Study Of 25 Years Of Carbon Offsets Reveals A Legacy Of Failure; Not Even 1 In 5 Projects Did Anything To Cut GHGs

The failure of carbon offsets to cut planet-heating pollution is “not due to a few bad apples”, a review paper has found, but down to deep-seated systemic problems that incremental change will not solve. Research over two decades has found “intractable” problems that have made carbon credits in most big programmes poor quality, according to the study. While the industry and diplomats have made efforts to improve the system, it found much-awaited rules agreed at a UN climate summit last year “did not substantially address the quality problem”. “We must stop expecting carbon offsetting to work at scale,” said Stephen Lezak, a researcher at the University of Oxford’s Smith School and co-author of the study, in Annual Reviews. “We have assessed 25 years of evidence and almost everything up until this point has failed.”

Carbon offsets are a tool to cut emissions efficiently by crediting rich polluters for financing cheap climate action abroad while pumping out the same amount of planet-heating gas at home. In theory, the practice could lead to lower levels of global heating by funnelling money to the places where it will do the most good as soon as possible. But voluntary carbon markets have long been plagued by “junk offsets” that overstate their impact.

The researchers said the worst problems were with issuing additional credits for projects that were already in the pipeline, such as building a windfarm that would have gone up anyway; impermanent projects, such as planting trees that later burn down in a wildfire; projects with leakage, such as protecting part of a forest but effectively pushing loggers elsewhere; and double-counted projects, such as restoring a peatland but letting the seller and buyer claim the drop in emissions.

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A meta-analysis published in Nature Communications last year found that less than 16% of the carbon credits investigated showed real reductions in greenhouse gas emissions. The lead author, Benedict Probst, founder of the Net Zero Lab at the Max Planck Institute for Innovation and Competition, who was not involved in the new paper, said it provided a “valuable high-level overview of the well-documented problems plaguing existing carbon crediting projects”, despite not providing a critical appraisal of the underlying studies. “This study echoes the main conclusions of our own research, but it provides a broader picture across the carbon crediting landscape,” he said.

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https://www.theguardian.com/environment/2025/oct/06/carbon-offsets-fail-cut-global-heating-intractable-systemic-problems-study