OSLO (Reuters) - An economic slowdown is sapping enthusiasm for a costly drive to fight climate change but persistently high oil prices are a lifeline for a "green revolution" of renewable energy technology, experts say.

U.N. talks on a new climate treaty to be agreed in Copenhagen at the end of 2009 resume in Ghana from August 21-27 -- overshadowed by worries about flagging growth and in an atmosphere soured by the collapse of world trade talks.

Weaker growth "will probably reduce the intensity of the negotiations," said Cameron Hepburn, an Australian environmental economist at Oxford University.

"But ought it to? The answer is a fairly clear 'No'."