Majority of offset projects that have sold the most carbon credits are ‘likely junk’, according to analysis by Corporate Accountability and the Guardian

The vast majority of the environmental projects most frequently used to offset greenhouse gas emissions appear to have fundamental failings suggesting they cannot be relied upon to cut planet-heating emissions, according to a new analysis.

The global, multibillion-dollar voluntary carbon trading industry has been embraced by governments, organisations and corporations including oil and gas companies, airlines, fast-food brands, fashion houses, tech firms, art galleries and universities as a way of claiming to reduce their greenhouse gas footprint.

A total of 39 of the top 50 emission offset projects, or 78% of them, were categorised as likely junk or worthless due to one or more fundamental failing that undermines its promised emission cuts.

Eight others (16%) look problematic, with evidence suggesting they may have at least one fundamental failing and are potentially junk, according to the classification system applied.

The efficacy of the remaining three projects (6%) could not be determined definitively as there was insufficient public, independent information to adequately assess the quality of the credits and/or accuracy of their claimed climate benefits.

Overall, $1.16bn (£937m) of carbon credits have been traded so far from the projects classified by the investigation as likely junk or worthless; a further $400m of credits bought and sold were potentially junk.