The agreement opened for signature on April 22, 2016. Within six months, 17 countries ratified the agreement.
By October 5, 2016, over 55 countries in total accounting for 55% of total greenhouse gas emissions ratified the agreement as well, enough for the Paris Agreement to enter into force.
Within a year after being open for signature, a total of 117 countries ratified the agreement.
Two years later, an additional 53 countries joined.
As of September 22, 2018, a total of 180 out of 197 countries have ratified the Paris Agreement. These countries account for over 90% of total global greenhouse gas emissions.