Viewers of ABC-TV news, and followers of ABC News Online, were treated to a story on Friday night about “Turtle hatchlings dying in extreme heat at Mon Repos”, as it was headlined at ABC News Online:
Piles of dead turtle hatchlings are lining Queensland’s famous Mon Repos beach amid a heatwave which has pushed the sand’s temperature to a record 75 degrees Celsius.
While the majority of hatchlings break free from their nests at night when the sand is cooler, those escaping in the day face overheating.
“They can’t sweat, they can’t pant, so they’ve got no mechanism for cooling,” Department of Environment and Heritage Protection chief scientist Dr Col Limpus said.
The extreme heat is also conducted down to the turtle’s nest, pushing the temperature to about 34C, which is approaching the lethal level for incubation.
That is the hottest temperature recorded in a nest in more than a decade.
A record 75 degrees sand temperature? Hottest nest temperature in more than a decade?
Time for a reality check.
I have no data on temperatures inside turtle nests, but I do have data on temperature at nearby Bundaberg Aero (Hinkler Airport), which is an ACORN site.
Using monthly Acorn data, here is a plot of all January maxima at Bundy.
January’s mean maximum of 31.6 degrees C was equalled or exceeded in 1924, 1931, 1969, 1998, 2002, 2006, 2013, and 2014. While monthly mean doesn’t tell us about individual days, it does give us a clue about daily temperatures in hot years. For that I also use ACORN daily data- adjusted, homogenised, and world’s best practice apparently.
How do temperatures at this time of year compare with those of previous years? The next figures show data for the first 45 days of every year, that is from January 1 to February 14.
The past three weeks at Bundaberg have been at the high end of the range, but no records have been broken, and no days have been even close to 35C. What about previous years? The next plot shows the number of consecutive days above 35 degrees: very likely to raise sand temperature above what it has been this year.
No days this year above 35C, but at least 27 occasions in previous years of single days reaching 35C, at least 6 of 2 days in a row, and one of 3 days in a row above 35C.
A 7 day running mean will show whether temperatures have been consistently high.
As you can see 2017 is high but not extreme. 2002 had a 7 day average just under 35C.
This graph plots temperatures of the first 45 days of years with similarly hot January temperatures. 2017 is the thick black line.
On one day- January 20- 2017 was hotter than the other years. Note how in several years the temperature drops to the mid 20s when heavy rain falls. Note also the temperature reached the high 30s in February 2002.
The final graph shows the 7 day average of the same period of similarly hot years.
Several previous periods were hotter than so far this year.
Once again we see misleading claims being made and reported by the ABC as gospel, without any attempt at fact checking. A simple check shows that, while it may be true that the reported temperatures are the hottest recorded by these researchers, it is extremely unlikely that these were as high as they were in past years. On every count- daily, monthly mean, 7 day mean, consecutive hot days- it can be shown that this year, while hot, is not as hot as many previously, and it follows that sand temperatures would similarly have been hotter in the past.
And that’s without considering the Holocene Optimum and the Eemian.
Another ABC fail.