"More is at stake in these negotiations than some seem to realize," said the lone figure on the low platform at the head of the giant meeting hall. "The future of human civilization is now threatened."
In an intense and sometimes emotional speech, former Vice President Al Gore called on the nations at the Copenhagen climate summit to speed up their negotiation process by five months. Since a binding agreement to reduce greenhouse gases is not likely to come from this week's meeting, Gore suggested they make one in July 2010 in Mexico City. That meeting is currently scheduled for the end of next year.
Participants in the Copenhagen meeting jammed the hall to hear Gore. They filled the seats and lined the walls, silent when he paused.
"I have reason to believe the Mexican government would be willing to undertake the enormous amount of work that would be involved to move the date of the next meeting to the middle of the summer," said Gore.
He also said it would be unwise to try to finalize binding carbon targets while distracted by America's midterm elections next November.
'Humanity's Fateful Fight'
Gore had been introduced by Yvo Dear, head of the UN's Framework Convention on Climate Change.
"We might not be at this turning point in humanity's fateful fight against climate change were it not for this man," he said.
Gore was the second American celebrity in a day to draw large crowds.
California governor Arnold Schwarzenegger had just spoken to another standing-room-only audience, his face beamed over large TV monitors throughout this sprawling convention complex.
Schwarzenegger said 80 percent of the fight against global warming is done by what are called "sub-national governments" like his -- states, cities and counties.
'The Ugly Duckling' and Humanity's Transformation
Schwarzenegger alluded to Copenhagen's literary history and a tale by the world-famous Danish author Hans Christian Anderson.
"The Ugly Duckling," said the former movie star (who also spoke openly of the importance of using celebrities to promote worthy causes), is a story of the great "power of personal transformation."
Copenhagen Global Warming Talks: Gore, Generals
In a reference to the sometimes-slow progress of the unprecedented global negotiations to curb greenhouse emissions, he said, "Let us regain our momentum... (and the) ... liberating transformational power" that the fight against global warming would have.
Then he invited the UN to convene a global climate summit in California that would be specifically designed for cities and states and other sub-national governments.
When he left the room, he was quickly mobbed by a hundred journalists just outside in the high-ceilinged hallway, and answered questions to the flashing of lights for another half an hour.
The climate summit has dozens of such "side-events" -- gatherings not part of the many formal negotiations.
Not all are so well attended. One led by Americans in a much smaller meeting room, just before Mr. Gore spoke, presented the concerns of "Operation Free: Secure America a With Clean Energy."
'A Threat Multiplier'- - Global Warming Aids Terrorism
Six American military officers, most retired, sat at a table with another six standing right behind them -- all with a military bearing their civilian clothes could not hide.
They almost outnumbered the audience
Former U.S. Army Captain Jonathan Powers, who served in Iraq, talked about how "Climate change makes the world a more dangerous place."
He spoke of the many studies by US intelligence and defense agencies that have already assessed the growing security threats created by human-induced global warming.
Asked by ABC News what impact climate change had on terrorists such as the Taliban and Al Qaeda, retired Army Major General Donald Edwards responded, "It's a proven fact that when young people are disaffected -- lands flooded, or drought and no food -- they lose respect for the government and become prime targets for recruiting."
Shifting into the jargon of military management, he added that "There will be a significant threat outflow."
Edwards said he did not want to mention specific terrorist groups, but other Department of Defense sources have told ABC News of analyses by military and intelligence teams that have found the effects of long-term drought, worsened by global warming, playing into the hands of the Taliban and their Al Qaeda allies.
Copenhagen Climate Summit: Obama Coming
Powers said there was a general understanding among military analysts that severe conditions that are expected only to worsen as global warming advances were what the military calls "threat multipliers."
120 heads of state and government are due to arrive before the end of the week.
US President Barak Obama is scheduled to appear on Friday.
Additional metal detectors have started to appear in some halls in preparation for the enormous security problems the leaders bring with them.