It’s another month of BOM Bingo. The ABC and BOM are trumpeting a “hottest” ever headline yet again, and Warwick Hughes is onto them already.
Conveniently the ABC forgets to mention that March Maximum Temps have been hotter before many times and with a pattern that has nothing to do with CO2. How many in the ABC audience would know that?
“You could be forgiven for not noticing the end of summer — March was a hot one.” says Sara Phillips. But actually, if you are human, you could be forgiven for thinking this was just another hot March like so many before. For SE Australia where most humans live, the hottest March, and wildly so, was in 1940. Across the whole of Australia these kinds of maximum temperatures in March have been occurring for decades and 1986 was much much hotter. See the BOM graph below.
Hands up who can spot the horrid effect of CO2 in this graph?
Stick with the logic. Must be CO2 that caused the cold spike in 2011 (and 1967, 1942 and 1913). This is witchcraft.
You could be forgiven for thinking the aim of the ABC is not to inform Australians about the weather that matters, but to score headlines involving the word “hottest”. When the coldest maximum March temperatures were set in March 2011, where was the ABC?
Do humans even notice “mean” temperatures?
Too tricky for words, the weather bureau was talking about hottest ever mean and minimum temperatures. Mean temperatures are almost never mentioned (not on the six o’clock news and weather) because we want to know the coldest and hottest temperatures each day, not the average of them. Nor are we too concerned with minimums in a middling month. It’s not about frosts or heat stroke.
In March the minimums really did hit a record. Effectively the Bureau of Meteorology (with a little help from the ABC) are marketing warm autumn nights as a form of extreme weather.
The mysterious hot spot that is Walungurru (Kintore) Airport
Warwick Hughes has spotted an oddity when comparing Giles to Walungurru which are 220km apart. Note the normal “pale yellow” minimums recorded at Giles near the border of WA-SA-NT. Giles is a specialist meteorology station and has been there since 1956. It is the only staffed weather station within an area of about 2,500,000 square kilometres (970,000 sq mi).
Contrast that with the big red blob on the border of WA and the NT at Walungurru “Airport”, which has only been recording since 2002 — admire the sparse graph of total monthly data there which shows how small this dataset is. Warwick Hughes notes that for most of its life that spot has recorded strange nightly hot temperatures which don’t match the thousands of square kilometers all around — see his post on the persistent night time error anomaly map. This is a vast desert plain. It shouldn’t have a climate all of its own here showing 3C warmer at night for entire whole years than the thermometers “nearby”.
How much of Australia’s “average” temperature depends on this one likely flawed station?
We got more rain than normal across inland Australia.
Does the extra rain matter? Hard to know — it may be clouds or humidity that matters more. The BOM March statements drown us in weather data, but did not mention “clouds” or “humidity”. Was it just a cloudy or humid month which kept night time temperatures up in places hardly anyone lives? It was an odd month (see the graph below where rain fell in different places to normal). Across inland Australia the soil moisture levels must be up (not too scary? Compare this week in March 2016 to March 2015).
Did CO2 cause that extra rain in SW WA, or the lack of it in NW WA? Or was that the El Nino, or the IOD?
Perhaps it was your air-conditioner?
Maximums seem to be more sensitive to extra rain,
It was even more rainy in inland central Australia back in 2011 when we got the coldest ever March Maximum temp.
Higher temperatures in Australia are more likely to be due to lower rainfall than to CO2. See this past post by Bill Johnston about hot days in Australia and their connection to lower rainfall, and electronic thermometers — not CO2.
Johnston found that for every 100mm of rainfall, the maximum temperatures were about a third of a degree cooler. But on minima rainfall has a very slight warming effect — too small to be called significant. To some extent rainfall would correlate with clouds or humidity which may be what we really need to understand why minima were at a record high.
Minor editing: I took out the line about minimums being “hottest in the areas in Australia where almost no one lives, and where there are almost no thermometers”. It’s true over most of the area (Graph 2, orange bits), but things were still warmer than usual in Victoria at night. The mean minimums there were a balmy 12-15C (54 – 59F) which might be 1 – 2 degrees C more than usual, but seriously, who cares? Actually, that rather makes my point — the BOM and ABC are turning slightly warmer autumn nights into “extreme weather”.