Christine Milne, who has resigned as leader of the Australian Greens, held the position for three years after succeeding the party’s founding leader, Bob Brown.

Immediately following her resignation, the parliamentary Greens elected a new leader, Victorian Senator and former GP Richard Di Natale – the first Greens leader not to come from Tasmania.

Milne’s explanation was that she will not be recontesting her Senate seat at the 2016 federal election, so decided to make way for a new leadership team (now comprising co-deputies Larissa Waters and Scott Ludlam) to allow for a smooth transition and give the party time to consolidate ahead of the campaign.

What sort of legacy will she leave, and how successfully has she guided the party’s agenda since Brown’s departure?

Electoral ups and downs

Under Milne’s leadership, and following the Australian Greens’ support of the previous Labor-led minority government, the party lost votes at the last election, but nevertheless retained all of its MPs and picked up another senator.

In Milne’s terms, the Greens’ role is to build political capital and then, when an opportunity like supporting minority government arises, to spend that capital on achieving policy outcomes like Labor’s clean energy bill, which ushered in the carbon tax in 2012.

This degree of influence on government policy was an impressive achievement for a farmer’s daughter, a fifth-generation Tasmanian from the state’s rural northwest, a one-time high school teacher and young mother whose life changed when she committed herself to environmental activism.

She was arrested and jailed in 1983 for blockading the flooding of the Franklin River, and then went on in the mid-1980s to unite farmers, fishers, scientists, environmentalists and community members against the billion-dollar Wesley Vale pulp mill.

Having risen from her self-described “humble beginnings in the rolling dairy hills of Wesley Vale”, she was elected to the Tasmanian Parliament in 1989 as member for the conservative, sprawling rural electorate of Lyons, and was party to the historic Labor-Green Accord in which five Greens supported a Labor minority government.

There were many environmental achievements under that Accord, including the creation of new national parks, additional world heritage and national estate forests nominations, abandoned forestry ventures and woodchip export limits.

Milne went on to become the Greens’ state leader – the first female leader of a political party in Tasmania. She remains the only female politician to have led a party at both state and federal levels.

In 1996, with Milne at the helm, the Tasmanian Greens ventured into new territory by supporting a Liberal minority government. The partnership delivered achievements such as national parks and forest reserve declarations, deferred logging, and greener state development policy .

Milne has reflected that her political highlights of this period, from 1996-98, included the introduction of gun law reform following the Port Arthur massacre, the liberalisation of gay laws, an apology to the Indigenous stolen generation and support for an Australian republic.

The legacy

Milne’s legacy straddles social and environmental policy successes. Her efforts as state Greens leader helped to push Tasmania towards what she called a “clean, green, clever” future, and as federal leader she embraced moves towards delivering a more sustainable, low-carbon economy.

When supporting the Labor minority government from 2010 to 2013, Milne advocated a successful multi-party approach to the unprecedented introduction of carbon pricing in Australia and the establishment of associated bureaucracy and processes.

This aspect of her legacy was removed by the Abbott government (the only government in the world to have repealed such action), but Milne claims it is “the last stand of the vanquished”, adding that “the community is now leaving behind the fossil-fool age and getting on with realising clean energy”.

The repeal of carbon pricing was indicative of the Abbott government’s hostility to Milne’s environmental agenda. But Milne has claimed the acrimony as a motivating factor – one that has afforded the Greens an opportunity to recover their base as recent successes have shown at state elections.

This viewpoint was evident in her dismissal of Treasurer Joe Hockey’s 2014 budget as a “vicious attack on the fabric of our society” that let big business off the hook, that widened the gap between rich and poor, and that “abandons the environment and … jeopardises our future”.

Her resignation leaves behind a party with reform challenges but that has now made inroads not only in urban electorates but in some regional areas (including in the recent NSW election) where Milne, as a farmer’s daughter, has helped built bridges on agricultural issues.

Action on climate change has been more than a political crusade for Christine Milne. And this area is where she will dedicate her efforts following her resignation. She has pledged to remain active in advocating for climate action, saying: “If ever our planet needed inspiring leadership, it is now.”