Geoff Sherrington
The daily temperature observations from many Australian weather stations have now been routinely updated by the Bureau of Meteorology, BOM, to the end of year 2024.
Year 2024 has been publicized GLOBALLY as the “hottest year evah!” so it is time to examine how Australia fared. Here, heatwaves are the medium used.
The frequent, accepted chant is that globally, heatwaves are becoming “hotter, longer and more frequent”. This chant is not supported by the following heatwave analysis which examines 10 Australian weather stations with lengthy historic observations. This study has generated 160 graphs that are linked by weather station/city that is the main part of this article for readers to examine.
Here is a snapshot of Adelaide, using only 3-day heatwave examples, 4 graphs out of a possible 16 for Adelaide.
RAW DATA
ADJUSTED DATA
In short summary, you can read almost any answer you seek into these 4 graphs and also for the whole set of160 graphs.
Dr Roger Pielke Jr expressed a similar complication in a recent article –
“In his classic paper on “How Science Makes Environmental Controversies Worse,” science policy scholar Dan Sarewitz referred to such circumstances as an “excess of objectivity,” which he characterized as:
. . . not a lack of scientific knowledge so much as the contrary—a huge body of knowledge whose components can be legitimately assembled and interpreted in different ways to yield competing views of the “problem” and of how society should respond. Put simply, for a given value-based position in an environmental controversy, it is often possible to compile a supporting set of scientifically legitimated facts.²
Climate Science Whiplash – by Roger Pielke Jr.
Australia’s BOM issue special statements about heatwaves.
The latest on this list concerns a heatwave in S-W West Australia (including Perth and Cape Leeuwin) in November 2023. It contains these messages in its 26 pages:
“In November 2023, south-west Western Australia, including Perth, experienced a heatwave exceptional for the time of the year.
Climate factors contributing to the heatwave conditions included record warm global sea surface temperatures, El Niño in the Pacific Ocean, a positive Indian Ocean Dipole and a positive Southern Annular Mode.
Heatwave conditions can be challenging for vulnerable people, including very young children, older people, people with disability and those with medical conditions. (Elsewhere are these BOM words: “Severe and extreme heatwaves have claimed more lives than any other natural hazard in Australia.”)
The likelihood of the record warm spring 2023 in Western Australia exceeding the previous record in the current climate compared to a world without climate change was at least 50 times greater.”
Do you see the point that Dr Pielke was making? Year 2023 does not even make the Top 40 3-day heatwave summary for Cape Leeuwin, below; nor for Perth; nor the 1-Day, 5-Day or 10-Day heatwave Top 40 list for both stations.
METHODOLOGY.
The observations reported here are of two types, both from the official Australian Bureau of Meteorology (BOM). First, there is “raw” temperature data under the shorthand “CDO” for Climate Data Online.
Climate Data Online – Map search
Second, there is adjusted data as the BOM ACORN-SAT, for Australian Climate Observations Reference Network – Surface Air Temperature at –
There is also a catalogue of 112 chosen weather stations for ACORN-SAT.
The adjustment process is described at the next link. Several more detailed articles are referenced there.
I have calculated and presented heatwave graphs over time, for both the full set of years available and the shortened “Top 40” of each of these hottest heatwave years. I have not covered stations that host 2 or more hot heatwaves in a year. Only each year and its hottest heatwave are reported here, with a choice of all recorded years or the hottest 40 heatwave years.
The heatwaves shown here are of four durations. These are 1, 3, 5 and 10 consecutive days, averaged. The hottest average for that station in that year is selected.
In simple factorial form, we have 8 weather stations, with all years and Top 40 options, with Raw and Adjusted, with 4 levels of duration, to give 10 * 2 * 2 * 4 for 160 combinations, hence 160 graphs.
The graphs are at these links:
https://www.geoffstuff.com/alicewaves.xlsx
https://www.geoffstuff.com/adelwaves.xlsx
https://www.geoffstuff.com/briswaves.xlsx
https://www.geoffstuff.com/darwaves.xlsx
https://www.geoffstuff.com/hobwaves.xlsx
https://www.geoffstuff.com/longwaves.xlsx
https://www.geoffstuff.com/leeuwaves.xlsx
https://www.geoffstuff.com/melbwaves.xlsx
https://www.geoffstuff.com/sydwaves.xlsx
https://www.geoffstuff.com/perwaves.xlsx
…….
The 10 weather stations were chosen from a short list of Australian stations with earliest historic start dates and least missing data. The chosen stations are the 6 State Capitals plus Darwin and Alice Springs, the latter two to give better geographic coverage of the map of Australia, plus Longreach and Cape Leeuwin for minimal Urban Heat Island influence.
The eight examined CDO weather stations are:
Adelaide, # 23000 West Terrace start 1889, until # 23090 Kent Town starting 1979.
Alice Springs, # 15540 Regional Office start 1879, until # 15590 Airport starting 1942.
Brisbane, # 40214 Regional Office start 1879, next # 40223 starting 1986, until # 40842 Airport starting 1995.
Cape Leeuwin, # 9518 Lighthouse station start 1907, until present day.
Darwin, # 14019 Post Office start 1885, until # 04015 Airport starting 1942.
Hobart # 94029, Ellerslie Rd starting 1918, until now.
Longreach, # 36030 Regional Office starting 1897, until # 36031 Airport starting 1967.
Melbourne, # 86071 Regional Office start 1856, until # 86338 Olympic Park starting 2013.
Perth, # 9034 Regional Office start 1897, until # 9021 Airport, starting 1965.
Sydney, # 66062 Observatory start 1859, until # 66214 new Observatory starting 2018.
NOTE 1: Many of these stations underwent a site shift, many in the middle of the study period, typically from a Post Office to an Airport. This has affected the distribution over time of these hottest heatwaves. There is no reliable method to adjust this by a single step change because the magnitude of such a step is not now knowable.
Note 2: Many Australian weather station temperature results (not heatwaves) have been examined in detail by colleague Dr Bill Johnston and reported on his Bomwatch blog. By correcting for a physics-based influence of rainfall, he has deduced that most Australian stations show essentially no warming over the whole period of their observations. It should follow that heatwaves likewise have not shown increases or decreases.
Cape Leeuwin, Western Australia – www.BomWatch.com.au
….
The same 10 CDO stations were used for ACORN-SAT analysis. A major difference between CDO and ACORN_SAT is the start date of the latter, all being 1910 or later (Brisbane starts in 1950).
….
An Excel spreadsheet of one of the stations (Longreach, a short one) is found here to show the methodology in more detail It is a 24 MB file, please allow time.
https://www.geoffstuff.com/longheat.xlsx
Here is a step-by-step description of the methods I used to generate these graphs.
https://www.geoffstuff.com/myway.xlsx
Some essential points:
- A day of missing data can lead to large damage to the calculations, because that 1 day affects 9 other days in the 10-DAY analysis. Therefore, all missing values were infilled, either by a subjective guess in the ballpark of surrounding values, or with the overall average Tmax value for the station. The shortest duration station, Brisbane, has some 50,400 days analyzed, with a few hundred missing values, so the odds of induced error are small. They can be traced.
- I have made the Excel commands as simple as possible. No knowledge of macros, programming or even Pivot tables is needed. The invitation is open for you to replicate the methodology for your own locations.
- I have not cherry picked the weather stations. Together, these 10 cities/locations house more than 70% of Australian population. This has meaning when planning for heatwaves, such as where to build hospitals and how large to make them.
- The chosen cities probably suffer from the temperature distortion of Urban Heat Island effect. There have been transect studies showing UHI in excess of a couple of degrees at times in both Sydney and Melbourne. I have now included two stations unlikely to have been affected by UHI, Cape Leeuwin and Longreach.
- Rebuttal of the misunderstanding that heatwaves are becoming “hotter, longer and more frequent” lacks credibility if actual data are used such s here, for 10 stations in far off Australia. It is hard to maintain that misunderstanding when simple graphs of real data are shown to those who make such claims. I am writing a more detailed analysis of these 160 graphs, should WUWT accept it.
- You are encouraged to make similar graphs for regions elsewhere. For heatwaves, they are hard to refute, in contrast with official/IPCC type studies, which usually commence after 1950 and which rely upon arcane definitions of heatwave to arrive at conclusions.
END.
Geoff Sherrington
Scientist,
Melbourne, Australia.
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