UN's concern on environment dates back to as early as 1972, but the efforts to draft general and binding disciplines on environment did not begin in earnest until late 1980's. In 1992, the United Nations Framework Convention on Climate Change(UNFCCC) was adopted by the General Assembly to combat irregular climate changes caused from global warming by stabilizing green gas concentration. In 1997, the so-called Kyoto Protocol was adopted to further strengthen the developed countries' obligation to reduce anthropogenic emissions of greenhouse gases. The current article overviews the mechanism and effect of climate changes; introduces the main contents of the UNFCCC and the Kyoto Protocol along with some of the issues that were discussed during the negotiations; and describes the post-Kyoto process including the recent Marrakesh Accords to implement the Kyoto Protocol. Korea faces the difficult task of securing green gases emissions quota sufficient enough to sustain economic growth, while at the same time participating in the international community's efforts to combat irregular climate changes. In conclusion, Korea should adopt policies and legislations to decrease green gases emissions by increasing the energy efficiency and by promoting environment-friendly substitute energy sources.