Prospects that the G8 would reach an agreement to how to fight global warming at their summit dimmed on Sunday as leaders began arriving in Japan.

The European Union is on track to hit its short-term target for reducing emissions of the gases that create global warming, but challenges remain.

Australian Prime Minister Kevin Rudd said on Monday he had ratified the Kyoto Protocol on climate change in his first official act after being sworn in as leader. "Today I have signed the instrument of ratification of the Kyoto Protocol," Rudd said in a statement.