The language of the agreement was negotiated by representatives of 197 parties at the 21st Conference of the Parties of the UNFCCC in Paris and adopted by consensus on 12 December 2015. The Agreement was open for signature by States and regional economic integration organizations that are Parties to the UNFCCC (the Convention) from 22 April 2016 to 21 April 2017 at the UN Headquarters in New York. The agreement stated that it would enter into force (and thus become fully effective) only if 55 countries that produce at least 55% of the world's greenhouse gas emissions (according to a list produced in 2015) ratify, accept, approve or accede to the agreement. On 1 April 2016, the United States and China, which together represent almost 40% of global emissions, issued a joint statement confirming that both countries would sign the Paris Climate Agreement. 175 Parties (174 states and the European Union) signed the agreement on the first date it was open for signature. On the same day, more than 20 countries issued a statement of their intent to join as soon as possible with a view to joining in 2016. With ratification by the European Union, the Agreement obtained enough parties to enter into effect as of 4 November 2016.