Eloise Gibson is Newsroom's environment and science editor. She's written for the New Zealand Herald, Stuff.co.nz, The Listener, and BBC Future.com. Twitter: @eloise_gibson.

environment

Drowning dreams: Billions at stake as Govt mulls sea level rules

We know the seas are rising, yet we’re still building large developments within a few metres of present-day sea levels. The tough decisions faced by one coastal council illustrate the struggles going on around New Zealand, report Eloise Gibson and Cass Mason.

There’s an empty lot at the end of Richmond street, Thames, at the watery junction where the Firth of Thames meets the Kauaeranga River.

From the bare corner section, you can see the ocean flickering between gaps in the mangroves, offering a glimpse of the sea views residents will have from a soon-to-be-built apartment block .

The ocean feels close here, and it’s about to get closer. If seas rise 50cm, which is roughly the minimum that scientists say we’re likely to see, an intense storm could flood the nearby roads and playing field, sending thin ribbons of water along the edges of the property.

After 1m of sea level rise, which is reasonably likely by the end of the century, the same kind of storm could turn the property into an island, separated from Thames by three blocks of flooded residential streets.

After 2m, which is plausible this century, a storm surge could submerge part of the land and, possibly, the bottom of the three-storey apartment block.

Those flooding scenarios are rough simulations by a Waikato Regional Council tool designed to raise awareness of sea level rise . They show what could happen after the kind of extreme storm that happens about once a century in the present day, a storm of the severity that engineers use to design safe floor levels. Such storms may become more frequent with climate change.

The designer of the simulator is Rick Liefting, the leading flood hazard expert at Waikato Regional Council. He says the tool is crude compared to a detailed, property-specific report because it excludes factors like friction slowing floodwater down, or waves pushing it up. “It’s for people who are looking to do some sort of development or purchase a property to have that first cut of, okay, are we within coo-ee of some sort of issue?” says Liefting. “Then they can go away and investigate.”

There wasn’t a more detailed, up-to-date assessment done for Richmond St before Thames-Coromandel District Council approved 73 new apartments on the empty section, earlier this year. The council didn’t ask for one. Instead, it relied on a flooding assessment carried out in 2001, incorporating 0.49m of sea level rise.

New Zealand has close to $20 billion worth of buildings on the lowest-lying parts of the coast. Moving, defending and compensating owners who are flooded will be expensive. The potential cost is growing with every new development.

Today, leading scientists recommend considering between double and quadruple that amount when planning new developments. The most up-to-date advice is codified in a new guide written by scientists and policy experts for the Ministry for the Environment.

That guide has no official status, but many councils know what it says, and the public learned of its contents when it was leaked earlier this year by the Green Party.

Based on the latest science, the guide says people should be planning for 1m of sea level rise for existing neighbourhoods, and 1.9m for “green-fields” developments or redevelopments that intensify land use in already built-up areas. The goal is to avoid adding lots of new housing to areas that might one day be flooded.

Yet, in the Coromandel alone, hundreds of new, permanent land titles have been created on low-lying coast in the past two years, after modelling at most 1m of sea level rise.

In 2015, Thames-Coromandel District Council approved a subdivision of 167 coastal sections after rejecting advice from flood experts at Waikato Regional Council to consider 2m higher seas. The district council factored in 1m, instead, noting in emails to the regional council that any updated government guidance wasn’t likely to arrive in time.

Two years later, the council allowed 72 new titles to be created along canals flowing from a harbour , again after modelling for a maximum of 1m higher seas.

These developments weren’t breaking any rules, or even going against best practice guidance, because the advice to factor in 1.9m higher seas was held back by the previous government until after the election.

Images from Waikato Regional Council's coastal inundation tool, showing flooding after 1/100-year flood

The guide remained near completion for many months, awaiting government sign-off. Last week, two separate ministerial briefings from Ministry for the Environment officials – one each to the incoming Ministers for the Environment and Climate Change – urged the new government to publish it. Newly-appointed Climate Change Minister James Shaw, who, in opposition, was part of the party that leaked the draft, told Newsroom he plans to publish the updated guidance before Christmas. He did not reveal whether it would differ from the leaked draft nor whether it would have any mandatory power.

New Zealand has close to $20 billion worth of buildings on the lowest-lying parts of the coast. Moving, defending and compensating owners who are flooded will be expensive. The potential cost is growing with every new development.

“The bottom line is, we should not be developing within 2m of present day sea level,” says Tim Naish, a sea level and polar ice sheet expert at Victoria University. Existing homes are one thing, but with large, new developments: “We still have a choice,” says Naish. “Don’t do it!”

New science

It was 2008 when the Ministry for the Environment issued its current guidance on sea levels to councils. The guide advises councils to look at the impact of 0.8m higher seas by 2090, a figure based on then-current projections from scientists including those on the Intergovernmental Panel on Climate Change.

The IPCC increased its sea level projections after the Ministry’s guidance came out. It will almost certainly boost them again when it next issues a comprehensive report.

“Ice sheet models are getting much more sophisticated, and they are including processes we know are happening right now,” says Naish. “When you build in those processes it looks like we’ve underestimated the contribution of the ice sheets, particularly the Antarctic ice sheet.”

It looks like half a metre of sea level rise is the minimum we’ve locked in with our past greenhouse gas emissions, says Naish. How much higher the oceans go depends on how much greenhouse gas we emit from now on, which is why sea level projections are always presented as a range. It’s the upper figures in that range that Naish expects to go up in the next IPCC report, thanks to the effect of polar ice sheets.

Drowning dreams: Apartment block where the waters meet

Drowning dreams: 72 new houses on man-made canals

Drowning dreams: A 167-lot subdivision

“How high they go up, whether to 1.5m or 2m, I still think is unclear. It’s totally plausible we could get 2m of sea level rise by the end of the century if Antarctica behaves in a rapid, runaway way,” he says.

A crucial factor is what happens to floating ice shelves, such as the Ross Ice Shelf. The shelves act as plugs, preventing the main ice sheet behind them from melting. If people save the ice shelves by making drastic emissions cuts, seas might never get to 1.9m higher than pre-industrial times.

“If we could keep global warming below 2C it looks like we will, potentially, save the ice shelves,” says Naish. “Then we might only get 0.5m of global sea level rise, forever. But if we go above 2C we don’t just get a little more sea level rise, we get a lot. How fast, is the big question.”

Naish is leading a $7.5 million government-funded programme to answer some of the unknowns. The five-year project will fine-tune sea level estimates for the whole New Zealand coastline, giving councils access to improved flood risk maps that take account of local factors like subsidence and the shape of the shoreline. The project will also try to improve on global sea level rise estimates. When they’re done, the researchers will supply councils and others with higher and lower local projections, depending on whether nations meet the Paris climate agreement.

The waterfront in Whitianga, which is at-risk of flooding from sea level rise in the future. New Zealand has close to $20 billion worth of buildings on the lowest-lying parts of the coast. Photo: Joe Dowling

The trouble is that even the best studies can’t tell people whether countries will meet their gas-reduction targets, or how close they’ll get.

Since nobody knows, people like Rob Bell, a sea level scientist at NIWA, say it’s time to forget trying to plan for a definite number of centimetres.

Bell was one of the main authors of the as-yet-unreleased guide to councils. For existing housing, he says, the best approach is to model sea level rise in increments. For example, you can take a map of your neighbourhood, add 10cm higher seas to a flood model, and see what happens in a storm. If there’s not too much flooding, add another 10cm, and repeat.

People will be able to see at what point the risk becomes unacceptable in their area, and that’s where they’ll probably need to think about moving away from the ocean or re-engineering their suburbs. People within a few cm of danger will need to act fast, while others have more time to plan, says Bell.

But that approach is only appropriate for managing housing that’s already been built. For large, new developments, which are supposed to last a long time, the guide takes the view that it makes more sense to locate them well away from the risk zone,

In fact, the guideline’s authors note, councils may be legally liable if they inappropriately zone new, risky areas for development.

“We now see building new suburbs on land prone to liquefaction in much of the country as foolish ... We should see allowing new subdivisions on vulnerable coastal land as equally foolish.” - Commissioner for the Environment, Jan Wright

Although we might never see 1.9m higher seas, the guide advises councils to test big, new developments against that level, because that represents the high end of what we’re likely to see by 2150. Even some of the rosier emissions scenarios have us reaching above 1.5m, eventually.

The authors quote the New Zealand Coastal Policy Statement, a document that’s supposed to steer development at the coastline, which distinguishes between building a few more houses in a built-up area that may flood (small increased risk) and developments adding lots of people and assets to a risk zone (big increased risk).

The draft guide doesn’t say how many homes are needed to trigger the more cautious, 1.9m, test. Also counted are major site redevelopments and changes in land use that intensify population and investment on the coast. “[The coastal policy statement] has an emphasis on locating such development away from areas prone to coastal hazard risk and avoiding increasing the risk,” says the draft guide.

The cost of continuing to develop these areas has been raised before, two years ago. Commissioner for the Environment, Jan Wright, asked former Minister of Finance Bill English to commission a special report on how we’d pay for moving and defending housing and other assets in the flood zone, since the cost was likely to be so large it would become an inter-generational issue. English declined.

Wright also called for an urgent review of the help that central government gives councils, since councils were left with the difficult task of managing coastal development.

“We now see building new suburbs on land prone to liquefaction in much of the country as foolish,” said Wright in her sea level report. “We should see allowing new subdivisions on vulnerable coastal land as equally foolish.”

Two years later, we’re still building, and councils have no more guidance than they did in 2015.

Images from Waikato Regional Council's coastal inundation tool showing flooding after 1/100-year flood.

Coastal conundrums

Thames-Coromandel District Council is one of several New Zealand councils with the delicate task of managing a coastline at risk from sea level rise. It’s also a district where people want to live close to the water, and the sandy shores that draw residents and holiday-makers.

Here, as around the country, most of the “easy” areas of land have been developed, says Liefting, the regional council hazard expert. Now people’s attention is turning to developing more marginal land.

The issue is acute here, since the Coromandel Peninsula is essentially a finger of steep bush, surrounded by 400km of beaches. It isn’t clear where people forced to move by rising seas will go to. Yet the process of capturing sea level rise in the district’s planning rules moves slowly.

The district council is keenly aware of the sea’s threat and has started consulting residents on a long-term plan to better prepare for it, including mapping risky areas. However, that plan is not yet written, even in draft form. The council wants to allocate money starting next year to begin the process of identifying the most at-risk areas, says a council spokesperson.

Until then people wanting a heads up can use the regional council’s online flooding simulator , which is available to anyone, or consult the regional council. The two councils, district and regional, stress that the online simulator doesn’t replace the need for a site-specific assessment.

Meanwhile the district plan builds in some sea level rise: for example, an allowance for 0.5m higher seas is factored into the minimum floor levels for houses at risk from river flooding.

On the coast, erosion-prone places like Matarangi have rules requiring buildings to be relocatable if someone wants to build in an area at risk of future erosion. That future risk zone has been expanded to incorporate 0.9m of sea level rise, but even that has been contentious.

Emails released to Newsroom after an official information request show that one of the council’s scientific consultants wanted to factor in 1m of sea level rise. But staff decided it was better to stick with using 0.9m “so as not to ‘rub salt in the wound’ for those who object” to the new provision. The difference might sound small, but it had the effect of moving the line denoting the hazard seawards by about 3.5m at Matarangi, according to the emails.

If the council faces pushback when it tries to prepare for sea level rise, it is also being lacerated for doing too little. In Whitianga, a $6.5-million-dollar refurbishment of the town centre has been challenged by Coromandel lawyer Denis Tegg, on the basis that the regional council’s simulator shows that much of Whitianga Town Centre may be flooded in the future. Tegg objects to ratepayers’ money (including his) being used improving assets that may end up underwater.

Tegg has lived in Thames since 1973 and has grown increasingly worried about sea levels and what he sees as a lack of serious action by the council. “I started to look and the more I looked, the more concerned I got,” he says. “Thames is one of the most at-risk areas in the country.”

His friend and local science teacher Thomas Everth has similar fears for Whitianga. He’s taken photos of water creeping up the lawns of new-ish houses during a present-day king tide, and sent them to the council. “As a rate-payer I sure hope that we will not be collectively held hostage by the property owners for bailing them out in the future,” he says.

One of Thomas Everth's photos of the Whitianga Waterways taken during a king tide. Photo: Thomas Everth

But others see the threat as distant – far more distant than the need to make improvements to their town. “Nah, I’ll be dead by then,” says the owner of a waterfront business in Whitianga, when asked if she’s worried about rising seas.

In response to Tegg’s queries, the district council asked the regional council if there was a future flood risk to Whitianga. Liefting’s team confirmed there was. But the district council told Newsroom that local businesses have been waiting for the upgrade for 15 years and it can’t wait any longer. “Due to the location of the township, and the value of assets, work will need to continue over time on responding with greater certainty, rather than deciding not to invest (because of rising seas),” it says.

We also asked Thames-Coromandel District Council about the gap between the 1m higher seas it is using to test new developments, and the 1.9m test in the draft Ministry for the Environment guidance. “The guidance you refer to continues to be in draft form and the most recent formal guidance from the Ministry for the Environment continues to be the 2008 guidance,” said a spokeswoman. “We are awaiting the new guidance being released officially before we update our assumptions as a council.”

Liefting is the team leader of regional hazards for the Waikato region, giving him purview of risks like coastal floods. He finds the district’s caution understandable, given the current guidelines.

Yet, in 2015, it was Liefting who strongly urged the district council to consider the effects of 2m higher seas before approving a major subdivision.

A chain of emails between the councils, released to Newsroom following an official information request, show staff at the district council consulted Liefting about a 167-lot subdivision on Purangi Estuary at Cooks Beach , known as Longreach.

Liefting was the regional council’s leading expert on coastal floods, and the district wanted his input before it decided whether to allow the subdivision.

The emails show that, sensing resistance, Liefting marshalled support from other senior leaders at the regional council to try to persuade the district council planning staff to use 2m.

One of those leaders, a senior policy planner, noted in an email that the developers would probably not like the idea of using the more cautious level. But they “will not be the ones that will be affected should the development go ahead without meaningful consideration of sea level rise”, he said. “It will be the property owners of the future (potentially after properties have been bought and sold a number of times) that will be physically affected.”

The email continued: “As an aside, it seems inconceivable in logic that we should place considerable store in collecting evidence upon which to base our resource management policies, yet when confronted with opposition to the best evidence available, capitulate.”

The district council decided to go with 1m, citing current Ministry guidance. “Given the timing of the application, a decision must be reached on this matter and it would appear that updated guidance will not be forthcoming within this timeframe,” reads the district council’s polite email to Liefting, rejecting his advice.

Liefting isn’t bitter. “There wasn’t a lot the regional council could do, to be honest,” he says. “It shows what a difficult space our territorial authorities are in, trying to deal with climate change. They were going under the current guidance that they had. It was always going to be a tricky one, because there was no legislated or even best practice guidelines about using the 2m line.”

“That’s hopefully being brought in with the new guidance.”

Images from Waikato Regional Council's coastal inundation tool showing flooding after 1/100-year flood.

Weak laws?

Niwa’s Bell says the first thing needed to help councils prepare better for rising seas is “getting the guidance out there”.

Senior Ministry for the Environment officials appear to agree, since their briefings to the incoming Ministers for climate change and the environment last week separately urged the ministers to publish the guidance. “The guidance will encourage good decision-making so that New Zealand faces fewer risks from climate change in coastal areas,” said one of the briefings.

There is already law on this, though more than one expert questioned how well it was working. Regional plans and the Resource Management Act already require consideration of rising seas, as does the 2010 New Zealand Coastal Policy Statement. The coastal policy statement requires councils to consider hazards like sea level rise “at least” 100 years into the future and to “avoid increasing the risk of social, environmental and economic harm” by putting more assets in risk zones.

But Bell says the policy isn’t always well-understood by council officers, and implementation varies. “If you read the Coastal Policy Statement carefully, there’s actually a lot of teeth in it,” says Bell. “And yet, you wonder how some of these developments arise, when the coastal policy statement [is there]. It’s around implementation.”

Other experts also spoke of a gap in central government direction. Even if nations manage to keep global warming to 2C, that means 400-700 years of sea level rise, says Andy Reisinger, deputy director of New Zealand Agricultural Greenhouse Gas Research Centre. Yet: “There is no key regulatory or legislative framework for councils to push back against very clear, vested, individual interests of ‘I want to build my house here because I own this land’,” says Reisinger.

“That battle is being played out over and over in different locations [and] it’s always a question of who pays, who benefits, and who loses.”

With so much uncertainty, councils can find themselves open to costly challenges from property owners. In 2013, after a high court challenge, Kapiti Coast council backed away from adding warnings that would have restricted new building and subdivision in the hazard zone. In 2015, Christchurch City Council enraged some residents by placing coastal hazard warnings on their properties, with homeowners protesting the “speculative” and “overly precautionary” limits.

Even if nations manage to keep global warming to 2C, that still means 400-700 years of sea level rise.

“Local authorities don’t quite have the legislation and regulations to have a consistent approach to green-fields development, and when they do try, they get tested in court and the science gets questioned,” says Naish. “But as soon as central government starts putting in regulations around development or lines on maps that affect LIM reports, that’s going to become a voting issue because a lot of people are going to have their assets affected.”

Without a firmer steer from the government, councils must decide themselves what constitutes too much risk. Building a new deck might be fine, but is allowing three new houses in a risk zone okay, or 50, or 100? And is building floor levels higher enough to adequately deal with the future risk, if the home is going to be surrounded by flooded roads and infrastructure?

Liefting, for one, isn’t sure it’s worthwhile raising floors to keep a few, new houses dry, when all around them may be flooded. “For a lot of these infill developments within existing developed areas there needs to be a bit of pragmatism, because is it really practical for them to be 1m or so above the rest of the development?” says Liefting. “They will be left as islands.”

Once houses are built in the flood path, he says, there are only three options. “We can work together on some sort of managed retreat, we can have unmanaged retreat, where we do nothing and let nature dictate what happens, or we can hold the line,” he says.

As Wright and others have noted before, all the options are costly.

Tough calls

Policy-makers call holding the line ‘the Dutch model’, after the virtually impenetrable flood defences that have been built in the Netherlands. “It’s when we say, it’s impractical to move, so we build bigger stop-banks,” says Liefting. “But, boy, does that cost money,”

Victoria University’s Naish says a mega-city such as New York will have little choice but to spend the many billions of dollars needed for a high standard of water-proofing.

“There is so much at stake in New York that they will have to engineer their way out of it, and it makes economic sense to do it,” says Naish. “But for somewhere like Thames, I don’t know. Unless the Thames-Coromandel council decides to build a big seawall protecting the whole of the Hauraki plan…. but even that’s not so simple because [although] these engineering solutions sound good, they are not necessarily great and they cost a hell of a lot,” he says.

A community meeting on coastal hazards in Thames, held with the district and regional councils, asked people to stick their concerns to a map of the area. Photo: Joe Dowling

NIWA’s Bell stresses that, unless they’re already at-risk, neighborhoods don’t need to commit now to a final plan. They can engage in a sort of pick-a-path exercise, choosing their route as it becomes clearer how high seas are going to go. For example, a town might decide to build a small, cheapish seawall to stave off the immediate risk, on the understanding that they’ll move inland if seas reach a certain threshold.

But any path that involves moving people will probably involve compensation. “I’m a property owner,” says Liefting, “and if someone said to me, ‘the long-term option is get out of here’, I’d think, ‘Well am I going to be compensated because I’ve bought in good faith that my property is going to be there forever.’ “We can’t even bring managed retreat to the table unless compensation is brought with it.”

Naish agrees reparation will be an issue. “Obviously, councils want development,” he says. “It’s good for their local economies, it’s what ratepayers want. But if there is going to be legislation put in place that says, ‘Okay, these people have to retreat and this area cannot be built on’, then the issue of compensation is going to have to be thought about.”

Whether people choose to move or build defences, the cost is likely to fall on future rate- and tax-payers.

To curb the cost, Liefting would like the government to consider issuing leasehold or limited-time land titles for new coastal subdivisions. “I don’t think we lock away all the land below that 1.9m and say ‘Don’t use it’, because potentially you might have a number of generations of use out of that land,” he says. “Perhaps we could have some sort of arrangement where you are signalling quite clearly that you might be okay for the next 50-100 years, but, after that, all bets are off.”

For now, though, freehold titles last forever, even if the land they represent may be at flood risk.

Liefting says it comes down to “buyer beware”. “People who are going into a property purchase who are near the coast, or a watercourse, or flat land that might be prone to hazard need to do some due diligence,” he says.

Already, he says, pre-purchase enquiries to the regional council from people wanting flooding information have “sky-rocketed” during the past few years.

Back in Thames, where the apartments will soon be built, some ratepayers are only too mindful that the district or country as a whole may pay if other people’s investments go wrong.

At an October community meeting to discuss the long-term plan, council officials asked residents to write their concerns on yellow post-it notes. One attendee stuck a sticky square on a map near the shoreline. It read: “Why are we still issuing building permits when we know that floods are likely?”

This story was written with help from the Aotearoa New Zealand Science Journalism Fund.