The United States, Russia, Canada and Japan had been pushing back against key details on plans for future negotiations. Developing countries, led by Pakistan, were outraged over talk that the U.S. Senate had passed a bill out of committee that would impose border tariffs on their carbon-heavy goods. And Chinese officials went public with complaints that the U.N. staff had scheduled two simultaneous meetings to keep developing countries off-balance.
While the Chinese claim turned out to have been a misunderstanding and ended with apologies all around, it was not before an exhausted de Boer stood up at the podium then left the room. He returned to a standing ovation.
"It kind of broke my heart a bit," said Jennifer Morgan, who was working then for Berlin-based consulting group EG3 and recently moved to Washington to lead the World Resources Institute's climate team. "I felt for him. I think everyone had a little bit of themselves in Yvo when that happened, because almost everyone in that room was working hard to try to get an agreement out of Bali."
Recalling the Bali negotiations, de Boer said another moment stands out as more important.
"It caused a couple of hours of delay," he said of his emotional exit. "It wasn't really the point. The representative of Papua New Guinea made the point."
At issue is another tense moment in Bali, when Kevin Conrad, the representative of the island nation, chastised the United States for blocking a final deal, declaring that George W. Bush's administration should demonstrate leadership or "get out of the way."
"That," de Boer said, "was the important one."
De Boer has lived a nomadic life, learning lessons along the way that have proven useful in his U.N. post.
De Boer's diplomat parents raised him on four continents. Among his mailing addresses: Finland, Egypt, Kenya, Uganda, Tanzania, Hong Kong, Ethiopia, Austria and Great Britain, where he went to boarding school.
"It exposes you early on to the fact there are more people in the world than the tribe you happen to come from," he said in a recent interview. "And it exposes you to the fact that life is different in different countries and tougher in some countries than in other countries. I think it's a good way to become a global citizen."
De Boer went to college in The Hague, studying social work. His first job was as a parole officer in Holland. He was frustrated in that job by the difficulty of keeping people from repeating mistakes and returning to jail.
"If you don't understand what motivated the action, then you can't change the parameters that will prevent a future action of a similar kind," he said. "And I don't want to compare countries to criminals, but I do think it's really important to understand properly why somebody is saying something. Not what's their position, but what's the underlying interest they're trying to address."
After his required service as a cavalry platoon commander in the Dutch army, de Boer got his first U.N. job, serving in Canada and Nairobi for the human settlement program. A brief stop in a Dutch ministry on housing led in 1994 to a job working on climate-change negotiations, something he knew little about.
Surrounding himself with atmospheric scientists, economists and political experts, de Boer turned himself by 1997 into his country's lead U.N. negotiator. He became well-known in climate circles.
By 2006, he was a lead candidate for his current U.N. post, following the death of his countryman, Joke Waller-Hunter.