Young people in colourful T-shirts bearing slogans of Stop Adani, and members of Renew and other green groups, have been fanning out across Sydney’s eastern suburbs to knock on as many doors as possible – not for any particular candidate, but for a specific cause.

Unlike most general elections or byelections where economic management, tax, health and education dominate voters’ thinking and candidates’ pitches, the byelection in Wentworth will be a referendum on climate change and the lurch to the right by the Liberal party.

The Liberals have done much themselves to make climate the central issue – and not in a good way.

The dumping of their national energy guarantee, inextricably linked with the dumping of the member for Wentworth, Malcolm Turnbull, from his job as prime minister, which ultimately triggered his resignation and Saturday’s poll, exposed the great schism within the Liberal party on this issue.

It has left the Liberal candidate Dave Sharma with little to say other than that he believes climate change is real and that Australia is on track to meet its Paris commitments. But has has offered no detail on how, other than to point to Snowy Hydro 2.0, a project close to his predecessor’s heart.

The Neg also laid bare the deep fissures in the Coalition between the pragmatic centre and the right wing, which Turnbull tried to bridge for three years but in vain.

The well-educated voters of Wentworth, who might once have felt reassured that Turnbull would prevail, now see that the party that they have supported for 60 years is not the moderate “small l” Liberal party they voted for.

Wentworth is a trial run for tactics for the election next year Gavan McFadzean

Add in a drought in Australia, record-breaking storms in the US and the Intergovernmental Panel on Climate Change report warning that the world faces a catastrophe without urgent action on climate change to peg global warming to 1.5%, and it’s no wonder the issue has become, perhaps, the defining factor in the Wentworth byelection.

GetUp’s climate campaigner, Miriam Lyons, says it’s not just Wentworth; climate change is now as big an issue as it was in the 2007 election campaign.

That does not bode well for the Coalition at the next election.

Converting that unhappiness over climate change into a vote for someone else has been the subject of an intense, co-ordinated campaign in Wentworth.

A coalition of environmental groups has been working together in the electorate to ensure that voters realise they have an opportunity to send a message on climate change.

The ScoMos, with lumps of coal, and the Tony Abbotts in their budgie smugglers outside candidate events are just the most visible parts of their efforts.

GetUp has organised an army of phone banking volunteers who have called more than 85,000 of Wentworth’s 103,000 registered voters.

“After the IPCC report came out and Scott Morrison said it didn’t apply to Australia, one man walked into our office and said: ‘what can I do?’. He’s one of our phone banking volunteers now,” Lyons says.

Over the past few days, volunteers have swelled to more than 100 each night.

GetUp will have literally hundreds of volunteers at polling places handing out cards that explain how to cast your vote for the environment. It gives four options: Greens, the independents Kerryn Phelps and Licia Heath, and Labor.

But in a controversial move, it has changed the Greens’ recommendation on preferences, instead advocating a preference for Phelps ahead of Labor’s Tim Murray.

The former Greens leader Bob Brown has also recommended putting Phelps ahead of Murray after voting 1 Greens, in a pragmatic recognition that there is a greater chance of the Liberals being defeated if she comes ahead of Murray.

Lyons says GetUp’s decision on who to recommend and how to preference is based on candidate responses to surveys and a scoring process that evaluates each candidate on their promises on climate policy, and other progressive issues such as ending offshore detention. Phelps has said she opposes the giant Adani mine, while the ALP supports it, although Murray has said he will work to halt it.

Several green groups also organised a candidate forum at Bondi Pavilion, which was attended by 300 people. But it received good national exposure, thanks to speakers from the conservative side of politics – John Hewson and Geoff Cousins, who were joined by coral expert Professor Terry Hughes.

Hewson, a former Liberal leader, has urged voters concerned with climate change to vote against the Liberals.

“The idea was to maximise turnout by getting more conservative voices to lead with the message: ‘its OK to put climate change as the top priority in deciding how to vote’,” says Gavan McFadzean, the Australian Conservation Foundation’s (ACF) climate campaigner.

Hewson’s intervention seems to have been a turning point, aided by Malcolm Turnbull’s son, Alex Turnbull, who has used his Twitter account and media interviews to advocate for a protest vote against the party his father once led.

Dave Sharma, Dr Kerryn Phelps and Tim Murray are seen during a community forum at the Bondi Surf Bathers Lifesavers Club in Sydney this week. Photograph: Dean Lewins/AAP

He says he’s doing it because climate change is the most important issue, and while he appears to have acted off his own bat, it has certainly helped underline the climate policy void on the conservative side of politics.

The ACF does not issue how-to-vote cards, but has sent its 5,000 supporters in Wentworth a scorecard rating each candidate on their environmental policies and has asked them to talk to their friends and family about the issues.

The advertising has also been more conventional, and the ACF has been running advertisements about climate change and drought in local cinemas, while GetUp has crowd-sourced funds for mobile billboards that have become regular features on the streets of Wentworth.

The ACF has also produced electorate-specific data on what climate change will mean for that community. It plans to replicate the work, by the Australian National University, for more electorates during the the general election.

Wentworth is proving a useful test bed for strategies the environmental groups plan to use next year.

“Wentworth is a trial run for tactics for the election next year,” McFadzean says. “The main challenge will be to keep climate as an issue through the UN Conference of Parties meeting in Poland and into next year.”