A key study found carbon credits to be "largely ineffective".

The Science Based Targets Initiative (SBTi), the top global regulator of private-sector climate targets, released a review that concluded “carbon credits are ineffective in achieving their intended mitigation outcomes,” according to Bloomberg. The SBTi report also said that corporate use of carbon credits could "stalemate decarbonisation efforts and reduce the flow of climate finance", according to Bloomberg. He adds: “The news is likely to reverberate in the carbon offsets market, which is already marred by allegations of greenwashing. In April, SBTi's board itself became the subject of controversy after it appeared to sanction wider use of carbon credits, prompting cheers for the offsets." -market participants but criticism from climatologists and environmental groups." Reuters says the review ultimately found that "there was insufficient scientific support for [SBTi] to lift restrictions on companies using carbon credits to offset their emissions". (Alastair Marsh, Bloomberg, carbonbrief.com)