The government could use carryover credits from beating its 2020 goal under the Kyoto Protocol against its 2030 Paris commitments.

Prime Minister Scott Morrison has said Australia will meet the Paris targets "in a canter" but some environmental experts and the Greens say they don't believe that.

Climate Analytics director Bill Hare said if Australia claimed the credits, it would encourage other nations to follow suit.

"This appears to be the 'canter' the government keeps talking about," Mr Hare told the Sydney Morning Herald.

"It is fake action and would be rorting the planet, and will undermine real action in Australia."

Meanwhile, Australia has ranked 55 out of 60 in the latest climate change performance index which was revealed at UN climate talks in Poland.

Countries are ranked on their greenhouse gas emissions, renewable energy, energy use and climate policy, with Australia scoring 31.27 out of 100.

The only countries behind Australia on the scale are Saudi Arabia, the US, Iran, Taiwan and South Korea, while Sweden, Morocco and Lithuania lead the charge.

"While Australian students are taking to the streets calling for our government to get serious about climate change, this ranking shows again that we are right at the back of the class when it comes to real action," Australian Conservation Foundation CEO Kelly O'Shanassy says.

"The Morrison government has no credible emission reduction policy, no regulation of transport emissions and no plans to phase out coal."

Australia's current Paris target is to cut emissions by 26-to-28 per cent below 2005 levels by the year 2030, but by using credits, it could meet the target with a 15 per cent cut.

Environment Minister Melissa Price declined to say how the government planned to use credits.

Australian Associated Press