"As you may know, last week I spoke to President-elect Mr. Trump, and I brought up many issues, peace and security issues, including the issue of climate change," Ban said at a press conference today in Marrakech, Morocco, where he is attending U.N. climate talks. "I remain very optimistic about our effort to combat climate change. Look at what we have achieved."
He added, "The global unity around climate change once seemed to be unthinkable, but now it has become unstoppable."
When asked whether the U.S. could take federal action against the Paris Agreement, Ban said, "I think I have explained at length about our expectations and our hope that the newly elected President-elect Mr. Trump will really hear and understand the seriousness and urgency of addressing climate change."
The head of the U.N. environmental program, Erik Solheim, told ABC News last week that Trump "can only withdraw in the long term" from the Paris Agreement and the earliest that this would be possible is in 2021.
Ban added today that the Paris Agreement is "not just a few countries" but a "wholehearted commitment by the whole world."
"Then as president of the United States, I am sure that he will understand this, he will listen, he will evaluate his campaign remarks. We have seen many such campaign rhetoric not only in the United States but in many parts of the world," Ban said.
"As President Obama said in his press remarks, press conference, yesterday, that he may have to understand the reality, the reality of the whole world’s problems, including particularly on climate change," Ban said of Trump. "I am sure that he will make a good, wise decision, and I’m going to discuss this matter more in person on this matter."