Warming 'already changing world'

The Intergovernmental Panel on Climate Change (IPCC) believes there is also a discernible, though less marked, impact on human societies.

The IPCC is to release a summary of its report on Friday but talks on wording have continued late into the night.

Officials said there were differences between various countries on the strength of the language.

"The Europeans want to send a strong signal. The US does not want as much quantification," one official told the French news agency AFP.

China and Russia had also raised concerns over some passages of the 21-page summary, the official said.

The last-minute wrangling is likely to affect the degree of certainty in the final version, the BBC's Richard Black reports, but not the overall direction.

Water shortages

Draft versions seen by BBC News warn it will be hard for societies to adapt to all the likely climate impacts.

The report is set to say that a temperature rise above 1.5C from 1990 levels would put about one-third of species at risk of extinction.

More than one billion people would be at greater risk of water shortages, primarily because of the melting of mountain glaciers and ice fields which act as natural reservoirs.

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http://news.bbc.co.uk/2/hi/science/nature/6524251.stm