Click photo to enlarge
Water lapping over the Forsyth Barr Stadium site, parts
of Portsmouth Dr under water and roads crumbling into the sea
on the Otago Peninsula - it is a grim picture painted by a
University of Otago climate change model.
And according to experts, the first signs of climate change -
which some scientists fear could bring a sea-level rise of up
to 1.5m over the next 90 years - may already be emerging in
Dunedin.
Otago Regional Council records highlighted a significant
increase in the intensity of rainfall events in the past
decade, resulting in more flooding within the city, ORC
strategy manager Mike Goldsmith said.
However, the data also showed the overall amount of rain
falling on the city was declining, even as the one-off events
intensified, he said.
There had also been a noticeable drop in the number of frosts
across Otago since 1953, and an increase in the number of
days with temperatures over 25degC, he said.
The changes were consistent with climate-change predictions,
although it could not be confirmed and could yet prove to be
"natural variation", he said.
"That's what's predicted to happen and that's what has
happened over the last few years," he said.
Tidal-gauge data from the Dunedin harbour basin also showed
the sea level was already creeping up at a rate of 1.3mm a
year, according to University of Otago professor John Hannah,
of the national school of surveying.
The rate, based on measurements dating back to 1899, would
equate to just a 12cm increase in Dunedin by 2100, but the
pace was expected to increase, he said.
There were no signs yet the rise was accelerating, but a
University of Otago masters student planned to study that
next year, he said.
Prof Hannah said he, like many climatologists, expected
sea-level rise to speed up as ice in Greenland and the
Antarctic melted more quickly, but a 1.5m rise by 2100 might
be "a little speculative".
He was more comfortable with the latest predictions by the
Intergovernmental Panel on Climate Change (IPCC) in 2007,
which predicted a 0.6m rise by 2100.
University of Otago geochemist Abigail Smith, of the marine
science department, said a computer model she helped develop
highlighted the challenges the city might face.
It showed a 1.5m sea-level rise left unchecked by engineering
or adaptation would have a dramatic affect on parts of the
city's coastline, swamping Portsmouth Dr and the harbour
mouth of the Water of Leith, where the Forsyth Barr Stadium
was being built.
Carisbrook Stadium Trust development director Darren Burden
said the stadium's floor was designed to cope with climate
change and wild weather, with a minimum floor level of 3.7m
above mean sea level.
That meant a 1.5m rise in sea levels would still leave the
stadium floor 2.2m above the water level, and underground
features - such as piles and drainage pipes - were also
designed to handle flood scenarios, he said.
chris.morris@odt.co.nz
The real lesson
The real lesson is that modelling based on uncertain knowledge and/or past conditions is not sufficient for definitive predictions. If only those predicting catastrophic climate change based on models constructed on similar uncertainties would learn the same lesson.
A lesson not learned
Farsighted-
I would have thought the real lesson is to be skeptical of all media and blog reports on climate science especially those relating to contarian views. Do you acknowledge that you had your facts back to front on this one?
Revisit
Perhaps we could revisit these model-based predictions in light of the retraction of the paper which confirmed the conclusions of the IPCC 2007 report
Yes, but it doesn't get any better
Farsighted, you need to get your facts straight. The IPCC 4th Assessment Report predicted sea level will rise between 18 to 59 cm by the year 2100. The retracted study examined how sea levels have changed over the past 22,000 years in response to temperature change. The authors used the results to predict sea level rise between 7 to 82 cm by the year 2100 for various warming scenarios. A more recent study (available here) using similar methods estimated sea level rise of 75 to 190 cm by 2100. The letter accompanying retraction (available here) thanks the authors of the more recent study for finding the errors that led to making sea level predictions that were too low.
Rising sea will pose threat to Dunedin
I think we should get John Key, Gerry Brownlee, Nick Smith etc as well as other eminent politicians of the previous government to together visit the foreshore of Dunedin at low tide.
Then as they stand at the half-tide mark and the tide begins to rise they can pass legislation, promise higher taxes, mortgage our future to a useless carbon trading scheme and do whatever else their political powers (and in NZ those powers are far too generous) allow them to do, in order to forbid the tide to rise any further.
This has been tried before and it failed, but nowadays humans control the planet (and the solar system), right?
Sleep secure in your beds, Dunedin.
Any significant change in the sea level will be due to normal tectonic plate movement and the City of Dunedin is more likely to rise (or fall) than the sea level is to change.
Read this link which reviews the latest survey of things in Antarctica (whose ice needs to melt if the sea level is to change measurably)by the Scientific Committee on Antarctic Research (SCAR)
http://www.powerboat-world.com/index.cfm?nid=64259
Of course they blame the lack of warming on the hole in the ozone layer. However, they don't explain the mechanism of this (very scientific).
Well, once one considers the Medieval Warm Period when the temp was higher than now and there was no human industry to increase CO2 in the atmosphere it dosn't take a lot of logical thinking to realise what a crock we are facing with Global Warming.
Lets put our tax money where it will save the planet - and it does need saving!
Ruining our economy running after the friendly lifegiving gas CO2 will not effect the planet in the least.
High and dry or all wet?
Roger-
I would be fascinated to learn where you got the information to be able to conclude: "Any significant change in the sea level will be due to normal tectonic plate movement and the City of Dunedin is more likely to rise (or fall) than the sea level is to change."
Tectonic plate movement etc and sea level
What I am trying to say is there will be no unusual change of sea level in Dunedin because of the current perceived danger from global warming.
ref Singer S. F. 1997 "Hot talk, cold science, Global Warmings unfinished debate" The Independant Institute.
Douglas P C 1992 Global Sea Level acceleration. Journal of Geophysical Research 97 12699-12706.
Cabanes, C, Cazenave, A and le Provost. C2001: Sea Level Rise during the past 40 years determined from satelite and in situ observations. Science 294: 840-842.
Any change in sea level, should any significantly occur, will therefore be from natural tectonic volcanic or post glacial rising etc.
But, as I have mentioned before, global warming theorists have no answer to the fact that the current global warming (which may have already peaked) is still within the normal fluctuations of global temperature, three of which are well documented in recorded history eg the Medieval Warm Period.
What all these previous warmings have in common is that they occurred when there was no human influence on atmospheric CO2 levels. Therefore any attempt to blame the current warming on CO2 simply cannot standup to scientific scrutiny, or even convince a layman.
Also global warming is not even proven to affect sea levels. If the climate warms, there is more evaporation and more precipitation, much of which will fall at the poles as snow.
This takes water out of circulation and may more than compensate for increased melting at warmer latitudes.
Suggest you bone up on Antarctic temps and ice thicknesses in Greenland.
Satellite data confirm sea level rise due to global warming
Your information is out of date. You can download a more recent peer-reviewed paper on sea level using this link. It reports that sea level rose an average of 3mm/yr based on satellite data over the period 1993-2003.
About half of this rise can be explained by thermal expansion and half by melting of glacial ice - both are consistent with global warming.
Mike Palin
I am impressed that you studied the references I sent in detail.
However you have missed the point I have emphasised in all my comments.
There is no connection between global warming and CO2. This is because we know from recorded history that the planet has been this warm before and probably warmer, and we also know that there was no significant production of CO2 by humans during that time.
Therefore the chance that this warming is due to human induced CO2 is very unlikely indeed.
So unless you can explain the link between CO2 and global warming taking into account the Medieval Warm period, Roman Warm period, the Minoan Warming and the cold periods in between, of which the last one ended early in the 19th century, I suggest that you start preparing for global warming in practical ways, like buying farmland at higher altitudes as it becomes productive and forgetting biofuel as the growing of it is causing food shortages as we speak, and concentrate on the real issues which we need to carry out in order to preserve our planet.
I think it is pointless to quote IPCC and associated publications because they have too much invested in this hoax to do anything else but to try and support it.
However, tectonic movement etc does have a very significant effect on apparent sea levels.
See Nunn P D., Ollier, C Hope, G., Rodda, P, Omura, A. and Peltier, W.R. 2002 :Late Quaternary sea level and tectonic changes in northeast Fiji, marine geology 187:299-311.
I remember on TV the shot of the Fijian girl at Copenhagen telling how her island was a victim of rising sea level. More likely her island was sinking, so I think she was at the wrong conference.
Al Gore predicts a 6 metre rise in the near future. At 1.8mm/yr suggested by the IPCC that would be in 3300 years. And you buy this?
Connection between global warming and CO2
It is very difficult to maintain the argument that human induced CO2 causes global warming when we look at history and realise that the planet has been this warm and even a few degrees warmer, several times in recorded history when there was simply no human induced CO2 in the atmosphere.
Indeed these warm times seem to have some correlation with increases in human population and general prosperity. Even the Roman civilisation was possibly aided by the warmer weather of the time and interestingly declined during the cooling of the dark ages.
your views lack support
Roger-
When you "look at history", where do you go for your information on past global temperatures and atmospheric CO2 levels? I ask because none of the most recent peer-reviewed sources of data that I am aware of support your case.
Reclaimed land
So, the greatest threat to the city relates mostly to land that was reclaimed in the last century? Perhaps the researchers could let us know what the impact of a breach in the coastal dunes at Kettle Park would imply for the formerly low-lying swamp that is St Clair/St Kilda/South Dunedin? And perhaps give some (peer-reviewed) indication of which event is more likely - inundation due to sea-level rise or coastal breach?
Sea level rise maps
There are a bunch of intercative maps available that let you explore for yourself - for example that map shows a 1m rise starts to flood small parts of South Dunedin (remember it's all sand). Probably more of an issue for Dunedin though:
You have to take these maps with a grain of salt since they're only accurate to a metre