A large scale investigation led by the Guardian references a highly significant research project with Bangor involvement.
The piece quotes research that shows that 90% of rainforest offset credits do not represent genuine carbon reduction.

Julia Jones is quoted in the piece: [...] 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.

“It’s really not rocket science,” she said. “We are at an absolutely critical place for the future of tropical forests. If we don’t learn from the failures of the last decade or so, then there’s a very large risk that investors, private individuals and others will move away from any kind of willingness to pay to avoid tropical deforestation and that would be a disaster.

“As someone who sits outside of the kind of cut and thrust of the wild west that is the carbon markets, I need to believe it can be made to work because money is needed to fund the emissions reductions from forest conservation.”