The Paris Agreement (PA), which addresses climate change through international cooperation, is set to take effect on November 4, 2016. With the ratifications by the European Union, seven EU member states, New Zealand, and India—along with earlier actions by the United States, China, and other countries—the threshold was passed for the treaty to enter into force: Entry into force occurs on the 30th day after at least 55 countries, representing at least 55% of officially reported greenhouse gas (GHG) emissions, deposit their ratifications, acceptances, or approvals with the United Nations treaty depositary. As of October 5, 2016, 72 governments (including the European Union) representing more than 56% of global GHG emissions had deposited their instruments. In all, 191 governments, including Russia, signed the PA; they do not become parties to it until they have deposited their instruments.
The entry into force of the PA will occur just before the 22nd meeting, beginning November 7, of the Conference of the Parties (COP) to the United Nations Framework Convention on Climate Change (UNFCCC). The UNFCCC is the umbrella treaty under which the PA was negotiated.
Following several international scientific assessments finding potential adverse impacts of rising human-related GHG emissions on the earth's climate, nations responded by negotiating the UNFCCC as a treaty under international law. Its negotiators intended it to have legal force on the parties to the agreement (henceforth Parties). The UNFCCC anticipated that further, subsidiary protocols or other agreements would be required to achieve its objective
to achieve, in accordance with the provisions of the Convention, stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system. Such a level should be achieved within a time-frame sufficient to allow ecosystems to adapt naturally to climate change, to ensure that food production is not threatened and to enable economic development to proceed in a sustainable manner.
President George H. W. Bush signed the convention and the U.S. Senate provided its advice and consent to U.S. ratification in 1992 (S. Treaty Doc. No. 102-38). On March 21, 1994—the 90th day following the date of deposit of the 50th instrument of ratification or acceptance—the UNFCCC entered force for the United States and the other 52 countries that had ratified the treaty by that time. It now has near-universal membership with 197 Parties. Since that date, the terms of the UNFCCC have been binding on the United States under both international and domestic law. The United States implements the UNFCCC under existing statutes without passing new implementing legislation.
The first subsidiary agreement was the 1997 Kyoto Protocol, entering into force in 2005, which the United States signed but did not ratify as it lacked sufficient support domestically. Because it contained a quantified GHG reduction target for the United States, the Kyoto Protocol would have required Senate approval in accordance with the terms of the Senate's consent to ratify the UNFCCC. One reason for insufficient U.S. support was that the Kyoto Protocol contained GHG targets only for relatively high-income countries. This perpetuated a bifurcation between industrialized and developing countries that had become untenable in the 21st century: Most scientists and governments agree that achieving the UNFCCC's objective requires concerted GHG emissions abatement by all major emitting countries. Besides concerns about effectiveness, many in the United States and elsewhere feared adverse impacts on economic competitiveness if some economies sought meaningful GHG reductions while others did not.
Under the PA, all Parties will participate in a common GHG abatement framework with common guidance and international assistance and review. Some Parties are allowed flexibility in line with their capacities. The negotiators intended the PA to be legally binding on its Parties, though not all provisions in it are mandatory. Some are recommendations or collective commitments to which it would be difficult to hold an individual Party accountable. The PA is expected to supersede the Kyoto Protocol after 2020.
President Barack Obama accepted the PA on behalf of the United States on August 29, 2016. It was handled as an executive agreement under U.S. law rather than a treaty, which would require the advice and consent of the Senate. While some Members of Congress supported this procedure, others pressed for the PA to be submitted to Congress for its consideration, with six resolutions introduced in the 114th Congress calling for such. To date, none has received further congressional action.
More information about the PA is available in CRS Report R44609, Climate Change: Frequently Asked Questions about the 2015 Paris Agreement, by [author name scrubbed] and [author name scrubbed].