The United Nations Framework Convention on Climate Change (UNFCCC), the first international measure against climate changes, was adopted in May 1992 and came into force in March 1994.

Having adopted the UNFCCC, governments knew that the commitments would not be sufficient to seriously tackle climate change. On 11 December 1997, in the Japanese town of Kyoto, they took a further step and adopted a protocol to the UNFCCC: the Kyoto Protocol. Building on the UNFCCC framework, the Protocol sets legally binding limits on greenhouse gas emissions from initially 38 industrialised countries and the European Community (the EU-15). It also introduces innovative market-based implementation mechanisms – known as the Kyoto flexible mechanisms – aimed at keeping the cost of curbing emissions low.

Industrialised countries are required to reduce their emissions of six greenhouse gases (CO₂, which is the most important, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons and sulphur hexafluoride) to around 5% below the 1990 level during the first Kyoto Protocol “commitment period” from 2008 to 2012. A five-year commitment period was chosen rather than a single target year to smooth out annual fluctuations in emissions due to uncontrollable factors such as weather. There are no emissions targets for developing countries.

Despite 160 countries and the European Community had ratified the Protocol, USA, Australia and Monaco had not ratified it yet.