When international negotiators reached a first-of-its kind climate change agreement in Paris this month, the United Nations' normally low-key leader, Ban Ki-moon, celebrated onstage, arms raised in victory and more exuberant than many had ever seen him before.
Nearly nine years had passed since, in his first days as secretary-general, Ban surprised world leaders by making global warming a top item on his agenda.
Now, on the eve of his final year in office, the cheers in Paris marked the culmination of his nonstop campaign, pressed with world leaders at summit after summit and in locales including melting glaciers and islands at risk of vanishing.
It was an emotional moment, and looking back at the road to Paris in an interview with The Associated Press, Ban paid tribute to many people, including the leaders of the US,China, India and France. He also spoke proudly of his own role.
No other leader in the world "has been raising, without fail, all the time, climate change," Ban said. "I have spent real passion...And most of my time and energy on this issue."
It was quite a shift for the ex-South Korean foreign minister, whose main focus before becoming the eighth UN secretary-general in 2007 was his country's standoff with North Korea.
Ban traced his interest in climate change to his yearlong campaign to lead the United Nations, which took him to many countries and broadened his vision of global issues.
Two weeks before he was sworn in as secretary-general, Ban told Tim Wirth, then president of the UN Foundation, that one of his two highest priorities would be climate change, along with empowering women.
"You could have blown me away," Wirth said of Ban's choice of tackling global warming. "He had a deep commitment then, and he has stayed with it, and stayed with it, and stayed with it."
At the time, climate change was not a popular topic.
The 1997 Kyoto treaty, which required only rich countries to limit emissions blamed for global warming, was set to expire in 2012. Negotiations on a new agreement had almost collapsed, Ban said.
"I thought that I needed to revive this one," he said.
His first high-level meeting as UN chief was with then-President George W Bush.
The original agenda for their January 2007 meeting didn't include climate change, Ban said, and Bush "seemed to be a little bit surprised" when he raised it.
Undeterred, Ban decided to hold the first-ever climate change summit at the United Nations in July 2007.
He invited Bush and told him that the success of the summit would depend on his participation. Bush came, though he didn't address the summit.
That connection paid off at a UN conference in Bali in December 2007.
The United States, the lone major industrial nation to reject Kyoto, was opposing India's proposal to strengthen requirements for richer nations to help poorer countries with technology to limit emissions.
