Sean Rush & Katharine Moody say NZ needs to be more realistic when it comes to policy development regarding sea-level rise projections & managed retreat

By Sean Rush & Katharine Moody*

The government could be said to be ‘screwing the scrum’ by ignoring the most recent findings of the IPCC, (Intergovernmental Panel on Climate Change), and persisting in using extreme climate change projections.

The IPCC is clear: its high-end, worse-case scenario, Shared Socioeconomic Pathway (SSP5-8.5), is “not likely” and “implausible to unfold”,¹ with the government’s higher-end of that high-end scenario (called 8.5H+) only having a 1 in 14 chance of happening on top of that!

To continue the rugby analogy, screwing the scrum is sneaky, opportunistic, and not really legal.

So, what advantage is being gained by inflating sea-level rise and other climate change effects to the extent of implausibility? And who benefits from this “over-egging” of these effects?

It is a particularly important question to ask today, given those affected by current weather events are being told these events are the result of climate change, but there will be no compensation until;

…they [Government] form a national policy response to the places severely affected by flooding and land instability, including managed retreat.

So, let’s follow the money, given it’s not getting to those affected (yet).

The research community

Central government has poured plenty of money into research into climate change, for example: here, here, and here. 

But a key tenet of the scientific method is that novel claims have to be published in a credible, peer reviewed journal.

Only then should such scientific findings be relied upon, particularly by regulators. So, a disturbing feature of the current managed retreat policy discourse and coastal planning guidance generally, is the emergence of novel estimates of New Zealand-specific sea-level rise that have not passed the required academic peer review. 

Readers may recall new claims, popularised by the media in May 2022 that large parts of coastal New Zealand are subject to a disturbing subsidence trend. The claims were that sea-level rise was happening twice as fast as previously thought.  Projections showed infrastructure and homes in Auckland and Wellington - as well as many other places – at risk of inundation decades earlier than previously expected. 

The study, known as the ‘SeaRise Project”, is a collaborative effort led by scientists at Victoria University, NIWA and GNS funded to the tune of $20 million by the Government. The projections relied on a short 7-year satellite dataset (2003-2011) measuring subsidence and uplift along coastal New Zealand.  

These projections were fast-tracked into policy via the ‘SeaRise tool’, an interactive map specifically designed to target the public, the media, and regulators. One headline projection was that parts of Wellington’s coast would subside up to 30 centimetres within the next 10 to 20 years. 

Coastal residents and regulators have been holding regular meetings ever since to discuss the study’s implications and next steps.

The findings were so inconsistent with what the much longer-term tide gauges showed, that their publication warranted closer scrutiny.  What was omitted from the media coverage was that despite submitting a manuscript to the American Geophysical Union’s, Earth’s Future, in July 2022, it was not published (and still has not been) as it did not pass the peer review process. 

This should not be unexpected. Several conclusions drawn by SeaRise are at odds with the peer reviewed and published works of several of the co-authors. Colleagues of the group, with established credentials in the world of land subsidence, pointed out that the short-term subsiding trends should not be extrapolated forward, particularly when they do not incorporate the often-balancing effects of earthquakes and slower, more subtle rises in land, known as ‘slow slip events’ (SSEs).

These events are well documented in the peer review and can completely cancel out subsidence.  Despite these warnings, the SeaRise tool went live on 2 May 2022 and remains online.

The project’s communications plan shows that publication of the online tool was agreed to go ahead irrespective of whether the manuscript had passed the peer review process.  

The timing of the publication coincided with the commencement of Minister James Shaw’s consultation on proposed managed retreat legislation and was subject to a carefully orchestrated, week-long series of media coverage, interviews with the Prime Minister, Shaw and other stakeholders. 

Concerns about the utility of the projections for policy making are ongoing.  For example, tide gauge measurements for sea level around Wellington have not materially changed since the end of the SeaRise data set in 2011. Individual scientists have pointed out that the SeaRise measurements of subsidence are in direct contrast with their own measurements. Even GNS have acknowledged that the Kāpiti Coast, which is shown by the SeaRise tool to be subsiding, was uplifted by a full centimetre during this year alone.

The ~$20 million funding for this project was sourced from the MBIE ‘Endeavour’ fund with an initial tranche of $7.1. million and a more recent tranche of $13 million. The more recent tranche will be applied to refining the coastal data points (from the current 2 kilometre spacing to 100 metres) along with solving, if they can, the issues raised in the peer review process. But it is entirely possible that broad spatial satellite measurements will never be as accurate as local tide gauge measurements.

This brings into question the value for money of this ongoing expenditure.

In the meantime, significant caveats should be applied to the SeaRise tool pending either its correction or abandonment. It should certainly not feature in the managed retreat debate and cannot be used in formal coastal policy planning processes.

Private sector consultants

Every local authority is required, under the New Zealand Coastal Policy Statement (NZCPS) Policy 24 to identify coastal hazards, taking into account “the likely effects of climate change on the region or district”. This work, commonly referred to as a coastal hazard risk assessment, is normally contracted out to consultants. The output is used to define boundary lines, or coastal hazard zones, for restrictive planning purposes – i.e., to determine rules about what one can and cannot do with their property if it is identified as being within a coastal hazard zone.

Anecdotal evidence suggests these reports cost in the vicinity of $200,000 – $400,000 depending on the length of the coastline and the nature of the geomorphological characteristics. Multiply that (at the low end) by our 57 local authorities with a coastline, gives a total in excess of $11m ratepayer funded dollars. And, if private property owners believe the results of such assessments are “over- egged” (referred to as ‘conservative’ in technical terms), then challenges to the associated Council plans have to be taken to the Environment Court for legal compliance and scientific merit review.

Hence, the cost of defending these often found to be overly ‘conservative’ findings, falls solely on the ratepayer – as, more often than not, the same firm providing the science underpinning the planning rules has to be hired/paid further for affidavit preparation and appearances associated with court processes.

It therefore makes little sense for central government to persist in recommending the use of the “implausible” IPCC sea-level rise projections (i.e., SSP5-8.5 and 8.5H+) in any coastal guidance material, as this simply adds unnecessary costs to local authorities, and cost and stress to the residents inappropriately caught up in this process.

Moreover, NZCPS Policy 24 requires that Council’s give “priority to the identification of areas at high risk of being affected”. As one pragmatic scientist explained, there is nothing complex or difficult about this – the most high-risk areas of coastline can be identified by simple observation of existing protective measures.

Communities know their coasts, but there is no money in following the historic/observational record, or in using local knowledge of coastal and estuarine processes as understood by residents and property owners. The ‘money’ is in the production of complex and yet inadequate technical models, purported to predict the future via weighty output reports, unable to be interpreted and/or easily understood by general public.

Public sector bureaucrats

As many readers will realise, nearly every government entity (including, the RBNZ) are busy developing their own unique climate change strategies. That bureaucratic expense aside, the main public service benefactor of these unfolding declarations of climate emergencies in our communities, is the Ministry for the Environment (MFE).

When resource management was reformed during the 1980s, the Department of Conservation (DOC) was set up to manage the very large conservation estate, and MfE to give even handed policy advice on the environment. Some would say MFE is going well beyond that into advocacy, supporting these exaggerated positions on climate change. We can see this trend reflected in growth in the environment budget over recent years. 

MFE output expenses rose from $114m in 2017/18 to $410m in 2022/23 whereas over the same period, DOC went from $386m to $720m – a near quadrupling of costs for advice on the environment versus not quite a doubling of costs for getting actual work done in the environment.

Where to from here?

Much more time, effort and expense is on the cards regarding the future Climate Adaptation Act. Already, councils are busying themselves with making adaptation plans, even though they are not a regulatory requirement at this stage. Hawke's Bay residents (view oral submission at 53 minutes 19 seconds) have been going through the gruelling process of coastal adaptation planning for 9 years now, with little action to show for all the talk.

The Environmental Defence Society (EDS) has commissioned a series of reports on the topic of public funding for managed retreat from climate-related hazards. These are big volumes of work, but for an enthusiast, worth reading. The emphasis is on publicly-funded compensation to residential property owners for moving away from the hazard as a preventative, or proactive measure, as opposed to an EQC-type, event-driven, or reactive measure.

From the authors' perspectives, we have not formed an opinion on the need, but foremost, we consider that any such considerations must not stray beyond planning for likely, if not near certain, climate change futures. Compensation can only be costly, and weather events (slips and floods) are more likely to threaten lives and properties far sooner than sea-level rise.

This means not using “conservative” or “novel” or “implausible” or “precautionary” methods and outputs from our coastal scientists and consultants. Instead, it means a far greater emphasis on observational data and a pragmatic application of it, responding to present-day events and what can be reasonably seen in the future.

In the end residents want to understand the likelihood of them being at risk in the future, based on a reasonable set of assumptions. That is what the law says should happen, but it is being ignored.

The Kāpiti Coast, for example recently mapped what they refer to as ‘Adaptation Areas’ – determined using the “implausible” SSP5-8.5 (H+) scenario. An estimated one quarter of all properties in the district are ‘caught’ by the lines drawn.

There will be consequences in the planning processes, but insurers are using this information today. While insurers generally write one-year policies, and slow progressive risks (such as sea-level rise) should be by and large, irrelevant, anecdotal evidence suggests they are already applying risk premiums to coastal properties in areas like those in Kāpiti’s adaption areas. Similarly, some banks are modelling climate risk, again, based on these “implausible” scenarios.

We need to be more realistic when it comes to policy development regarding sea-level rise projections and managed retreat. ‘Screwing the scrum’ with the use of unlikely and implausible climate change scenarios (SSP5-8.5 and 8.5H+) needs to be yellow carded.

1) IPCC, AR6 WG1, Chapter 4, section 4.4.2. p. 13

*Sean Rush (LLB, LLM, MCCSP) and Katharine Moody (BSc, PGDipPlan) recently collaborated on the preparation of expert evidence for an RMA plan change hearing. This article summarises some of those matters raised in that regulatory process.