Extra-Ordinary Heat Wave

The heatwave which invaded England recently was no ordinary one.

At numerous locations the temperature exceeded 40°C (104°F) which, as far as we know, has never before happened in the British Isles. England definitely isn’t prepared for such temperatures, as Melissa Harrison makes abundantly clear in the Washington Post; an airport closed when the runway deformed in the heat, railway tracks buckled, the London fire department got so many calls it was their busiest day since world war II. The U.K. Meteorological Office advised people (especially the young, the old, and the ill) to go nowhere and do nothing but stay hydrated.

Not an ordinary heat wave.

The “central England temperature” record (CET, data here) is not the temperature at one location, but the average over a sizeable region you could call “central England.” While individual locations in England did meet or exceed the 40°C value, the area-wide average did not, although it did set a new record of 37.3°C (99.1°F).

The CET data report daily high temperature for 52,795 individual days from January 1, 1878 through July 19, 2022 when I downloaded it; they have posted data for a few more days since, but this includes the extreme heat of the last few days. Notice that the two hottest days in the record are this last Monday and Tuesday:

Surely this summer has had extreme heat, but others have had heat waves last a lot longer. The CET data enables us to compute the “average summer temperature” for each year, with summer defined as June-July-August and the average of daily high temperature. Since the beginning of the record, it has shown an upward trend which is “statistically significant” — summers in England have been getting hotter on average, all the while showing incessant fluctuations from year to year:

The blue line shows the linear trend, which has increased by 1.4°C (2.5°F) since the record began in 1878, while the red line shows a non-linear smooth, which estimates an increase of 1.6°C (2.9°F) since 1878. They agree that the average summer temperature has gotten hotter, by about a degree and a half Celsius (about 2.7 degrees Fahrenheit).

In spite of the tremendous heat over the last few days, the “summer average” this year (so far) isn’t even close to being the hottest on record. That would be 1976, when the heat wave was milder but lasted longer. But the “great summer of 1976” didn’t get nearly as hot as this summer, it peaked at 33.1°C (91.6°F), a record-setter at the time, but a figure which has been surpassed in four separate years since.

We can record the hottest day of the year for each year in the CET record, and this is where 2022 sticks out like a sore thumb, a whopping 3.1°C (5.6°F) hotter than before:

Again the blue line shows the linear trend (increased by 2.9°C = 5.2°F over the period of record), while the non-linear trend (red line) suggests an overall increase (of the trend, not the fluctuations!) of 4.9°C (8.8°F) since the record began. Again the blue line is “statistically significant” — the hottest day of the year has been getting hotter in central England.

One might think that of course the hottest day of the year is getting hotter, for no other reason than that summer is getting hotter. If that were true, then the difference between the hottest day of the year, and the average summer temperature, would show no trend. But it does:

Again the blue line shows the linear trend, and again it is statistically significant. Lest you think that might be an accident due to this year’s extreme value, note that if I omit this year entirely, the analysis still shows statistical significance. The difference between the hottest day of the year and the summertime average, has been getting hotter in central England — and this year is the pinnacle of that.

Again the red line shows a non-linear smooth, which indicates that the hottest day of the year has warmed by 3.3°C (5.9°F) more than the average summer temperature in central England. Add in the upward trend in the summer average itself, and that’s a lot — from just the trend, not even including the inevitable fluctuations. Add those in, you get this year’s English summer. No ordinary heat wave.

The evidence suggests that climate change played a big role in how extreme this event was. There’s more happening — according to the data, that is — than just a mild increase in average summertime temperature. That’s why Melissa Harrison cautions that “We can’t downplay it,” because this was no ordinary heat wave, nothing like the 1976 summer however hot that may have been. As she says, “Living through the British heat wave was unbearable.”

Yet some want you to think that what those in England felt with their own skin through their own sweat, what they saw with their own eyes, what they read on the thermometer, isn’t really real … this was just another “ordinary” heat wave, nothing of consequence. They insist that the 1976 heat wave was much worse, that we’re just “too sensitive” and have forgotten how to enjoy the heat, we’re always blowing things way out of proportion and imagining things, the whole thing was just a natural occurence only “slightly” affected by global warming so we should stop being such hyper-sensitive snowflakes about it!

Which reminds me of the 1944 film “Gaslight.”

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19 responses to “Extra-Ordinary Heat Wave

  1. Charles Steven Nagy
  2. The most used measure of climate change is Global Mean Surface Temperature, which (we are told) stops increasing when net-zero emissions happen. Some describe the end of rising GMST as a halt to global warming.

    However, other measures of global warming keep increasing: ocean heat content, the loss of ice mass, the extent of permafrost thaw. These do not stop with net-zero emissions, but they do not receive the same attention as GMST.

    Another measure showing the change in weather variability is needed, but this seems more difficult to define than GMST and these other measures.

    “The difference between the hottest day of the year and the summertime average” seems a good index of climate variability.

    Let’s see more of it.

    • Two quibbles:

      1. GMST is NOT the “most used” measure of climate change.
      2. “We” are NOT “told” that net zero leads immediately to any halt in warming.

      • Media reports frequently claim that the world is facing “committed warming” in the future as a result of past emissions, meaning higher temperatures are “locked in”, “in the pipeline” or “inevitable”, regardless of the choices society takes today.

        The best available evidence shows that, on the contrary, warming is likely to more or less stop once carbon dioxide (CO2) emissions reach zero, meaning humans have the power to choose their climate future.

        CarbonBrief: Will global warming ‘stop’ as soon as net-zero emissions are reached?

        By “warming is likely to more or less stop”, Zeke Hausfather means GMST will stabilise.

  3. The heat wave of ’76 went on for quite a long time but at peak it was more than 4℃ (7.2℉) cooler than the peak heat we experienced this week.

    I’ve also seen several Americans from Southern states sneeringly suggest on Twitter that “104℉ is nothing”. I’m sure they don’t realise that Connigsby in Lincolnshire where this week’s record was set is at 53.1° North—which in N.America is well north of the Canadian border.

  4. Cornwall is almost completely surrounded by ocean, and the temperature here reached a mere 36 ℃. However our exposed location means we’re also one of the wettest places in Southern England. Even before the recent heatwave water levels in our reservoirs were remarkably low:


    I seem to recall that embedding images in comments here is non trivial, but let’s try this:


    This week’s water level update is anxiously awaited!

  5. The summer of ’76 was worse, it just wasn’t as hot. It was the culmination of nearly two years of drought. Water was rationed throughout the country, reservoirs dried up, Parliament passed a Drought act and a minister for Drought was appointed, this in a country noted for rain not the lack thereof. Ironically the drought was heralded in June ’75 with abnormally cold weather, a cricket match I planned to watch was postponed due to snow! The next week the heating up started and the drought persisted for about 15 months.
    What those in the Southern states probably don’t realize is that the sun rises ~5am and sets ~9pm in Coningsby this week.

  6. The summer of 2022 isn’t over….

  7. Always good to see a new post from Open Mind. Thanks, Tamino!

  8. Heatwaves and heat records also being broken in Japan:

    The nationwide average temperature has risen by 1.26 degrees Celsius over the last 100 years. In Tokyo, that figure is 2.4 degrees Celsius.

    Japan seldom had temperatures in the 40 degrees Celsius until recently. Besides a blip in 1933, the hottest 30 days on record have all been in the last 30 years.

    Japan: Summer 2022 already breaking climate records

    • The 2.4°C of warming in Tokyo seems a bit high and is probably based on unhomogenized data including a bit of the urban heat island effect (UHI). The homogenized data from GISS indicate a warming in the Tokyo region of about 1.5°C over the last 100-140 years.
      Oslo in Norway has warmed about 2°C over the same period, which is virtually the same as at Færder Lighthouse roughly 100 km south of Oslo, indicating that the UHI effect in Oslo has been accounted for.

      • It is important to correct for UHI when calculating area averages or when attributing warming. However, when discussing temperatures at a particular location (especially cities) UHI is still part of the actual temperature experienced by the people living there, and it cannot just be discounted.

      • When you compute the lifetime trends for GHCN daily stations (raw data, neither ‘adjusted’ let alone ‘homogenized’), you obtain, for TOKYO resp. OSLO, the following trends, in °C / decade:

        JA000047662 1951 2022 TOKYO 35.68 139.77 0.30
        NOM00001492 1937 2022 OSLO BLINDERN 59.94 10.72 0.22

        Thus, the 2.4 number for Tokyo imho is very certainly not ‘a bit high’.

      • I acknowledge that UHI is an important part of the climate experienced by people in cities, including during life threatening heat waves as we have seen recently.
        However, the large-scale impacts of global warming on agriculture, wildlife, ice melt, sea level rise and so on isn’t caused by UHI but by an increased greenhouse effect, and I think it’s important to tell these two apart.

  9. By the way, thanks to Tamino for this good work.

    I tried to obtain from Met Office the individual time series of all UK stations contributing to CET in text form, but unfortunately they did not reply.

    It would have been interesting to compare these stations’ daily maxima, low minima and high minima in the same way I did using GHCN daily for
    – CONUS

    – the Globe

  10. bindindon:

    Thank you very much for providing those graphs. I wish you luck in getting the data you need to do a similar analysis for CET.

    We’ve had a post and discussion on the recent UK heat wave over at Skeptical Science, and a particular misguided commenter has been saying all sorts of things about CET that do not bear up under analysis. I have taken the liberty on that thread to point to your comment here: