Kyoto Protocol

An international agreement promoted by the UN in 1997 that aims to reduce greenhouse gas emissions (carbon dioxide, methane, nitrous oxide, and fluorinated industrial gases). It includes instruments such as carbon credits. Its implementation was very complicated, as it did not enter into force until 2005, when Russia ratified it (something the US, the largest emitter of these gases, has never done). It is not legally binding on the signatory countries.