'We need to get cracking' - As seas rise, time for planning running out

Storms and flooding driven by climate change are already causing massive damage in Aotearoa and will only becoming increasingly common. So how do we adapt?

You can try to hold the ocean back with walls, put houses on stilts and build infrastructure up higher, or get the hell out of the way.

This month the government will finally release the first part of a plan for how Aotearoa will respond.

Bombshell sea level rise data in May shows there is half as much time as previously thought to take action in some places - with once-in-a-century flooding expected every year by 2040.

Significantly populated places in Auckland, Nelson/Tasman and Napier are in the climate change bullseye: coastal, low lying and in some cases sinking fast.

And there are fears that poorer home owners, rural communities and Māori could end up with a raw deal.

What can be done? The four main options

Environmental engineer Rob Bell, who advises councils on how to adapt to climate change, said the emphasis used to be on building protection.

But sea walls are expensive, and eventually they won't work because the sea level is rising.

"You start to lose your beach because the waves reflect off such structures.

"And often that might address for a short time the erosion hazard but doesn't often deal very well with the flooding hazard.

"Because every wall has an end, and when you get flooding around the ends of the wall it doesn't often protect a whole community."

Walls can make sense to protect high value infrastructure or a large number of houses, but kitting out a city's CBD with protection could cost hundreds of millions of dollars to build and maintain.

Then there is accommodating the water, learning to live with it - by for example jacking houses up on poles, and building infrastructure higher up.

Bell said that might eke out a few more decades from housing stock - but it was not very scalable.

"Whether the house is designed to float or they're designed to get them off slab on ground onto piles so that they can be relocatable.

"But again, they have physical limits - it comes to a point where you might have a nice dry house but you can't get to it very often because the road [to your home] is flooded so often."

Avoiding waters means closing areas off to new development, and the final option is managed retreat - abandoning areas entirely. (More on that in a story coming later in the week on RNZ.)

Bell said over time vulnerable waterfront properties could become rentals - raising serious issues about social equality - to no longer being viable dwellings at all.

He said ultimately you can't fight the sea - and communities and local and central authorities need to have realistic and robust conversations about what is worth saving.

One in seven could be in harm's way

It is a nation-wide problem - one in seven people in Aotearoa live in areas prone to flooding or projected sea level rise - and more than $100 billion worth of homes are in harm's way.

Insurance claims from extreme weather events have doubled in the past five years, hitting more than $320 million last year - and insurers are going to be increasingly wary of covering risky properties.

Meanwhile, polling shows people are becoming less tolerant of those who build in harm's way.

'The rich ... get protection ... the poor get managed retreat'

Incredibly, given the size of the problem there has never been a nation-wide strategy to tackle the effects of climate change, but the first pass at a plan - the National Adaptation Plan - will be released by the government in August.

Further work will be done in the massive Resource Management Act reform currently under way.

But on-the-ground changes could still be years away and in the meantime homes and roads will continue to be washed away.

Victoria University of Wellington climate professor and NZ SeaRise programme co-leader Tim Naish said it was absolutely critical action happened quickly.

"If we're not careful we could be batting this back and forth between central and local government and not achieving a lot.

"I don't know what the answer is, I don't think the government at the moment knows what the answer is, and I don't think local government quite know what to do either."

Prof Naish said based on overseas experience some communities would be winners and some losers.

"Those richer communities and cities that are proactive will defend themselves and work out options.

"But the poorer, coastal, rural, potentially Māori communities could be left, wondering what the hell to do."

Communities taking the lead

Owhiro Bay on Wellington's south coast has been repeatedly slammed by storms, damaging roading infrastructure with waves crashing over the road into houses, smashing windows and prompting evacuations.

The land is also slowly sinking, making it more vulnerable to sea level rise.

Wellington City Council has spent tens of thousands of dollars digging out the beach to protect houses and roads - but it is only a temporary fix.

Until the government lays out how costs will be distributed councils and communities around the country are in a holding pattern.

Resident Eugene Doyle is agitating to form a taskforce made up of the community and local government to make a plan.

He has formed the group 4C - Coastal Communities and Climate Change - bringing together multiple residents associations, mana whenua, government and councils and scientists to accelerate the preparations for what is coming their way.

"Communities are actually stepping up and saying 'government's responding too slowly, cities [are] responding too slowly, regions [are] responding too slowly. We need to get cracking on this.

"One of the key themes for us is nothing for us, without us."