Climate change policy was a key difference between US presidential candidates Donald Trump and Hillary Clinton. Credit:Charlie Riedel The government's target of cutting 2005-level emissions 26-28 per cent by 2030 now becomes a global commitment, that "we look forward to actively and fully implementing", he said. Australia joins more than 100 nations to ratify the global deal agreed last December in Paris. The accord, which aims to stop global temperatures rising more than 2 degrees above pre-industrial times, came into force last Friday. Temperatures have risen about one degree in the past century as CO2 levels have climbed. Trump cloud

A cloud, however, hangs over the agreement with the Trump election. The Republican candidate and much of his party have vowed to overturn the climate policies of incumbent Barack Obama when the administration changes in January. Hazelwood, Australia's dirtiest power station, will close next March. Credit:Eddie Jim President Obama had made the US commitment to Paris an executive decision, and so is one that his successor could reverse. Under the Paris agreement, any country signing up cannot exit within three years and must then wait another year before formally renouncing it - although a President Trump may find a faster departure route. Australia's ratification will bring some cheer to climate negotiators in Morocco, many of whom were stunned by the US election of a climate-denying president.

One European delegate told Fairfax Media that some had become upset as the results rolled in on Wednesday. "Shock. Terrible. Some were in tears," said the delegate, describing the reaction. "Many - like me - were blocking it out and seeking refuge in sarcasm." Malte Mainshausen, director of Melbourne University's Climate & Energy College, said it may be best for the Paris agreement if the US withdraws given Mr Trump's anti-climate stance. "While likely detrimental to the geopolitical interests of the US itself, that would open the door for the club of the willing to move forward...rather than being held up on that common journey by a destructive voice from within," Professor Mainshausen said. "If Australia plays its cards correctly, it could still manage to grab the opportunity of becoming the energy superpower in a zero carbon world now that the US seems to have temporarily abandoned that contest."

'Important signal' Erwin Jackson, deputy chief executive of The Climate Institute, said Australia's move "sends an important international signal" that nations would stick by their climate pledges. Investors and the wider community in Australia would also take some heart the government was staying its course, he said. "China's not going to stop decarbonising, [billionaire] Elon Musk is not going to stop building his giga-battery factory," Mr Jackson said. Frank Jotzo, deputy director of the Crawford School of Public Policy at the Australian National University, said ratification would give Australia a stronger position in the climate talks in Morocco.

"The Paris Agreement has entered into force, so part of the Marrakech meeting serves as a meeting of the parties to the agreement, Australia can now be part of that," Professor Jotzo said. "The day after Donald Trump's election, it sends a signal that one of the United States' strongest allies remains committed to the UN climate change process," he said. 'Direct threat' Ms Bishop also stressed the importance economic opportunities from carbon curbs. "The global low-emissions economy is estimated to be worth around $6 trillion and is growing at some 4-5 per cent per annum," she said. "We believe, through the use of technology and research and science and innovation, there will be many opportunities for Australian businesses."

"Australia has a strong track record on international emissions reduction targets. We beat our first Kyoto target by 128 million tonnes and are on track to meet and beat our second Kyoto 2020 target by 78 million tonnes." Mark Butler, Labor's climate spokesman, welcomed the ratification but noted Australia's commitment is not yet backed with policies, citing research by the Climate Action Tracker. "The Turnbull Government has no policy for renewable energy investment post 2020, which is also crucial to meet our Paris obligations," Mr Butler said. "As the ACTU has also pointed out, nor does the Government have a plan for a Just Transition to a clean energy economy, as the Paris Agreement calls for." Adam Bandt, the Greens climate change spokesman, also applauded the government's move. "The Trump presidency is a direct threat to the Australian way of life as it makes it harder to stop runaway global warming," Mr Bandt said.

He noted President-elect Trump reportedly plans to appoint Myron Ebell, a prominent climate change denier, to head the US Environmental Protection Agency. The EPA has been a key conduit of President Obama's climate policies. "Trump has started a climate war in the United States and if he carries out his threats, there will be a rise in civil disobedience as people start taking direct action to stop new gas and oil developments in particular." 'Vital step' Simon Bradshaw, Oxfam Australia's climate change adviser, said the government now had to introduce policies so the promised targets could be achieved. "While ratification is a vital step and should be celebrated, the government is yet to do the math on what the agreement means for Australia and the scale of action we must take if we're to do our part and help avoid a much more dangerous future," Dr Bradshaw said.

The ratification, though, was not without its critics. Loading Prior to Thursday's announcement, One Nation senator Malcolm Roberts took to social media to call for the government to drop its plans: Follow Peter Hannam on Twitter and Facebook.