Tag: coastal policy

The encroaching sea: new NZ sea level rise maps

This guest post is by Jonathan Musther, who has just published an amazing series of highly detailed maps projecting future sea level rise scenarios onto the New Zealand coastline. If you live within cooee of the sea, you need to explore his maps. Below he explains why he embarked on the project.

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The effect of 10m sea level rise on Christchurch: say goodbye to St Albans, prepare to paddle in the CBD. Full map here.

For humans, sea-level rise will almost certainly be the most directly observable effect of climate change, and specifically of global warming. As the climate changes, many of the effects will be subtle, or if not subtle, they will at least be very complex. Summers may be warmer, or cooler; we may experience more rain at some times of year, and less at others; tropical storms may increase and they may be sustained further from the equator, but all of these changes are complex, and not necessarily obvious against the background complexity of any climate system. In contrast, there is something obvious and unstoppable about sea-level rise, there is no question that it will send anyone in its path running for the hills.

For some time I have been involved in searching for land appropriate for specific uses such as arable farming, water catchment, and off-grid living. When searching for land in this way, there are many, many criteria to consider, and of course one of these is potential future sea-level. Using GIS (Geographical Information System) software, and elevation models of the New Zealand landscape, it is possible to visualise sea-level rise, and select sites accordingly. Naturally, the next question is what sea-level rise to consider. It is possible to place an upper-limit on sea-level rise – after all, there’s only a finite amount of ice that could melt – but beyond that, we’re limited to informed guesswork.

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25m sea level rise: a sunken city and Banks Island. Full map here.

What is the maximum possible sea-level rise? It depends who you ask. Many sources place the maximum potential sea-level rise at around 60-64 metres, but these figures are rarely referenced, and don’t concur with the latest research. Other sources place the figure at around 80-81.5 metres, and while this appears to be well referenced and researched, it is based on work that is somewhat out of date. The best estimates I’ve been able to locate, based on recent measurements (and lots of them) are around 70 metres, but quite what the margin of error is remains uncertain. Of course, when considering future sea-level, we must remember that here in the South Pacific, we will likely experience increased numbers of more powerful tropical storms, with associated storm surges.

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At 80m, West Melton is a seaside township. Full map here.

The maps I created showing sea-level rise for the whole of New Zealand depict rises of 10, 25 and 80 metres. I have certainly received criticism for not focussing on more modest sea-level rises (e.g. 1 or 2 metres), but there are some good reasons for this: firstly, the resolution of the elevation models of New Zealand do not allow accurate predictions of such small rises. Secondly, larger sea-level rises pose a huge threat, and are therefore worth considering. I made a point of avoiding time frame predictions when producing the sea-level rise maps, partly because the time frame is largely irrelevant (if 80% of our homes are flooded, it’s bad news, no matter when) and partly because the range of expert estimates is huge. Study after study shows that we have underestimated ice-sheet instability, and it is almost universally accepted that large sea-level rise will be a consequence. Unfortunately, most studies place this sea-level rise at some unspecified time in the future – when, we’re not sure, but it’s far enough away that we needn’t worry…

So is a 10 or 25 metre sea-level rise likely? Unfortunately, the broad answer is yes. The Greenland, West and East Antarctic ice sheets are showing growing instability, and many researchers agree that they may have past a ‘point of no return’. Remember, the Greenland ice sheet alone, if completely melted, would lead to approximately a 7 m rise in global sea-level. Of course, we return to the issue of when this is likely to happen, and on that, the jury is out.

I firmly believe that to be good scientists, we must investigate the possibility of large sea-level rise, and its consequences. The time frame is unclear, the absolute rise is also unclear, but there really is something unstoppable about rising oceans. We are now well outside the sphere of collective human experience and expertise, and we should be very careful to prepare, as best we can, for a range of scenarios.

Shelter from the storm

Towards the end of a recent Yale Environment 360 interview, following a technical discussion of hurricane formation in a changing climate, scientist Kerry Emanuelis asked a question. Given the likely increase in intensity and power of storms and sea level rises, what needs to be done now in the US to start planning for this? His answer caught my attention and set me thinking about New Zealand. Here’s what he had to say about his country:

“…we need to stop subsidizing people to live in dangerous places. The United States is one of the few places in the world that does that, and it does it heavily. So we are basically paying people to move to places where they’re at risk. And, it doesn’t make any sense…”

 

It’s an indirect form of subsidy whereby people living in safer places are paying perhaps 10 percent too much premium on insurance policies whereas those living in dangerous coastal regions are paying far less than the risk warrants.

He points to the irony of a so-called free market economy capping the premiums insurance companies are allowed to charge. Unsurprisingly it’s wealth and political connections which achieve regulation from legislators setting a cap. The insurance companies need premium income, so they are quietly permitted to overcharge people living inland.

“…it’s a very unfair system. It’s a net transfer of wealth from poor to rich, and the worst aspect of it is it promotes huge coastal development. And, therefore, huge damages when even ordinary storms make landfall in the United States.”

He compares this with the east coast of Taiwan, which is battered regularly by storms. There are a handful of fortresses built by wealthy people to withstand a category 5. Otherwise people build holiday plywood sea shanties which are easily replaced when they get blown away.

The subsidies provided in the US are not limited to manipulation of premiums. Emanuel adds  federal flood insurance, which pays for storm surge damage, and federal disaster relief. Yet storm damage to coastal properties is predictable disaster and risk is knowingly undertaken.

The interviewer asks what is going to happen as the century rolls on in places like Miami and the South Florida coast where development is intense and only a few feet above sea level on the beach.

“I think we know what’s going to happen. There will eventually be a hurricane there, and it will do far too much damage for the state to cover. You know, the state basically has become the insurer of property in Florida. Everybody knows that a relatively small hurricane will bankrupt the [state hurricane insurance] plan, and they will all go with hat in hand to the federal government. So the rest of us will bail them out. And so we have the situation of hard-working people in factory jobs and farmers subsidizing the landowners of Palm Beach. It’s crazy.”

I found myself thinking of what Christchurch mayor Bob Parker had to say after the earthquake when questioned as to why the City Council had permitted building on sites vulnerable to liquefaction. It was a mixed picture. Some of the building was done in the past when the phenomenon was not understood. Some more recently was done with foundations adequate to the danger. But what struck me was the fact that there were cases where the Council did not want building to go ahead but developers won out by going as far as court and winning.

It’s hopefully a reminder to us all that regulations relating to development and building should be made as tough as they need to be.  The financial costs of the damage done by the earthquake will be borne by the whole New Zealand community, and few of us would want it to be any other way. But it’s permissible to reflect that the cost and the heartbreak may have been somewhat less in newly developed areas if more stringent regulations had been in place and not vulnerable to challenge from developers.

This is an important issue for future climate change impacts in New Zealand. Coastal development is one obvious area where appropriate standards set in place now can save great expense later as the sea level rises. Local government bodies have responsibilities to avoid or manage coastal hazard risk, and the Ministry for the Environment provides guidance in the task as it relates to climate change. The document Coastal hazards and climate change: A guidance manual for local government in New Zealand is available here. It contains much useful material. It recommends a precautionary approach to new development and to changes to existing development, based on the avoidance of risk. It promotes the need to secure and promote natural coastal margins. I wrote about it in more detail here last year.

There is also a revised New Zealand Coastal Policy Statement under consideration, which includes reference to the impacts of climate change on coastal hazards. However this appears to be stalled as controversy has developed over the report of a Board of Enquiry which considered submissions on the draft document and has recommended changes to it.

It is clear that, for the present at least, much responsibility devolves on local government bodies and it’s not too difficult to imagine the pressures that they will come under. Risky new development projects will be promoted vigorously. Expensive protection will be sought for areas already developed and threatened by sea level rise and accompanying storm surge damage. It will require strong planning measures and savvy councils to ensure that the future problems from climate change facing coastal developments are not permitted to grow bigger than they already will be. One wonders whether guidance to local bodies will be sufficient. National level prohibitions may need to be brought into play, for which we would need national politicians who understand the seriousness of the risks ahead.

The impacts of climate change on New Zealand coasts may not reach the level of seriousness which confronts the US, but we would be wise to prevent the investment of financial capital and human expectations in development which will prove unsafe in the course of the century.

[Mr Zimmerman]