The 1,000-page assessment on the effects of climate change had been completed as a draft and released in summary form by the Intergovernmental Panel on Climate Change (IPCC) in April.

Martin Parry, a British expert who co-chaired the IPCC group behind the study, said Africa, small island nations, the Arctic and Asia's sprawling mega-deltas are the regions most at risk this century.

Northern and southern Africa are at risk of greater aridity, while the central swathe of the continent faces the problem of greater flooding, he told AFP in an interview.

Small island nations and Asia's delta cities, home to hundreds of millions of people, face the risk of higher sea levels and storm surges, while Arctic sea ice is shrinking fast, posing a threat to the region's wildlife and peoples.

Some effects of global warming are already starting to happen, which means vulnerable countries need help now, whereas emissions reductions, known as mitigation, take "20, 30, 40 years" take effect, said Parry.

"The item of most relevance that emerges is that, even if we take the most hopeful scenario for a rise in warming, of 2 degrees Celsius (3.6 degrees Fahrenheit), we cannot simply mitigate our way out of this," he said.

The figure of 2 C (3.6 F) constitutes the rise in average global temperatures compared with pre-industrial times.

But most experts believe this figure is bound to be surpassed, given the surge in carbon pollution by large developing countries and meagre efforts to constrain these emissions.

"Adaptation is so often left out of the equation," said Parry. "But the approach has to be two-pronged, of mitigation and adaptation."

The report was compiled by IPCC's so-called Second Working Group. The panel has three Working Groups, each of which delivered a massive tome on the state of scientific knowledge about global warming, its impacts and ways of tackling the problem.

Put together, the three documents comprise the fourth assessment report on climate change by the IPCC since its founding in 1988.

Talks to deepen action against global warming take place in Bali, Indonesia, from Dec 3-14. They will focus on commitments after 2012, when the current round of pledges under the UN's Kyoto Protocol expires.

Two meetings take place next week as part of the political process -- one, gathering heads of state and government, will be at the United Nations, New York on Monday, and the second, at ministerial level, will unfold in Washington on September 27 and 28 under US chairmanship.

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