Some communities in Aotearoa may be abandoned, with climate change driving increasing storms and flooding making continued occupation untenable.
The government will today release the first-ever national strategy for dealing with the inevitable effects of global heating - the National Adaptation Plan.
It will include plans for the next six years for what's called "managed retreat" - moving communities out of harm's way.
What happened to Matatā
In 2005, torrential rain in hills behind Matatā in the Bay of Plenty smashed masses of debris into the community, destroying dozens of homes and damaging nearly 90 others.
The process that followed was essentially the first time Aotearoa has done managed retreat at scale.
It took 17 years, cost millions in relocation payouts, and resident Grant Wilkins said it brutalised and traumatised some locals.
"It was gut wrenching, I put 35 years' worth of work and income into that property; it was basically ripped out from under us.
"The stress and the toll it takes on your daily living is horrendous."
The problem is there is no roadmap for how to do managed retreat for local and central authorities to follow.
Councils from all over the motu have contacted Matatā residents and the councils involved to find out what they learned.
The Matatā experience showed the need for a national framework with clearly defined roles and responsibilities for all parties.
But it is so complicated and potentially costly it needs legislation to be passed. The government will today release the first go at a plan covering the next six years.
Those living in Matatā say losing their homes traumatised them.
Moanataiari in Thames likely candidate for managed retreat
The Thames suburb of Moanataiari - home to more than 100 properties - is coastal and low lying and is a likely candidate for some form of managed retreat.
The suburb has flood barriers and water which accumulates after heavy rains or large swells has to be pumped out.
For now it can hold against a one-in-100-year storm.
But Amon Martin from the Thames-Coromandel District Council said the sea is rising and climate change will make even more ferocious storms happen more often.
He said in the long term, protection was not the right option.
In the past three years the council has held about 150 consultations and public meetings to talk through ideas.
Martin said managed retreat would likely be needed once there has been about 0.4m relative sea level rise in the area (factoring in land movement and assuming similar levels of flood protection for the suburb) which could happen within four decades.
"What we need to do now is understand - is that actually 40 years? [Does earth movement make it] less time?
"You can think 40 years is a long time, but there's actually a lot of urgency."
Martin said more work would be done to see if there were transitional protection options available, while individual home owners in harm's way would also be spoken to.
While the council was looking to adopt the next phase in its coastal planning next month, lots more work on the detail still needed to be done in the coming years.
Councils looking to govt for answers
About one in seven people in Aotearoa live in areas prone to flooding or projected sea level rise.
Environmental engineer Rob Bell advises councils on how to deal with the effects of climate change.
He said while there remained a lot of scientific and technical work to be done, in the next couple of decades places like Granity on the West Coast, Haumoana in Hawke's Bay, parts of Avonside and Heathcote in Christchurch and Petone in Wellington could start the slow process of some form of managed retreat.
"What type of scale it might be? Some might do it in a small piecemeal scale, others might decide [to] build another community somewhere else.
"We need to give space and time for those kinds of discussions with communities."
Bell said councils were waiting for answers from the government on some crucial questions.
"Is it a regional council or district council who leads the process? Who makes the decision, finally, to do managed retreat?
"How involved and engaged are the public? What sort or type of managed retreat is it? Is it [buying people out and they disperse], or do we try and recreate small communities further inland?
"So there's a whole lot of questions around process."
He said managed retreat should be planned over decades.
"When you journey with people and it's ongoing engagement you can start to build trust that it's not someone who's going to knock on your door next week and tell you to 'get out'."
There would be considerable interest in whether the National Adaptation Plan will give an indication on how costs would be split between homeowners, local and central government.
And insurance claims from extreme weather have doubled in five years which will eventually see firms boost the cost of cover or start to pull it altogether.
Community urged to get proactive
Victoria University of Wellington climate professor and NZ SeaRise programme co-leader Tim Naish said the plan would necessarily involve more talks and consultation, and it could be years before there was any concrete action.
He said overseas experience showed the more resourced communities successfully lobby for protection, while poorer areas - particularly Māori - could end up with managed retreat.
"Get proactive, talk to your government, talk within your community ... talk with your counsellors ... figure out what your options are.
"Waiting for some magic solution won't be great ... people ... need to take responsibility."
Climate Change Minister James Shaw has said previously the government's duty "first and foremost" was to look after those who could least afford to adapt to climate change.
Meanwhile, Matatā resident Grant Wilkins said whatever the government decided the most important thing was to be transparent and honest with communities.
"They needed a programme ... in place ... to support these people.
"Work with them, support them, don't put things in place really basically so you can't shaft them - that's as blunt as I can put it."
The National Adaptation Plan is to be released later this morning - with legislation needed to put it into effect.
Other work dealing with the effects of climate change will come as part of Resource Management Act reform.