By Larisa Epatko for PBS Newshour

NEW YORK CITY – Thirty-one more countries formally joined the Paris climate agreement on Wednesday, doubling the number of those who had previously ratified the document, and bringing it well past one of the the thresholds needed for implementation. But in order for the agreement to go into effect, the countries need to account for at least 55 percent of total global greenhouse gas emissions.

“What seemed at one time impossible is now inevitable,” said U.N. Secretary-General Ban Ki-moon. “I am confident by the time I leave office (on Dec. 31), the Paris agreement will have entered into force.”

Image: UN Secretary-General (R) with Rafael Pacchiano Alamán, Minister for Environment and Natural Resources of Mexico, at the High-level Event on the Entry into Force of the Paris Agreement | Image Credit: UN Photo/Rick Bajornas