“There’s big motivation on both sides to do it wrong,” he said.

Injy Johnstone, a researcher specializing in carbon neutrality at Oxford University, told AFP the fact that nations can set their own standards in these country-to-country deals was a major concern.

She said overall the risk of greenwashing makes Article 6 “the biggest threat to the Paris agreement”.

Alongside this decentralized, state-to-state system, there will be another UN-run system for trading carbon credits, open to both states and companies.

On the opening day of COP29, nations agreed a number of crucial ground rules for setting this UN-administered market in motion after nearly a decade of complex discussions.

“There are many projects waiting” for the market, Andrea Bonzanni of the IETA International Emissions Trading Association, told AFP. The IETA has more than 300 members including energy giants such as BP.

Despite these positive signs, some experts expressed doubt that the quality of the carbon credits traded on the regulated market would be much better than those that came before.

Erika Lennon of the Center for International Environmental Law said it would be necessary to make sure these markets do not create “even more problems and more scandals than the voluntary carbon markets”.

These “voluntary” markets have been rocked by scandals in recent years amid accusations that some credits sold did not reduce emissions as promised, or that projects exploited local communities.