Newcastle, north of Sydney, is the world's largest coal port. It ships some 100 million tons of coal 24 hours a day, mostly to Japan and Taiwan.
A lone protester walked onto the train tracks early Sunday morning, stopping a fully loaded coal train. Dozens of protesters then chained themselves to an 8,000-ton coal train, including a local official and Buddhist monk.
The standoff lasted for six hours before protesters were removed by police and arrested, an 86-year-old man among them.
At Copenhagen, world leaders agreed to limit global warming to 2 degrees Celsius above pre-industrial levels, but with no binding emission targets.
"The U.S., Australia and other wealthy countries wrecked the Copenhagen climate talks," said Steve Phillips, spokesman for protest organizer Rising Tide Newcastle, an environmental activist group, according to its Web site.
"They refused to lift their paltry greenhouse pollution targets to the levels required to avoid catastrophe," Phillips said of the leaders. "They could have done something great, but they failed. They let greed and self interest take precedence over the survival of life on Earth, and we are here today to condemn them in the strongest possible terms."
Rising Tide has warned of further protests.
"We put world leaders on notice that their continuing failure to solve the climate crisis will result in widespread direct action against the causes of climate change, as we are seeing here today," Phillips said.
Australia's heavy reliance on coal -- providing about 80 percent of the country's electricity -- makes it the world's biggest per capita producer of emissions. It is also the world's largest exporter of coal.
Australia exported a monthly record 25.2 million tons of coal in October, up from 24.7 million tons in September. According to the Australian Broadcasting Corp., Australia plans to double its coal exports by 2030.
The burning of coal is responsible for 40 percent of global emissions.
Australian Prime Minister Kevin Rudd, who was not part of the inner group that finalized the statement at Copenhagen, described the outcome of the 10 days of talks as a political commitment to act, rather than a legally binding agreement, The Sunday Mail newspaper reports.
Rudd said it was the best possible outcome under the circumstances because it was the first time the whole world had agreed to the 2 degree Celsius maximum warming limit.
"It's a huge sense of frustration, which is: You push as hard as you can, you give it everything you've got, to produce the biggest outcome for Australia possible," Rudd told The Mail.
"But what's equally the case is just how frustrated you get when you feel that people don't see sense."