Federal cabinet is said to be finalising a cautious emissions trading scheme offering higher compensation to big trade-exposed polluters and a "soft" start in pollution-reduction targets.

The Government's strategy is to negotiate the scheme through the Senate next year with the coalition, rather than the Greens and independents, The Australian said.

Australian Greens leader Bob Brown said the report had changed his opinion of Prime Minister Kevin Rudd.

"I thought more of this Prime Minister than what we're going to get here," he told reporters.

"But he's turning out to be much more a political hack for the big end of town than a man responsive to the needs of this nation."

The Government is due to make an announcement about the operation of an emissions trading scheme on December 15.

It will also nominate its 2020 reduction target on the same day, having delayed the announcement until after the latest round of UN climate change talks in Poznan, Poland.

The Greens believe it will be a "weak" target - between 5 and 15 per cent - at the lower end of the range nominated by the government's climate change expert Ross Garnaut.

The target was so weak, Climate Change Minister Penny Wong was too embarrassed to announce it before the Poznan talks, Senator Brown said.

"It is tribute to power over Labor policy of the polluting coal, logging and minerals industries lobbies."

The Greens are pushing a minimum reduction target of 40 per cent by 2020, but will accept the 25 per cent figure nominated by the Intergovernmental Panel on Climate Change.