* Poor want climate aid up from $100 billion/year from 2020
* Rich nations unwilling to give guarantees of rise
By Alister Doyle and Megan Rowling
BONN, Germany Oct 22 (Reuters) - More funds to help poor nations cope with climate change will be the make-or-break issue when a Paris summit seeks a U.N. deal in December to slow global warming, the main group of developing nations said on Thursday.
Poor nations say they are far more vulnerable than the rich to powerful hurricanes, heat waves, droughts and rising sea levels and want clear promises that aid will rise from an existing goal of $100 billion a year by 2020.
For many developing nations "climate change poses an existential risk, it's a matter of life and death," Nozipho Mxakato-Diseko, South Africa's delegate who speaks for more than 130 developing nations, said at U.N. climate negotiations.
"Whether Paris succeeds or not will be dependent on what we have as part of the core agreement on finance," she told a news conference in Bonn during the Oct. 19-23 U.N. talks among almost 200 nations, the final preparatory session before Paris.
Developed nations have promised to raise climate funds to $100 billion a year, from a wide range of public and private sources, by 2020 to help emerging economies curb greenhouse gas emissions and adapt to impacts of climate change.
Mxakato-Diseko's Group of 77 and China, which has expanded to 134 members from 77 at its founding, wants guarantees that aid will be "scaled up from a floor of $100 billion from 2020".
The United States and other rich nations favour vaguer wording that stops short of promising a rise from 2020.
Other controversies in Paris are likely to be how to toughen national plans for curbs on greenhouse gas emissions beyond 2025 and 2030. Developed nations want guarantees that the poor will step up their actions to slow rising emissions.
Mxakato-Diseko said a report by the Organisation of Economic Cooperation and Development on Oct. 7, which said climate finance totalled $62 billion in 2014 had no legal status. She said poor nations had not been consulted.
And she said it was "simplistic" to say that barriers between rich and poor were breaking down over finance. China, for instance, last month pledged $3 billion in aid for developing nations.
"South-South cooperation is welcome, but putting it in the deal is something that is not acceptable" to developing nations, said Harjeet Singh of ActionAid. "The money to prepare for and deal with climate impacts must be at the centre of the deal." (Reporting by Alister Doyle; Editing by Tom Heneghan)
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