Guest contribution by Willis Eschenbach
This is an extension of my previous post titled February Fantasy vs Reality. Please read this to get the basic ideas. To recap, says a study by Science magazine
Despite the rapid warming that is the main feature of global climate change, particularly in the Arctic, where temperatures are rising much faster than anywhere else in the world, the United States and other regions of the Northern Hemisphere have had a conspicuous and increasingly frequent number of episodes of extreme cold winter weather for the past four decades.
…
The Arctic is warming twice as fast as the global average and severe winter weather is reported to be increasing in many densely populated mid-latitude regions, but there is no consensus on whether there is a physical link between the two phenomena.”
In my previous post, to test this claim of increasing “severe winter weather,” I looked at the average continental US February temperature to see if it was cooling. It wasn’t chilled.
However, some commentators rightly pointed out that the issue discussed in the study was not average temperature. Instead, the authors spoke of “episodes of extremely cold winter weather” as experienced in Texas in February 2011 and 2021.
Looking for a more accurate measure of extremely cold winter weather, I obtained daily temperature data for the Southern Great Plains from NOAA. Here is a map of the area in question.
Figure 1. Map of the regions of the National Climate Assessment.
Then I calculated the standard deviation (a measure of how widely spread temperatures are) for February temperatures. I argued that the standard deviation would be larger if there were short, sharp cold spells.
Figure 2. Standard deviations of February minimum daily temperatures for the Southern Great Plains. Cold spells are indicated by an increase in standard deviation.
In Figure 2, we can clearly see the Texas cold spells of 2011 and 2021. But is there a “conspicuous and increasingly frequent number of episodes of extremely cold winter weather over the last four decades”?
Well… in a word, NO. Figure 2 shows that in 1951 there was a severe cold spell. And the Texas State climatologist agrees, saying:
Jan – Feb 1951: Freeze. On 31.01.-02. On February 3 and again on February 13-17, cold waves swept across the state bringing snow and sleet. Truck and citrus crops were badly damaged in the lower Rio Grande Valley, particularly in the earlier of these northern states. In the north from January 31st to February 2nd. 3, the temperature rose to -19°F in Dalhart.
However, there were few “episodes of extremely cold winter weather” in the thirty years after 1951 until the decade and a half from 1981 to 1996. During this time there were a number of cold spells, though not as intense as February 1951. The coldest of these, February 1985, San Antonio got a rare snowfall and they saw the coldest day on record in Midland, Texas became.
However, in the quarter century since 1996 there have only been the two extreme cold periods mentioned above, in 2011 and 2021.
If we divide the 72 years of record into three 24-year periods, we have only one “episode of extremely cold winter weather” in the first period; six slightly warmer episodes in the second period; and only two episodes in the last 24 years.
So no, in the Southern Great Plains there is not a “conspicuous and increasingly frequent number of episodes of extremely cold winter weather. Also, “severe winter weather…is not increasing,” they claimed. None of these statements are true.
Then I thought, “Well, maybe I’m looking too far south. Perhaps the claimed effect is visible in the northern Great Plains.” So it went back to the drawing board, and here’s what I found.
Figure 3. Standard deviations of February minimum daily temperature for the Northern Great Plains. Cold spells are indicated by an increase in standard deviation
Although the Northern Great Plains NCA region has greater disparities in February low temperatures, the same situation prevails as in the Southern Great Plains — one “episode of extremely cold winter weather” in February in the first 24 years, half a dozen or so in the middle 24 years and the two cold February 2011 and 2021 in the last 24 years. And there is no trend in the data.
Another beautiful theory runs hard on a riff of ugly facts.
best to all,
w.
data access—I have placed the 72 years (1951-2022) of daily temperatures in the southern Great Plains, both maximum and minimum, in my Dropbox for download. It’s a fairly small file titled Great Plains South nClimDiv.csv, 588 KB, in CSV format so it can be opened in Excel or other programs.
my usual—I can defend my own words. I choose them very carefully. I cannot defend your (mis)understanding of my words. So please, if you comment, cite the exact words you are discussing.
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