International Emission Trading (IET)
International Emission Trading (IET) was initiated in The Kyoto Protocol (1997) and introduced one such international approach to reducing CO2 emissions.
"Emissions trading is a market-based approach to controlling pollution by providing economic incentives for reducing the emissions of pollutants."
However, wealthier countries and more giant corporations dominate the IET market, so they purchase large amounts of credits instead of reducing their emissions. This could lead to inequalities and hinder actual emissions reductions.
If we say this system in ordinary people's language, its concept is like letting pollutants or house garbage into our neighborhood's yard in exchange for small rewards. Trashes are still there, and the volume of contaminants is not reduced.