The UN climate panel issued its strongest warning yet on Friday that human activities are heating the planet, putting extra pressure on governments to do more to combat accelerating global warming.
The Intergovernmental Panel on Climate Change (IPCC), the most authoritative group on warming which groups 2,500 scientists from more than 130 nations, predicted more severe rains, melting glaciers, droughts and heat waves and a slow rise in sea levels.
The final text of the report said it was "very likely" — meaning a probability of more than 90 percent — that human activities led by burning fossil fuels explained most of the warming in the past 50 years.
That is a shift from the last report, in 2001, when the IPCC said the link was "likely", or at least 66 per cent probable.
"Most of the observed increase in globally averaged temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic (human) greenhouse gas concentrations," said the text.
The talks among government representatives and IPCC scientists, meeting in Paris since Monday, ended after midnight after a wrangle over rising ocean levels. IPCC leaders will formally unveil the results of six years' work in Paris at 0830 GMT.
A 20-page summary for policy makers outlines threats such as a melting of Arctic sea ice in summers by 2100 and a slowing of the Gulf Stream.
UN officials hope the report will prompt governments and companies to do more to cut emissions of greenhouse gases, released mainly by burning fossil fuels in power plants, factories and cars.
The report also predicted a "best estimate" that temperatures would rise by between 1.8 and 4.0 Celsius (3.2 and 7.8 Fahrenheit) in the 21st century with a likely range from 1.1 to 6.4 Celsius.
Temperatures rose 0.7 degrees in the 20th century and the 10 hottest years since records began in the 1850s have been since 1994. Many European countries have had their warmest January on record.
"The IPCC's latest report provides the most conclusive evidence to date that human activities are causing dangerous climate change," said Camilla Toulmin, head of the International Institute for Environment and Development, a London-based research group.
"Time is running out to cut greenhouse gas emissions," she said.
"For those who are still trying to determine responsibility for global warming, this new UN report on climate change is a scientific smoking gun," Democratic Congressman Edward Markey of Massachusetts said.
"We ignore it at the peril of our children and their children," he said.
Thirty-five rich nations have signed the Kyoto Protocol that sets caps on emissions of greenhouse gases — but Kyoto's first period runs only to 2012 and big emitters led by the United States, China and India have no targets.
President George W Bush said last week that climate change was a "serious challenge". He pulled out of Kyoto in 2001, saying Kyoto-style caps were an economic straitjacket and that it unfairly omitted developing nations.
Sea levels are likely to rise by between 28 and 43 cm (11-17 inches) this century, according to an earlier draft of the IPCC report.
The range is lower than forecast in 2001 but delegates said they clarified that the projection did not include the possibility of an accelerating melt of Greenland ice, which some studies suggest is under way.