Great Barrier Reef: No Basis for Alarming Sea Fevel Fear, Second Report Finds

By David Mason-Jones

Analysis of a second tide gauge in the waters of the Great Barrier Reef has confirmed the results of an earlier study at the Port of Townsville and nearby Cape Ferguson. The new Report focusses on the tide gauge at Cooktown on the Queensland coast, facing the Reef lagoon.

Figure 1. The Cooktown storm surge tide gauge (arrowed) located on the wooden-decked wharf prior to its restoration in 2015. (Photo 44740 from the Cultural Atlas of Australia.)  

Researcher and author of the Report, Australian scientist Dr. Bill Johnston, states, “Claims that anthropogenic global warming is causing sea level to rise, particularly in the northern sector of the Great Barrier Reef, are unfounded.

“What the raw data from the Queensland Government Ports Authority website shows is an apparent rise of .036 metres per decade at Cooktown. This can be simplistically derived by comparing the start point of readings at Cooktown with the end point of the series over a period of years. However, such a method of analysing data by just comparing a start point with an end point is naïve. Instead, the mis-identified trend ‘found’ by such poor analysis is easily shown to be a series of sudden step-ups in the data, none of which is attributable to a change in climate.  

“It is misleading that researchers should label a series of step changes like this as a steadily rising trend,” says Johnston.  

Cooktown lies in the Tropics and, as a consequence of the combined effects of siltation from the Endeavour River and violent winds and sea surges from cyclones – all normal events in this part of the world – a major dredging program was implemented adjacent to the wharf to allow continued access by vessels. In this process 108,000 cubic metres of silt was dredged right next to the wharf in 1997. This caused the pylons on which the sensor was attached to settle 40 mm into the bed of the river. Interestingly, dredging of 26,000 cubic metres further away from the wharf in 1999 to create a turning bay for ships, caused no pylon sinkage.

Following Tropical Cyclones Ellie and Hamish in early 2009, further dredging near the wharf resulted in 37 mm additional sinking. In 2015 there was more dredging associated with a wharf refurbishment where the wooden wharf was strengthened and re-decked with a new composite structure capable of allowing small trucks to load and unload. This resulted in a further 32mm sinkage. The combined effect of all this dredging and extra loading was a massive 109mm settling of the pylon, thus making the sea look as if it was rising.

“All these sudden step changes can be seen clearly in the analysis,” says Johnston. “They stand out when they are correlated with government records of dredging and other work. The full research Report deals with several additional factors to those outlined here.”

The Queensland Government has taken time-series aerial photographs of the coast including around the Port of Cooktown and these are publicly available from Queensland Government archives. Aerial photographs taken in 1969, 1974, 1979, 1983, 1987, 1989, 1991, 1994 compared with high-definition Google Earth Pro Satellite imagery show no signs of tidal encroachment at Cherry Tree Bay just east of Cooktown across the peninsula.

Dr. Johnston says, “Ground-truthing of the satellite data shows the scary claims of rapid sea level rise in the Reef are illusory. The Mean Surface Level of the water in relation to the terrain of the coast has not changed. Historic aerial photographs, and satellite imagery show this.”

Figure 2. Aerial photograph of Cherry Tree Bay, east of Cooktown taken on 11 September 1969 overlaid on Google Earth Pro (GEP) Satellite image for 16 September 2018; upper-left, GEP opacity 0%, 50%; lower-left 75%, 100%. Tidal wetting fronts, littoral zones, rocks and shoals show no encroachment or change in exposure due to rising sea levels over the intervening 49-years.

Despite this, the Great Barrier Reef Marine Park Authority (GBRMPA) maintains its claim that, due to global warming, sea level in the Reef is increasing and that the fastest rate is in the northern sector.

The notion that the sea may be rising more rapidly at Cooktown than at other places along the Reef is fanciful. 

The Intergovernmental Panel on Climate Change (IPCC) predicts sea level will rise by around 26 to 29 centimetres over the next 9-years, that is, by 2030. For this IPCC prediction to eventuate in the waters of the Reef in just nine years, the sea had better hurry up because the prediction now requires an annual rise of more than three centimetres per year. And if the sea delays rising for just another 12 months, the required annual rate will need to lift to 3.5 centimetres per year. With no evidence at all of this happening in the Townsville and Cooktown areas, it is just mind-boggling to grasp the idea that the IPCC prediction will be fulfilled.

From where do these guys get all this stuff?

On what hard data do they base their claims?

Do they ever deeply question their assumptions?

Dr. Johnston’s full Report, including a downloadable PDF with graphs and full tables of data and full descriptions of methods used can be found here: http://www.bomwatch.com.au/bureau-of-meteorology/trends-in-sea-level-at-cooktown-great-barrier-reef/

An exasperated Johnston states, “As with almost anything to do with claims about Australia’s iconic Reef, the more you look at the data, the more questions you have.  

“The research at Cooktown provides no evidence for the belief in rapid sea level rise and this backs up my previous research around Townsville,” he says.  

Political grandstanding, emotional media releases, uninformed media reportage and commentary about the health of the Reef is not justified. Data at Cooktown shows that extreme claims about what has happened in the past, together with extreme predictions about what will happen in the future, are false and should be called out.  

David Mason-Jones is a freelance journalist of many years’ experience. www.journalist.com.au

Dr. Bill Johnston is a former NSW Department of Natural Resources senior research scientist and former weather observer. www.bomwatch.com.au

For the full research Report go to:

http://www.bomwatch.com.au/bureau-of-meteorology/trends-in-sea-level-at-cooktown-great-barrier-reef/

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November 21, 2021 at 04:25PM

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