A Shore Thing: The 17,600 coastal Auckland homes at risk from sea level rise

Auckland has 3200 km of coastline, and as sea levels rise and cliffs erode, some 17,600 of the region’s homes lie in harm’s way. A Shore Thing is a Stuff series that talks to the people whose properties are threatened, the scientists attempting to warn us, and the engineers trying to hold back the ocean.

Auckland’s coastline is the most densely populated in the country and council estimates show 6 per cent of the region’s properties will be affected by coastal erosion or rising sea levels in the next century.

That equates to roughly 25,400 properties, based on current assumptions of global warming that will lead to a 1m sea level rise.

Over two-thirds, or 17,600, of these properties are homes.

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Auckland Council’s head of engineering resilience Ross Roberts says these are big numbers, but they represent unregulated climate change.

“It’s a big number, but it’s not a big number today, and it’s not a big number if we do our job right, and manage to control emissions,” he says.

Later in this series, Stuff visits the communities whose homes are likely to contribute to the council’s estimate.

We talk to residents of a port town watching neighbouring homes slowly be surrendered to the sea, and owners of cliff-top properties in an affluent suburb who have accepted erosion will one day claim their land.

But for now, we follow the council’s efforts as they try to refine their estimates, plan the defences, and prepare communities to make the decisions over what is saved, what is lost, and where retreat is the best option.

Council general manager of resilient land and coasts Paul Klinac says current estimates are relatively crude, being based on the number of land parcels that intersect with hazard zones.

His team is at the beginning of a five-year effort to map the risks around Auckland’s shores, which will lead to the creation of 16 area-specific shoreline adaptation plans.

A key part of the work is speaking to the community and iwi about what public assets are most important to save, because saving it all will likely prove impossible.

Coastal management practice lead Natasha Carpenter says Auckland is ahead of many other councils, which was down in part to the council already having datasets on erosion and inundation rates.

Once fully developed, the shoreline adaptation plans will inform future investment, including the renewal of sea defences and the creation of new ones.

The first adaptation plan was a pilot undertaken on the Whangaparaoa Peninsula and is nearly completed. The second covers the Beachlands and east area, and has recently commenced.

The council is also undertaking a modelling project to assess the value of council-owned assets that may be at risk.

This will take six months, at which point Roberts says the council will have a better idea of how much financial damage the council will sustain with sea level rise.

Klinac says the council cannot even start work around saving private homes until the Government reforms the Resource Management Act, because until then, it’s unclear who will have to pay to defend homes.

“If we started now, it would likely be made invalid by the new Climate Change Adaptation Act (CCAA), so it’s much more efficient use of ratepayers funds to get the science right now, and apply it to council owned assets, then we’ll be ready when the new act comes into effect,” he says.

Roberts says ministers are going to have to decide which is acceptable – or perhaps least unpalatable – option for who has to pay to defend homes.

The council’s submission to the Government stresses the need for clarity and direction from central Government, but doesn’t argue for who should pay for defences.

Roberts expects a balance to be struck over whether the bill falls on council or the owners.

“These plans will help by guiding the decision-making process so that any new assets are created in the areas where the need is highest,” Klinac says.

Klinac says managed retreat – where communities and infrastructure is moved away from coastal areas over time – is also an option, and this had already happened at Muriwai and Stanmore Bay.

Klinac says the council’s role currently is to educate as many people as possible about the realities of climate change, and the council is fielding increasing calls from potential buyers wanting to know how properties might be affected.

“I’m seeing a lot more of that happening at the moment.”

Iwi ‘will be participating fully in discussions’

Back in 2017, Ngāti Whātua Ōrākei’s urupā (cemetery) near Okahu Bay was flooded after Cyclone Debbie. The same thing happened a couple of years before.

Ngāti Whātua Ōrākei Trust spokeswoman Sharon Hawke says the council installed a larger water pump in 2017, which has kept the urupā from flooding again.

However, Hawke says she doesn’t expect the water pump to work forever as climate change takes hold, and a couple of new possible spots have been selected for a new urupā higher up the hill, near the marae.

The areas are in a reserve and a feasibility study and a request to change the designation of land is still pending, Hawke says.

The urupā has been on its current site since before 1840, Hawke says, and there’s still a lot of resistance from the iwi’s kaumātua, who wish to be buried beside their ancestors and relatives.

Hawke says relationships with the council have been poor in the past, but more recent communications have been good, and the effort to solve issues with the urupā were collaborative.

She says the iwi has a strong working relationship with the council and it would be taking part in any consultation to do with climate change.