Australia is falling behind China and the United States in tackling climate change, with new investment in renewable energy falling by 70 percent, a study released Monday said.

The independent Climate Council report found that while Australia had high per capita carbon emissions, it had moved from being a leader to a laggard in terms of one of the most common means of combating climate change -- renewable energy.

"The future of Australia's renewable energy industry remains highly uncertain due to a lack of clear federal government renewable energy policy," said the report, entitled Lagging Behind: Australia and the Global Response to Climate Change.

"Consequently investment in renewable energy in 2014 has dropped by 70 percent compared with the previous year."

Since coming to power last year, conservative Australian Prime Minister Tony Abbott has scrapped a tax on carbon emissions and defended the use of coal as crucial to Australia's prosperity.

Meanwhile the largest emitters of greenhouse gases, China and the United States, are leading the way in terms of developing and investing in renewable energy, while other nations were increasingly embracing carbon pricing schemes, the report said.

"We've had a loss of 70 percent of new investment in renewable energy in this country, and when you compare that with the US and China, which are powering ahead -- China particularly at record levels -- it's a pretty sorry state of affairs," the council's Tim Flannery said.

Flannery added that uncertainty about the Australian government's position on renewables was resulting in investment heading overseas.

"The big international companies are just looking across-the-board and saying 'there's a favourable environment here in Texas or there in Europe or China, we'll put our money there'," he told the ABC.

Australia's climate action is in the spotlight ahead of this weekend's G20 leaders summit in Brisbane, with Canberra resisting pressure to put the item on the agenda.

Australia plans to cut emissions to five percent below 2000 levels by 2020, and is establishing a Aus$2.55 billion (US$2.25 billion) Emissions Reduction Fund to give polluters financial incentives to reduce emissions to help meet the target.

But in a second report released Monday, the independent Climate Institute said changing circumstances and growing scientific evidence meant that Australia needed to ramp up its ambitions and aim to reduce new emissions by 40 percent of 2000 levels by 2025.

"Australian politics is fixated on 2020 but the world is now increasingly looking beyond 2020," said deputy chief executive Erwin Jackson.