Bali: As the UN climate conference entered its last days, the United States encountered - and rejected - fresh demands on Wednesday that it accept ambitious guidelines for negotiating future cuts in emissions of greenhouse gases.

Pressure came even from a one-time ally on climate, Australia, whose new prime minister urged Washington to "embrace" new binding targets.

But UN Secretary-General Ban Ki-moon, after opening the ministerial-level final segment of the two-week meeting, told reporters he believed suggesting specific emissions guidelines in the "Bali roadmap" for future talks may prove "too ambitious."

The tenor of the talks pointed, instead, toward a least-common-denominator outcome by week's end: a vague plan to negotiate by 2009 a new deal on emissions cutbacks, replacing the Kyoto Protocol when it expires in 2012.

The warming climate, meanwhile, seemed to pursue its own accelerated timetable.

'Ice-free' Arctic

Through November, the year 2007 ranked as the globe's second-warmest on record, after 2005, Nasa's Goddard Institute of Space Studies reported yesterday. The latest Nasa satellite data, meanwhile, showed Arctic Ocean ice melted last summer at an even greater rate than found previously, reports from Washington stated.

One Nasa scientist said the Arctic might be almost ice-free in the summer of 2012, much sooner than predicted just months ago. The growing threat drew emotional appeals from islanders among the 180-odd nations at the Bali talks. "It is a story of untold human dimensions, of people becoming environmental refugees," Grenada's Angus told the hundreds of assembled delegates on Friday.

Some islands are already beset by encroaching seas, he said, adding, "No island should be left behind." An early draft of the conference decision document here at Bali says nations should negotiate the post-2012 pact while recognising that deeper cuts, in the "indicative range" of 25-40 per cent below 1990 levels by 2020, will be required. And the draft specifies "quantified commitments" - not voluntary measures.

The United States rejects the Kyoto deal, President George W. Bush complaining it would harm the country's economy and cutbacks should have been imposed on such poorer but fast-developing nations as China and India.

The Bush administration instead promotes a voluntary approach to reducing emissions.

In the next round, "we expect all developed countries to embrace a further set of binding emissions targets," said Prime Minister Kevin Rudd, whose new Australian government last week ratified Kyoto, leaving the US alone as a major industrial nation repudiating that pact.