The UN Intergovernmental Panel on Climate Change made the strongest ever plea for concerted efforts to reverse the process of global warming. The panel also established beyond doubt the link between mankind''s activities and global warming, which is gaining widespread recognition.

"I can''t believe it," Pachauri said, adding, "I feel privileged sharing it with someone as distinguished as him (Al Gore)."

Al Gore "is probably the single individual who has done most to create greater worldwide understanding of the measures that need to be adopted," the Nobel citation said.

The United Nations committee, a network of 2,000 scientists, has produced two decades of scientific reports that have "created an ever-broader informed consensus about the connection between human activities and global warming," the citation added.

Gore, who lost the 2000 US presidential election to George W. Bush, has said he is not interested in running again but has not flatly rejected the notion.

The former vice president said in a statement that he was deeply honoured to receive the prize and planned to donate his half of the prize to the Alliance for Climate Protection, a nonprofit climate group that he heads.

"We face a true planetary emergency," Gore said in the statement. "The climate crisis is not a political issue, it is a moral and spiritual challenge to all of humanity. It is also our greatest opportunity to lift global consciousness to a higher level."

In New Delhi, Rajendra K. Pachauri said the award was "not something I would have thought of in my wildest dreams."

The award should now settle the scientific debate on climate change and governments should now take action, he said, adding, it was "entirely possible to stabilise the levels of emissions but that climate change and its impact will continue to stalk us."

"We will have to live with climate change up to a certain point of time but if we want to avoid or delay much more serious damage then its essential that we start mitigation quickly and to a serious extent," he said.

The Nobel award is sure to have political ramifications in the United States. But the chairman of the Norwegian Nobel Committee, Ole Danbolt Mjoes, dismissed questions on whether the awards were a criticism of the Bush administration.

He said the committee was making an appeal to the entire world to unite against the threat of global warming.

Global warming has been a powerful issue this year, attracting more and more public attention. The film documenting Mr. Gore''s campaign to increase awareness of climate change, "An Inconvenient Truth," won an Academy Award this year. The UN committee has issued repeated reports and held successive conferences to highlight the growing scientific understanding of the problem.

Meanwhile, signs of global warming have become more and more apparent, even in the melting Arctic. The Norwegian Nobel Committee said global warming "may induce large-scale migration and lead to greater competition for the earth''s resources."

Such changes will place particularly heavy burdens on the world''s most vulnerable countries," it said. "There may be increased danger of violent conflicts and wars, within and between states."

President Pratibha Devisingh Patil congratulated the UN climate panel chaired by Pachauri for sharing this year''s Nobel Peace Prize with Al Gore.

The award is a recognition for the crucial work done by Pachauri and his team members on the IPCC for the benefit of humanity and future generations, she said.