New global role for retiring Milne

Christine Milne is stepping onto the world stage in her fight against global warming.

As the former leader of the Australian Greens and retiring senator prepares to formally pull the pin on federal politics, she revealed the new role that will continue her personal passion of tackling global warming.

"I've just been appointed as the first ambassador for the Global Greens," she told reporters.

"I can imagine I will be spending a fair bit of time helping the development of Green politics around the world and addressing global warming."

The group brings together Greens members from Africa, Europe, America, Asia and the Pacific and holds periodic conferences to formulate joint action.

Having risen from Tasmanian MP and state Greens leader to federal senator and head of the Australian party, Senator Milne on Thursday handed her upper house ticket to Nick McKim, who was endorsed by a ballot of members.

The 62-year-old soon-to-be grandmother, who is retiring to spend more time with her family, made it a wrap on Thursday.

"This is my last press conference as a Greens senator and I want to thank everyone who's supported me for so long in both the Tasmanian and then the federal parliament.

"I certainly won't be stopping representing Tasmania and the Greens but it certainly won't be as a party political representative."

Senator Milne shunned the idea of taking up an executive role and said she would not be found working in a "UN-bureaucracy position".

Her replacement in federal parliament by a man raises no gender concern, she added.

"In the federal party room we have a majority of women," Senator Milne said.