Australia has been left behind by most other wealthy nations in failing to disclose its post-2020 carbon reduction goals by the first quarter of 2015 as agreed at a global gathering in Peru last December.

The 28-nation European Union has announced that it would cut greenhouse gas emissions by at least 40 per cent on 1990 levels by 2030.

On Tuesday, US President Barack Obama formalised in a submission to the UN the United States' commitment to cuts that were first revealed in a landmark announcement with China last year.

China and the US are the world's two largest greenhouse gas emitters.

Mr Obama has pledged that the US will cut its emissions by 26 to 28 per cent on 2005 levels by 2025.

Mexico, Norway and Switzerland have also declared their plans to reduce emissions after 2020 when the current global treaty, the Kyoto Protocol, expires.

The UN wants nations to release their longer-term targets well in advance of the Paris summit late this year that will aim to thrash out a new worldwide climate treaty.

However, the Abbott government has stuck to its plans to announce its post-2020 goal by the middle of the year.

Last week, it released an issues paper to draw submissions from business and the community.

"Thirty-two countries including Mexico responded to [UN Secretary-General] Ban Ki-moon's call to submit their post-2020 target by the end of March," Greens leader Senator Christine Milne said. "Australia is deliberately dragging its feet to avoid scrutiny ahead of the Paris meeting, and the inevitable condemnation that our pathetic target will be met with."

Assuming the US goal was unchanged from the pledge made by President Obama during a visit to China last October, Australia would need a much deeper goal than its current bipartisan aim of slicing gas emissions by 5 per cent of 2000 levels by 2020 to keep up, said Pep Canadell, a CSIRO research scientist and executive director of the Global Carbon Project.

"If you want the effort to be proportional to what US and Australia committed for the 2005-2020 period, it would be something like [a cut of] 17 per cent by 2025 [for Australia]," Dr Canadell said.

Australia joined Canada in holding off on making any commitments for now.

The Abbott government's issues paper, released on Saturday, appears to lay the groundwork for Australia to argue for special treatment in the talks because of the country's heavily resource-based economy.

Environment Minister Greg Hunt said at the weekend: "We are one of the few countries in the world to have met and beaten our first round of Kyoto targets and to be on target to meet and beat our second round of Kyoto targets."

An unexpected drop in demand for electricity – the source of about one-third of Australia's emissions – had been one factor in making the 2020 goal more achievable than in earlier projections, the government said last week.

However, the emissions intensity of the power sector is on the increase, countering some of the benefits of slowing demand, as shown in National Greenhouse Gas Inventory data released without fanfare last week.

Emissions from power plants in the 12 months to September totalled 181.9 million tonnes, or about 1.5 million tonnes more than for the year to June.

If the emissions shift were to be maintained, it would increase emissions from electricity generators by about 4 per cent this year, Hugh Saddler, principal consultant with Pitt & Sherry, said.

John Connor, chief executive of the Climate Institute, said it was a poor showing by Australia to fall short of the March 31 goal for releasing its post-2020 target.

"Australia, as a wealthy country with over 20 years' experience in detailed climate policy analysis, should be amongst those – including Mexico – who have met that deadline," Mr Connor said.

While the timing of goal-setting was useful to help negotiations later in the year, it was more important that countries implemented promises that would keep global temperatures from rising 2 degrees above pre-industrial levels, he said.

"For Australia to match the US efforts, our post-2020 target would have to be around 30 per cent below 2000 levels by 2025," Mr Connor said.

"This is well beyond our current minimum target of 5 per cent by 2020, but still not sufficient to be a fair contribution to the internationally agreed goal of limiting global warming to less than 2 degrees," he said. "For that, our 2025 target should be 40 per cent below 2000 levels."