Christiana Figueres is stepping down as executive secretary of the United Nations Framework Convention on Climate Change. Credit: Sarah Fretwell/UN Photo

Christiana Figueres has charmed the world. As executive secretary of the United Nations Framework Convention on Climate Change, she helped to lead a remarkable transition from nearly collapsed climate negotiations in Copenhagen in 2009, to an agreement between the world’s governments in Paris last year. She transcended her once-thankless — and largely powerless — post as facilitator-in-chief to become a popular and influential advocate for action on global warming. Figueres has now announced that she will be stepping down in July. She will leave on a high note, but whoever fills her shoes will have to deal with significant head winds.

Figueres’s departure, which became public knowledge on 19 February, is part of a larger shake-up in the UN climate shop. On the same day, Héla Cheikhrouhou, executive director of the Green Climate Fund, which was created to help developing countries to reduce emissions and adapt to climate change, announced that she will leave her post at the end of her term in September. And on 15 February, former French foreign minister Laurent Fabius, who skilfully guided the negotiations to a smooth conclusion in December, announced that he is stepping down as president of the climate talks. French environment minister Ségolène Royal will take his place until November, when the leadership transitions to Morocco at the next major meeting, in Marrakesh.

In her letter to governments, Figueres lauded the Paris agreement as a historic achievement and said that the world is now transitioning into a phase of “urgent implementation”. From a political perspective, it is certainly true that the Paris agreement was historic. After all, there was no guarantee going into the meeting that anything at all would come out of it, let alone the formal agreement that will be opened up for ratification on 22 April, Earth Day, this year.

Both Figueres and Fabius deserve credit for making that happen, but their successors have plenty of work ahead. It is no secret that the actions that governments have committed to thus far fall well short of those needed to limit warming to 2 °C, let alone to 1.5 °C, which is the stated goal of the agreement. Nor is it clear that the world is urgently moving forward.

The Green Climate Fund, which was created more than five years ago and has approved just eight projects, is still trying to collect the money promised by nations. The US Supreme Court has put US President Barack Obama’s regulations for power-plant emissions on ice, pending a legal challenge. Policymakers in the United Kingdom are still debating how to proceed in the wake of a government decision last November — just before the climate talks got under way — to pull the plug on a programme supporting the development of carbon capture and sequestration technologies. And in another branch of the UN, the International Civil Aviation Organization has proposed a rule on aircraft emissions that is so weak as to be irrelevant.

Nor is the Paris agreement a done deal: crucial details about the framework for monitoring commitments must still be negotiated. For instance, countries have yet to agree on precisely what kind of information they should submit to the UN. To track progress, build confidence and hopefully pave the way for more ambitious policies, scientists, environ­mentalists and governments need these data to be solid. Given that this objective is the only thing resembling accountability in an other­wise voluntary agreement, negotiations on this point could determine whether the Paris agreement is indeed a success.

Figueres was optimistic about the work to come. “The journey that lies ahead will require continued determination, ingenuity and, above all, our collective sense of humanity and purpose,” she wrote to government officials. “I know that together you will again rise to the task.” Let us hope that she is right.