Gill-Wiehl, Daniel Kammen and Barbara Haya published a study in Nature Sustainability examining 51 cookstove projects across 25 countries, representing approximately 40% of credits issued under the five methodologies they examined.
Their independent calculations estimated that the projects had issued 9.2 times more credits than their actual emissions reductions justified. Even the Gold Standard's more rigorous metered methodology was estimated to be 1.5 times over-credited.
The researchers identified problems with fuel assumptions, stove adoption, actual usage, stove stacking and increased cooking demand. They also warned that additionality and leakage required further investigation.
This is substantially stronger evidence of a widespread cookstove-credit problem than one village experiment. The documentary would have benefited from making the distinction between its particular experiment and the wider industry much clearer.
Sources: Aung et al., Environmental Science & Technology; Gill-Wiehl et al., Nature Sustainability.
A projected carbon saving is not a record of credits delivered
The documentary describes the Koppal initiative as distributing approximately 43,000 improved stoves to 21,500 families in exchange for selling 43,215 tons of carbon offsets annually for ten years.
That figure needs a more careful examination.
The United Nations Clean Development Mechanism registry identifies the project as Project 4478, the Improved Cook Stoves CDM project of Janara Samuha Mutual Benefit Trust.
Its registry entry lists expected annual reductions of 42,637 metric tonnes of CO₂ equivalent and a fixed crediting period running from May 2012 to May 2022.
More importantly, the registry records three issuance tranches:
- 15,699 certified emission reductions.
- 68,195 certified emission reductions.
- 65,481 certified emission reductions.
That is a total of 149,375 issued credits across the three recorded requests. The final posted monitoring period ends in January 2018.
The documentary's 43,215-ton annual figure is not supported as a record of credits actually issued or sold over the promised decade. The UNFCCC registry distinguishes the project's expected annual reductions from its recorded issuances.
Issuance is also different from selling or retiring a credit.
This distinction is essential. Carbon projects routinely begin with optimistic projections. Their environmental performance must subsequently be measured against actual results.
The documentary should have followed the project through its registry records rather than leaving viewers with a projected annual figure that sounds like an accomplished financial transaction.
Sources: UNFCCC Project 4478; First issuance; Second issuance; Third issuance.
Hawk Mountain was already conserved, but the legal situation was more complicated
Wendover's most compelling opening example is Hawk Mountain Sanctuary in Pennsylvania.
The documentary's argument is simple: a forest that had been protected since the 1930s could not reasonably claim that carbon payments had prevented its destruction.
There is substantial evidence supporting the criticism.
Rosalie Edge purchased the sanctuary's original 1,400-acre core in 1934. Hawk Mountain's own account says the forest subsequently regenerated with minimal human impact.
Its conservation mission was therefore established long before the carbon-credit arrangement.
However, the documentary leaves out an important development.
The carbon project placed the forest under a conservation easement through the Nature Conservancy's Working Woodlands programme. It also established a forest management plan, with carbon revenue helping fund seasonal crews to improve forest health and control invasive plants.
The American Carbon Registry subsequently explained that the property had no legal restrictions on timber harvesting before the carbon project. The easement introduced a permanent legal commitment that restricted future harvesting.
ACR's position deserves scrutiny because it operates the registry responsible for the project. Its defence is not independent proof that extensive logging would otherwise have occurred.
But it identifies a real distinction the documentary overlooks: a conservation organisation's intention to preserve land is not the same as a legally binding guarantee that the land will remain protected indefinitely.
The opposing evidence is also important.
Bloomberg's original investigation quoted Hawk Mountain conservation scientist Laurie Goodrich saying the organisation had no intention of cutting most of its trees and would continue managing the land in the same way without carbon payments.
That statement seriously challenges the project's assumed baseline.
The Nature Conservancy's response was that carbon payments funded improvements and established permanent legal protection, including protection against future financial difficulties at the sanctuary.
Both facts matter.
A forest can be managed as a sanctuary today while remaining legally available for harvesting tomorrow. Conversely, the existence of a new conservation easement does not automatically prove that the aggressive harvesting scenario used to calculate the credits was realistic.
The actual question is whether the easement and carbon payments changed the forest's likely future management enough to justify the number of credits issued.
The documentary treats that question as already settled. It was not.
Sources: Hawk Mountain's account of its carbon project; Bloomberg's original investigation; ACR's responses concerning forest projects.
California's over-crediting figure needs its proper denominator
The documentary's California example is one of its strongest pieces of evidence.
A 2021 study published in Global Change Biology examined California's Improved Forest Management offset programme.
The researchers found that regional forest classifications could produce inaccurate baselines because ecologically different forests were grouped together.
Their analysis identified estimated net over-crediting of 30 million tonnes of CO₂ equivalent, representing 29.4% of the 102.1 million upfront credits they were able to analyse.
The estimate had a 90% confidence interval of 20.5–38.6 million tonnes.
This is a serious finding. It is also important to understand what the figure measures.
The researchers had sufficient public information to analyse 65 projects representing approximately two-thirds of California's forest offsets and half of the state's entire offset programme at the September 2020 cutoff.
The 29.4% figure applies to the credits in that analysis, not every credit issued in California.
The researchers also identified some under-credited projects. Their study explicitly described the errors they identified as only a subset of the possible problems in the programme.
The documentary gets the central problem right, but does not give viewers enough information about the study's scope and limitations.
This is not evidence that every California forest credit is fraudulent. It is evidence that a major regulatory programme used baseline calculations capable of systematically awarding credits without equivalent additional climate benefits.
The documentary treats several different markets as one
Another weakness is the way the documentary moves between different carbon-credit systems.
Its examples include:
- Voluntary forest credits issued through the American Carbon Registry.
- California's regulated cap-and-trade offset programme.
- United Nations Clean Development Mechanism credits.
- Gold Standard cookstove projects.
These systems share fundamental problems involving additionality, baselines, permanence and leakage. But they do not operate under identical rules or serve identical buyers.
A voluntary credit purchased by JPMorgan to offset business travel is not the same financial instrument or regulatory obligation as a compliance credit purchased by a California industrial emitter.
Likewise, a UN-registered cookstove project operates under different methodologies from an American forest project.
Comparing these examples is useful. Treating their failures as proof of one uniform market mechanism requires more evidence.
There is nevertheless substantial independent evidence supporting the documentary's wider criticism.
A 2024 Nature Communications study examined the 20 largest corporate buyers of voluntary carbon credits between 2020 and 2023. Those companies accounted for approximately 21% of retirements across the three major registries examined.
The researchers found that 87% of the credits purchased came from high-risk project categories. This does not mean that 87% were individually proven worthless, but it demonstrates how extensively major buyers relied on credit types with significant additionality and accounting risks.
In 2025, research published in the American Economic Journal: Applied Economics found that at least 52% of approved carbon offsets allocated to Indian wind projects under the Clean Development Mechanism went to projects that would very likely have been built anyway.
The researchers estimated that selling those credits to regulated polluters resulted in substantially higher global CO₂ emissions.
These findings strengthen the documentary's central warning. They also show why different crediting systems must be investigated separately rather than treated as interchangeable examples.
Sources: Trencher et al., Nature Communications; Calel et al., American Economic Journal: Applied Economics.
The carbon market is changing, even if its underlying problems remain
The documentary's final argument is that the market rewards cheap credits rather than reliable environmental results.
There is considerable evidence supporting that criticism, but the market has not remained static since the film was released in June 2022.
In July 2024, the American Carbon Registry updated its Improved Forest Management methodology.
The revisions introduced baseline evaluations before each reporting-period issuance, limits on assumed harvesting intensity, and more specific assessments of legality, site accessibility, timber-market capacity and existing easements.
These changes do not retrospectively validate earlier credits. They demonstrate that the rules governing forest-credit calculations have evolved.
MSCI's September 2025 assessment also identified a change in buyer behaviour.
Its data showed that the lowest-rated CCC projects accounted for 11% of retirements, less than half the proportion recorded in 2022. Its high-integrity credit price index was more than four times the low-integrity index during parts of 2025.
MSCI is a commercial ratings provider, and its proprietary ratings are not independent proof of actual emissions reductions. Nevertheless, the figures challenge the documentary's suggestion that the cheapest option invariably wins.
There is now also stronger evidence for the documentary's argument about moral licensing.
A July 2026 CEPR discussion paper, An Autopsy of the Voluntary Carbon Market, examined corporate offset purchases and emissions disclosures using a buyer-linked dataset.
The researchers found that companies which stopped purchasing offsets after the 2023 carbon-market scandals subsequently reduced their direct operational emissions (Scope 1) approximately 20% more than companies that continued purchasing credits.
The authors interpret this as evidence that access to offsets can weaken incentives for companies to reduce their own emissions.
This is a discussion paper, not yet a peer-reviewed journal publication. It also does not prove that individual travellers necessarily take additional flights because they purchase offsets, or that the entire global market increases net emissions.
But it provides meaningful empirical support for the corporate behavioural mechanism that Wendover discussed.
Sources: ACR's 2024 methodology update; MSCI's 2025 State of Integrity report; Panizza, Tripoli and Weder di Mauro, CEPR Discussion Paper 21788.
The verdict: A sound warning is not a substitute for accurate accounting
Wendover's central warning survives scrutiny. Carbon markets have repeatedly rewarded projects whose claimed environmental benefits exceeded their demonstrated results.
The California forest programme, the international cookstove industry and the corporate purchasing patterns documented in subsequent research all provide substantial evidence of systemic problems.
But the documentary is less rigorous than its subject demands.
It misrepresents the comparison in its most important cookstove experiment. It presents projected carbon savings without adequately distinguishing them from actual credit issuance. It treats a sanctuary's conservation history as conclusive proof about its future legal protection. And it moves between different carbon-credit systems without sufficiently examining their individual rules.
None of these problems makes carbon offsets reliable.
They make the documentary less reliable as an independent investigation.
A carbon credit should not be accepted merely because a registry approved it, a corporation purchased it or a conservation organisation issued it. Equally, an investigative documentary should not expect its audience to accept a conclusion simply because its examples are disturbing.
The carbon-offset industry deserves aggressive scrutiny. Wendover's accounting deserves the same.
References
- The Carbon Offset Problem — Wendover Productions (3 June 2022). Original video. The work examined in this investigation.
- Impact of Fuel-Efficient Biomass Cookstoves on Indoor Air Quality and Health in Rural India — Environmental Science & Technology (2016). Original research. Provides the randomized household experiment and the correct treatment-versus-control results.
- Improved Cook Stoves CDM Project of JSMBT — United Nations Framework Convention on Climate Change. Project registry. Establishes the project's registered annual reductions, crediting period and actual recorded issuance requests.
- Help the Climate and the Mountain — Hawk Mountain Sanctuary (22 April 2020). Institutional account. Documents the conservation easement, management plan, forest history and use of carbon revenue.
- These Trees Are Not What They Seem — Bloomberg Green (9 December 2020). Original investigation. Provides interviews with Hawk Mountain staff, the Nature Conservancy and carbon-market experts, including competing accounts of the project's additionality.
- ACR Responses to Project-Related Questions — American Carbon Registry. Registry responses. Sets out the registry's defence of the Hawk Mountain easement and its argument that future harvesting was legally and economically possible.
- Systematic Over-Crediting in California's Forest Carbon Offsets Program — Global Change Biology (2022). Peer-reviewed study. Quantifies the baseline problem and identifies its precise statistical and ecological limitations.
- Pervasive Over-Crediting from Cookstove Offset Methodologies — Nature Sustainability (23 January 2024). Peer-reviewed study. Evaluates 51 projects across 25 countries and identifies the scale of cookstove credit over-issuance.
- Demand for Low-Quality Offsets by Major Companies Undermines Climate Integrity of the Voluntary Carbon Market — Nature Communications (10 August 2024). Peer-reviewed study. Examines the purchasing patterns of major corporate buyers and the prevalence of high-risk credits.
- ACR Adds Precision to Evaluation of Baselines in Update to IFM Methodology — American Carbon Registry (2 July 2024). Methodology update. Documents changes to baseline assessments and harvesting assumptions.
- Do Carbon Offsets Offset Carbon? — American Economic Journal: Applied Economics (January 2025). Peer-reviewed research. Finds substantial non-additionality among Indian wind projects receiving CDM credits.
- 2025 State of Integrity in the Global Carbon-Credit Market — MSCI (September 2025). Industry assessment. Provides current market-rating, purchasing and pricing trends, subject to MSCI's proprietary methodology.
- An Autopsy of the Voluntary Carbon Market — CEPR Discussion Paper 21788 (26 July 2026). Research paper. Investigates whether access to carbon offsets weakens companies' incentives to reduce their own operational emissions.
Make the opening thesis more preciseTrim repeated qualifications and verdicts