BBC NEWS | Science/Nature | Through the climate window

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The higher degree of certainty that changes are down to human activities - up from at least 66% in 2001 to at least 90% now - is significant, as is the judgement that human activities are responsible for about 13 times as much of the warming we see as changes in the Sun's output.

As to what all that should mean, Achim Steiner, executive director of the United Nations Environment Programme (Unep), was in little doubt.

"Friday, 2 February 2007 may go down in history as the day when the question mark was removed from the question of whether climate change has anything to do with human activities."

The IPCC Report

The Intergovernmental Panel on Climate Change (IPCC) said temperatures were probably going to increase by 1.8-4C (3.2-7.2F) by the end of the century.

It also projected that sea levels were most likely to rise by 28-43cm, and global warming was likely to influence the intensity of tropical storms.

At variance

But a study published on the eve of the IPCC report suggested that the international body's previous reports may have actually been too conservative.

Writing in the journal Science, an international group of scientists concluded that temperatures and sea levels had been rising at or above the maximum rates proposed in the last report, which was published in 2001.

The paper compared the 2001 projections on temperature and sea level change report with what has actually happened.

The models had forecasted a temperature rise between about 0.15C-0.35C (0.27-0.63F) over this period. The actual rise of 0.33C (0.59F) was very close to the top of the IPCC's range.

A more dramatic picture emerged from the sea level comparison. The actual average level, measured by tide gauges and satellites, had risen faster than the intergovernmental panel of scientists predicted it would.

Global climate efforts 'woeful'

Rich countries have focused on ways to reduce carbon emissions but have largely ignored helping poor nations cope with the consequences, it says.

The findings appear in the UNDP's Human Development Report 2006.

The authors say farmers whose crops are reliant on rainfall are already having to cope with unpredictable weather.

The report, called Beyond Scarcity: Power, Poverty and the Global Water Crisis, says climate change "now poses what may be an unparalleled threat to human development".