GENEVA A global fund to help poorer countries switch to green industrial technology is vital in any new international pact to battle global warming, Switzerland's top climate change negotiator said on Wednesday.
The official, Franz Perrez, was speaking at a news conference on the eve of a two-day gathering of environmental ministers and experts from some 45 countries to discuss how to reach agreement on a funding deal.
"An agreement on viable long-term financing is one of the very important building blocks for a new convention to combat the challenge of climate change," said Perrez, whose country has organised the informal meeting together with Mexico.
In December, Mexico is to host a new formal effort to clear the way for a convention. A United Nations summit in Copenhagen at the end of last year ended in serious disarray.
Developing nations say billions of dollars are vital to help them start acting to slow global warming by shifting from fossil fuels, and to cope with challenges created by climate change ranging from droughts and floods to rising sea levels.
Big emerging economies like China, India and Brazil say they should not be hog-tied by environmental rules unless the West -- which they blame for global warming -- helps pay the cost.
It was agreed in Copenhagen that what Perrez dubbed a "fast-track" financing of some $30 billion was needed for the years 2010-2012 to create confidence, but the larger goal is to ensure by 2020 that $100 billion a year can be mobilized.
Environment ministers hope for progress on financing when they gather in Cancun from November 29 to December 10, despite austerity programmes adopted by rich nations in the wake of the world economic and financial crisis of 2008-09.
Perrez said the Geneva talks will try to pin down differences on how the funding will be set up and who might provide it, adding that he hoped an agreement might be reached by 2012 on how to create the mechanism.
The Copenhagen accord does not lay out who pays, or how to raise money, but among suggestions for 2020 are carbon markets, air travel levies and taxes on ships' fuel.
A Reuters overview last week showed that although specific promises so far for the 2010-12 period total $29.8 billion, some of this was old funding dressed up as new.
Japan, for instance, is promising half the total -- $15 billion -- but most of this is from a previous "Cool Earth Partnership" agreed several years ago to run from 2008-12.
The ministers' meeting will be the first since a review team called on Monday for a sweeping overhaul of the management of the U.N. Intergovernmental Panel on Climate Change after it admitted there were errors in a 2007 report.
The review endorsed the main finding of the IPCC's report -- that mankind is to blame for global warming -- but Perrez said the furor over the errors might make it more difficult to raise the funds needed to tackle the overall challenge.
"But the basic understanding is still there," he said. "The developed countries recognize that they have to live up to their responsibilities."
(Writing and additional reporting by Robert Evans; Editing by Jonathan Lynn and Tim Pearce)