Former UN Secretary-General Ban Ki-moon Calls on U.S. to Rejoin Paris Climate Agreement in IOP Forum

Former United Nations Secretary-General Ban Ki-moon urged the United States to return to the Paris Climate Agreement “as soon as possible” after President Donald J. Trump withdrew for a second time last January at a Tuesday Institute of Politics forum.

In the forum, titled “Global Climate Leadership: Our Planet at a Crossroads,” Ban focused on the changing landscape of international climate policy and the role of more powerful nations in guiding the agenda, alongside moderators R. Nicholas Burns, a Harvard Kennedy School professor, and Center for Public Leadership Director Anthony R. Foxx.

Ban, who led the United Nations from 2007 to 2016, said that he was “just as regrettable” that the United States had withdrawn from 66 international organizations, including the World Health Organization and UNICEF, under Trump.

Trump has now withdrawn from the Paris Climate Agreement — an international agreement binding signatories to make efforts to limit the impact of climate change — twice. His withdrawal in November 2019 was reversed by former President Joe Biden in 2021. But Trump again pulled the U.S.’s involvement when he returned to office in January 2025, and the change took effect a year later.

Ban argued that this withdrawal had caused a strain on the international community, saying that the United States was the “biggest contributor” and “leader country” in international diplomacy.

“When the U.S. is out of 66 international organizations, what can you expect?” Ban added. “That’s why the United Nations is now in very difficult circumstances at this time”

Ban drew a contrast between Trump’s withdrawal from international organizations and the active involvement of former President Barack H. Obama in World Health Organization Ebola eradication efforts.

“I was very grateful to the initiative of President Obama, who spent thousands of soldiers together with the United Kingdom and France,” Ban said.

Ban also questioned the veto power of Security Council member states, calling it “absolutely not fair” that only one of these states can sink motions with broad support.

The five permanent members of the United Nations Security Council — the United States, Russia, United Kingdom, France, and China — have the power to veto any substantial resolution.

“We have 193 member states of the United Nations. The one means if United States vetoes, 192 countries are just powerless,” he said.

During his remarks, Ban also addressed pessimism regarding both climate change and the future of international relations, urging the next generation “to do more than inherit the international system.”

“It is easier to demand change than to negotiate the compromises necessary to achieve it, and it is easier to say that a system is broken than to repair it,” Ban said.

Ban emphasized the need for the next generation to rise up to the challenges of climate change. He outlined the hurdles needed for future diplomats to meet this issue, including having good character, intelligence, and morals.

“The reality is simple, the world is too interconnected for isolation,” Ban said.