Output was halved for five hours at the coal-fired Loy Yang power station near Melbourne after activists forced a shutdown by breaking in and chaining themselves to equipment.
"We need to see real action now," activist Michaela Stubbs said of a protest timed to exert pressure on the Asia-Pacific Economic Cooperation (APEC) forum, being held Sep 2-9, to adopt binding targets to cut greenhouse gas emissions.
"We're already seeing the effects of climate change, and it's our generation and future generations that are going to be dealing with the long-term consequences of climate change."
Howard, the host of this week's meetings of the 21-member group, has played down the likelihood of a breakthrough when US President George W. Bush, Chinese President Hu Jintao, Russian President Vladimir Putin, Japanese Prime Minister Shinzo Abe and Indonesian President Susilo Bambang Yudhoyono meet over the weekend.
He predicted the leaders would settle for agreeing to a "long-term aspirational goal" of reducing the emissions that cause global warming rather than adopting Kyoto-style targets favoured by the Europeans.
"The key task in Sydney is to give political direction to the shape of a future framework for climate change that is truly global," Howard said. "At APEC, we should strive to find agreement on principles for international action that genuinely address the problem whilst allowing countries such as China and Indonesia to continue to grow and prosper."
A leaked draft of the APEC leaders' final communiqué said energy efficiency and keeping forests was the way to abate climate change rather than binding, Kyoto-style emission-reduction targets. The UN-sponsored Kyoto Protocol, agreed to in Japan in 1997, sets binding reduction targets for developed countries that signed the treaty.
The US and Australia are the only developed countries to reject the Kyoto initiative, arguing that its targets would slow their economies. Howard also argued that Kyoto is unfair because it doesn't demand that developing countries immediately join in sharing the pain of abating climate change by adopting emission-reduction targets themselves.
Australia, Brunei, Canada, Chile, China, Hong Kong, Indonesia, Japan, South Korea, Malaysia, Mexico, New Zealand, Papua New Guinea, Peru, Philippines, Russia, Singapore, Taiwan, Thailand, the US and Vietnam comprise APEC, which represents half of the world's trade and a third of its population.