Planning for South Dunedin, but wait….

Received from Malcolm McQueen
Wed, 20 Apr 2016 at 8:44 p.m.

Planning for South Dunedin in the face of the rising sea level

The floods last year in South Dunedin have provoked discussion as to what are appropriate policies that Dunedin should adopt regarding planning for this area.
Concern that rising sea levels as a result of global warming brings urgency to consider this problem.
The area is low lying and even a modest rise in sea level may make the frequency of flooding a serious problem at some time in the future, possibly to the extent that the area becomes unviable as a residential area. A rise of 300mm may increase the danger of severe flooding to an unacceptable level.
A timely but not precipitate response is required. The cost of the response may be huge in both financial and social costs for the city if a solution such as “a retreat from the sea” is undertaken.

But predictions are predictions, they are not yet actual.

We are fortunate in Dunedin to have an accurate and reliable record of sea level. Indeed the safety record of our port attests to this. This record indicates that the sea level in Dunedin is rising at the rate of 130mm per century. Figure 1 shows the sea level as measured at Port Chalmers taken from the “PSMSL Data Explorer” And note that there is no observable increase in the rate of rise over time.
At this rate it will be 230 years before a 300mm limit is reached, well beyond our planning horizon, say 2100.

Figure 1. Sea Level measured at Port Chalmers via PSMSL Data Explorer []Figure 1. [click to enlarge]

However, claims are made that the rate will greatly increase and so pose a threat that we must consider immediately. But note that in order to reach a 300mm rise before 2100 the rate of sea level rise would have to increase by a factor of 270% above that currently observed.
It would be irresponsible in the extreme to undertake extreme action without carefully examining the validity of the claims.
We must consider if and when a response is required. What reasons do we have to expect such a catastrophic rise?

I address four points as to why I do not consider the predictions of catastrophic sea level rise to be well founded.

Validity of predictions

1) As discussed above, the available sea level data gives no indication of an impending catastrophic sea level rise.

2) Rising sea levels are a claimed consequence of rising temperatures. Thus for the prediction of rising sea levels a precondition is that temperatures should be rising. That this should be so is confidently accorded to by the IPCC. However, reality is not quite so simple.
Figure 2 shows the average temperature as recorded at the Musselburgh Pumping station by NIWA in its CliFlo database.

Figure 2. Average temperatures at Musselburgh []Figure 2. [click to enlarge]

Although this is a local measurement and rising sea levels are claimed to be a consequence of rising global temperature, the absence of significant warming and no evidence for any increase in the rate of warming must cast doubt on predictions of imminent catastrophic sea level rise.

3) The track record of predictions regarding climate change does not give rise to confidence in the validity of those predictions.
For instance in 2007 the Australian Climate Commissioner, Tim Flannery, claimed that Sydney was “facing extreme difficulties with water”, in 2008 that: “The water problem is so severe for Adelaide that it may run out of water by early 2009.“ and others regarding an endless Australian drought.
These claims were influential in the decision to construct desalination plants in Australian seaboard cities at a cost of about $10 billion. His predictions have not come true, the drought broke and the plants have not been needed. This expense is probably not a complete waste as the plants do provide insurance against future droughts which are sure to occur.
Other predictions that have been made:
– from the UN in 2005, “50 million climate refugees by 2010”
– from Dr David Viner, of University of East Anglia, who confidently asserted that within a few years winter snowfall will become “a very rare and exciting event”.
– and many others too numerous and many too silly to comment on.
All these predictions have failed to eventuate.
I suggest that we should not take at face value the predictions of claimed experts without corroborating evidence such as trends in the historic record or the success of previous predictions.

4) Sea level rise is largely due to melting of continental ice sheets exceeding their gain from snowfall. This is not an easy measurement to make accurately. It has been assumed that melting exceeds accumulation thus contributing to sea level rise. However, recent satellite measurements by NASA cast this in doubt. In fact they indicate that the opposite is the case.


It is critical that we should have a high degree of confidence in the predictions of sea level rise before committing ourselves to very expensive and socially destructive remedial or mitigation policies.
The issue at hand is not one of the reality or otherwise of global warming, we need make no commitment on that issue before deciding the fate of South Dunedin. The climate has changed over the millennia and will continue to do so. The issue is the making of a timely and appropriate response to its flooding problems.
The points I make above are intended to show that the confidence in alarmist predictions is misplaced and are insufficient in themselves to provide a sound basis for planning.
It is clearly unnecessary to address this problem immediately but continued attention is required so that appropriate actions can be taken if the situation is observed to change.

Fortunately in New Zealand the data relevant for making decisions such as that posed by planning for South Dunedin’s future is publicly available and of high quality. Citizens should avail themselves of this the opportunity of consulting the data themselves to draw their own conclusions rather than rely on second hand interpretations.

“You don’t need a weatherman to tell which way the wind blows” Bob Dylan.


█ For more, enter the term *flood* in the search box at right.

Posted by Elizabeth Kerr


Filed under Climate change, Democracy, District Plan, Dunedin, Economics, Geography, Infrastructure, New Zealand, People, Politics, Property, Proposed 2GP, Public interest, Resource management, South Dunedin, Town planning, Urban design

11 responses to “Planning for South Dunedin, but wait….

  1. Elizabeth

    Interesting timing Malcolm, since our beloved Mayor is today [at ODT on….. MUDTANKS] casting about and not looking at himself and his political cohorts before stupidly apportioning blame to others…. for the flood of June 2016.
    Embarrassing for council management (who produced the infrastructure report) and the business he thinks to fry.

    It fails to get much worse.

    Election Year.
    Save South Dunedin by allowing it fair and competent representation. Amen.
    May accurate data and balanced interpretation, as you say, win the days/years ahead.

    ODT: Mud-tank contract ‘dual failure’ – Cull
    ODT: Flood report findings ‘no surprise’ to residents

  2. Elizabeth

    Bloody Hell. Even the sainted Royal Society is submerged by CC propaganda/drivel.
    Lies lies lies and more lies.

    ### 8:49 am on 19 April 2016
    RNZ News
    Sea level rise threat to NZ coasts
    By Eric Frykberg – Wellington Newsroom
    Climate change could swamp significant areas with even modest rises in sea levels, a report by the prestigious Royal Society of New Zealand says. Places at risk include eastern Auckland along Tamaki Drive, where a 0.5 metre surge would inundate popular areas. The following map shows the damage from sea level rises of several gradients between 0.5 and two metres.
    Coming from New Zealand’s pre-eminent research body for science, the report confirms the severity of the local threat posed by climate change. Chair of the expert panel which wrote it, Professor James Renwick, said New Zealanders were particularly vulnerable.

    Read a summary of the report here.

    “Many New Zealanders live on the coast and two-thirds of us live in flood-prone areas,” he said.

    In South Dunedin, a high water table meant high tides would lead to frequent surface ponding and a lack of drainage for storm water.

    The report added that the east coasts of both the North and South Islands were sensitive to erosion and inundation caused by climate change.
    The Royal Society’s warnings come just a day after New Zealand was accused of cheating over its main climate change weapon, the Emissions Trading Scheme.
    In its report, the Royal Society broke down its analysis into several key areas. One was the effect of climate change on coastal environments. Depending on how greenhouse gas emissions were managed, the sea would rise between 30 centimetres and 1.1 metres by 2100, it said. This would have an exponential impact, making it likely the current one-in-100-year extreme sea level event would occur every year in some places and making storm surges much more potent. Ponding and soil saturation from previous floods would aggravate the effect.
    Read more

  3. Hype O'Thermia

    “the sea would rise between 30 centimetres and 1.1 metres by 2100”
    If it starts this week it will have to rise between 3.57mm and 13mm (average) per year.
    Currently the Dunedin readings are lagging well behind.
    Perhaps it won’t start till, say, 2130.
    Then it will have to rise between 4.28mm and 15.7mm (average) per year.
    And so on.
    Perhaps it will start off rising gently, then accelerate until one may go to the seaside one day and find that the tide is coming in – and in – and in, and doesn’t go out.
    I wish they would be a bit more specific about these things. What about us careful people who park well above the high tide level, are we liable to find our Kias and Toyotas drifting out to sea, into the path of passing cruise liners?

    • Hype O'Thermia

      Another thing they don’t say – or perhaps they do but it’s not reported in mainstream media – is what happens next.
      Will the “rise between 4.28mm and 15.7mm (average) per year” continue past 2100? For how long, approximately?
      And what of the alternative I was pondering, above – starts off rising gently, then accelerates? Does it cease in 2100, according to the models on which predictions are based?
      These are not trifling matters to consider. A couple now, perhaps at last settling into their own home and contemplating starting a family, could reasonably expect their child to still be alive in 2100 – but would they want to inflict such a fate on someone who by then would be elderly and quite likely to have difficulty running uphill from rapidly rising sea?

      • Elizabeth

        Uh-oh. Don’t tell me the all-protective farsighted climatechangers are being shortsighted and ad hoc about our collective trajectory to doom. Not telling us the whole story is punishable by death, but (in the fine print) it doesn’t specify drowning, or athleticism.

      • ab

        A songe in future shock: Then we will be called/what we have always been called/ The Folks Who Live On The Hill.

        (don’t talk to me of The Hill, son, two doctors sent me there).

  4. Calvin Oaten

    Again, just repeating verbatim the out of date utterings of the IPCC. These people in the Royal Society are plagiarists with not a single bit of empirical input whatsoever. Throughout the Tertiary area this slack approach is prevalent. Disgusting.

  5. ab

    Actually, you Do need A Weatherman. A man from the Weather Underground. Dylan was not singing about the forecaster.

  6. Elizabeth

    It’s a religion with Zealots. Hosanna….

    WHAT IMMACULATE HOPE —Bah, let’s press ‘atheism, agnosticism, religious dissidence, and secular humanism’ for the safety of our environment from they CCers.

    Fri, 22 Apr 2016
    ODT: Climate-change remedies promoted
    Just under 700 people turned out to hear “climate change guru” Prof Tim Flannery at the Regent Theatre last night. Prof Flannery’s talk, labelled “Atmosphere of Hope”, outlined how quickly the planet was warming and suggested possible remedies. The Australian commissioner for climate change and former Australian of the year was reluctant to say climate change could be stopped completely.

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