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UK Summer Temperature Not Becoming More Extreme

December 20, 2014
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By Paul Homewood  

 

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http://metofficenews.wordpress.com/2014/12/17/has-there-been-a-recent-increase-in-uk-weather-records/

 

The Met Office report on a fairly meaningless study, which tells us that since 2000 there have been more hot records set than cool ones in the UK. They say:

 

Temperature records:

  • Since 2000, there have been 10 times as many hot records as cold records.
  • Taking into account the weighting, the period since 2000 accounts for two-thirds of all hot records in a national series from 1910, but only 3% of cold-records.
  • The longer Central England Temperature (CET) series, which dates back to 1659, reveals a similar trend – with seven out of a possible 17 records set since 2000 but no record cold periods.
  • The increase in hot records and decrease in cold records seen in recent decades is consistent with the long-term climate change signal. Seven of the warmest years in the UK series from 1910 have occurred since 2000.

 

It is hardly surprising that, since we have warmed up since the 19thC, and particularly in the last 20 years or so, we see more hot records set than cold. This does not mean that we are still getting warmer, simply that we have plateaued.

What is much more relevant is whether summers are becoming more extreme, whether hot or cold, compared to the “norm”. After all, are London summers more extreme than Sheffield’s, simply because London lies further south and is a bit warmer as a result?

Put another way, are summer temperatures more variable these days?

The Met study looks at annual, seasonal and monthly records, so let’s test out variability in summer months, which is logically the only season we should be worried about hot records.

 

I have taken the CET summer mean temperatures, starting in 1659, and plotted anomalies against the climatological norm of the previous 30 years, For instance, the summer of 2014, which was 15.9C, is compared against the 1983-2014 baseline of 15.8C, giving an anomaly of 0.1C.

The results in Figure 1 don’t tell us an awful amount, but it is worth noting some of the extremes:

1) The two “hottest” extremes were 1826 and 1976, both recording 2.4C.

2) These are followed by 1933, with 2.0C, and 1911, 1995 and 1846, all with anomalies of 1.9C.

3) The most recent year with a hot anomaly of more than 1.0C was 2006.

4) 1726 had the coldest anomaly, with 2.1C, followed by 1816 and 1695.

5) The anomaly of 1.1C in 2011 was the coldest in recent years.

 

Remember that all these years are compared against the climatological norms of their times.

 

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Figure 1

 

However, it gets more interesting when we combine negative and positive anomalies together. In other words, all anomalies, whether positive or negative, are plotted as positive, as in Figure 2.

 

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Figure 2

 

1826 and 1976 still appear as the standout peaks, but visibly the anomalies in recent years are not unusual, as the 30-year running average shows.It appears that the most volatile period was in the early 19thC, which followed a very stable period in the mid 18thC.

Since 1900, there has been little change in the trend, which has started to drop in the last decade. 

 

Unless Central England temperatures drop back to earlier levels, we will no doubt continue to see more hot records set than cold. Indeed, it is ludicrous to expect cold records to keep up, when we are comparing against the much lower temperatures of the Little Ice Age.

The real issue is whether our summers are becoming more extreme, and the answer is clearly that they are not.

 

I will take a similar look at winter temperatures tomorrow, and also rainfall records which the study also addresses.

5 Comments
  1. Mikky permalink
    December 20, 2014 9:46 pm

    What really matters in heatwaves is the daily maximum temperatures, it may well be that they have barely changed for decades. The daily minimum (night time) temperatures may have risen a bit, which of course increases the mean temperature, but not at all in a scary way, in fact it would reduce one of the major problems that most living things have to cope with, the diurnal temperature variation.

    If AGW results in warmer nights and warmer winters then I say bring it on.

    • Green Sand permalink
      December 21, 2014 12:37 am

      Mikky

      Simply, we keep records so we can keep recording records!

      As this planet has existed for over 4 billion years some need to rely on “our” short term records in order to keep recording records! Hardly surprising that they keep giving!

      Breaking a “record” makes some folks feel good, contribution or erosion of time matters not, they have a “record”.

  2. A C Osborn permalink
    December 21, 2014 12:20 pm

    Paul, this is off topic but you really should have a read of Chris Booker’s latest missive about DECC, it is shocking and exposes them for fantasists that they are.

    http://www.thegwpf.com/christopher-booker-the-insanity-of-zero-carbon-britain/

  3. Kelvin Vaughan permalink
    November 24, 2015 7:11 pm

    Looks like they have been looking for a reason for the step change around 1988.
    http://phys.org/news/2015-11-climate-evidence-global-shift-1980s.html

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