Sydney Harbour sea levels rise less than 1 mm since 1886
Cairns residents living on the coastline need not worry about going under water. You will have to wait for a few millennia. The $20 million given by the Federal Government to Torres Strait islanders for the construction of sea walls, ostensibly to keep out sea water from an alleged increase in sea levels is perplexing. Have the islanders investigated the natural geological occurrence of sinking islands?
Measuring sea levels
Posted: 22 Nov 2015 – by Don Aitkin
This is my last foray into the SCM document on ‘climate change’ that I have investigated twice before, here and here. But before I get into it, readers in New South Wales will have noticed that the Government of their State has issued drafts of a new approach to how local government councils should determine building regulations for coastal communities. The new approach simply ignores the IPCC’s predictions of rapidly rising sea levels. The Minister’s press release says: Since the original Coastal Protection Act was enacted in 1979 our understanding of coastal processes has improved dramatically. We know our coastline is not a fixed object, but a dynamic, ever-changing environment with a range of natural processes.
The new approach has a three-month consultation period, and my guess is that the Greens and others who believe in the orthodoxy will run a campaign against the draft. I hope the Minister is confident and determined. He would gain some support from a droll speech intended to be given by our PM at the Paris meeting, and written by Geoff Derrick, a sceptical geologist. You can get it from him at geoffd. Derrick includes a graph displaying the trend in sea-levels in Sydney Harbour over the period 1886 to 2010.
As you can see there are highs and lows, but the outcome is a tiny increase over a century and a quarter. The Sydney region is geologically pretty stable, and there’s not much sign of anything dramatic there.
OK, on to the SCM paper, or, for newcomers, a paper by the Société de Calcul Mathématique SA in France entitled ‘The battle against global warming: an absurd, costly and pointless crusade’. What interests me about the long paper is that it is mostly directed at problems of measurement, and it assembles those problems in a succinct and accessible fashion. The paper points out, once again, that we don’t have a lot of accurate data that extend over time. If one wanted to make a case that the oceans were raising at a faster rate (than when?) one would need a good deal of data over time. We just don’t have it.
What we do have are tide gauges and satellite estimates. The gauges don’t go back past about 1800, and the satellite measurements start in 1992. It is estimated that the end of the last ice age, say 20,000 years ago, was followed by an irregular melting of ice, which increased the height of the oceans by about 120 metres. That’s an average of about 6.6 mm a year. That process stopped several thousand years ago, and since then there has been a much slower increase. Tide gauges put it at about 1 mm a year, the satellites at about 3 mm a year. Given that tidal changes can run at metres a day, that a warming sea will increase in volume and thus rise, and that the Antarctic and Greenland ice melts vary in output over time, to be able to say with hand on heart that sea-level rises of a millimetre or two are worrying is an extraordinary claim, one which needs extraordinary evidence. Alas, it just isn’t there.
Saibai Island Torres Strait
The CSM paper goes on to pile even more possibilities on top of those already mentioned. Our planet is changing its shape as time goes on; an undersea mountain will have a higher sea level above it; the earth is rebounding following the loss of kilometres of ice above it; variations occur in the internal temperature of the planet; our rivers abrade the land, dumping earth onto the seabed and thereby raising it; el Ninos have a powerful effect on sea levels; and so on.
Why are we so exercised about sea levels, given the problems of measuring them accurately? Millions of human beings live on or close to the sea, and are naturally interested in what is happening there. Australia is an excellent example, with all our major cities save Canberra on the coastline. So it is easy to run a scary story about the possible flooding of coastal suburbs, the loss of great sections of Bangladesh, the submerging of Kiribati and Tuvalu, and other awful possibilities.
And, of course, so much these days comes from ‘what the models say’. About the use of models the SCM paper is politely scathing: Conclusions based on any kind of model should be disregarded. As the SCM specializes in building mathematical models, we should also be recognized as competent to criticize them. Models are useful when attempting to review our knowledge, but they should not be used as an aid to decision-making until they have been validated. Now, validating a climate model requires thousands of years.
I return to a question I have asked myself many time before. How did we get into this? How did our measuring instruments become subverted to assist in something else altogether? As Geoff Derrick shows, in the piece I mentioned at the beginning, William Dawes, who came with the First Fleet, established an observatory on what is now know as Dawes Point and, among other things, kept accurate temperature measurements for the new colony. They seem remarkably similar in their trend to the average for the last 150 years, but that’s not really the point. Dawes was a scientist and a competent astronomer. He was laying the foundations of knowledge regarding aspects of weather.
Early settlers inland did much the same. They measured river heights, took temperature measurements, and collected rainfall data. Why? They just didn’t know anything about this new land, or area. They needed to know when the rain came, how high the rivers went in flood, when was the right time to plough, how reliable was the water supply, and how cold it might get in winter. Their purpose was straightforward: we are new here and we need to know a lot.
Of course, some of their measuring instruments weren’t all that good, and they were not meticulous with when they took the measurements. Some of their data has been lost. There are great gaps. But slowly, over time, our society got better at it. Australia was one of the early investors in good data of all kinds, censuses, temperature, tide gauges and the like.
To take this great body of data of varying quality and quantity, and ‘homogenise’ it so that its truth, spotty though it is, is pushed aside, but the message of ‘climate change’ is somehow revealed, is to prostitute science — and to dismiss the work of numerous people who maintained the data in the past.
Those who do this do not seem to realise that they are thereby reducing the status that science and scientists have had in the past — to the cost of all of us.
Posted on November 23, 2015, in General, Global warming, Greens, northern development and tagged Don Aitkin, Moa Island, rising sea levels, Saibai Island, Torres Strait. Bookmark the permalink. 2 Comments.