SCIENTISTS and environmentalists attacked the Government's plan, saying it was unlikely to reduce greenhouse pollution to levels that would prevent dangerous climate change.

"I think the message it sends to industry is that your money is better spent going to Canberra and lobbying the Government than reducing emissions," said Iain McGill, of the Centre for Energy and Environmental Markets at the University of NSW.

Dr McGill said the concessions to industry made any environmental benefits uncertain.

"It's definitely far weaker than the model Ross Garnaut was proposing and it's therefore far weaker than we really need," he told the Herald . "Given that the target for 2050 is already probably behind what the science is recommending, this is not sending a very positive signal internationally."

Barry Brook, the director of the Research Institute for Climate Change and Sustainability at Adelaide University, said the breadth of the scheme, and promised compensation for low- and middle-income earners, was positive.

"Unfortunately, some parts of the science are crudely handled - and this matters in terms of its effectiveness," Professor Brook said. "For instance, the effect of methane as a climate-forcing agent is downplayed in two ways. First, the impact on global warming is diluted by averaging its impact over 100 years … Second, the agricultural sector will not initially be included - yet this is the sector that produces most of the methane".

The Greens and environment groups said the plan to give free permits and other forms of compensation to big polluting industries such as coal and aluminium was tantamount to a "golden handshake".

The fewer permits that are sold the less money the Government will raise to distribute to households to help them with higher energy and other bills.

A Greens senator, Christine Milne, said the proposals for the scheme were not strong enough to get households or business to change their behaviour.