The Rise and Fall of Central England Temperatures

  • Date: 08/03/18
  • Tony Brown, Climate Etc

This article examines the continued cooling of CET this century

  • Looks at a similar scenario of regional cooling in America
  • Examines CET related urbanisation issues, and the current Met office allowances for this
  • Notes the centuries long general warming of our climate.
  • Notes considerable English seasonal variability over the centuries
  • Examines the key component parts of the weather that affect the British Isles
  • Queries whether wind direction, strength and longevity are major factors in shaping our climate over the centuries.

Note: Weather comprises the day to day events that we all experience. Climate is officially the trend of the weather (often temperature and rainfall) taken over a continuous thirty year period. The two terms have sometimes been used in an interchangeable manner here, when a period of more than a year is being examined.

Some two years ago I wrote this article The Rise and Fall of Central England Temperature. This article commented on the interesting-but not climatically valid-observation that no one born in England this century has known warming; in fact there had been a slight decline in temperatures, albeit still maintained at a historically high level.

This data – using Central England Temperature (CET) which is maintained by the Met Office – has now been updated to the end of 2017 as shown in Figure 1. It shows this decline continuing, although recent warm seasons have slightly reduced the downwards trend.

Figure 1

To put this into a much broader context, here is the seasonal data from the start of the CET record in 1660.

Figure 2

Figure 2a linked here [2a ], shows the seasonal temperatures in much greater detail.

The recent cooling was interesting, as it appeared that CET fitted into the pattern of an earlier article I co-authored with Verity Jones In Search of Cooling Trends.

This graphic shows some of the stations identified as cooling over the statistically meaningful period of at least 30 years

Figure 3

The take home message was that whilst undoubtedly most stations around the world had warmed in recent decades, it could be observed that there were large warming AND cooling trends in many places. With regards to cooling, some one third of stations worldwide showed a trend that was downwards, rather than upwards. This was confirmed by Richard Muller of the BEST project several years ago in a personal email, but it must be said there are many caveats to this observation, especially as regards the length, amount and consistency of this cooling.

In 2016 Professor Muller wrote an article in which he observed the areas of sustained cooling in America;

Figure 4

He wrote [link]

I attach a plot that shows climate around the US. The blue circles show locations where the trend line has indicated cooling weather over the last 100 years. The red crosses show where it has warmed. The fact that ⅔ of the spots are warming illustrates that global warming is real, although to be careful and scientific we have to avoid the heat island effects (not part of global warming) and average equally over all land and sea. The cooling parts on the map don’t indicate that the world is cooling, but only that local variability in climate is still larger than the global warming trend.

Now neither America nor England constitutes the entire world land surface of course, but both countries have especially good weather records. In Britain’s case, the temperature records go back to 1659, which I reconstructed further back to 1538 in this article from 2011 The Long Slow Thaw.

This showed the oscillation of temperatures throughout the period and in particular the depths of cold in the ‘Little Ice Age.’ (The results can be seen in Figure 6, below.)

The keepers of the CET records-the UK Met office  had recognised that since its inception over 350 years ago, Britain – and more specifically England – had become much more urbanised and accordingly made adjustments to the temperatures in recent decades to compensate. In the ‘Long Slow Thaw’ I wrote this:

The modern era of CET is potentially showing the effects of needing a uhi adjustment greater than the Met office currently apply. * However, as we had earlier observed that instrumental records should not be considered accurate to tenths of a degree we are perhaps splitting hairs. Consequently, more accurately we should observe that the ‘direction of travel’ of temperatures, when combined and constrained by historic records, shows that at several points from 1538 there are similarities to the modern era as regards warm periods.

*Note; Since 1974 the data have been adjusted by the Met Office to allow for urban warming: currently a correction of -0.2 °C is applied to mean temperatures. The context of this UHI adjustment can be seen in this graphic showing population growth.

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