The ABC reports – Perth’s Kwinana Freeway will be permanently flooded by 2100, oceanographer warns – In 2012 I blogged To understand Perth sea-levels is a complex issue – much of the Perth plain has subsided in recent decades
Just as well it happened near low tide or it could have been blamed on rising sea levels. Similar happened in 2011. Sinkhole swallows car, caravan at campsite near Queensland’s Rainbow Beach
Recall that about a month ago I posted – No evidence of warmer summers from Wollongong City Council swimming pool attendance figures
At that time I emailed Wollongong Council to ask about historic survey data re heights of their ocean pool walls – for my questions click on more below. Just got a reply saying – [Thanks for your enquiry. Unfortunately information on height of walls with respect to historical mean sea level is not available.
Any actual effects on the utility of pools have not been observed other than storm impacts.]
If anybody has ideas to access historic coastal survey data? Must be data in archives – I am sure our pioneers measured and recorded exactly where they were and where they built things on the planet. Continue reading Wollongong Council says sea level rise not affecting utility of their coastal swimming pools
I saw this news about repairs to the ocean pool at Austinmer north of Wollongong. I have been interested for a while in the issue of the height of the oldest ocean pool walls and how they might relate to historic survey heights and modern survey heights – on the basis there should be another line of evidence here establishing the rate of sea level rise over a century or more.
Wollongong City Council have www page about their pools and there is a downloadable 9 page pdf report – Future of Our Pools Strategy 2014-2024 –
I thought – surely there must be comments here about sea level rise. Not so – not a word about sharks hoiking themselves over the walls during King tides and carrying off the odd swimmer. But I noticed this gem at the end of a string of bullet points on page 7 –
And earlier in the report was this graphic showing declining attendance figures –
All seems logical to me.
by Dr David Kear (former Director-General, NZ DSIR; United Nations consultant; & South Pacific geoscientist)
I remember Dr Kear as Director of the NZ Geological Survey when I was at University in the early 1960’s – hence my interest in his article now.
“Climate Change” has become an important international topic – one might almost say religion. It began life as “Global Warming”. So very many people, including politicians and “news people”, appear to have been overwhelmed by it, and have led others to believe, and follow the doctrine. It has sponsored a good deal of international co-operation, which can only have been good.
However, the cost of “Combating Carbon” has been extremely high, and the debt and economic consequences are being passed on to present citizens, and, worse still, to future generations, including all our grandchildren. This booklet 180KB pdf – attempts to raise, in citizens’ minds, questions regarding the enormous sums of money and effort being wasted on this topic.
The ABC report –Victorian Government ‘not happy’ about extension to Lindsay Fox’s Portsea property – for the uninitiated Mr Fox is a well known trucking magnate.
I quote – “The high-water mark has fallen in recent years,…”
Perhaps the Mornington Peninsular is rising? I have not heard.
Hoping an informed reader can cast some light.
I like the idea the Victorian Govt is furious with something – shows a sign of life I suppose.
I came across this paper at the end of last year – hoping to obtain a pdf copy or find a library with a hard copy of the journal – or maybe a reader could scan the 14 pages.
Anyway, it is worth a post just for the title alone – particularly in view of recent publicity about subsidence in the Perth area.
See my post from last December.
To understand Perth sea-levels is a complex issue – much of the Perth plain has subsided in recent decades
Just came across this under-reported gem from Geoscience Australia, I note their disclaimer – “…the length of the time series is too short for reliable vertical station velocity estimation….”
As the years roll on these data should become more reliable guides as to the changes in tide gauge heights. But what they show so far is worth reporting.
Cook Islands – steady
Fiji – steady
Kiribati – down
Manus Islands (PNG) – down
Micronesia – down
Nauru – down
Samoa – steady
Tonga – up
Tuvalu – steady
Vanuatu – down
Marshall Islands – data too short
Recent media publicity around a “State of Australian Cities” report has beaten up claims that Perth sea-levels are rising at three times the global average, or near 10mm per year. A matter that Federal Infrastructure Minister Anthony Albanese described as “disturbing and extraordinary”. Chris Gillham shows that the claims in the State of Australian Cities report re Perth sea level rise are over-hyped.
This chart fom a 2010 WA Govt planning report shows long term sea level changes at Fremantle.
The State of Australian Cities report concentrates on shorter term more sensational trends in the last 20 years but omits to quote recent research measuring rapid subsidence of large areas of the Perth coastal plain.
A 2012 paper – Anthropogenic land subsidence in the Perth Basin: challenges for its retrospective geodetic detection – says subsidence at Gnangara for the 14 years 1997-2011 has averaged 4.6mm per year – see Table 1 below.
In recent decades subsidence has been worsened by increased drawdown ground water for Perth water supplies – a process which has eased post 2005.
This online chart shows CGPS readings from the Hillarys tide gauge installation and indicates steady sinking of ~3mm per year 2006-2012. There are no CGPS readings I can find from Fremantle.
Hillarys has CGPS data from 1997 and Featherstone et al say those data – “…are not in a form that can be readily analysed in a short time frame, particularly because of the multiple equipment changes that make the time series very discontinuous.” Other published versions of the Hillarys CGPS data quote a 1998-2009 subsidence averaging just over 5mm per year. Watson PJ – Is There Evidence Yet of Acceleration in Mean Sea Level
Rise around Mainland Australia?
Journal of Coastal Research, Vol. 27, No. 2, 2011
Featherstone et al 2012 discuss surveying to detect level changes and say – “There is some scope for detecting subsidence in the Perth Basin if levelling is repeated now or sometime in the future. However, the costs are likely to be prohibitive.”
I fail to see how a few repeat levelling traverses from the Darling Ranges to the coast costing what ? – a few $million ? – should be beyond the wealth of a First World nation like Australia. Apparently some traverses were carried out in the 1980’s.
There is no shortage of Govt grant monies to waste on shonky Greenhouse inspired “research”.
Tide gauges and harbours are often located in places where the crust is sinking due to say sedimentation from a river. Any harbour structure attached to piles will slowly sink into the muddy substrate over the decades – factors like traffic vibration, a century of ships banging into piles – all can contribute to piles sinking. Dock areas where tide gauges tend to be installed are often the sites of reclaimed land, Auckland is an example. This tends to quietly settle for decades which can confound tide gauge data. At Fremantle 150 years of urbanization – including storm-water drainage direct to the sea – can lower ground water levels and cause subsidence – quite apart from deliberate ground water harvesting.
The claim of a 6cm per decade rise is from their 1990 Executive Summary.
Note on the graphic 2012_rel4: Global Mean Sea Level Time Series (seasonal signals removed) – from this IPCC compliant Org – the claimed rate from adjusted satellite data is only 3.1mm per year – HALF of IPCC 1990.
But there is more – checkout the new Jo Nova article – Are sea-levels rising? Nils-Axel Mörner documents a decided lack of rising seas. Nils-Axel Mörner says the unadjusted satellite data show negligible trend and in his new pdf paper SEA LEVEL IS NOT RISING – has this stunning graphic.
So the rate of sea level rise is just an artifact of IPCC compliant adjustments.