UN Secretary-General Ban Ki-moon will host the gathering on September 21 on the sidelines of the General Assembly meeting.
The Paris climate deal will enter into force 30 days after at least 55 countries, accounting for 55 per cent of global greenhouse gas emissions, have ratified the accord.
While 175 countries have signed the agreement, only 19 including France and many island-states threatened by rising sea levels, have actually ratified it.
The Paris pact calls for capping global warming at well below two degrees Celsius, and 1.5 C if possible, compared with pre-industrial levels.
The accord -- which could enter into force later this year, far sooner than expected -- sets ambitious goals for capping global warming and funnelling trillions of dollars to poor countries facing an onslaught of climate damage.