The Kyoto Protocol, which was adopted in 1997, is an international treaty that focuses on reducing the emissions of six greenhouse gases, which include carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride. These are pollutants that contribute to global warming and climate change. The protocol required developed countries to reduce their emissions of greenhouse gases to an average of 5.2 percent below the 1990 level during the first commitment period, which ran from 2008 to 2012.