"Climate change, and what we do about it, will define us, our era, and ultimately the global legacy we leave for future generations," the secretary general said, according to a UN transcript of his statements.

The discussion of climate change was a part of a larger meeting of the UN General Assembly that also hoped to address international concerns over Iran’s growing nuclear programme. Iranian President Mahmoud Ahmadinejad delivered a fiery speech proclaiming his country’s peaceful intentions and defying UN sanctions meant to halt Tehran’s enrichment of uranium. French President Nicolas Sarkozy warned the deadlock could lead to war.

General Secretary Ban demanded a breakthrough in climate talks at a key conference taking place in Bali, Indonesia, in December.

"The time for doubt has passed," said Ban, as he noted the grim 4th assessment on climate change by the United Nations’ top scientific panel this year.

"If we do not act now, the impact of climate change will be devastating," he added. "We have affordable measures and technologies to begin addressing the problem right now. What we do not have is time."

Summit gets high level turn out
The exceptional one-day summit entitled "The Future in Our Hands: Addressing the Leadership Challenge of Climate Change," gathered around 150 nations, some 80 of them at the level of head of state or government.

It aimed to break the deadlock in efforts to deepen cuts in emissions of greenhouse gases, which trap heat from the sun and are inflicting damaging change to Earth’s climate system.

The chairman of the UN’s Intergovernmental Panel on Climate Change (IPCC), Rajendra Pachauri, gave a brief summary of the 4th assessment report.

Glaciers and Arctic sea ice were retreating rapidly and "major precipitation changes" – droughts and floods – were occurring.

By present trends, hundreds of millions of people faced worsening water scarcity as a result of glacier loss in the Himalayas, which fed key rivers in China and South Asia. Water scarcity would affect the growing of key crops.

"Climate change is accelerating," he said.

Where was Bush?
Conspicuously absent from the climate change talks was US Presdient George Bush, who will hold meetings on Thursday and Friday with the world’s 16 most polluting economies in Washington.

While his administration has exhibited six years to the hard science climate change and flatly refused to sign the Kyoto protocol, Bush has made a somewhat conciliatory gesture to speak to these nations about their goals for tackling greenhouse-gas emissions, encourage cleaner technologies, spur the private sector and identify industries that could be coaxed into the global carbon-cleanup.

The meeting will be chaired by US Secretary of State Condoleeza Rice and attended by representatives of the European Union.

UN and Europe suspicious of White House
But given Bush’s glaring record as a footman for big industry and oil, suspicions are rife within the UN and among Kyoto’s European and environmentalist defenders that the Washington initiative may carry a dark sub-text.

Despite US protestations to the contrary, the fears are that Bush will peddle an agenda for fast-track voluntary curbs among a small club of polluters, thus undermining the global forum, which moves at slower a speed but sets much tougher goals.

"There are obvious temptations here, but we expect the EU (European Union) to be vigilant," a Western European diplomat told Agency France Presse, adding "there is no support from the developing countries either" for ditching the UN framework.

Apparently unwilling to give Bush too much limelight, some EU countries will be sending only junior ministers or senior officials to Washington rather than ranking ministers, other European told AFP.

In a veiled message to Washington about any breaks Bush intends to slide under the table to his friends in pollution industries, Ban said Monday that: "All other processes or initiatives should be compatible with the UN’s Framework Convention on Climate Change process and should feed into it, facilitating its successful conclusion."