Leading scientists and officials completed a fresh climate report Sunday expected to lay bare the grim impact of climate change, with warnings that global food shortages could spark violence in vulnerable areas.
Part of a massive overview by the United Nations' Intergovernmental Panel on Climate Change (IPCC) set for release on Monday, the report is likely to shape international policy on climate for years to come, and will announce that the impact of global warming is already being felt.
Some 500 scientists and government officials have been gathered since Tuesday in Yokohama, south of Tokyo, to hammer out its wording.
It will serve as the second of three volumes into climate change's causes, consequences and possible solutions by the expert panel.
The work comes six months after the first volume in the long-awaited Fifth Assessment Report declared scientists were more certain than ever that humans caused global warming.
A leaked draft seen by AFP warned that rising greenhouse gas emissions will "significantly" boost the risk of floods while droughts will suck away sustainable water supplies.
A "large fraction" of land and freshwater species may risk extinction, and a warming climate is projected to reduce wheat, rice and corn yields, even as food demand rises sharply as the world's population grows.
Meanwhile hundreds of millions of coastal dwellers around the world will be displaced by the year 2100, the draft said, while the competition for dwindling resources could even spark violent conflicts.
However, the world can avoid many of the worst-case scenarios with swift and decisive policy steps to cut emissions now, the scientists urged.
The delegates were originally expected to finish drafting the official summary text late Saturday evening, but needed extra time to update definitions and digest new approaches.
"I felt the meeting was very constructive, and governments appreciated why the authors did things the way they did them," said Maarten van Aalst, director of Red Cross/Red Crescent Climate Centre.
"While it may seem as if a long meeting could signal we had problems to solve, it was actually a sign of a very productive and collaborative process," said Van Aalst, who is one of the IPCC lead authors.
The panel has issued four previous "assessment reports" in its quarter-century history.
The IPCC's last big report in 2007 helped unleash political momentum leading to the 2009 UN climate summit in Copenhagen.