; (B) methane; (C) nitrous oxide; (D) hydrofluorocarbons; (E) perfluorocarbons; (F) sulfur hexafluoride; or (G) any other anthropogenically emitted gas that is determined by the Administrator, after notice and comment, to contribute to global warming to a non-negligible degree. (2) United States greenhouse gas emissions The term United States greenhouse gas emissions means the total quantity of greenhouse gas emissions calculated by the Administrator on an annual basis and reported to the United Nations Framework Convention on Climate Change Secretariat.