This paper gathers together information that is relevant to the condition of Christchurch, New Zealand. It raises some `home truths' that will be unpalatable to many, particularly at a time so close to the recent series of tragic events.
But as a Christchurch-born boy I feel I have a duty to drag these harsh realities into the open; to discuss The Emperor's Clothes. So, before you shoot the messenger, please listen to what he has to say.
Introduction
As the dust begins to settle on another devastating earthquake in my dear hometown, the clamour to resume business as usual and rebuild something new and `iconic' on the rubble of the old is gaining momentum.
Our government is struggling to find the money to help restore the city to its former glory, especially with the multiple hits of the earthquakes on top of the generally depressed economic conditions nationally and globally.
Deep down I'm sure the decision-makers know that they are going to have to be very careful with every penny that is spent on Christchurch.
The city is proud of its heritage. The combined European and Polynesian presence has left its mark on place and history stretching back atleast 800 years. If we are to build a new and more resilient city then we must look for a place and manner of community function that has a genuine potential to provide a future at least as long as the city's noble past.
We must use the knowledge we have of the state of the world today to must ensure that what we re-build today will be of service to our children, and to their children for many generations; to ensure that our efforts will reap the same rewards that we enjoy today from the efforts of our forefathers many centuries ago.
Among the mud, dust and rubble of this trembling town there are many spirits stirring. Some will urge us to take swift and decisive action with the risk of repeating many of the errors of the past; others, three in particular, will demand of us the utmost strength to think deeply of them, and to find the courage to make very hard choices based on what these spirits tell us.
These three sleeping spirits stand on each other's shoulders; each reinforces the effect of the ones beneath as time passes.
The first spirit will awake and open its eyes in a time frame of years, perhaps months. Its name is FIRE.
The second spirit raises its head in a time frame of decades, perhaps years. Its name is FOOD.
The third spirit bares its teeth in timeframes of centuries, perhaps decades. Its name is FLOOD.
FIRE
To support in just a few years the building of a third of a city that has taken 150 years to build before will require a significant amount of energy. That first build and work to date was enabled by the fire of cheap readily available high-density energy; first coal, then oil.
In one of its many increasingly blunt statements about the global energy predicament the International Energy Agency stated in 2009 that "…global oil supply is expected to decline at about 6.7% per year from its peak in 2008."
This means that by 2020 the theoretical oil supply for NZ will be only 55% of the 1990 level. That's the IEA, and they should (and do) know.
The recent Parliamentary Research Paper The next oil shock? restates warnings by other agencies that: "…another supply crunch is likely to occur soon after 2012 due to rising demand and insufficient production capacity…"
The report Peak Oil Vulnerability Assessment for Dunedin (Dr Susan Krumdieck et al.; 2010) notes that: "The peak and decline in world oil supply will be a driver for long-term fuel consumption reduction to around 50% of current levels by 2050. The possibility of fuel shocks will be ever-present."
Comment: These are not idle threats to our way of life; these are plain realities that we ignore at our peril. Sometime soon we will have another oil price spike and within the next 10 to 40 years (2020 to 2050; that long, if we are so lucky) global supplies of conventional oil (the stuff we use to rebuild cities with and to take Johnny to school with) will be down to 50% or less of today's level.
This will impact not only on the choice of urban form for a rebuilt city but also on our ability to move food supplies long distances, and to obtain materials for the production of essential manufactured goods and agricultural efforts.
The FIRE is flickering now, and it will surely die.
FOOD
Christchurch's new town will continue to rely on the production of its rural hinterland as the cornerstone of its economic wealth and reason for being. How viable is that production? Remember that by 2050 for sure we will be fortunate to have perhaps half the oil for transport, agricultural chemicals and production that we do today. We will `eat local', or we will not eat at all. What else can go wrong with our ability to feed ourselves in Christchurch?
Refer to the New Zealand Ministry of Agriculture and Forestry: The EcoClimate Report - Climate change and agricultural production. http://www.maf.govt.nz The EcoClimate report presents projected changes based on the Intergovernmental Panel on Climate Change (IPCC) third and fourth assessment reports.
Figure 7: `Projected changes to the frequency of droughts' shows the projected driest annual conditions in the 2080s under (a) low medium and (b) medium high scenarios for conditions that currently occur on average once every 20 years.
This Figure shows Canterbury experiencing once every 20-year drought conditions every 5 to 10 years under the low medium scenario and every 2.5 to 5 years under the medium high scenario.
Comment: So, bearing in mind the necessarily conservative approach adopted by the IPCC, it is virtually certain that Canterbury will be experiencing once-in-20-year drought conditions every 5 to 10 years by 2080, possibly as frequently as once ever 2.5 years.
The eastern areas of New Zealand have already had samples of these conditions, and the Ministry's report confirms that these dry conditions will continue to arrive with increasing frequency. Agriculture (particularly with low energy inputs) will be hard to sustain as Plains dry out. 2080.
Because, by 2080, the Earth's atmosphere and temperature will not yet be in balance with the climate-altering forcings we have imposed, these conditions in Canterbury will continue to get worse for some considerable time beyond 2080.
The absence of readily available or affordable oil for transport, agri-chemicals, fertiliser, and energy for irrigation will make it very difficult for Canterbury to sustain a form of agriculture that will provide local food to a population of four to five hundred thousand people.
Agricultural production will be in dire straights, as will one of Christchurch's main reasons for being. In Christchurch by 2080 the combination of the energy situation and the increasing frequency of drought conditions will mean that FOOD will be hard to find.
FLOOD
If we are looking at local food supplies, then the most productive land (before much of it was filled over for housing – Bad move!) was on the coastal soils including Marshland and in the rich soils of the valleys of the Port Hills (Watch that rock-fall!). In common with all coastal cities, Christchurch has to consider the impact of sea level rise on its plans for investment in the development of the repaired town.
Hansen recently suggested that a 10-year doubling time in the rate of ice sheet melting was plausible; pointing out that such a doubling time from the current observed base of 1 mm per year ice sheet contribution to sea level in the decade 2005-2015 will lead to a cumulative 5 metre sea level rise by about 2095. Hansen has found that actual data points to a shorter doubling time of around 8 years.
Comment: The steps into Christchurch's Cathedral are at 6.197m above mean sea level, or less than 5 metres above high tide.
So by the Year of Our Lord 2100, high tide will see ocean fish nibbling the Cathedral's altar cloth and the coastal strip containing the premium market gardening soils will be awash. By 2200 AD with at least 10 m of sea level rise Captain Cook will be right, its 'Banks Island' not 'Banks Peninsula'; Lyttelton Port becomes inaccessible from The Mainland and two-thirds of present-day Christchurch City is reclaimed by the sea. 200 years is barely the duration of European association with the Cathedral City. Not long. Certainly not long enough.
With the absence of cheap oil that will be evident by late in the century our ability to transport food and commodities long distances will be compromised, and drought conditions will make it difficult to produce sufficient food to meet the local demand of a large city. Rising seas will by 2100 have inundated prime coastal market gardening areas further exacerbating the food supply situation, as well as taking over a third of the existing urban area including most of the parts of Christchurch which have suffered the worst effects of liquefaction in the recent earthquakes.
The sea will rise faster and faster over a number of centuries until the amount of grounded ice left to melt begins to decline significantly.
As James Hansen declared in his 2008 testimony to Congress: "No stable shoreline would be re-established in any time frame that humanity can conceive."
Sea levels will eventually stabilise when all the ice that there is to melt is melted, and the seas have risen about 75 metres, plus a bit for thermal expansion. Rangiora and Rolleston will be gone, and Dunsandel and Ashburton will be seaside towns perched on the 15 metre high eroding sea cliffs of the shrinking and desolate Canterbury Plains.
By late in the century the lack of oil-powered transport and construction equipment will mean that it is impractical to consider building any sort of barrier to the rising sea (after all it would have to be built by hand), and the inevitability of continued sea level rise for centuries makes any development or reconstruction within the long reach of the rising ocean a temporary arrangement at best, and a criminal waste of the effort, money and resources used in its construction at worst.
By 2100 the sea's inroads will confirm that the continued habitation of what is currently Christchurch City is unwise, and indeed pointless.
In time FLOOD will wipe clean the slate that was Christchurch.
Conclusion
We have lit the fire and consumed the oil, the burning of the fire has changed the climate, the changed climate is bringing the heat and drought, and the heat is melting the ice that is filling the oceans.
Within the next couple of years the all-sustaining fire of cheap energy is going to flicker, and oil (and all it means for us) will be beyond our economic reach within 10 to 40 years. In particular the city’s ability to source staple food supplies from long distances away will be compromised; the principal source of food will have to be that grown locally. Two years to perhaps 40 years, if we're lucky.
Over the next 60 to 70 years progressively worsening drought conditions on the Canterbury Plains will become so extreme that, in combination with the lack of oil supplies to support drought-tolerant agricultural production, the overall viability of large-scale commercial food production will be suspect. 60 to 70 years, and it will not get better.
Within the next 50 to 100 years the progressive and inexorable rise in sea levels will become evident as coastal areas are inundated. By 2100 the surf could be running through Cathedral Square. The sea will continue to rise and "...No stable shoreline would be re-established in any time frame that humanity can conceive".
These are the realities that a local view of the much-discussed impacts of resource depletion, climate change and the inevitable and progressive rise in sea levels will have on the existing city of Christchurch.
Over our lifetimes and the lives of our children and grandchildren these impacts are – as far as we are concerned – inevitable and unavoidable.
So Where and How for Christchurch?
The changed climate is expected to give rise to more floods in the rivers over the plains. Perhaps a modest new city in the foothills at the top of the plains watered by gravity fed canals from the great rivers may be a possibility.
The hills above Timaru will eventually be the best harbour on the edge of the plains, and the downs there may become a safe haven if water supply can be assured.
But whatever the solution we have a marvellous opportunity to take part in a consciously joyful process to re-establish a meaningful and viable city that can look forward to a future at least as long as its past. To achieve that we must bring the talents of the entire community to bear on the realities that confront us.
We must ask: “Where is the best place to apply the effort and money we are planning to spend rebuilding Christchurch?” Sadly, one place is sure; NOT Christchurch.
We have no time and no money to loose. The informed community must debate the final answer to that question before any more money is wasted.
With the right outcome from this debate we can look forward to the best and most meaningful times of our lives.
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