UK Temperature Trends
By Paul Homewood
According to the Met Office, mean temperatures in the UK last year averaged 9.6C, 1.0C above the 1971-2000 baseline. But what does this tell us about the long term trends?
A look at the Met’s temperature graph is a good place to start, as shown in Figure 1.
We can see straight away that the 1970’s marked a cooler phase, following a warmer period in the 1940’s and 1950’s, so the use of a 1971-2000 baseline can be misleading. A baseline of 1981-2010, for instance would yield an average of 8.9C, instead of 8.6C. It is also worth pointing out that, based on the six months to June, the mean temperature is likely to finish the year around 9.1C, not significantly high, and lower than most years in the last decade.
We can get a better idea of the trend by looking at a five year running average.
The Met record starts in 1910 and since then there has been a gradual increase around the trend line. The years between 1960 and 1990 dipped below the trend, followed by a warmer interlude. In the last two years, however, we have seen temperatures returning to the long term trend. This can be seen more clearly in Figure 3, which focuses on the last couple of decades.
However, let’s take a longer perspective. The CET (Central England Temperature) Record goes back to 1659. The temperatures are, of course, just for England, and therefore are not directly comparable with the UK figures above. Figure 4 again shows five year running averages.
A couple of things stand out.
1) The figure for 2011 is only very slightly above the trend line. Remember these are five year running averages.
2) Temperatures in the 1730’s were pretty much the same as now. For several years in that decade, the five year average reached 10.0C, with the temperature in 1733 itself recorded at 10.5C. In comparison, the five year average still stands at 10.0C, and the warmest year on record, 2006, was only 10.8C. One could be excused for wondering what the all the fuss is about!
I would also invite readers to compare Figure 4 with the graph at the top, which is the CET graph that the Met show prominently on their website. Spot the difference? Even though the CET record starts in 1659, the Met have deliberately chosen to start their graph from 1772. It is surely no coincidence that this was around the time when lower temperatures became prevalent again. Could it be that the Met are not keen on people discovering that, 280 years ago, it was as warm as it is now? I cannot divine their intentions, but surely this is not something real scientists do?
It would be reasonable to assume that higher temperatures have led to more intense heatwaves. According to the UK Climate Impacts Programme, the body set up by the UK government, “An increase in frequency of heatwaves is one of the effects of climate change we have already experienced in the UK”. But what do the facts tell us?
Sheffield is, geographically, fairly representative of England as a whole, being centrally positioned. Daily temperature data supplied by the Met Office gives the following distribution of days when the maximum temperature reached 30.0C or more.
As can be seen, there has been nothing unusual happening in the last decade. The two hottest days on the record, which goes back to 1930. were 2nd and 3rd August 1990, when the mercury reached 33.4 and 34.3C respectively. The summer of 1975 also stands out, when, on five days, temperatures exceeded 30C. Apart from 2006, the last decade has been noticeably lacking in heatwaves, as Figure 6 amply shows.
It will come as no surprise that the UK Climate Impacts Programme have used the 1960’s as the starting point for their comparisons. It is, of course, a common tactic.
I would also like to show the Met’s graph for sunshine hours.
Now where have we seen this shape before? Why, surprise, surprise! Temperature are higher when the amount of sunshine increases, and fall when it decreases. Now who would have thought that? Instead of trying to link climate to CO2, maybe the Met Office should spend a bit more time looking into the effects of sun and clouds.