Great Barrier Reef Sea Surface Temperature: No Change In 150 Years

by David Mason-Jones  

Come November and December this year (2021) it will be exactly 150 years since a scientific expedition made meticulous observations of water temperatures along the Great Barrier Reef.

On the voyage from Sydney to Cape Sidmouth in far north Queensland scientists took hourly sea surface temperatures between 6:00am and 6:00pm every day ‘of the warm current setting south along the east coast of Australia’ now known as East Australian Current. The measurements commenced out to sea from Port Stevens, north of Sydney, and continued to near the tip of Cape York. They did the same on the return trip 2-weeks later.

Headed by government astronomers from Melbourne and Sydney, the voyage was organised by the Royal Society of Victoria to observe a total eclipse of the sun predicted for the 12^th December, 1871. With other scientists the party travelled aboard the steamer Governor Blackall out of Sydney on 27 November 1871.. Consequently, the measurements were not just a matter of idle curiosity by passing mariners, they were the subject of formal scientific research and followed the same protocol and used the same thermometer for every observation.

Published in 1877 by Henry Chamberlain Russell, the 1871 data is the earliest consistently collected sea surface temperature dataset around the Australian coast.

Russell’s data established a baseline against which current sea surface temperatures can be compared. The comparison renders Null the commonly accepted hypothesis of rising sea surface temperatures in the Great Barrier Reef.

If the sea surface temperature of the Great Barrier Reef has been trending upwards – and if this trend could be characterised as ‘rapid’ – then a 150-year comparison should be sufficient to confirm it. The problem is that it establishes no such thing. When compared with today’s readings, it shows no upward trend.

The main finding of the recent research Report will come as anathema to multiple research bodies. The Australian Institute of Marine Science (AIMS) and organisations like CSIRO, the Great Barrier Reef Marine Park Authority, Great Barrier Reef Foundation, WWF and the Climate Council have consistently claimed survival of the Reef is imperilled by rising sea levels and sea surface temperatures.

The Great Barrier Reef Marine Park Authority states that, ‘sea surface temperatures in the Australian region have warmed by around 1°C since 1910, with the Great Barrier Reef warming by 0.8°C in the same period.’

 The main findings of the research were:

Firstly, compared at the same times of the year (November and December), there is no difference in average sea surface temperature over the last 150 years. That is a long time and it shows that temperatures are homeostatic, that is, self-regulating.

Secondly, during the warmest time of the year (from December to March) the monsoonal water cycle acts a self-regulating heat pump that maintains average sea surface temperature between 29 and 30degC. If the water entering the Reef Lagoon cannot warm, neither can the North Queensland or East Australian Currents. There is no evidence that the process has broken-down or is likely to do so in the future.

Operation of the heat pump closely regulates sea surface temperature between 27degC and 29degC but less than 30degC for up to five months and more than 20degC during winter (July to September). Low water temperature in winter sets the southern limit for Reef ecosystems, not high water temperatures in summer, which rarely (and only briefly) exceed 31degC.

Scientist, Dr. Bill Johnston, located the 1877 paper when undertaking research in The National Library on H.C. Russell’s contribution to meteorology in Australia. The former New South Wales senior research scientist has collated the 1871 data analysed it meticulously and correlated the temperature readings with the latitude at which they were taken. This is vital because the warm East Australian Current slowly cools as it flows south from the tropics, eventually into the Tasman Sea.

The 1871 observations were used to baseline recent data derived from 27 Australian Institute of Marine science (AIMS) data loggers from Thursday Island in the north to Boult Reef in the south. Both datasets were robust, comparable and fit for the purpose of examining time-evolution of sea surface temperature. AIMS data for equivalent times and latitudes were not significantly different to data measured in November/December 1871. It is shocking that this vital piece of scientific evidence is not featured more prominently in all the Reef research of recent years.

The result of this analysis surely dismantles the assertion that sea surface temperatures in the Great Barrier Reef are rising and rising rapidly.

The results have now been published in full detail on an Australian website BoMwatch – a site devoted to keeping an eye on Australia’s Bureau of Meteorology. The dataset with calculations is provided separately as a supplement to the report on the Bomwatch website.

Dr. Johnston’s detailed Report can be accessed at http://www.bomwatch.com.au . The full Report with tables of data is at http://www.bomwatch.com.au/bureau-of-meterology/trends-in-sea-surface-temperature-at-townsville-great-barrier-reef/ The researcher and publisher at BoMwatch want to make this a completely open field for science investigation.

In his final conclusion, Dr. Johnston states, ‘No difference was found between temperatures measured at Port Stephens and Cape Sidmouth by astronomers from Melbourne and Sydney using bucket samples in November and December 1871 and data sampled at those times from 27 AIMS datasets spanning from Thursday Island, in the north to Boult Reef in the south. Alarming claims that the East Australian Current has warmed due to global warming are therefore without foundation.’

Reference: Lomb, Nick (2016) Australian solar eclipse expeditions: the voyage to Cape York in 1871. Journal of Astronomical History and Heritage 79-95. 

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.