Attacks on the Greens' crusade against climate change are "a badge of honour" and put them in the same company as the suffragettes and the anti-slavery movement, says Australian Greens leader Bob Brown.

Senator Brown, who addressed the final day of the New Zealand Greens' annual meeting in Auckland yesterday, is at war with Rupert Murdoch and his media empire over plans to introduce a carbon tax.

The issue is reaching boiling point ahead of a decision expected on July 1.

Australian voters have been urged to "Say Yes" to the tax in an advertising campaign featuring actor Cate Blanchett, and thousands rallied in support of it across the country over the weekend.

But a poll commissioned by Mr Murdoch's News Ltd and published yesterday found just 28 per cent of 500 Australians asked were in favour of it compared with 58 per cent against.

Mr Murdoch fuelled ill-feeling between himself and Senator Brown last year when he warned that "the bloody Greens" were a threat to Australia's economy.

The senator told yesterday's meeting: "Whenever I get a little bit despondent about the attacks, I go and look at what happened to the suffragettes or the people who were going to get rid of slavery, or get children out of the mines.

"In every case those who were living for these huge advances in civilisation were condemned on economic grounds.

"It's a badge of honour to know we're just following in the good company of the past."

Senator Brown said his party's stance on climate change policy was based on advice "from the best economic as well as environmental experts in the country".

He was confident his negotiations with Julia Gillard's Labor Government would be successful.

The Greens - who from next month will hold the balance of power in the Upper House and whose one vote in the Lower House is vital to keeping Labor in government - are negotiating the shape and price of the tax against stiff opposition from the Liberal Party and industry.

Failure to agree on the tax could break Ms Gillard's tenuous hold on the Treasury benches by forcing a snap election.

But while the Greens have a far more ambitious target than Labour for reducing greenhouse gas emissions, Senator Brown said yesterday that he accepted "it won't be a Green carbon price" if the tax went ahead.

"It is a compromise; we are responsible about this," he said.

What happens in Australia with regards to a carbon charge has implications for the future of New Zealand's emissions trading scheme (ETS), which is under review.

Prime Minister John Key has said he will not throw the agriculture sector "to the wolves" by forcing it to enter the scheme in 2015 as scheduled if our main trading partners are not taking similar measures.

Senator Brown said the Australian carbon tax was likely to be a "tighter and more targeted" scheme than the ETS and would "challenge New Zealand to look again at the structure of that trading system".

* Would effectively tax Australia's 1000 largest polluters on their greenhouse gas emissions.
* Much of the money would go to offsetting the impact of higher power prices on households.
* Would not apply to petrol.
* Would transition to a cap-and-trade system after three to five years.