The leader of the United Nations did not pull any punches.
"If we take action now, it may not be too late," United Nations Secretary General Ban Ki-Moon said in an interview today in the garden of U.N. headquarters in New York.
His "may" gave this correspondent pause. His words were clearly carefully considered.
The subject was global warming. How serious does he think it is?
"The science has made it quite clear. The impact has been felt seriously around the world. Now only lacking largely is a political will," said Ban.
"As a human being, a whole international community is standing at the very critically important juncture. Whether or not we address this issue properly and collectively, the whole future of our generation and planet Earth will depend."
Ban has declared that global warming will be a priority of his tenure at the United Nations.
He also clearly considers it a matter of the greatest gravity.
When this reporter pointed out that some scientists are writing books and saying in public that they believe this crisis is so serious that if humanity goes on with business as usual -- not significantly cutting overall greenhouse gas emissions -- it could seriously lead to the collapse of civilization, even in the lifetime of today's children, he replied:
"I think that is a correct assessment. People say that action should have been taken yesterday. If we take action today, it may not be too late."
Ban had worked hard to convene Monday's special high-level meeting at U.N. headquarters. The meeting was the largest meeting of heads of state and government ever held to debate the problem of global warming -- a gathering that set the tone for the annual opening of the United Nations General Assembly Tuesday.
Notably absent at the all-day high level meeting was President Bush, who has in the past cast doubt on the vitrtually unanimous scientific consensus that dangerous global warming is now under way and is attributable in large part to human activities.
Dinner & Diplomacy
Bush did, however, accept an invitation to a closed-door dinner Ban held after the Monday meeting.
He shared his dinner plans with ABC News, offering a small glimpse into the tactics of the world's most prominent diplomat:
"I have invited a limited number of leaders, biggest emitters, most vulnerable and important negotiating group representatives to an informal gathering over dinner," said Ban.
"The purpose of this: to get the leaders engaging in more candid and frank exchange of views ... and be more responsible for the future of our generation and ... planet Earth. .... They can agree on generating more political commitment."
Ban has already begun conversations directly with Bush on the subject of global warming, he told ABC News. "My discussions with President Bush over telephone, over meeting at the White House, were encouraging. I am grateful for his willingness to participate in this high-level dialogue," he said.
Bush has come under increasing criticism over his six years in office for ignoring or downplaying the urgency of global warming.
The United States has long been the biggest emitter of greenhouse gases, though China, with its booming economy, much of its boom powered by coal-fired power plants, has now about caught up and is on track to surge ahead.
But Chinese leaders said that they will not impose strict carbon emissions caps on themselves until the United States, which has long enjoyed the benefits of economic boom, takes the lead.
Ban Ki-Moon -- like many leaders around the world -- agrees, saying the United States must set the example if humanity is to have any chance of controlling the problem.
"I need American leadership," the secretary general told us, sitting under the shade trees along the U.N.'s riverside promenade. "America is the biggest emitter," he noted, adding, however, that America also has the greatest financial, technical and political resources to set global action in motion.
"United States and other industrialized countries should demonstrate their political leadership, a historical leadership," said Ban. "They are the greatest emitters, which have been making these problems. They should feel more responsibility on this."