The Greens leader, James Shaw, MPs and candidates have announced details of the Green Party’s action plan to fight climate change at Unity Hall on Queen St, Auckland.

The National Party has confirmed a candidate will attend a political debate on climate change, hours before the debate is set to start.

Labour, the Greens, New Zealand First, The Opportunities Party, The Maori Party and United future have leaders or spokespeople attending the World Wildlife Fund-New Zealand Climate Debate in Auckland on Tuesday evening.

World Wildlife Fund for Nature (WWF) campaigner David Tong said National had been in contact regarding organising a candidate to attend. But by noon on Tuesday the party had still not confirmed if anyone would be there.

HAMISH MCNEILLY/STUFF Climate change protesters outside a branch of ANZ bank in central Dunedin in 2016.

Stuff contacted National for comment. Just before 2pm, WWF contacted Stuff to say National had just confirmed Erica Stanford, the party's candidate for East Coast Bays, would be attending.

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National then contacted Stuff with the same information. A spokesman said: "She's passionate about environmental issues, and as a mother of small kids wants to ensure we're all doing our bit to tackle climate change."

About 5pm, WWF tweeted that National had updated their decision, and Andrew Bayly would instead attend.

Tong said WWF sent invitations to leaders and climate spokespeople about three weeks ago.

National leader Bill English and minister for climate change, Paula Bennett, had offered apologies when invited.

The party spokesman said: "The Prime Minister and Minister Bennett are not available due to other commitments, but both are proud of National's track record of addressing climate change issues. They believe the most important thing isn't what you say, but the actions you take, and Erica will be talking about those things tonight."

Act was invited by WWF but also responded with apologies.

Tong said invites were sent at short notice, but "we decided, given the attention... it was the most important [environmental issue] to organise a debate on".

Other politicians confirmed as taking part are: Labour's climate change spokeswoman Megan Woods, Greens leader James Shaw, the Māori Party's Pakuranga candidate Carrie Stoddart-Smith, NZ First's Denis O'Rourke, who holds the party's climate change portfolio, United Future leader Damien Light, The Opportunities Party's co-deputy leader Teresa Moore.

Have you seen the amazing lineup of candidates speaking at Tuesday’s #ClimateDebateNZ yet? 7pm, AMRF auditorium, Akl. https://t.co/shkQ6yYnHW pic.twitter.com/yZxDBKDSsr — WWF-New Zealand (@WWFNewZealand) September 17, 2017

Business journalist Rod Oram will host the debate, four days out from election day.

Promotion for the event asked: "Will political parties come together to set a course for a 100 per cent renewable energy, zero carbon future? Or will climate action remain a political football?"

It was scheduled for 7pm at the University of Auckland's Grafton Campus AMRF Auditorium on Tuesday September 19. Entry to the auditorium, which had a capacity of 300 people, was on a first come, first served basis. It was planned to run until about 8.30pm.

For those who can't make it along, it can be watched via live stream. It would also be on the WWF-New Zealand Facebook and Twitter pages.