OSLO, Dec. 10 — He has said it again and again, with increasing urgency, to anyone who will listen. And on Monday, former Vice President Al Gore used the occasion of his 2007 Nobel Peace Prize lecture here to tell the world in powerful, stark language: Climate change is a “real, rising, imminent and universal” threat to the future of the Earth.

Saying that “our world is spinning out of kilter” and that “the very web of life on which we depend is being ripped and frayed,” Mr. Gore warned that “we, the human species, are confronting a planetary emergency — a threat to the survival of our civilization that is gathering ominous and destructive potential even as we gather here.” But, he added, “there is hopeful news as well: we have the ability to solve this crisis and avoid the worst — not all — of its consequences, if we act boldly, decisively and quickly.”

The ceremony marking the 2007 prize, given to Mr. Gore and to the Intergovernmental Panel on Climate Change, comes as representatives of the world’s governments are meeting on the Indonesian island of Bali to negotiate a new international agreement on reducing greenhouse gas emissions. The new treaty would replace the Kyoto protocol, which expires in 2012.

At the ceremony in the city hall in Oslo, Mr. Gore called on the negotiators to establish a universal global cap on emissions and to ratify and enact a new treaty by the beginning of 2010, two years early. And he singled out the United States and China — the world’s largest emitters of carbon dioxide — for failing to meet their obligations in mitigating emissions. They should “stop using each other’s behavior as an excuse for stalemate,” he said.

In an interview before his speech, Mr. Gore said that the Bush administration was “the principal stumbling block to progress in Bali right now” but that he foresaw a change in American policy, regardless of which party won the 2008 election.

“I think that they do not accurately represent the wishes of the American people,” he said of the United States government. “We are in the midst of a process of massive change. The world is coming to grips with this crisis, but we are in a race against time. The United States of America, the natural leader of the world community, should lead instead of obstructing.”

In his speech, Mr. Gore said his loss in the bitter 2000 presidential election had forced him to “read my own political obituary in a judgment that seemed to me harsh and mistaken, if not premature.” But the “unwelcome verdict also brought a precious if painful gift,” he added — the chance to focus on the environment.

The documentary about Mr. Gore’s climate-awareness campaign, “An Inconvenient Truth,” won an Academy Award, but its conclusions were dismissed as exaggerated and alarmist by his political opponents. He has repeatedly said that while he has no plans to re-enter politics, he has not ruled out the possibility.

If Mr. Gore represents the well-known face of the call for action on climate change, Rajendra K. Pachauri, chairman of the international climate panel, represents the science that underlies the message. Mr. Pachauri, who gave the Nobel address on behalf of the group, a United Nations network of scientists, presented a sober, fact-filled account focusing on the potential effects of climate change on some of the world’s most vulnerable populations.

Mr. Pachauri, who is from India, said the prize committee’s decision to award the Nobel to the panel “can be seen as a clarion call” for the world to face up to the gravity of the situation.

“Peace can be defined as security and the secure access to resources that are essential for living,” he said. He outlined how climate-driven disruption of resources like food, water and land had the potential for disastrous effects on world stability, including the loss of islands and coastal communities to flooding, mass migration leading to increased tensions between rich and poor countries, and a rise in disease and malnutrition.

“The impacts of climate change on some of the poorest and most vulnerable communities in the world could prove extremely unsettling,” Mr. Pachauri said.

The climate panel, which is considered the world’s leading authority on climate change, was established in 1988. In the past two decades, it has issued a series of increasingly grim reports, most recently this year, about the warming of the planet and human responsibility for it.

Speaking of the meeting in Bali, Mr. Pachauri said that “hopes are alive that unlike the sterile outcome of previous sessions in recent years, this one will provide some positive results.”

In his speech, Mr. Gore invoked Churchill, Robert Frost, Gandhi, the Spanish poet Antonio Machado and the Norwegian playwright Henrik Ibsen, among others, to underline the urgency of his message. He wrote the speech himself, he said in the interview, “with the help of Mr. Google.”

During the cold war, he said in the address, scientists used to warn of “nuclear winter” — the consequence of nuclear war, in which smoke and debris would block the sunlight from the atmosphere. Now, he said, “we are in danger of creating a permanent ‘carbon summer,’” in which pollution traps the heat that is normally radiated back out of the atmosphere.”

“As the American poet Robert Frost wrote, ‘Some say the world will end in fire; some say in ice,’” Mr. Gore said. “Either, he notes, ‘would suffice.’”

Now is the time, he said, “to make peace with the planet.”

Mr. Gore added: “The future is knocking at our door right now. Make no mistake, the next generation will ask us one of two questions. Either they will ask, ‘What were you thinking; why didn’t you act?’ Or they will ask instead, ‘How did you find the moral courage to rise and successfully resolve a crisis that so many said was impossible to solve?’”