March Update: Mediation Ongoing, Temperature Tipping Point Already Exceeded

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From Jennifer Marohasy

March 28, 2023 By jennifer 

Thanks to everyone who has enquired about the outcome of the Administrative Appeals Tribunal hearing with John Abbot versus the Bureau of Meteorology first heard on 3rd February in Brisbane. Unfortunately, mediation has not yet ended, and so there is nothing that I can report beyond my note from 4th February. Hopefully I will have something to report by the end of April.

At the end of each month I usually send out an email update via MailChimp, you can subscribe here. These updates no longer make it through the university spam filters with my Climatelab email address now marked as a source of disinformation. To know how that works read The Twitter Files. Anyway, there is also the problem of these emails being increasingly caught in more regular spam filters, so for a limited period of time, at least this month, I am posting a version of this monthly update here.

One of the first detailed studies of climate change in Australia was by E.L. Deacon published in the Australian Journal of Physics back in 1953. The Professor identified a period of significantly higher mean summer maximum temperatures during the period 1881 to 1910, than during the subsequent period 1911 to 1940. This early study, based on raw observational data from mercury thermometers, concluded that ‘the good consistency of the changes suggests the cause to be mainly climatic rather than changing observational technique or exposure’ (p. 213). To be clear, the professor was claiming the thirty years before 1910 to be hotter than the next thirty.

The chart from the same article shows dramatic cooling to circa 1950 and of more than 1.5 degrees Celsius. I posted the chart at my blog back in 2014, with comment that more people died in Australia from extreme heat events in 1896 than in any other year, with 450 dead nationally. The second worst year was 2009 with 432 dead, followed by 1939 with 420.

All this history is being forgotten. Buried. Denied.

The claim is that the data before 1910 was recorded with non-standard equipment because the mercury thermometers where not always in Stevenson screens. In fact, since 1 November 1996 when the Bureau began transitioning from mercury thermometers to probes in automatic weather stations the Bureau has been using non-standard equipment. We really only have a reliable temperature record for Australia from the period 1910 to 1996.

This Larapuna temperature series is very typical of unhomogenised maximum temperature series from many other places in Australia.

Ignoring all of this, we have a new cultural obsession of not exceeding an illusionary 1.5-degree Celsius tipping point and it is truly bizarre.

Individually, and combined, Australian temperature series generally show that we have already exceeded this whichever equipment is used and whichever time periods are chosen. I blogged about this last week, including a table of data from locations in New South Wales with long records, showing we exceeded this tipping point more than ten years ago for many locations.

This week I’ve been looking at long temperature records for different parts of Tasmania, and you see the same pattern in these records. At Larapuna (Eddystone Point Lighthouse), for example, there is cooling of more than 1.5 degrees Celsius to circa 1950, then warming at a rate of about 3 degrees Celsius per hundred years since.

Many Australian temperature series showing warming from at least 1960 to a few years ago. Temperatures series recorded with mercury thermometers show a bit drop over the last few years, though series recorded with probes in automatic weather stations show continuous warming.

I suspect the warming after 1 November 1996 is hyped in the official record, because that is when the Bureau started transitioning to probes in automatic weather stations. Over the last month or so I’ve written a whole series about this in 8 parts at my blog, entitled ‘Hyping Maximum Daily Temperatures’. Part 6, is here; type ‘hyping’ into the search bar at my website and the others should appear. The entire series was also republished at Watt’s Up with That, with many comments showing much emotion, certainly more emotion than common sense that can be so disheartening.

The reliability of any historical temperature reconstruction becomes difficult because of the emotion and also, after 1 November 1996 in Australia, the transition away from mercury thermometers.

To satisfy my own curiosity, and sort out the possible mess, I would so like access to the parallel data, which are the measurements from mercury thermometers in the same weather stations as the new probes recording with automatic weather stations.

The Bureau has a policy of not allowing this data to be made public. Making this data public is the point of our Administrative Appeals Tribunal Hearing that is still in mediation. Hopefully I will have something to report by the end of April, hopefully there will be some news by then.