An unprecedented summit on climate change has ended at the United Nations. Secretary-General Ban Ki-moon says the event has sent a powerful political signal to the world that there is the will and the determination at the highest level to act decisively on global warming. From U.N. headquarters in New York, VOA's Margaret Besheer has more.

The Secretary-General said he heard a clear call from world leaders for a breakthrough on climate change. He added that he now believes there is the political commitment to achieving that at an upcoming conference in Bali later this year.

More than 150 nations and 80 heads of state and governments came together at Monday's summit, making it the highest-level meeting on climate change the United Nations has ever hosted.

Mr. Ban called on industrialized countries to take the lead in halting global warming.

"Undoubtedly, there is a need for much deeper emission reductions by industrialized countries, which must continue to take the lead in this respect," said Ban Ki-moon. "It was encouraging to hear many of the leaders from the industrialized countries themselves expressing their willingness to do so."

Mr. Ban said international cooperation needs to increase to assist developing countries with increasing energy needs to move in the direction of renewable energy and cleaner fossil fuel technologies.

Throughout the day world leaders, ministers and other figures addressed the issue of global warming.

Former U.S. Vice President Al Gore told a luncheon gathering that the world is facing what he called a "planetary emergency." Citing rising sea levels, he warned that global warming could create a new class of refugee.

"Even a one-meter rise would lead to 100 million climate refugees in our world," said Al Gore. "A six-meter rise would lead to 450 million climate refugees in our world."

French President Nicolas Sarkozy, told reporters the world needs to make difficult decisions now, before it is too late and the atmosphere becomes too warm.

"It is our duty to take decisions straight away, because otherwise it is going to be too late," said Sarkozy. "And let me spell that out for you, 'too late' means one thing - it means an additional two degrees centigrade. And an additional two degrees centigrade means we have reached the point of no return."

Secretary-General Ban organized the summit on the sidelines of the 62nd General Assembly to build political momentum ahead of a U.N.-sponsored climate change conference in Bali in December. That meeting aims to launch negotiations for an emissions -reduction agreement to succeed the Kyoto Protocol in 2012.