An authoritative report on global warming will say it is "very likely" — or 90 per cent certain — climate change is caused by humans burning fossil fuels, and warns of rising temperatures and sea levels and extreme weather in the coming century, according to officials involved in writing the report.

Dozens of scientists from the Intergovernmental Panel on Climate Change representing 113 nations are working on the final wording of the report expected to be released Friday in Paris.

Dr. Rajendra Pachauri of India chairs the Intergovernmental Panel on Climate Change conference in Paris on Monday.
(Jacques Brinon/Associated Press)

The fourth report since 1990, it is widely expected to include the strongest wording yet on the impact burning fossil fuels has on climate change and to predict significant changes could start to appear in the next 10 years.

"That is a big move. I hope it is a powerful statement," said Jan Pretel, head of the department of climate change at the Czech Hydrometeorological Institute.

The last report, in 2001, said global warming was "likely" caused by human activity.

According to drafts, the report will forecast a temperature increase of two to four degrees Celsius by the year 2100, which would lead to a rise in sea levels and extreme weather, such as droughts and heat waves.

Hurricanes are also for the first time considered "more likely than not" linked to climate change, with the report predicting fewer but more powerful occurrences of the tropical storms.

The report is expected Friday, though participants are said to be behind schedule in agreeing on the wording of the 12- to 15-page summary.

The initial report — authored by more than 2,000 scientists — will be followed by three subsequent sections to be issued throughout the year, including examinations of climate change impacts expected in April.

UN Secretary General Ban Ki-moon is said to be considering the idea of an emergency international summit on climate change later this year amid growing concerns about rising temperatures.

The world's 10 warmest years in temperature records dating back to 1850 have all occurred since 1994, according to the United Nations weather agency.

A UN report issued two months ago said greenhouse gases in the atmosphere reached record levels in 2005 and were expected to increase in 2006. Concentrations of carbon dioxide and nitrous oxide both rose in 2005, the study's authors found.

Under the Kyoto accord that went into effect in 2005, 141 nations have committed to reducing emissions by an average of five per cent below 1990 levels by 2012.

But the agreement does not include the world's biggest emitter — the United States — and also excludes developing countries like China and India.

The Chinese delegation was resistant to strong wording on global warming, according to Barbados delegate Leonard Fields and Zimbabwe delegate Washington Zhakata.

As the delegates hold their evening session, the Eiffel Tower and other Paris monuments will turn off their lights for five minutes at 1:55 p.m. ET, to draw attention to energy consumption and the environment.

With files from the Associated Press