Associate Climate Change Minister Tim Groser says the success of the Copenhagen climate change conference rides on the involvement of the United States and China.
The conference begins on Monday in the Danish capital. Meetings of government officials are scheduled to take up the first week.
During the next fortnight, delegates will try to find a successor to the 1997 Kyoto Protocol - which the United States and China are not bound by.
Mr Groser says any new deal will need buy-in from both countries.
He says it's likely the talks will result in a politically binding agreement and a full ratifiable treaty within the next year.
The first phase of the Kyoto Protocol ends in 2012.
The UN's top climate official has given an upbeat assessment on the prospects of a global deal at the summit.
Executive secretary Yvo de Boer said things were in "excellent shape".
He said never in 17 years of climate negotiations have so many different countries made so many pledges.
Concern down - poll
Meanwhile, an opinion poll shows world concern about the issue has fallen in the past two years.
The Nielsen/Oxford University survey shows 37% of more than 27,000 internet users in 54 countries said they were very concerned about climate change.
The figure is down from 41% in a similar poll two years ago.
The survey indicates the highest levels of concern are in Latin America and Asian-Pacific countries, while those living in eastern Europe are the least worried by global warming.
The poll did not cover most of Africa.