Christiana Figueres has announced she will step down from her UN climate role in July.
In a letter to parties of the UN, she said she won’t accept the extension of the role of Executive Secretary of the United Nations Framework Convention on Climate Change (UNFCCC).
Ms Figueres stayed in the post for six years and played a part in steering governments to sign the climate deal at COP21 last December.
The search of a replacement will begin immediately by inviting all countries to submit candidates for consideration, the letter added.
Ms Figueres said: “We now move into a phase of urgent implementation. The journey that lies ahead will require continued determination, ingenuity and above all, our collective sense of humanity and purpose. I know that together you will again rise to the task.
“My gratitude goes to the UNFCCC secretariat. I am continuously inspired by this top performing organisation by its highly qualified and deeply committed team. Their competence, impartiality and dedication is no small part of the remarkable outcomes of Paris.”