On December 12, the United States and other Parties to the United Nations Framework Convention on Climate Change (UNFCCC) signed the historic Paris Agreement at the 21st Conference of the Parties. We expect the Agreement to have significant ramifications for U.S. law and policy across all sectors of the economy.
The Paris Agreement has been structured to define and to elaborate upon obligations under the UNFCCC, which was ratified by the United States over two decades ago. Therefore, we expect that the Obama Administration will take the position that it is unnecessary to submit the Paris Agreement to the Senate for its advice and consent. Rather, the Administration is expected to pursue the reductions in the nation’s greenhouse gas emissions called for in the Agreement using existing authority, including the Clean Air Act, under which the administration has already adopted or proposed regulations that will reduce emissions from several sectors of the economy.
The Paris Agreement defines the UNFCCC's objective of preventing “dangerous anthropogenic interference with the climate system.” The Agreement clarifies this objective, stated in Article 2 of the the UNFCCC, by providing that the Parties will “enhanc[e] the implementation of the Convention” by “[h]olding the increase in the global average temperature to well below 2° C above pre-industrial levels and by pursuing efforts to limit the temperature increase to 1.5° C above pre-industrial levels.”
The Paris Agreement translates this goal into specific emissions reduction goals and requirements. The Parties agreed to limit greenhouse gas emissions so that the emissions stop increasing as soon as possible and then decrease to achieve reach carbon neutrality by the second half of this century. All Parties are required to develop “nationally determined contributions” toward achieving those goals and to update those contributions at least every five years. The Developed Country Parties, including the United States, are required to take the lead “by undertaking economy-wide absolute emission reduction targets.”
The United States had previously submitted its “nationally determined contribution” to achieve a 2020 target of reducing net emissions in the range of 17% below 2005 levels and to achieve net greenhouse gas emission reductions of 26-28% by 2025, making best efforts to achieve a 28% reduction. The United States intends to achieve these reductions through a variety of mechanisms that are already in place, such as the Clean Air Act mobile source regulations and the Clean Power Plan, or proposed, such as the methane reduction regulations.
The structure of the Paris Agreement as a clarification of existing treaty obligations may support the view that its terms implementing the UNFCCC constitute international law binding on the United States even if the United States does not ratify the agreement. Moreover, because the United States has identified the Clean Air Act as an implementing law for the UNFCCC, the emissions reductions objectives in the Paris Agreement could be construed as binding objectives for applying the Clean Air Act. Such an interpretation would not be unprecedented. The U.S. Supreme Court’s 1804 decision in Murray v. Schooner Charming Betsy and decisions governing construction of Indian treaties and related laws support the notion that domestic law implementing a treaty should be construed consistent with that treaty.
Regardless of how the Paris Agreement is ultimately construed, the Obama Administration's commitment to significant emissions reductions confirms that regulation under the Clean Air Act will expand to cover new source categories and to require further reductions that will be necessary to achieve carbon neutrality within the century.
