President George W Bush proposed a summit next year among major emitters of greenhouse gases that would set a long-term global goal for curbing this dangerous pollution.
Mr Bush also endorsed the UN as the final arena for tackling global warming, but gave not an inch of ground to those demanding the United States slap a legally-binding cap on its own massive carbon emissions.
"Energy security and climate change are two of the great challenges of our time.
“The United States takes these challenges seriously," Mr Bush says.
"By setting this goal, we acknowledge there is a problem.
“And by setting this goal, we commit ourselves to doing something about it.
"By next summer, we will convene a meeting of heads of state to finalize the goal and other elements of this approach, including a strong and transparent system for measuring our progress towards meeting the goal we set."
Opposing mandatory caps
But he also rammed home the message that the United States, hugely dependent on oil, stood by its six-year-long opposition to setting mandatory caps on its own emissions.
“We must lead the world to produce fewer greenhouse gas emissions and we must do it in a way that does not undermine economic growth or prevent nations from delivering greater prosperity for their people," he says.
"Each nation will design its own separate strategies for making progress towards this long-term goal. These strategies will reflect each country's different energy resources, different stages of development and different economic needs."
Centrality of UN
Mr Bush also offered an olive branch to those who had suspected that the Washington meeting — staged in the run up to new global climate talks in December — aimed at undercutting the UN process and pushing through a US-led agenda for easier, voluntary emissions cuts.
To applause, he hoped the Washington approach would advance negotiations under the UN Framework Convention on Climate Change (UNFCCC), the parent treaty of the Kyoto Protocol.
UNFCCC chief Yvo de Boer says he was reassured by Mr Bush's remarks.
"He pointed to the centrality of the UN process," he says.
Representing the EU, Portugal's deputy environment minister, Humberto Rosa, says: "It's good to hear President Bush speak with such a firm and strong message on climate change, which is in such a sharp contrast to the attitude some time ago.
"The world should all look at this as a hopeful sign, but of course we are still in the need to see how this (US) national effort and tone of President Bush will feed into the international process."
A German diplomat says: "A speech like this could not have been expected from the US President a few weeks or months ago.
“It is clear progress that the President acknowledges this problem, says that the United States is willing to do something about this and do it under the UN."
Nuclear ‘not only solution’
But he stressed there remained many doubts on the substance of Mr Bush's ideas, including his push on nuclear, which is being phased out in Germany in favour of "clean renewables" such as wind.
"If we propagate nuclear as THE solution to the climate problem, we will have to build several thousand nuclear power stations around the world," he says.
"It doesn't make any sense to spread the risk of nuclear bombs if we also spread the risk of rogue states and terrorists making a nuclear bomb."