The danger is in the definition
Ken Stewart has been diligent at trying to understand the Bureau of Meteorology (BOM) method for finding heatwaves. He’d heard BOM head, Rob Vertessy speak on ABC radio, declaring that heatwaves were the “number one cause of death” from natural disaster in Australia. Ken wrote to Vertessy repeatedly but for some reason, despite the deadly risk to Australians, Vertessy was unable to answer the question of how to define and estimate heatwaves. (Perhaps if the BOM had The Internet, he could have sent Ken Stewart this link, which Stewart has now found himself four months later.)
The Excess Heat Factor: A Metric for Heatwave Intensity and Its Use in Classifying Heatwave Severity, John R. Nairn and Robert J. B. Fawcett (2015) 
With these instructions Ken has now replicated the BOM results for the 2014 heatwave in Melbourne. He has also used the same technique on Marble Bar, Western Australia, and Mawson, Antarctica and found that potentially heatwaves are a killer danger to our Antarctic researchers, and if heatwaves kill, they’d be much safer in Marble Bar. For the record, Marble Bar is the place that had 160 days in a row [...]
Let’s play the Heatwaves PR game. If CO2 had an effect we’d see a significant increase in the rate of global warming over the decades since WWII, the models would work, and climate scientists would be able to predict our climate. Since none of that is true, those with a political agenda have to clutch at noisy but marketable extremes instead. Apparently even a half-true, noisy, non-causal link is good enough for post-modern scientists.
Heatwaves are perfect for generating scientific sounding fear, but not so useful for generating actual scientific knowledge. There are an infinity of ways to measure them. They can last 3 days – 160 days, and be cut off at any number from 35 – 40C, or at some percentile outlier. They can be measured one town at a time, or on a regional or state-wide level. The permutations are rich with headline scoring possibilities. And in the end, on a long warming trend that started 300 years ago, it is obvious, inevitable, and predictable that we should score more now. What’s surprising is how often we don’t.
On ABC radio before Easter, Dr Vertessy, Director and CEO of the Bureau of Meteorology, claimed that we are seeing [...]
Heatwaves are a wonderful headline generator. That’s because the term sounds scary, yet the “wave” itself is undefined. A hundred different types of heatwave are theoretically possible, but they all sound the same in a headline. It means an activist team could pick and choose the particular one that scores a “record”. Heatwaves can be 3, 4, 5, 7 or 10 days. They can be measured by town, city, state or national data and they are can be above 35, 37, 40 degrees or… pick a number. A heatwave can be measured as days above some percentile of average. That means a few warm days in a cold town can be defined as a heatwave.
Geoff Sherrington, drawing no dollars from the taxpayer, takes a simple and obvious approach, and looks at 5 capital cities with the BOM raw and adjusted ACORN data. He considered 4, 5, and 6 day heatwaves to see if there was a trend. With 5 cites, 2 data types, 3 lengths of heatwave, Sherrington created 30 graphs. After testing all those different combinations of heatwaves, there were only three graphs out of 30 that showed an increasing trend. Over half of the heatwave graphs showed [...]
There are waves piling on waves in the weather.
A new press release tells us that there have been an “exceptional” number of weather extremes in summer.
Weather extremes in the summer — such as the record heat wave in the United States that hit corn farmers and worsened wildfires in 2012 — have reached an exceptional number in the last ten years. Human-made global warming can explain a gradual increase in periods of severe heat, but the observed change in the magnitude and duration of some events is not so easily explained.
Heatwaves lend themselves to headlines. Not only are they scary, but for climate researchers at a loose end, there are 1,000 flavors of wave to comb through. Is that a 3 day, 4 day or 7 day wave you are interested in? Is the cut-off 40C, 38C, 35C or a flexible percentile anomaly above the monthly average? Is it a statewide average, a national record, or a hot week in Houston? Shall we analyze that in seasons, by months, years, or part thereof? The combinations and permutations can keep a supercomputer up late at night. There’s a whole field of cherry trees ripe for the plucking.
The CSIRO decided to leave out some information about the state of our climate in their State of the Climate Report CSIRO.
CSIRO published these “Fast Facts” in bold. I’m publishing the things they didn’t say, but could have, in points in between.
Fast Facts from the CSIRO and BOM “Australia’s climate has warmed by 0.9°C since 1910, and the frequency of extreme weather has changed, with more extreme heat and fewer cool extremes.” The CSIRO-BOM team could have said: Scientifically, extreme weather measures are lousy indicators. They’re noisy and not very meaningful. They are however useful for getting newspaper headlines. It depends on what your aim is… Australia’s had extreme hot days for as long as we’ve been measuring the temperature. Charles Sturt recorded 53C in 1828 which seems fairly extreme. Thomas Mitchell did it too in 1845 and are many others (see the map below, check Trove, ask the BOM — no don’t ask the BOM). The records prior to 1910 seem to have gone down the memory hole, but if the BOM and CSIRO were trying to give Australians a true sense of the state of our climate perhaps Australians might like to know that [...]
Heatwaves have become a publicity tool. Far from there being a clear trend in Australian heatwaves, Geoff Sherrington shows that it’s also legitimate to claim heatwaves were worse 80 – 100 years ago in Adelaide and Melbourne and things are getting better. Those officials who cherrypick their claims might be technically correct, but it’s outrageously deceitful and unscientific at the same time.
Just how hard is it to get a record heatwave? It’s so easy that if it’s summer in Australia, it’s hard not to set a record. That’s because heatwaves come in so many flavors – there are seven capital cities which can all have 3 day, 4 day, 5 day or 6 day heatwaves. Then there are the heatwaves over 40C, or over 38 C, or over 35C… already that makes 84 flavours of wave. If a hot spell doesn’t break one type of wave, it could easily break another. Then there is the pre-heatwave, and there would be another 84 types of heatwaves that we haven’t had, but might get, you never know. You might think I’m kidding, but pre-heatwaves get headlines already:
“More Canberra heatwaves forecast”
“A heatwave could return to Canberra next month, [...]
There were not many long term sites (in black dots) in the centre of Australia in 1930.
This summer the Bureau of Meteorology (BOM) invented a whole new metric to measure average national heat, which might be all very well except no-one (other than the BOM) seems to know what it is.
On January 7th the BOM claimed Australia set a new “average maximum daily temperature record”. Now the headlines are about the “hottest” Australian summer.
With both records, no one outside the BOM team has access to the methods or data. This post is about the new “daily” temperature of Australia used to declare Jan 7th was a record, but the same point applies to the “hottest summer” records, even though they may be a different data set. Where is the data? Where are the methods?
Is the BOM a science agency or a PR bureau?
The January 7th heatwave supposedly broke all previous “daily” records in this category — a dubious honor since no-one can remember any records like it.
It’s a bit like winning the Side-Jump. It’s not an event anyone knew was on until the medal ceremony. Worse, no one knows how the [...]
Eight reasons why this current heatwave is a boring, overhyped example of weather being used for political purposes.
1. It’s the long term trends that matter — not a few weeks of hot weather
As climate scientists keep telling us (except when they have a heatwave to milk), ”weather is not climate”. It’s the long term trends that matter. One short four week period is not a long term climate trend, but it is an excellent opportunity to create hype and scaremongering in the newspapers. Scientists with little scruple and low standards are making the most of this.
2. The “records” we are breaking are pitifully short
Even if this is the hottest heatwave “ever recorded”, it doesn’t mean much in the long term scheme of things. Natural climate cycles work on scales of 11 years, 60 years, 200 years, 1500 years, and 100,000 years. We have decent temperature records for many locations for only 50 years. We have a scratchy patchy thermometer record for 150 years. Any scientist raving about breaking a 50 year record as if it means something is … embarrassing. There is too much noise in this system and too little data.
3. If a few weeks [...]
The media are in overdrive, making out that “the extreme heat is the new normal” in Australia. The Great Australian Heatwave of January 2013 didn’t push the mercury above 50C at any weather station in Australia, yet it’s been 50C (122F) and hotter in many inland towns across Australia over the past century. See how many are in the late 1800′s and early to mid 1900′s. You can’t blame those high records on man made global warming. [feel free to post some old records of your own and the source reference we can check and we will update the map]
Did CO2 cause extreme heat in the 1820′s?
In explorer Charles Sturt’s time it was so hot that thermometers exploded. Was this Australia’s hottest day all the way back in 1828? It was 122F or 53.9C! Naturally it is not a BOM-registered-record (the BOM did not exist then). Nonetheless, Charles Sturt was engaged to explore the nation and given careful instructions to take accurate readings of the climate. Yes, inadequate thermometer shading may have exaggerated the maximum by 1C, 2C, maybe even 3C, but at 50.9C it would still have been considerably hotter than anywhere in January 2013.
Even that [...]
Photo: Jo Nova
Post by: Lance Pidgeon with assistance from Chris Gillham and others.
It is as if history is being erased. For all that we hear about recent record-breaking climate extremes, records that are equally extreme, and sometimes even more so, are ignored.
In January 1896 a savage blast “like a furnace” stretched across Australia from east to west and lasted for weeks. The death toll reached 437 people in the eastern states. Newspaper reports showed that in Bourke the heat approached 120°F (48.9°C) on three days (1)(2)(3). The maximumun at or above 102 degrees F (38.9°C) for 24 days straight.
By Tuesday Jan 14, people were reported falling dead in the streets. Unable to sleep, people in Brewarrina walked the streets at night for hours, the thermometer recording 109F at midnight. Overnight, the temperature did not fall below 103°F. On Jan 18 in Wilcannia, five deaths were recorded in one day, the hospitals were overcrowded and reports said that “more deaths are hourly expected”. By January 24, in Bourke, many businesses had shut down (almost everything bar the hotels). Panic stricken Australians were fleeing to the hills in climate refugee trains. As reported at the time, the government felt [...]
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