UK's Brown proposes $100 billion annual climate fund
Global talks to agree in December in Denmark a new treaty to fight climate change have struggled to determine how rich countries pay for climate action in poorer nations.
"I propose we take a working figure for this purpose of around $100 billion per annum by 2020," Brown said in London.
"If we are to achieve an agreement in Copenhagen I believe we must move the debate from a stand-off over hypothetical figures."
(Reporting by Gerard Wynn; Editing by Sue Thomas)