Australian Prime Minister John Howard said the leaders agreed on long-term "aspirational" goals in the fight against global warming, although there were no firm commitments.
Howard said the leaders agreed that all countries -- both rich and poor -- should contribute what they could to the overall target.
The presidents of the United States, Russia and China were among 21 leaders attending the Asia Pacific Economic Cooperation summit in Sydney.
Up to 5,000 thousand protesters rallied several blocks from the Sydney Opera House where APEC leaders gathered among tight security.
Nine protesters were detained and two police officers injured when a scuffle broke out, but the protests were largely peaceful.
(compiled from agency reports)