COPENHAGEN - Barack Obama stepped into the chaotic final hours of the Copenhagen summit today saying he was convinced the world could act "boldly and decisively" on climate change.

U.S. President Barack Obama attends the morning plenery session of the United Nations Climate Change Conference (COP15) at the Bella Center in Copenhagen, Denmark, December 18, 2009. (REUTERS/Larry Downing) But his speech offered no indication America was ready to embrace bold measures, after world leaders had been working desperately against the clock to try to paper over an agreement to prevent two years of wasted effort - and a 10-day meeting - from ending in total collapse.

Obama, who had been skittish about coming to Copenhagen at all unless it could be cast as a foreign policy success, looked visibly frustrated as he appeared before world leaders.

He offered no further commitments on reducing emissions or on finance to poor countries beyond Hillary Clinton's announcement yesterday that America would support a $100bn global fund to help developing nations adapt to climate change.

He did not even press the Senate to move ahead on climate change legislation, which environmental organisations have been urging for months.

The president's speech followed the publication of draft text, obtained by the Guardian this morning, that reveals the enormous progress needed from world leaders in the final hours of the Copenhagen climate change summit to achieve a strong deal. The draft says countries "ought" to limit global warming to 2C, but crucially does not bind them to do so. The text, drafted by a select group of 28 leaders - including UK prime minister, Gordon Brown - in the early hours of this morning, also proposes extending negotiations for another year until the next scheduled UN meeting on climate change in Mexico City in December 2010.

In his address, Obama did say America would follow through on his administration's clean energy agenda, and that it would live up to its pledges to the international community.

"We have charted our course, we have made our commitments, and we will do what we say," Obama said.

But in the absence of any evidence of that commitment the words rang hollow and there was a palpable sense of disappointment in the audience.

Instead, he warned African states and low island nations who have been resisting what they see as a weak agreement that the later alternative - no agreement - was far worse.

"We know the fault lines because we've been imprisoned by them for years. But here is the bottom line: we can embrace this accord, take a substantial step forward, and continue to refine it and build upon its foundation," he said.

"Or we can again choose delay, falling back into the same divisions that have stood in the way of action for years. And we will be back having the same stale arguments month after month, year after year - all while the danger of climate change grows until it is irreversible."

He also took a dig at China, drawing attention to its status as the world's biggest emitter and reinforcing America's hardline on the issue of accountability for greenhouse gas emissions.

The lacklustre speech proved a huge frustration to a summit that had been looking to Obama to use his stature on the world stage - and his special following among African leaders - to try to come to an ambitious deal.

The president was drawn into the chaos within minutes of his arrival at Copenhagen, ditching his schedule to take part in a meeting of major industrialised and rapidly emerging economies.

Responding to Obama's speech, a British official said: "Gordon Brown is committed to doing all he can and will stay until the very last minute to secure a deal... but others also need to show the same level of commitment. The prospects of a deal are not great."

Many reactions were strongly critical of Obama. Hugo Chávez, the president of Venezuela, described Obama's speech as "ridiculous" and the US's initial offer of a $10bn fund for poor countries in the draft text as "a joke".

Tim Jones, a spokesman for the World Development Movement, said: "The president said he came to act, but showed little evidence of doing so. He showed no awareness of the inequality and injustice of climate change. If America has really made its choice, it is a choice that condemns hundreds of millions of people to climate change disaster."

Friends of the Earth said in a statement, "Obama has deeply disappointed not only those listening to his speech at the UN talks, he has disappointed the whole world."

The World Wildlife Fund said Obama had let down the international community by failing to commit to pushing for action in Congress: "The only way the world can be sure the US is standing behind its commitments is for the president to clearly state that climate change will be his next top legislative priority."

The extent of crisis in the talks has taken leaders by surprise. The Brazilian leader, Lula da Silva, told the conference that the all-night negotiating sessions took him back to his days as a trade union leader negotiating with his bosses.

The full text of President Obama's prepared remarks are below:

Good morning. It's an honor to for me to join this distinguished group of leaders from nations around the world. We come together here in Copenhagen because climate change poses a grave and growing danger to our people. You would not be here unless you - like me - were convinced that this danger is real. This is not fiction, this is science. Unchecked, climate change will pose unacceptable risks to our security, our economies, and our planet. That much we know.

So the question before us is no longer the nature of the challenge - the question is our capacity to meet it. For while the reality of climate change is not in doubt, our ability to take collective action hangs in the balance.

I believe that we can act boldly, and decisively, in the face of this common threat. And that is why I have come here today.

As the world's largest economy and the world's second largest emitter, America bears our share of responsibility in addressing climate change, and we intend to meet that responsibility. That is why we have renewed our leadership within international climate negotiations, and worked with other nations to phase out fossil fuel subsidies. And that is why we have taken bold action at home - by making historic investments in renewable energy; by putting our people to work increasing efficiency in our homes and buildings; and by pursuing comprehensive legislation to transform to a clean energy economy.

These actions are ambitious, and we are taking them not simply to meet our global responsibilities. We are convinced that changing the way that we produce and use energy is essential to America's economic future - that it will create millions of new jobs, power new industry, keep us competitive, and spark new innovation. And we are convinced that changing the way we use energy is essential to America's national security, because it will reduce our dependence on foreign oil, and help us deal with some of the dangers posed by climate change.

So America is going to continue on this course of action no matter what happens in Copenhagen. But we will all be stronger and safer and more secure if we act together. That is why it is in our mutual interest to achieve a global accord in which we agree to take certain steps, and to hold each other accountable for our commitments.

After months of talk, and two weeks of negotiations, I believe that the pieces of that accord are now clear.

First, all major economies must put forward decisive national actions that will reduce their emissions, and begin to turn the corner on climate change. I'm pleased that many of us have already done so, and I'm confident that America will fulfill the commitments that we have made: cutting our emissions in the range of 17 percent by 2020, and by more than 80 percent by 2050 in line with final legislation.

Second, we must have a mechanism to review whether we are keeping our commitments, and to exchange this information in a transparent manner. These measures need not be intrusive, or infringe upon sovereignty. They must, however, ensure that an accord is credible, and that we are living up to our obligations. For without such accountability, any agreement would be empty words on a page.

Third, we must have financing that helps developing countries adapt, particularly the least-developed and most vulnerable to climate change. America will be a part of fast-start funding that will ramp up to $10 billion in 2012. And, yesterday, Secretary Clinton made it clear that we will engage in a global effort to mobilize $100 billion in financing by 2020, if - and only if - it is part of the broader accord that I have just described.

Mitigation. Transparency. And financing. It is a clear formula - one that embraces the principle of common but differentiated responses and respective capabilities. And it adds up to a significant accord - one that takes us farther than we have ever gone before as an international community.

The question is whether we will move forward together, or split apart. This is not a perfect agreement, and no country would get everything that it wants. There are those developing countries that want aid with no strings attached, and who think that the most advanced nations should pay a higher price. And there are those advanced nations who think that developing countries cannot absorb this assistance, or that the world's fastest-growing emitters should bear a greater share of the burden.

We know the fault lines because we've been imprisoned by them for years. But here is the bottom line: we can embrace this accord, take a substantial step forward, and continue to refine it and build upon its foundation. We can do that, and everyone who is in this room will be a part of an historic endeavor - one that makes life better for our children and grandchildren.

Or we can again choose delay, falling back into the same divisions that have stood in the way of action for years. And we will be back having the same stale arguments month after month, year after year - all while the danger of climate change grows until it is irreversible.

There is no time to waste. America has made our choice. We have charted our course, we have made our commitments, and we will do what we say. Now, I believe that it's time for the nations and people of the world to come together behind a common purpose.

We must choose action over inaction; the future over the past - with courage and faith, let us meet our responsibility to our people, and to the future of our planet. Thank you.