The Nobel Laureate was addressing more than 1,000 climate campaigners in Copenhagen's City Hall Square on Sunday as negotiators at the UN climate summit struggle to reach agreement on carbon emission cuts and funds to mitigate the effects of climate change on developing countries.
He said the effects of climate change were being felt "most dearly" by the poor and the vulnerable.
"People are having to pay for something they didn't cause. Thousands of people around the world are dying as a result of poverty caused by emissions coming from rich countries," he said.
"Don't give us a political agreement, give us a legally binding agreement. This is one problem where if we don't resolve it, no one is going to survive. We will either all be winners, or all losers."
He handed a clock to the executive secretary of the United Nations Framework Convention on Climate Change, Yvo de Boer, symbolising the more than half million signatures gathered by the Countdown to Copenhagen campaign across 20 countries.
Signatures were gathered from people signifying their pledge to help save the planet by reducing their personal carbon footprint through recycling, reusing and reducing consumption, and to write to political leaders to press for a climate change agreement fair to poor countries.
Mr Boer said: "Inside the conference centre where I have just come from, people are fretting over a financial crisis, an economic crisis, an industry crisis.
"But it's a moral crisis that is standing in the way of us addressing an environmental crisis. Copenhagen is the one chance we have to get things right."
Yesterday the Archbishop of Canterbury Dr Rowan Williams urged political leaders to "act for the sake of love" to save the planet.
"In this season of Advent … We reaffirm our conviction and commitment in the name of love; and we say 'don't be afraid' to all who stand uncertainly on the edge of decision. Don't be afraid; act for the sake of love," he said.
He was preaching at an international ecumenical service in Copenhagen Cathedral attended by the Queen of Denmark, ambassadors, negotiators from the UN summit, and other religious leaders.
"The deepest religious basis for our commitment to the environment in which God has placed us is this recognition that we are called to be, and are enabled to be, the place where God's love for the world comes through," he said.
"We have to flesh out in our lives that fundamental biblical conviction that when God looks on the world he finds it good. We have to show in our lives some echo of the delight God finds in creation".
"And as we should have learned by now, the truth is that we cannot show the right kind of love for our fellow-humans unless we also work at keeping the earth as a place that is a secure home for all people and for future generations."