The European Union aimed to reduce greenhouse gas emissions, like CO2, as part of the Kyoto Protocol. They committed to lowering emissions by 8% compared to 1990 levels by 2012. To achieve this, they used a plan called cap and trade, along with other methods, to control emissions. The cap and trade system helped cut almost half of the needed emissions. By looking at data from 14 European countries, which are big greenhouse gas emitters, it was found that the EU hit its Kyoto Protocol goals by combining cap and trade with other ways to reduce emissions.