Quote from Xspurt:
11.41am:
Obama complains of decades of "stale argument". There is no time to waste, he says. "We will do what we say, now its time for the nations of the world to come to a common purpose," Obama. There has to be action from all sides, he says.
That's it. He leaves the stage to no more than polite applause.
11.38am:
We must have financing that helps developing nations adapt to climate change, Obama concedes. He repeats US backing for a $100bn fund. But he repeats that this depends on a genuine accord about emission reductions.
We're running out of time, Obama says. Do we prefer posturing or action, he says.
"We know the fault lines because we have been inprisoned by them for years," the president adds.
11.34am:
We are convinced that changing the way we produce and use energy is essential to our future, for our own self interest, Obama says.
No matter what happens in Copenhagen we will pursue this, but he pleads for collective action.
"I believe the pieces of that accord should be clear," Obama says after describing the days of negotiations.
He calls for decisive national ambitions and praises the countries that have already done so. He says he is confident the US will follow.
11.32am:
Finally Obama takes the floor. "This is not fiction it is science. Unchecked climate change will pose unacceptable risk to security, economy and planet," he says.
"Our ability to take collective action is in doubt," Obama warns. I come here not to talk but to act, he says to applause. As the world's second highest emitter the US has a responsibility, he says.