Australia's climate negotiator is urging nations to show their cards at ongoing Bonn talks, warning the fight against global warming will falter unless governments commit to clear -- but realistic -- goals.

Climate Minister Penny Wong visited Washington, where she welcomed US President Barack Obama's push on global warming along with new legislation introduced in Congress on curbing carbon emissions.

In an interview with AFP late Tuesday, Wong said the talks in Bonn -- part of the runup to a major climate conference in Copenhagen in December -- have to "get beyond the point where we give our national interest speeches.

"We need to change the negotiating dynamic," she said. "If everybody adopts a wait-and-see approach, nothing will happen."

The Copenhagen meet is meant to approve a new treaty to fight the planet's rising temperatures after 2012, when commitments run out under the Kyoto Protocol.

Australia and the United States were long the main holdouts from Kyoto, arguing that it was too costly and unfair because it made no demands of fast-growing emerging economies such as China and India.

Obama and Australian Prime Minister Kevin Rudd -- who held a warm first summit last week -- both sharply changed gears on taking office by vowing to fight climate change.

But Wong said the debacle over Kyoto still offered a clear lesson: the next treaty must be realistic.

"The first lesson about what not to do is not to have a situation where an agreement may look good on paper but it's not going to be implemented," she said.

"Unless we get action from all nations, particularly from our major emitters and our major economies, we will not start to reduce the growth in emissions."

She defended Australia's target of cutting carbon emissions by up to 15 percent from 2000 levels by 2020 -- faulted by some environmental groups as not ambitious enough.

"That's a very substantial commitment from Australia," Wong said, noting that the nation generates the vast majority of its energy from coal.

A bill introduced in the US Congress on Tuesday by Henry Waxman, a member of Obama's Democratic Party, would introduce a "cap-and-trade" system to force emission cuts of 20 percent, but from 2005 levels.

China and India have both declined to specify how much they would reduce carbon emissions under a Copenhagen agreement, saying they are waiting to see commitments from wealthy nations, particularly the United States.

Anticipating a domestic backlash against environmental measures, US Energy Secretary Steven Chu has floated slapping a tariff on imports from nations that do not require carbon emission reductions.

Wong, who met Tuesday with Chu, said Australia rejected border taxes in the fight against global warming.

"We don't believe it's in our national interest to argue for a position which may lead to increased trade barriers," she said.

But Wong said the world should be heartened by the new US dedication to fighting climate change, even in the midst of a painful recession.

"You can't have a deal without the United States engaged and they are -- and more than just being engaged, they are indicating they are prepared to act," she said.