Former Prime Minister John Howard's rail against 'left progressive' climate change action, positions himself as a muddled right anti-progress thinker parallel to the American Tea Party leader, Greens Leader Bob Brown said today.

"He says he's agnostic on climate change, though in 2007 he advocated carbon trading. Agnostic is Howard code for inaction. He was much more comfortable back in the last century," Senator Brown said.

Australian Greens Leader Bob Brown went to Dalby in Queensland to address a rally outside the courthouse where the case involving Lock the Gate activist Drew Hutton was being heard.

Australian Greens Leader Bob Brown and mining spokesperson Larissa Waters will attend a rally in Dalby today to support Drew Hutton, President of the Lock the Gate Alliance, in his appearance before the Magistrates Court.

"I have known Drew for 30 years. He is a co-founder of the Australian Greens. His courage and integrity are formidable characteristics when lined up against this money-hungry, invasive coal seam gas industry," Senator Brown said.

Australian Greens Leader Bob Brown, speaking to reporters in Hobart, responds to key measures from the ALP national conference.

Australian Greens Leader Bob Brown responds to the Gillard Government's budget update and outlines the Greens' more responsible approach. Speaking to reporters in Canberra, Senator Brown also answered questions about the Gold Pass, the Murray Darling Basin plan and immigration.

"The Gillard Government's plan to balance the books by imposing a higher ‘efficiency dividend', a tired euphemism for public sector cuts, is short-sighted and driven by political constraints," Australian Greens Leader Bob Brown said today.

The Australian Greens today released official Treasury costings obtained under formal arrangements as part of the agreement to form government. The costings show that abolishing a range of fossil fuel subsidies would help to re-balance the budget.

"Billions of dollars could be made available for the public over the next four years if the Gillard government adopted measures proposed by the Greens to raise revenue fairly and reduce distortions in the tax system," Australian Greens Leader Bob Brown said in Canberra.

The Australian Greens' efforts to secure a fairer mining tax have so far resulted in another $140 million for the public purse, to offset the $100 million that MP Andrew Wilkie arranged with the Gillard government to hand back to mining companies, Greens Leader Bob Brown said today.

Australian Greens Leader Bob Brown and the Member for Melbourne Adam Bandt talk to reporters in Canberra about the mining tax, after the Prime Minister's MRRT announcement.

Senator Brown said superannuation taxation arrangements can be made much more socially equitable and the Gillard Government's open cheque book approach to refunding mining companies for royalties paid to states should be reviewed by the Senate.

Adam Bandt also commented on his move in the House of Representatives to amend the McCarthyite Building & Construction Commission bill.