CRS Report R46204, The United Nations Framework Convention on Climate Change, the Kyoto Protocol, and the Paris Agreement: A Summary, by Richard K.
Lattanzio. President George H. W. Bush signed the instrument of ratification and submitted it to the UN on October 13, 1992 (depositary notification C.N.148.1993). Conference of the Parties to the United Nations Framework Convention on Climate Change (UNFCCC), "Adoption of the Paris Agreement," in Report of the Conference of the Parties on Its Twenty-First Session, Held in Paris from 30 November to 13 December 2015, Addendum, Part Two: Action Taken by the Conference of the Parties at Its Twenty-First Session, FCCC/CP/2015/10/Add.1.

Decision 1/CP.21, January 29, 2016 (hereinafter UNFCCC, "Adoption of the Paris Agreement"). Paris Agreement to the United Nations Framework Convention on Climate Change, December 12, 2015, T.I.A.S. The threshold for the PA to enter into force was for at least 55 countries to ratify the agreement, accounting for at least 55% of global greenhouse gas (GHG) emissions.