Greens co-founder backs dissenting senators on 'very big moral issue'

Australian Greens founding figure Bob Brown has backed the three senators who took the rare step of crossing the floor to vote against the party but does not believe the split weakens the leader's authority.

He acknowledged that those who voted with Labor "in a way" chose "the lesser of two evils" but ultimately sided with those who crossed the floor.

"It's a very big moral issue that's at stake here and, were I in the Senate, I would have made the same decision," Mr Brown said.

At the heart of the issue is the development of the Great Koala National Park on the New South Wales Mid North Coast.

A crucial hurdle is the successful registration of the project under a federal government scheme known as the Improved Native Forest Management [INFM] method.

The INFM allows state governments to earn carbon credit units by ceasing planned logging in defined areas of "multiple-use public native forests that would otherwise be used for commercial forestry," according to the government's website.

Those credits can then be sold to organisations that want or need to offset emissions.

Greens leaders say issue divisive among 'good hearts' and 'reasonable minds'

The issue divided environmentalists and the Greens, but ultimately the party struck a deal with Labor to support the scheme after securing changes, including restrictions to stop coal and gas projects from using offsets.

On Thursday, Greens senators Nick McKim, Vanessa Bleyer, and Jordon Steele-John defied the usually cohesive bloc to vote with the Coalition on a disallowance motion.

That motion was voted down in the chamber, 27 to 34.

Liberal senator Andrew McLachlan also crossed the floor to vote with Labor.

In the lead-up to the vote, Senator McKim told the chamber that he, Senator Bleyer and Senator Steele-John strongly disagreed with the INFM method.

"Labor is holding koalas hostage … and threatening their extinction unless they can profit from their habitat," Senator McKim said.

But he acknowledged there were different views in the party room.

"I want to be very clear that people of good heart and clear mind, both in our party room and in the environment movement, can and have come to different positions on this issue," he said.

Greens leader Larissa Waters expressed a similar sentiment, and acknowledged "reasonable minds, with good hearts, can differ on the outcome."

She explained her vote as protecting 176,000 hectares of native forest and the habitat of 12,000 koalas.

The ABC requested further comment on Thursday night from Senator Waters and several other members following the vote, but they all either declined or were unavailable.

Asked on 7.30 last night whether he thought the Greens leader's authority had been "fatally weakened" by the split, Mr Brown responded, "no, I don't".

Labor accuses opposing Greens of 'ludicrous fearmongering'

Mr Brown accused Labor of seeing "forest as a commodity to be traded one way or another for their corporate supporters".

"I do have a great deal of alarm that we are now setting in place a system … where unless money is to be made out of the environment, we won't get future national parks," he said.

But the Assistant Minister for Climate Change, Josh Wilson, described that claim as "ludicrous fearmongering".

"This is a method that rightly attributes value to the carbon storage that occurs when native forests keep growing and aren't subject to harvesting or logging as is currently the case," he said.

"There's no trade-off here".

But Mr Brown pushed back, arguing the best way to tackle climate change was to "stop logging forests and have the carbon come out of the atmosphere into those forests".

"It's perverse, it's wrong, and history will show us that it's extremely costly as climate change comes to change the lives of everybody," he said.

Energy Minister Chris Bowen said the motion was a "test" for the Greens.

"The majority of the Greens passed that test," he told Afternoon Briefing.

"If you believe in ending native forest logging or moving away from it and reducing it, then you vote for this method."