Down by the seaside

This year’s NZ Climate Change Centre conference, to be held at Te Papa in Wellington next month, focusses on sea level rise, and how communities can adapt to the inevitable encroachment of the ocean. The organisers have laid on some excellent speakers, include Aussie oceanographer and sea level expert John Church, as well as many directly involved with the issues raised by sea level rise in New Zealand. The conference programme aims to:

  • Present the latest science of sea-level rise associated with climate change, including the role of polar ice-sheet melt
  • Present a synthesis of recent projections for sea-level rise and discuss the uncertainties associated with these projections
  • Identify anticipated impacts on New Zealand coastal environment and infrastructure resulting from climate change
  • Discuss whether adaptive risk management for adapting to sea-level rise will be adequate given the ranges projected and their uncertainties
  • Stimulate discussion of how end-users can manage present and future coastal issues and how social and bio-physical scientists, central and local government, and infrastructure operators can work together with communities to build resilient systems
  • Describe approaches that have been taken to planning coastal futures, which take into account community and resource-user needs underpinned by plausible climate change projections, adaptive approaches to manage uncertainties, and sound approaches to developing coastal policies.

Sounds like a very worthwhile couple of days. It’ll be interesting to hear what the “synthesis of recent projections for sea-level rise” suggests we’re in for, so if any HT readers are planning to attend, I’d be very happy to carry some conference reports.

For what it’s worth, in my view two numbers and one uncomfortable fact are of prime importance. We’re committed to warming, and therefore to sea level rise. The peak level of atmospheric CO2 that we reach (unless we can cut it very quickly after the peak by active carbon removal) will set the final quantum of sea level rise the planet will experience. The latest paleoclimate evidence suggests that current CO2 levels are putting us on course for an eventual 20 metres of sea level rise. Pick your final CO2 concentration, and calibrate against times past. At 300 ppm in the last interglacial, sea level was 6 metres higher than present.

The consequence of where we end up on the atmospheric carbon scale is a long term inevitable and uncomfortable commitment to continuously increasing sea level. It might be enough for some purposes to consider only a metre or two over the the next century, but if you’re planning to rebuild a city, perhaps you should look a little further ahead. Fascinating discussions are in store in Wellington, I confidently predict…

I was lucky enough to attend (and speak) at last year’s conference1, and I’m sure that this year’s effort will be just as worthwhile.


  1. The proceedings of last year’s forum are now available from the NZ CCRI. []

33 thoughts on “Down by the seaside”

  1. The tragedy for Christchurch is that there is NO acknowledgement of the hazard of sea level rise in the plans at all, with no mention in the news media and Letters to the Editor unpublished. In a city where (according to Google Earth anyway) the Cathedral Square is only 4m above sea level. It’s clear that the rebuild will take decades, but we’re on track to have it kneecapped by the realisation that it’s all futile anyway.
    The big advantage for the Cardboard Cathedral at least is that it will (hopefully) be removable, which the suggested rebuilt stone building will definitely NOT be.

    1. Yes, I’ve hunted through the plan and appendices and can’t find much, if anything – certainly no evidence that there’s been any strategic consideration of the issue. That has to be a major failing of the process.

      Personally, I wouldn’t be keen on major infrastructure investments less than 6m above current sea level.

      1. Which means bulldozing everything east of Cathedral Square? Personally, it seems like a good idea, since the area is stuffed, and it is what we intend to do with our house.
        What do you do with the 100 ,000 people is the question.

        1. I’d suggest thinking of it more as “planned retreat”. No need for bulldozers, because immediate SLR impacts are probably some way off (decades?), but it’s not worth investing in a city pattern which will have to change. Make the current CBD a tourist/culture/entertainment zone, and allow businesses to find their own loci further east, and on higher ground.

          1. 1) Of course one takes building lifetimes into account.

            2) Look hard at sewage systems, where treatment plants want to be *below* their sources, and near sea level. That can be awkward.

            3) As usual, the Dutch think ahead about water. See Netherlands floating. I liked the floating gold course for the Maldives.

            1. Actually John there are a number of sewage systems around the country – even close to the sea – where the old method of pumping the outflow into the ocean is no longer used. Many now take the treated effluent and literally pump it up hill! 😉 Forests are good discharge areas.

        2. That is resolving itself, albeit slowly, as folk find that they are not allowed to move their sound house off their dodgy dirt, because all the existing subdivisions are laced with restrictive covenants. Perfectly reasonably, given the demands and expenses the Councils place upon the developers. Eventually the Councils or the Gummint will have to establish special subdivisions that do allow movement of older houses or risk a permanent flight from the city.

          Personally, I wouldn’t build anything that couldn’t be tossed onto the back of a truck below the 20m contour, possibly higher. It’s perceptions that determine the value of property, by the time South Shore has gone, so will confidence in anything that just might be inundated. Of course, by then the same problem will be looming all over NZ and the rest of the world, so I would bet on getting any flood insurance..

          1. I have a beach property at Whiritoa, and councils are already reacting to the potential erosion of sea side properties built on sand dunes by requiring all new buildings close to the sea to be relocatable.
            As for ChCh I wonder that the authorities have not responded to the obvious need for quick temporary accommodation with the importation from around the country of these very livable relocatables.

    2. Well what might we expect from a government and a country as heavily in denial of AGW as we have. Just because SL rise is being measured in mm at the moment doesn’t mean that it will always be the case, as most here understand. And it’s not just Chch that is under threat. downtown Auckland, Wellington, and many, many coastal towns are as much under treat if not more so than Chch.
      I worked on the recent widening of Fanshaw St into Auckland – reclaimed land in the late 19thC. Dig down 2m and you need to start pumping. But much of Auckland’s recent development is in this part of town and the entrance to the new Victoria Park tunnel is just up the road. Of course Wellington’s Basin Reserve and Lampton Quay were at sea level originally.
      Here in Thames, part of the town is on reclaimed land from gold mining tailings (that’s another story involving high levels of arsenic)! and it is just centimetres above SL as you can see dramatically when you walk along the raised footpath along a bund protecting the houses from the sea.
      Then there is Ohope. One decent storm surge…..

      1. Maybe we should evacuate the entire country then? The Aussies are taking the right approach by evicting an 80 year old couple from their own seaside home. At present rates of sea level rise, they will be inundated by the year 4000, but you can’t be too careful eh?

        1. Nah, Andy, let’s just line the coast with straw men provided by you and the rest of the Denialerati – that should keep us going forever.

  2. I don’t think an orderly retreat will be possible, Gareth. Not without a lot of people losing homes etc…..which is happening now of course. Allowing businesses to build on threatened land is OK since most tilt-slab monstrosities are only planned to last a couple of decades anyway. But I can’t see the Council being willing to invest in roads, sewers etc, well, a sensible, far-sighted Council.

    It will be an interesting process to see the encroachment, humanity hasn’t had to deal with it since Noah…. or maybe Atlantis. Actually Noah was probably a legend based on glacial outwash flood, there were some doozies back at the end of the last ice age.
    There will undoubtedly be calls to build a Dutch dyke from Scarborough to Waipara, oblivious of (1) the rivers (2) Lake Ellesmere (3) the porosity of Canterbury gravels and (4) that it will be happening when flooding is occurring globally and there won’t be money for that sort of project. New York or London maybe, but not ChCh.

    What is sad is that we are missing the opportunity to rebuild on safer ground to the west, it will necessary eventually, we could have had a 50 year head start on everyone else.

  3. I’ve mentioned this before, but people might look at a good conference on preparing for sea level rise.

    This starts with review of science, moves to government officials talking about mitigation and adaptation, then goes into more details, The fiercest segment was we split into groups with simulated towns and were asked to do plans for next 50 years or so. The politics will get very exciting, because it is not accidental that there exists so much sea-level infrastructure.

    Most people were local government planners wanting to learn about SLR and be thinking harder about policies to prepare for next 50-100 years.

  4. I think we should approach it strategically rather than making compulsory evacuation type moves in advance. In a place like ChCh there are obvious restrictions on placing houses, but step back and look overall.

    Where do you build hospitals, schools, fire stations, courthouses, emergency coordination centres and other buildings important for the community long-term? Where do you promote parklands, wetlands, market gardens? I think Gareth’s point about the 6m line should be obligatory for schools, shopping centres and hospitals, churches and community halls too – they’re important when bad things happen. More importantly, proximity to good services encourages domestic development close by.

    Nearer the sea, you can put your market gardens and parklands – even if you have to raise the soil a bit – and let them drain off into parkland and wetland. If you’re lucky, the salt from occasional storm surges will bypass or be flushed into wetlands or open areas and leave the soil usable. If you’re unlucky and salt incursions quickly become unmanageable and make the gardens unworkable, you thank your lucky stars you only have to find new garden areas rather than move tens of thousands of people into new housing. Saved yourself a few billion dollars there. Not so sure about orchard placement though. These areas between the city and the sea would also be restricted for some commercial operations as well. As much by expense for insurance and finance as any other consideration.

    The serious outstanding issue is where do you put the sewage processing plant, and how do you choose an area to set aside for replacement further from the current placement.

    1. Thank you Adelady for one of the most thought provoking postings I’ve seen hereabouts. A veritable pearl amongst the pig-poo. Maybe suggestions of what can be done will fall on less deaf earns than warnings of what shouldn’t be done. May I plagiarise you without mercy?

      1. Yes it’s a really great comment. An obligatory 6m line for schools would mean no schools east of a line somewhat west of Cathedral Square.

        This would render all property in this area virtually worthless (about 200,000 people affected) , which it almost is anyway.

        It’s hardly surprising the council are not acting on this kind of advice is it?

        1. I hate to break the news, but in a few decades or may be even years, a helluva lot of people will find that their investments are dog-tucker, on both a personal and community level. This is what the climate scientists have been warning of, though most of those warnings have fallen on deaf ears. We don’t handle decades into the future well, there are alway more pressing immediate problems plus those whose fortunes can be enhanced by selective deafness keep up a cacophony of distractions.
          Sadly, I think humanity will get what it deserves, or at least, our grandchildren will get what we deserve.

      2. Feel free.

        Looking at a couple of later contributions, remember 6 metres isn’t so much the issue. Drawing that line _somewhere_ is the issue. 2, 4, 5, 6m are all options. All have advantages and disadvantages.

        You don’t want to be like Los Angeles, with so many important facilities built directly on top of the San Andreas fault. Given the seismic instability of the whole area, you’d expect them to be close or not-as-secure-as-you’d-like. But right on top? When things go pear-shaped, having 10-15% of your fire engines and police cars lurching crazily and irretrievably into holes in the ground seems a bit too much like bad management.

        Same thing goes for SLR issues. You might not like having a hospital 10 mins or x number of kms travel further from where you’d really prefer it to be on a day to day basis. The big issue is whether it will fulfil community needs when it’s really desperately needed. And school gyms and church or community halls should not be the first to be inundated or otherwise unavailable. When people need emergency shelter, these are the places that are most useful.

  5. It would be refreshing to hear some factual information re sea level rise. Something less emotive and alarmist perhaps – something that is science based. In the meantime, an interesting recant from James Lovelock, who admits he was wrong re the extremes of climate change prediction…

    …Environmental scientist James Lovelock, renowned for his terrifying predictions of climate change’s deadly impact on the planet, has gone back on his previous claims, admitting they were ‘alarmist’.
    The 92-year-old Briton, who also developed the Gaia theory of the Earth as a single organism, has said climate change is still happening – just not as quickly as he once warned.
    He added that other environmental commentators, such as former vice president Al Gore, are also guilty of exaggerating their arguments.

    Read more:

    1. Bennydale, since you never agree with anything that is science based in the firstplace why asking for more science? You are like the guy in the forest with the chainsaw not seeing any trees….

  6. Thomas, it obviously hasn’t occurred to you that many people- including myself- find that attempted wide spread intimidation via scare stories – think An Inconvenient Truth – are an alarm bell that remind us of the classic observation by H L Mencken “The urge to save humanity is always a false front for the urge to rule it.” Hence Al Gore’s hysteria and stridency from green red utopians who habituate this site has become a big part of a lost cause and a losing game.

    1. Do you know what a non-sequitur is, Benny?

      And ‘a lost cause’ and ‘a losing game’?!? 😉

      Um… could you then explain why you’re here bothering to comment?

      Actually, please don’t – that was a rhetorical question.

      If you want useful scientific summary of where we’re at and what we can do about – and featuring lots of very pretty bits of NZ, to boot! – you could always spend an hour perusing Earth – the Operators’ Manual.

      (With a registered Republican!)

      Or you could not bother and carry on living in a world of uninformed, paranoiac darkness. Your choice.

  7. Macro
    “Then there is Ohope. One decent storm surge…..”

    I lived there in 1957 and learned of a storm surge in 1951, if I rember correctly. A resident told us any section on the beach could have been bought for a song afterwards.

    Before that I lived near Napier, traveling to school across land below sealevel, now all built over. I saw it after a cloudburst in 1955 – wheelbarrows floating round front lawns and some wit at the back of the bus yelling “Choose your sections now”.

    There are reclaimed lands all over the place. If there is one thing I remember from all the Sunday school classes I went to as a child, it is the parable of the man who built his house upon the sand versus the man who built on rock. I remember it every time I go near a sandspit development or a built over swamp or salt marsh. Though now I also think of the rocks coming down on Lyttleton.


    1. “I remember it every time I go near a sandspit development or a built over swamp or salt marsh.”

      Even dry as dust Adelaide has suburbs like this. Heaps of them along the Torrens “River” on the flat section down from the city to the sea. Apparently land agents and local councils don’t often mention that the previous name for this area was “Reedbeds”. The river, really a seasonal creek, didn’t ‘run’ to the sea, it just spread out over several sq miles of marshes.

      The number of letters to the editor after some wet weather about “This is the 3rd time we’ve been flooded in 10 years. Hrrrrmph!” would be laughable if it weren’t so sad.

      1. Yes Regional Authorities have a lot to answer for! One development I worked on at Ruakaka (south of Whangarei) was exactly like that. It should never have been zoned residential, but it was beside the sea and all the local council could see was dollars in rates.
        It was ex dairy farm, (why sell off with dairy prices going through the roof? well it was also “reclaimed” wetland and very wet – just over a metre above SL. It’s a long story – but the developers went bust – the consultants plan of twin lakes for storm water was a fizzer, so a $1m storm water drain had to be installed – and then! OMG! the sections were all peat! 3 m deep in some places and they all had to be excavated and replaced with compacted sand. How that storm water drain is going to work in a few years time is anyone’s guess. It has practically zero gradient, and of course I’ll bet the septic which linked into an already sluggish system will be – well “wiffy”.

  8. There is something quite sickening watching these pseudo scientists engaging in their publicly funded gabfest whilst the rest of us have to deal with real environmental issues at our own expense.

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