Published March 2026 · 8 min read

The Sea Level Rise Gap in Auckland's Unitary Plan — What Coastal Buyers Need to Know

If you're buying near the coast in Auckland, there's a gap between what the planning rules say and what the science says about sea level rise. Whether that gap closes or not, it's something coastal property buyers should understand before signing.

The short version

Auckland's planning rules currently assume the sea will rise by 1.0 metre over the next 100 years. That's the number used to draw the main coastal flood overlay that triggers development controls and appears on your LIM report.

New Zealand's government scientists, through the Ministry for the Environment's 2024 guidance, recommend higher figures for most of Auckland — somewhere between 1.2 and 1.6 metres, depending on your exact location on the coast.

Whether Auckland's planning rules will adopt the higher figures is uncertain. But the gap between the two numbers is real, and understanding it puts you in a stronger position when making a coastal property decision.

What the current rules actually say

Auckland's Unitary Plan — the rulebook that governs what can and can't be built — defines three coastal hazard areas: the coastal erosion hazard area, the coastal storm inundation 1% AEP area (present-day risk), and the coastal storm inundation 1% AEP plus 1m sea level rise area. It's this last one — known as CSI1 — that matters most for property buyers.

Under Chapter E36 of the Unitary Plan, if you want to build or extend a home in the CSI1 area, the finished floor level of any habitable room must be above the 1% AEP coastal storm inundation level plus 1 metre of sea level rise. This is a legal rule with real consequences — it determines your consent requirements, your minimum floor level, and whether certain types of development are even possible on your site.

The CSI1 overlay is what appears on your LIM report. If your property boundary intersects this layer, you'll see a coastal inundation notation on your LIM, and any development will need to address the coastal flood risk.

What you can actually see on council's maps

Here's something many buyers don't realise: Auckland Council's GeoMaps viewer actually shows five different coastal inundation scenarios under the 1% AEP event — not just the 1.0 metre one. The available layers range from present-day risk (no sea level rise) through 0.5m, 1.0m, 1.5m, and up to 2.0 metres of sea level rise.

This means you can already see, for free, what the coastal flood zone looks like under the MfE-recommended range. The 1.5 metre layer roughly aligns with what the science recommends for most of Auckland's coast. If you're buying near the coast, toggle between the 1.0 metre layer (the current AUP control) and the 1.5 metre layer — and check whether your property falls inside the larger zone.

These additional layers don't trigger any legal requirements today. But they give you a picture of what could happen under different futures — and that's useful information when you're making a decision about where to put your money.

What the scientists recommend

In 2024, the Ministry for the Environment updated its national guidance on coastal hazards and climate change. This guidance draws on the latest international climate science and on a New Zealand research programme called NZ SeaRise, run by NIWA.

The key finding: for most of Auckland's coastline, the sea is expected to rise by more than 1.0 metre by 2130. The actual number depends on your exact location, because of something most people don't think about — the land itself is moving.

In most parts of Auckland, the ground is very slowly sinking. It's a tiny amount each year, but over a century it adds up. When the sea is rising and the ground is sinking at the same time, the water ends up higher relative to your property than the global average would suggest.

NZ SeaRise has calculated location-specific projections for every 2 kilometres of New Zealand's coast. For most Auckland coastal areas, the projected sea level rise by 2130 under a medium-high emissions scenario is roughly 1.2 to 1.6 metres — not 1.0 metre. You can check the projection for your stretch of coast yourself at searise.niwa.co.nz.

The gap between the rules and the guidance

The AUP's 1.0 metre figure is a legal control — it's what council can enforce when assessing resource consents. The MfE guidance is a recommendation — it tells councils what the science says they should consider, but it doesn't have the force of law unless it's written into a plan.

Whether Auckland Council will formally adopt the higher MfE figures into the Unitary Plan is an open question. PC120 is moving in that direction — Auckland Council's guidance document GD15 (updated November 2024) now references the NZ SeaRise projections and encourages their use for site-specific coastal assessments. But PC120 is still going through hearings, and the final form of the coastal rules won't be settled until mid-2027 at the earliest. There's no guarantee that the higher figures will be mandated.

What we can say is that the tension already exists in practice. Auckland Council's engineering teams are increasingly asking consultants to use the higher MfE-recommended figures when assessing coastal flood risk for new developments — even though the operative plan rule still says 1.0 metre. Some consultants adopt this voluntarily as a conservative approach. Others push back, because the higher figure isn't legally required.

For a property buyer, the question isn't really about what council will or won't do. It's about what level of risk you're comfortable with. The 1.0 metre scenario is the legal baseline. The MfE guidance shows a range of higher scenarios that the science supports. Both are publicly available. Which one you plan around is ultimately your decision.

How much difference does it actually make?

More than you might think. The difference between 1.0 metre and 1.5 metres of sea level rise doesn't just raise the water line by 50 centimetres. Because many coastal Auckland properties sit on flat or gently sloping land, even a small increase in sea level rise projections can push the inundation boundary a significant distance further inland.

It also affects the minimum floor level for new buildings. Auckland's Stormwater Code of Practice requires new habitable floors to be set at least 500mm above the peak flood level. If the peak flood level is calculated using a higher sea level rise figure, the required floor level goes up — which affects building design, foundation costs, and potentially whether a site is economically viable to develop at all.

For a practical example: a site-specific flood assessment for a coastal property on Auckland's Hibiscus Coast found that using the NZ SeaRise projection instead of the AUP's 1.0 metre raised the modelled coastal flood level by about 13 centimetres. That doesn't sound like much, but it pushed the recommended minimum finished floor level up to over 4 metres. On a site where the existing ground level sits around 3.2 metres, that means nearly a full metre of elevation is needed between the ground and the floor — which fundamentally changes the building design and cost.

What you can do right now

If you're buying or already own a coastal Auckland property, here's what we'd suggest:

1. Check multiple scenarios on GeoMaps. Auckland Council's GeoMaps viewer lets you toggle between five sea level rise scenarios — from 0.5m up to 2.0m. Compare the 1.0 metre layer (the current legal control) with the 1.5 metre layer (roughly aligned with MfE guidance for most of Auckland). If your property is outside one but inside the other, that tells you something about the range of possible futures for your site.
2. Check the NZ SeaRise tool. Go to searise.niwa.co.nz and look up the sea level rise projection for your stretch of coast. This is free and takes two minutes. Compare it with the 1.0 metre assumption currently in the AUP. This gives you the site-specific picture that a single number can't.
3. Don't assume "outside the overlay" means "no risk." The CSI1 overlay on your LIM uses a 1.0 metre sea level rise scenario. If your property is near but just outside that boundary, it's worth understanding what a higher scenario would mean for your site.
4. Ask about sea level rise assumptions. If you're commissioning a flood risk assessment for a property, ask your engineer which sea level rise figure they're using and why. Some engineers will use the AUP minimum, others will use the MfE-recommended figures. Understanding the difference helps you interpret the results.
5. Factor the uncertainty into your decision. Nobody knows exactly how much the sea will rise or whether the rules will change. But you can see the range of possibilities for free using council's own tools. A property that's comfortable under the 1.0 metre scenario but vulnerable under the 1.5 metre scenario carries a different risk profile than one that's clear under both. That's information worth having before you commit.
6. Check your property's current coastal inundation status. A Know Your Risk NZ report checks whether your property intersects the 1% AEP plus 1.0m sea level rise coastal inundation zone — the same layer used in Auckland's Unitary Plan and on LIM reports — along with 6 other hazard layers. This tells you where your property stands under the current legal framework for $49. For a view of higher sea level rise scenarios, use the free GeoMaps layers described above alongside your report.

The bottom line

There's a gap between the sea level rise figure in Auckland's planning rules and the figure the government's scientists recommend. Whether that gap closes through rule changes, stays as it is, or lands somewhere in between is something nobody can predict with certainty. What you can do is look at both numbers, understand what each means for the property you're considering, and make your decision with the full picture in front of you. The tools to do that are free and publicly available — the question is whether you use them before or after you've signed.