OSLO Oct 26 Climate change may have "serious, pervasive and irreversible" impacts on human society and nature, according to a draft U.N. report due for approval this week that says governments still have time to avert the worst.
Delegates from more than 100 governments and top scientists meet in Copenhagen on Oct 27-31 to edit the report, meant as the main guide for nations working on a U.N. deal to fight climate change at a summit in Paris in late 2015.
They will publish the study on Nov. 2.
European Union leaders on Friday agreed to cut emissions by 40 percent below 1990 levels by 2030, in a shift from fossil fuels towards renewable energies, and urged other major emitters led by China and the United States to follow.
"The report will be a guide for us," Peruvian Environment Minister Manuel Pulgar-Vidal, who will host a U.N. meeting of environment ministers in Lima in late 2014 to lay the groundwork for the Paris summit, told Reuters.
He said the synthesis report by the Intergovernmental Panel on Climate Change (IPCC), drawing on three mammoth scientific reports published since September 2013, would show the need for urgent and ambitious action in coming years.
Many governments want the 32-page draft to be more clearly and punchily written in warnings of more powerful storms, heat waves, floods and rising seas. The United States said some tables "may be impenetrable to the policymaker or public".
In a paragraph summing up the risks, the draft says that a continued rise in world greenhouse gas emissions is "increasing the likelihood of severe, pervasive and irreversible impacts for people and ecosystems."
It adds that "a combination of adaptation and substantial, sustained reductions in greenhouse gas emissions can limit climate change risks."
Among more than 2,000 comments on the text by governments, the European Union said the IPCC should add that "all regions are affected, regardless of wealth".
The United States called for clarification of the meaning of "irreversible". Jonathan Lynn, spokesman of the IPCC, said that the meeting would take account of all comments.
Past reports have warned that warming could, for instance, trigger impacts irreversible on human time scales such as a runaway meltdown of Greenland's ice that would raise sea levels and swamp coasts from Florida to Bangladesh.
Two artists were to unveil 100 tonnes of ice on Sunday in 12 massive blocks brought from near Nuuk, Greenland, outside Copenhagen's City Hall to remind delegates of the risks.
"We can save the ice by burning less coal, conserving electricity, and driving better cars," Danish Climate Minister Morten Helveg Petersen said of the Ice Watch exhibit.
The IPCC says that it is at least 95 percent certain that human activities, led by the burning of fossil fuels, are the main cause of climate change since 1950, up from 90 percent in the previous assessment in 2007 and 66 percent in 2002.
Opinion polls indicate many people, especially in the United States, are unconvinced and suspect that natural variations in climate are to blame. That gap between public and scientific opinion is a big complication for work on the Paris accord.
(Reporting By Alister Doyle; Editing by Stephen Powell)