The Paris Agreement (French: Accord de Paris) is an agreement within the United Nations Framework Convention on Climate Change (UNFCCC) dealing with greenhouse gas emissions mitigation, adaptation and finance starting in the year 2020. The language of the agreement was negotiated by representatives of 195 countries at the 21st Conference of the Parties of the UNFCCC in Paris and adopted by consensus on 12 December 2015. It was opened for signature on 22 April 2016 (Earth Day) at a ceremony in New York. As of May 2017, 195 UNFCCC members have signed the treaty, 147 of which have ratified it. After several European Union states ratified the agreement in October 2016, there were enough countries that had ratified the agreement that produce enough of the world's greenhouse gases for the agreement to enter into force. The agreement went into effect on 4 November 2016.
The head of the Paris Conference, France's foreign minister Laurent Fabius, said this "ambitious and balanced" plan is a "historic turning point" in the goal of reducing global warming.
One year on, the ratification of the Paris Agreement was celebrated by the Mayor of Paris Anne Hidalgo by illuminating the Eiffel Tower and the Arc de Triomphe, Paris' most iconic monuments, in green. Wikipedia