Revealed: more than 90% of rainforest carbon offsets by biggest provider are worthless, analysis shows

But doubts have been raised repeatedly over whether they are really effective.

Verra, which is based in Washington DC, operates a number of leading environmental standards for climate action and sustainable development, including its voluntary carbon standard (VCS) that has issued more than 1bn carbon credits. It approves three-quarters of all voluntary offsets. Its rainforest protection programme makes up 40% of the credits it approves and was launched before the Paris agreement with the aim of generating revenue for protecting ecosystems.

Verra argues that the conclusions reached by the studies are incorrect, and questions their methodology. And they point out that their work since 2009 has allowed billions of dollars to be channelled to the vital work of preserving forests.

The investigation found that:

To assess the credits, a team of journalists analysed the findings of three scientific studies that used satellite images to check the results of a number of forest offsetting projects, known as Redd+ schemes. Although a number of studies have looked at offsets, these are the only three known to have attempted to apply rigorous scientific methods to measuring avoided deforestation.

For example, if an organisation estimates its project will stop 100 hectares (247 acres) of deforestation, it can use a Verra-approved formula to convert that into 40,000 CO2e (carbon dioxide equivalent) of saved carbon emissions in a dense tropical forest if no deforestation takes place, although the formula varies according to habitat and other factors. Those saved emissions can then be bought by a company and applied to its own carbon reduction targets.

The two studies from the international group of researchers found just eight out of 29 Verra-approved projects where further analysis was possible showed evidence of meaningful deforestation reductions.

The journalists were able to do further analysis on those projects, comparing the estimates made by the offsetting projects with the results obtained by the scientists. The analysis indicated about 94% of the credits the projects produced should not have been approved.

Separately, the study by the University of Cambridge team of 40 Verra projects found that while a number had stopped some deforestation, the areas were extremely small. Just four projects were responsible for three-quarters of the total forest that was protected.

The studies used different methods and time periods, looked at different ranges of projects, and the researchers said no modelling approach is ever perfect, acknowledging limitations in each study. However, the data showed broad agreement on the lack of effectiveness of the projects compared with the Verra-approved predictions.

Two of the studies have passed the peer review process and another has been released as a preprint.

The carbon standard said its projects faced unique local threats that a standardised approach cannot measure, and it works with leading experts to continuously update its methodologies and make sure they reflect scientific consensus. It has shortened the time period in which projects must update the threats they face to better capture unforeseen drivers, such as the election of Jair Bolsonaro in Brazil. Verra said it already used some of the methods deployed by the researchers in its own standards, but does not believe they are appropriate for this project type.

Julia Jones, a co-author and professor at Bangor University, said the world was at a crossroads when it came to protecting tropical forests and must urgently correct the system for measuring emission reductions if carbon markets are to be scaled up.

Yadvinder Singh Malhi, a professor of ecosystem science at the University of Oxford and a Jackson senior research fellow at Oriel College, Oxford, who was not involved in the study, said two of his PhD students had gone through the analysis without spotting any errors.

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