Are English Summers Getting Hotter?
By Paul Homewood
Are summers in the UK getting hotter?
It seems to be one of those ideas that are ingrained in the public psyche, fed by headlines like the one above, which was based on the CCC’s latest report claimed:
Heatwaves in the UK like that experienced in 2003 are expected to become the norm in summer by the 2040s. The average number of hot days per year has been increasing since the 1960s.
But what do the facts tell us?
For the purposes of this exercise, I am only looking at England, as that is where summers are hottest. I have certainly never heard a Scotsman complain that his weather is too hot!
I am also only considering daily maximum temperatures, as it is these which are normally referred to when discussing heatwaves. Also, night time temperatures are less reliable, being affected by UHI.
If we look at the Met Office graph below, the trend line seems to have flattened out in recent years. However, trend lines over such a short period of time must be treated with extreme caution.
Nevertheless, this graph tells us more about the relative absence of COLD summers recently, rather than whether summers are actually becoming hotter.
This is a critical consideration. Whether average temperatures are increasing, and whether summers are getting hotter are two separate things.
It is readily apparent that the hottest summer by far was 1976, while the second hottest was way back in 1911. The last really hot summer was in 2006, but there was certainly nothing unusual about that one.
In short, there is nothing in the data to show that maximum temperatures in summer are increasing, or that hot summers are becoming more common. Never mind providing evidence that they will in future.
Perhaps the clearest way to appreciate this is to look at the ten hottest summers below:
In other words, two each in the 1970s, 80s and 2000s.
Contrary to popular myth, it seems that summer temperatures have actually been very stable since the exceptional summer of 76.
Naturally, it is the South East which tends to be hottest and is where heatwaves would be most problematic, so we can do a similar exercise there.
In fact, we find a very similar pattern to England as a whole. The hottest summer, again, was 1976, while 1911 was notably warmer than 2003 and 2006.
The distribution of the ten hottest summers is also nearly the same, with the exception that 1975 drops out, to be replaced by 1949.
I’ll finish with a graph you should all be familiar with, the distribution of days in the CET which were over 30C. After all, average temperatures across the whole of the summer don’t necessarily tell you everything about short bursts of heat.
It does not need a statistician to tell you that daily temperatures have refused to go above those recorded in July 1976 and August 1990 ever since. It is almost tempting to say that there is a ceiling above which temperatures will no go.
As for the claim by Krebs’ committee that temperatures could reach 48C, such nonsense belongs in a comic book, and not a supposedly serious study.
There certainly appears to have been a shift change in summer temperatures after 1970, whichever metric you look at. But anybody who claims that “summers are getting hotter”, or that heatwaves in the UK like that experienced in 2003 are expected to become the norm in summer by the 2040s , is selling you snake oil.