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Extreme Winter Claims – Part II

September 10, 2014

By Paul Homewood

 

 

image_thumb39

https://notalotofpeopleknowthat.wordpress.com/2014/09/09/new-attempt-to-claim-more-extreme-weather-not-supported-by-data/

 

 

Revisiting claims that UK winter weather is growing more extreme, I looked yesterday at extremely cold winters, and found that the data did not support the claims. Indeed, cold extremes recently have been less common than in earlier years. Recall that I measured temperatures against a 30-yr running average, so that “extremes” were relative to current climate norms, and not, say, to 18thC climate.

 

I have now looked at the other end of the spectrum to consider whether there is any justification for the claim that more wet and mild winters have been occurring in recent years.

First, temperatures. As I did with the first post, I have used CET mean winter temperatures, and calculated anomalies against a 30-yr running average. So, for instance 2014 is measured against a baseline of 1985-2014. (For more detail , see yesterday’s post here.)

Figure 1 plots the years when  this anomaly was more than 2C.

 

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Figure 1

http://www.metoffice.gov.uk/hadobs/hadcet/

 

Much warmer than usual winters have been notably absent recently, the last two coming in 1989 and 1990. Notice also, there is a suggestion of clustering at certain times.

 

And precipitation?

 

 

Here, I have used the England & Wales Precipitation series, which dates back to 1766. Again using a 30-year running average, I have plotted winters when the anomaly was greater than 100mm.

 

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Figure 2

http://www.metoffice.gov.uk/hadobs/hadukp/

Last winter stands out, but the anomaly was actually greater in the winter of 1914/15, and just 1mm lower in 1876/77.

Prior to last winter, we have to go back to the winters of 1989/90, 1993/94 and 1994/95 to find extremely wet winters. The sort of clustering seen in the 1990’s is also seen at other times, notably between 1910 and 1916.

 

 

Summary

So, as with cold winters, the data simply does not support the notion that extremely wet/mild winters are on the increase. 

The Telegraph’s report, presumably based on a Press Release, states:

 

The results suggest the idea of a typical British winter is increasingly becoming a myth, with wide swings from mild but stormy conditions like those which hit the UK this year to extremely cold temperatures and snow in another year becoming more common.

 

The reality is that there never has been a “typical British winter”. The whole idea is preposterous, and seems to belong alongside other myths about the past. The data shows quite clearly that there has been enormous variability from year to year.

Why is that climate scientists seem to be so oblivious to the past?

4 Comments
  1. September 10, 2014 12:54 pm

    Climate scientists are oblivious to the past because the whole of “global warming/climate change” depends heavily on people having memories no longer than a year, maybe two, back. If people remember, they realize nothing really changed. Then the “statistically significant” mantra has to be dragged out and someone might actually check the calculations. Better to encourage lack of memory. (Actually, they’re not oblivious—they’re just hoping you won’t remember or check. I’m sure they find your blog very annoying!)

  2. David permalink
    September 10, 2014 2:09 pm

    We have to look at what the paper actually says, as opposed to the Tele’s spin on it (or the dreaded press release!).

    The main claim is that since the 1990s there’s been “a striking increase in *variability* of the winter – especially December – NAO” [my emphasis]. They base this claim on the observation that 3/5 highest and 2/5 lowest Decembers on the NAO record occurred in the decade 2004-13. A total of 5 out of the 10 most extreme years on record apparently occurred between 2004 and 2013. No attribution for this observation is given.

    They crunched the numbers on the odds of this happening in a 115 year data set and concluded that they were pretty small (0.3 – 0.4% probability). The published paper doesn’t claim that British winters are becoming more extreme; though one author is quoted by the DT as suggesting that they “have become increasingly unsettled”. What he means by this personal comment isn’t defined.

    I haven’t been able to replicate the 3/5 – 2/5 finding using NAO data available online. Using the NOAA data, which runs from 1950, I get 3/10 ‘extreme’ years from the period 2004-13: 2011 is the highest value on record but the only one from 2004-2013 in the top five; and 2009 and 2010 are in the top 5 lowest values (2009 is lowest, 2010 3rd lowest).

    • David permalink
      September 10, 2014 2:32 pm

      That should be extreme ‘Decembers’, not ‘years’ in the last paragraph.

    • September 10, 2014 3:37 pm

      I think you summed it up when you said “press release”.

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