The head of the United Nations Framework Convention on Climate Change (UNFCCC) has used an address to ANU to express optimism about a new global agreement to fight climate change.
In a public lecture, Christiana Figueres, Executive Secretary of the UNFCCC, discussed progress on negotiations ahead of the global summit to be held in Paris later this year.
Ms Figueres said despite the challenges, she was increasingly optimistic that the 194 countries were serious about a global commitment to address climate change and carbon emissions.
"In the lead up to Paris, I am astonished that every day, there is another piece of good news," Ms Figueres said in her lecture, hosted by the Fenner School of Environment and Society. "I call it aligning the stars - every day, one more star gets aligned.
"There is an increasing sense of optimism that we are actually going to get to a Paris agreement."
The United Nations Climate Change Conference in Paris aims to achieve a new binding global agreement to address climate change from 2020.
Ms Figueres, who has been involved in climate change negotiations since 1995, was appointed Executive Secretary of the UNFCCC in 2010 following the 2009 UN Copenhagen conference on climate change.
She said the global mood on climate change had undergone a big change since the Copenhagen meeting of world leaders.
Unlike the Copenhagen meeting, Ms Figueres said countries have already accepted a draft negotiating text well ahead of the Paris conference.
"All countries are currently taking (this) very seriously and doing their homework to figure out where are the opportunities to reduce emissions at home," she said.
However, key challenges for the global agreement were yet to be resolved.
She said the challenges included how to make any agreement fair to all countries, how to make it legally binding, how to enforce any agreement and who bears the costs.
Audio of the public lecture is available at the Fenner School of Environment and Society website.