Is Antarctica Boiling Over With Heatwaves? Simple Answer Is No

Written by John Dee on September 29, 2023. Posted in Current News

Now and then a headline comes along that smells so darn fishy as to warrant fainting, followed by smelling salts

Sky News are the providers of such a headline this week, and I felt it my solemn duty to don my apron and grab my filleting knife.

Now, a 39°C hike is extraordinary – not just quite extraordinary or even molto extraordinary, but what-the-fudge-is-going-on extraordinary. This is extraordinary layered with marzipan, frosted icing, sprinkles and dark chocolate shavings.

We are told this singular event took place on 18 March 2022 at a place called Dome C. Note use of the word singular – we’re talking one location for just one day – whereas the misleading headline implies a continental meltdown.

I hope readers are snarling!

As it so happens, Dome C is a big icy bump deep inland, being a hot favourite place for cold ice core samples. There isn’t a WMO/GHCNd weather observatory there so we don’t have a historic record of official maxima, which raises suspicion from the outset.

How can we tell whether this was rogue reading due a localised heat source or a wacko reading arising from an undetected equipment malfunction or a genuine reading that is run-of-the-mill… or something utterly extraordinary?

The answer is we can’t, no matter how upright and earnest the scientists on the ground, and unless another rig in the region yielded similar results we can’t judge the veracity of the data, and neither can they.

What we can do, however, is to trawl the continent for historic maxima from every darn base that ever stuck a thermometer up just to get a gist of what has been happening over time, and what was happening back in March 2022 in particular.

For this task I once again turned to the fabulous resource that is KNMI’s Climate Explorer.

If we select all Antarctic bases that have been in operation for at least 1 year we end-up with a listing of 56. A few more button presses later and we have the maximum daily temperature recorded amongst this sample of 56, with records dating back to 1956.

The Hottest Daily Hot

The sample of 56 GHCNd stations yielded 24,684 data records for the absolute maximum with only 6 missing values over the period 3 February 1956 – 8 September 2023.

The mean absolute daily maximum was 2.29°C, with a median of 2.70°C, minimum of -27.2°C and maximum of 18.4°C. The latter offers a measure of the hottest daily hot and I can tell you now that this was likely recorded on the peninsular outside of the Antarctic circle rather than down at Dome C (please see this article series for further elucidation).

If I sort the daily absolute maxima for the continent in descending value then the gold goes to 7 February 2020 (18.4°C), with silver going to 13 March 1979 (18.0°C) and bronze going to 21 March 2015 (17.5°C).

Looking down the listing I find last year down in 24th place for the hottest of daily hot with 14.7°C on 21 January 2022. As for 18 March 2022 this manages 7,262nd place with an absolute daily maximum of 4.8°C.

We may deduce that whatever was going on at Dome C on 18 March 2022 wasn’t going on anywhere else and thus we are likely looking at artefact of some kind.

To give us confidence in this assertion I thought it prudent to calculate the mean absolute daily maximum as well as derive the absolute daily maximum for the month of March for the period 1956 – 2023 for the 56 station sample and crayon these figures out as a pair of time series plots:

Absolute Daily Maximum

In terms of the hottest daily hot for the month of March we need to consider the top slide. It’s pretty darn obvious that March 2023 was on the cool side, but we may ask how many stations fed into this figure for this particular month.

The answer is 25, so this isn’t some freak of nature but a rather more robust assessment than the single measurement at Dome C.

In terms of medals March 2023 passes the finish line in 48th place with 8.3°C, with gold going to 1979 (18.0°C), silver going to 2015 (17.5°C) and bronze going to 1965 (15.3°C). The green snaky line (a LOESS function) suggests that the March absolute daily maximum may well be in decline, which might explain MSM desperation to get mileage out of Antarctica while they can.

Keen readers may wish to note that the linear trend (black line) was estimated at a warming rate of 4.43°C per century (p=0.016) so something has been warming over this period for certain.

Pinning the blame on ‘climate change’ certainly remains a possibility but we first have to rule out several confounding factors starting with contamination of base records with local heat island sources as bases develop over time.

Mean Absolute Daily Maximum

The bottom slide offers the mean absolute daily maximum for the month of March, this being a more robust measure of the hot side of the thermometer since we average absolute values for the entire month rather than just plot out the hottest single day.

In doing so we observe March 2023 to be a fairly cool month across the continent, coming 29th in the ranking with a mean absolute daily maximum of 4.54°C. In this instance gold goes to 2013 (6.53°C), with silver going to 1965 (6.44°C) and bronze going to 2017 (6.34°C).

The green snaky line once again suggests possible recent cooling, with linear regression offering a warming rate of 4.39°C per century (p<0.001). This is a wonderfully clear trend but only an exceptionally blinkered soul would argue that the sole cause must be atmospheric CO2.

BADWARM is Back!

My guess at this stage is that we’re looking at a bad case of BADWARM, in which case I’m expecting the curve to saturate as bases reach full development potential. Despite evidence of warming during the last few decades, the extraordinary Dome C result heralded by Sky News isn’t looking at all reliable in comparison with established land station data and I’m going to assume something peculiar was going on.

Cross-Checking Carbon Dioxide

At this stage we can do two things:

1. We can try a bit of that cross-correlation stuff to see whether atmospheric CO2 is the one and only big lever underpinning these extortionate Antarctic March hyper-warming trends.
2. We can look at what the NSST v6 satellite record says for the month of March over the South Pole as a whole and see if this explains the hyper-warming seen by the land stations.

CO2 In The Dock

If increasing global CO2 is indeed the driver then we should see a statistically significant correlation in the differential series at some lag or other. The reasoning here is simple: more atmospheric CO2 = more retained heat down below (though we ought to expect lags for thermal transfer).

If we cross-correlate the year-on-year change in atmospheric CO2 with the mean absolute daily maximum March temperature we arrive at this slide:

OK, so this is not a good look for alarmism.

Despite the hyper-warming rates for the month of March (as witnessed by up to 56 bases) there is absolutely no correlation between year-on-year changes in global atmospheric CO2 and the mean absolute daily March maximum at any lag out to ±24 years (n.b. and beyond – I surreptitiously checked whilst brewing a cuppa).

This indicates that the hyper-warming we do see isn’t being forced by variations in atmospheric CO2 concentration: a brutal fact that lends support to my BADWARM hypothesis.

Satellite Sizzler

We ought to now ogle at the NSST v6 lower troposphere temperature anomaly for the South Pole region from 1978 onward and compare it to the mean absolute daily March maximum in one of those dual axis graphs:

The general impression is of general agreement, though there are a couple of subtle but important differences. Firstly, we’ve got a hike in the lower troposphere temperature back in 1980 that wasn’t picked up by the land stations, and we’ve got a hike in the land station record from 2010 onward that isn’t reflected in the lower troposphere temperature profile.

This latter is what we’d expect if the temperature record was contaminated through BADWARM, and the former is going to accentuate any land station warming trend derived using linear regression.

Quite why bases failed to detect early and most significant warming is anyone’s guess.

As for linear warming rates we observe 2.39°C per century (p=0.036) for the mean absolute daily March maximum and 0.75°C per century (p=0.164) for the NSST lower troposphere South Pole anomaly.

The former squeaks past the 95 percent level of confidence (p<=0.05) whilst the latter crumbles into statistical insignificance. The satellite record thus tells us that there is effectively no long term warming for the month of March across the lower troposphere immediately above the South Pole, in which case we ought to ask where all that land surface warming is coming from – it certainly ain’t the polar atmosphere!

Wind In The Willows

The bods who measured the 39°C hike at Dome C are placing the blame on warm winds:

The authors say a “highly unusual” weather pattern triggered strong winds from the north, bringing warm and moist air from Australia, and it was made 2C worse by climate change.

So what we ought to do next is expand the NSST satellite series to look at the lower troposphere Southern Extent (20°S – 90°S) in order to capture all that warm air coming from the North. Try this:

The match this time seems a little better to my eyeballs but we still need to excuse the inability of the land stations to record an early warming period around 1980, and again around 2000. There’s also evidence of BADWARM sneaking in just after 2010.

So what does the linear regression spanner say? Well, I can report a statistically significant lower troposphere southern extent March warming rate of 0.60°C per century (p=0.003).

Whilst this is going in the right direction we are still faced with a discrepancy amounting to +1.79°C per century that is going unexplained, this effectively being an estimate for BADWARM.

Whilst we are busy attributing cause we ought to note the Dome C gang reckon that 37°C of that 39°C heatwave is down to natural causes – one of those salient points that somehow managed to escape the churnalist’s pen!

Strange as it may seem this Sky News article, that is clutching at a thin straw of one rogue reading on one day at one location, has inadvertently drawn our attention to what appears to be ‘climate change’ proper at +0.60°C per century, whilst contamination of the Antarctic land surface record by localised heat sources accounts for a further +1.79°C per century.

This could be a new and rather subtle statistically-flavoured definition for shooting oneself in the foot!

See more here substack.com

Header image: Earth-Sky

Bold emphasis added

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