"It is going very slowly, things have to speed up a bit -- there are lots of difficult issues to resolve today," said an environmental scientist who has participated in all the IPCC climate assessments since 1999.

The Eiffel Tower nearby was to extinguish its lights for five minutes at 7:55 p.m. (1855 GMT) as part of a campaign to raise awareness about energy efficiency and fossil-fuel pollution.

Compared with previous IPCC gatherings, the source said, "there is a strikingly low degree of conflict and a high degree of agreement by governments" on the core conclusions that the planet is warming and mankind is overwhelmingly responsible for it.

"None of the 'usual suspects' -- the United States, the oil-producing countries and China -- have attempted to obstruct the discussions" or "corrupt the science in the report," said another participant.

But the line-by-line vetting was slowed by the sheer task of making the document intelligible for policymakers without sacrificing scientific accuracy.

There was also sharp debate, both sources said, about what should be included, or not, in the phonebook-sized report's all-important summary.

"The two main sticking points have been how to describe the temperature projections and the rise in sea levels," said the environmental scientist.

Leaked drafts of the assessment predict that Earth's surface temperature will rise by 4.5 C (8.1 F) or even higher if carbon dioxide levels in the atmosphere increase by half compared with today's concentrations. The figures are hedged with qualifications and different scenarios, though.

Government representatives complained that this yardstick was too fuzzy for the general public and decision-makers, which means the final document will simply project the expected temperature rise by 2100.

A forecast in the draft that sea levels will rise by 28 to 43 centimeters (11.2 to 17.2 inches) have also been contested as too conservative by some scientists, both sources said, as it does not factor in recently-observed melting of ice in Greenland and Antarctica.

"The paleontologists point out that during the last intergalacial period, sea levels rose at one meter (3.25 feet) or higher per century," a source said.

As the week-long meeting got underway, global warming initiatives announced around the world underscored the extent to which climate change is fast becoming a top priority for policy makers.

The United Nations Environment Programme (UNEP) joined with the UN Framework Convention on Climate Change (UNFCCC) -- the offshoot of the 1992 Rio Summit -- to call on new Secretary General Ban Ki-Moon to call a special summit on global warming.

US lawmakers called Tuesday for an end to American complacency over global warming as the new Democratic-controlled Congress weighed measures to reduce greenhouse gases.

Two more volumes of the IPCCC assessment are due out in April and early May. They will assess the environmental and social impacts of these changes and ways of mitigating climate shift.

earlier related report
Global temperature set to rise between 1.8 and 4 C by 2100: UN panel
Paris (AFP) Feb 1 - The earth's surface temperature will probably rise by between 1.8 and 4.0 C (3.24 and 7.24 F) by the turn of the century, according to a "best estimate" agreed Thursday by the UN's top scientific panel for global warming, sources said.

The estimate was released as the world's top climate experts struggled against the clock to hammer out a consensus report on global warming that is already radiating political shockwaves.

The 1.8-4.0 C warming is experts' "best estimate" in forecasts for 2090-2099 compared to 1980-1999, depending on how much carbon dioxide, the principal greenhouse gas, enters the atmosphere by 2100.

In 2001, using a somewhat different method of calculation, the IPCC gave a temperature range of between 1.4 and 5.8 C (2.52-10.4 F).

The consensus estimate will feature in a major update about global warming due to be unveiled in Paris on Friday by the UN's Intergovernmental Panel for Climate Change (IPCC) after a four-day debate.

The first review of the evidence since 2001, it summarises the work of thousands of climate scientists, working in fields as diverse as ice cores, coral reefs, ocean current observation and atmospheric monitoring.

Greenhouse gases are carbon gases that trap the sun's heat instead of letting it radiate into space.

They exist naturally, but the IPCC report is expected to declare that man-made gases -- especially carbon pollution from fossil fuels -- are almost certainly to blame for most of the warming observed in the last half-century.

This warming is already affecting the climate, causing shrinking snow and ice cover, retreating permafrost, longer droughts and changed precipitation patterns.

More than 500 scientists huddled at the closed-door meeting in Paris, poring over the first review of the scientific evidence for global warming in six years.

"None of the 'usual suspects' -- the United States, the oil-producing countries and China -- have attempted to obstruct the discussions" or "corrupt the science in the report," said a participant.

But the line-by-line vetting was slowed by the sheer task of making the document intelligible for policymakers without sacrificing scientific accuracy.

There was also sharp debate, sources said, about what should be included, or not, in the phonebook-sized report's all-important summary.

"The two main sticking points have been how to describe the temperature projections and the rise in sea levels," said the environmental scientist.

A forecast in the draft that sea levels will rise by 28 to 43 centimeters (11.2 to 17.2 inches) has also been contested as too conservative by some scientists, both sources said, as it does not factor in recently-observed melting of ice in Greenland and Antarctica.

"The paleontologists point out that during the last intergalacial period, sea levels rose at one meter (3.25 feet) or higher per century," a source said.

As the week-long meeting got underway, global warming initiatives announced around the world underscored the extent to which climate change is fast becoming a top priority for policy makers.

The United Nations Environment Programme (UNEP) joined with the UN Framework Convention on Climate Change (UNFCCC) -- the offshoot of the 1992 Rio Summit -- to call on new Secretary General Ban Ki-Moon to call a special summit on global warming.

US lawmakers called Tuesday for an end to American complacency over global warming as the new Democratic-controlled Congress weighed measures to reduce greenhouse gases.

Two more volumes of the IPCC assessment are due out in April and early May. They will assess the environmental and social impacts of these changes and ways of mitigating climate shift.

The Eiffel Tower, near the conference venue, as well as the Colosseum in Rome and other landmarks throughout Europe, extinguished their lights for five minutes at 7:55 pm (1855 GMT) as part of a campaign to raise awareness about energy efficiency and fossil-fuel pollution.

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