The UN's top panel on climate change was sifting Friday through the final details of a report aimed at guiding policies on global warming for years to come, sources said.

Green organisations attending the Copenhagen meeting as observers said crafting of the landmark document was heading smoothly towards the finishing line.

"Things are progressing," said Alden Meyer of the US-based Union of Concerned Scientists (UCS).

"The report is going to tell a fairly clear story" about climate change and options for tackling it, he told AFP by phone.

The document crowns a vast overview of the existing scientific evidence for global warming, predictions of its impacts, and solutions for curbing greenhouse-gas emissions which cause the problem.

It is the final chapter in a massive report by the Intergovernmental Panel on Climate Change (IPCC) -- compiled by top scientists and approved by governments.

The years-long process of compiling the review is criticised as conservative and cumbersome by some, but praised by others as giving the panel greater political clout.

Three volumes in the Fifth Assessment Report have been published over the past 13 months, comprising thousands of pages written by hundreds of experts.

These are now being distilled into a synthesis report, along with a summary for national policymakers, which is being hammered out line by line in a five-day meeting that began on Monday.

The report and summary will be unveiled at a press conference in Copenhagen on Sunday, attended by UN Secretary General Ban Ki-moon.

UN members have vowed to limit warming to two degrees Celsius (3.6 degrees Fahrenheit) over pre-industrial levels.

But heat-trapping carbon emissions are rising so fast that in the worst-case scenario sketched by the IPCC, the planet could be up to 4.8 C warmer by 2100 and sea levels up to 82 centimetres (32 inches) higher.

Ban last month organised a special summit aimed at whipping up momentum for a global climate pact.

The deal would commit all countries, rich and poor, to rolling back carbon emissions and shoring up defences for people facing worsening drought, floods, storms and eroding coastlines.

It would be sealed in Paris in 2015 and take effect from 2020.

But there are many blanks waiting to be filled, including the accord's legal status and compliance provisions.

Who would do what to reduce emissions will be discussed next year, after a ministerial-level climate conference in Lima from December 1-12.

Australia set to pay polluters to cut emissions
Sydney (AFP) Oct 31, 2014 - Australia is set to approve measures giving polluters financial incentives to reduce emissions blamed for climate change, in a move critics described as ineffective environmental policy.

The so-called "direct action" plan, which will see the government pay companies to increase energy efficiency, passed through the upper house Senate early Friday following a marathon debate.

The bill is expected to be approved next month by the lower House of Representatives where the conservative government of Prime Minister Tony Abbott has a majority.

It comes after Abbott axed a tax on greenhouse gas emissions introduced by the previous Labor administration, fulfilling a central pledge from last year's elections.

"We have delivered on our promise to implement an emissions reduction fund to ensure that there is real and practical action to achieve our emissions goals and targets without a carbon tax," Environment Minister Greg Hunt told reporters.

China and the United States are the biggest greenhouse gas polluters, according to a report by international scientists issued last month, but Australia's output is considered high per capita.

The Aus$2.55 billion (US$2.25 billion) Emissions Reduction Fund is part of the government's plan to meet its emissions reduction target of five percent below 2000 levels by 2020.

Under the plan, competitive auctions will be held, with the government entering into contracts to buy emissions reductions from successful bidders at the lowest cost, Hunt said.

He added that the emissions reductions would be "real and significant" as payments would only be made when the pollution cuts occur.

- 'Not the right way to go' -

But the Labor opposition leader Bill Shorten criticised the scheme, describing it as "paying big polluters to keep polluting, which is terrible policy".

"In terms of 'Direct Action', Labor just doesn't believe it is the right way to go. We believe in trusting the marketplace to set the price signal," Shorten said Friday.

The policy has also been slammed by the Greens party, with leader Christine Milne saying there was "no modelling or any evidence to suggest it will do anything at all to reduce pollution".

The plan passed with the backing of the Palmer United Party. As part of the government's deal with mining magnate Clive Palmer's party, Hunt agreed to keep the Climate Change Authority (CCA) and set up a three-stage, 18-month inquiry into an emissions trading scheme (ETS).

The government had been planning to abolish the CCA, an independent climate change agency set up by the previous government.

The University of Queensland's John Quiggin, a CCA member and economics professor, welcomed the inquiry into an ETS.

"The overwhelming view of economists is that a price-based measure such as an ETS is a critical component of a carbon mitigation policy," Quiggin said.

Although the government rejected setting aside some of the fund to purchase international carbon credits, environmental economist Caroline Sullivan said similar offset schemes within Australia should be considered.

Carbon offset schemes allow individuals or firms a way to reduce their carbon footprint by investing in projects that absorb greenhouse gases.

"This relatively large sum of money (from the fund) can not only help to motivate carbon reductions from large emitters, but could also provide a hugely important -- and much needed -- economic stimulus for rural and regional Australia," Sullivan, from Southern Cross University, said.