CRS report via FAS – Climate Change: Frequently Asked Questions About the 2015 Paris Agreement, Jane A. Leggett, Specialist in Energy and Environmental Policy; Richard K. Lattanzio, Specialist in Environmental Policy. June 28, 2017.

“The Paris Agreement (PA) to address climate change internationally entered into force on November 4, 2016. The United States is one of 149 Parties to the treaty; President Barack Obama accepted the agreement rather than ratifying it with the advice and consent of the Senate. On June 1, 2017, President Donald J. Trump announced his intent to withdraw the United States from the agreement and that his Administration would seek to reopen negotiations on the PA or on a new “transaction.” Following the provisions of the PA, U.S. withdrawal could take effect as early as November 2020. Experts broadly agree that stabilizing greenhouse gas (GHG) concentrations in the atmosphere to avoid dangerous GHG-induced climate change would require concerted efforts by all large emitting nations. The United States is the second largest emitter of GHG globally after China. Toward this purpose, the PA outlinesgoals and a structure for international cooperation to slow climate change and mitigate its impacts over decades to come…”