The Temperature Of The UK Over The Last 100 Years (part 4)

A butcher's at daily maxima and minima over the last 100 years. Are things getting worse, and what does ‘worse’ mean?

Just as things were getting interesting in part 3 the meter ran out. We took another look at just 2 UK weather stations (Heathrow Airport and Wick Airport) and I used their mean daily maximum temperature records (tmax) to explain a few things about temperature anomalies. We saw how useful anomalies can be, and we saw how they can easily deceive the naked eye if you are not used to working with them. I then cooked-up another estimate of the urban heat island effect (UHIE) that fetched-up at 1.6°C over 70 years, this comparing favourably with my first estimate of 1.8°C per century that may be found in this newsletter.

Plat Du Jour

Today I’m going to wear a clean apron because I’m going to be cooking-up a very special dish indeed, this being the anomaly series for mean maximum daily temperature (tmax) derived from all 34 stations in the sample. I encourage folk with plenty of spare time to do the same by using the historic data the Met Office thoughtfully supply on this page.

Today’s meal ends with a cheeky little dessert, whereby we take a look at the impact of establishment of the IPCC on UK mean daily maximum temperature. I’ve always wondered why this should be an inter-governmental panel on climate change and not an inter-scientific panel but that’s another story for another day. Bon appétit!

Spaghetti Bolognese

At long last we arrive at the anomaly series for the mean daily maximum temperature (tmax) for a sample of 34 weather stations across the UK:

I’ve crayoned Heathrow in thick red since this is where many of our temperature records are set, and because we’ve been studying Heathrow’s data in a weeny bit of detail. Anybody thinking Heathrow was running cool back in 1953-1969 needs to go back and re-read the previous newsletter and let my words about the illusion of the anomaly and the analogy of pinning the donkey’s tail sink in. In sum, Heathrow looks cooler in 1953-1969 because it is running hotter in 1991-2020 - all depends on where you grab the tail!

Some may ask why I didn’t do the sensible thing and use the WMO climatological normal of 1961-1990 to normalise my data and the answer to that is 7 of the stations were not operative in 1961 so I cannot determine their anomaly unless I fudge the process and go for truncated normalisation. What is important is that all stations are normalised in a consistent manner.

A Palate Cleanser

Now that all 34 stations are normalised in a consistent manner we can set about calculating their grand mean anomaly on a year-by-year basis to arrive at an estimate for the UK as a whole. Here’s what this looks like:

I’ve started the series at 1865 and not 1853 since 1865 is when 2 stations crop up in the sample (Oxford and Armagh). Two heads are better than one sort of thing, and you can’t calculate an average from just one number! On this point please do bear in mind that the sample size increases as time passes, and the first year we see all 34 stations putting their thermometers out is 1986. The half-way mark of 17 stations was reached in 1948.

So what do we observe? I would argue that we see two big features, the first being a soaring mean anomaly since 1985 or thereabouts along with a cyclical period from 1865-1985. Before 1985 it is doubtful whether the mean anomaly shifted much at all apart from oscillating but I shall put this to formal statistical testing in a short while.

What The Stats Say

What we need to do now is ignore the awkward cyclical aspect and order up some classic linear regression to give us an estimate of the general rate of warming witnessed over these 157 years. Herewith the key tables:

This tells us that the mean daily maximum temperature (tmax) for the UK has been rising at a rate of 0.007°C per year, on average, this point estimate being highly statistically significant (p<0.001). This equates to 0.7°C per century, which is a lot less than the 1.5°C estimate for mean global temperatures offered by the IPCC.

Before we get into convoluted discussion about the UK not being globally representative over the period 1865-201 (which would suggest ‘global warming’ is a misnomer), we may stop and realise that the arithmetical mean global temperature is necessarily derived from minimum as well as maximum temperatures, which in turn means that it must be a significant rise in minimum temperatures that is driving that 1.5°C. There’s plenty of research out there that reveals this is indeed the case but it’s nice to confirm this stage-by-stage using a sprinkling of home-spun data and simple techniques.

Subscribers might like to start cogitating on why the minimum, rather than maximum temperature, is in the global driving seat. Minimum means night time: what, then, is keeping our nights warmer than they should be? A clue is given in what we decide to take to bed to keep us warm. Given the option of a flask of hot carbon dioxide or a bottle of hot water or a warm concrete slab what would you put on your tootsies on a cold winter’s night?

The Hand Of Solomon

At this point I suggest you forget everything you know about climate change and cover up the right-hand side of the slide from 1985 onward with your hand. What do you see? My eyeballs report an oscillating anomaly that goes up then down without going anywhere warmer or cooler in the long term.

How is this possible given we’ve been burning fossil fuels since the 18th century, with a near-exponential increase in CO2 emissions since the industrial revolution?

Obviously, anthropogenic global warming (a.k.a. man-made global warming, a.k.a. global warming, a.k.a. climate change, a.k.a climate crisis, a.k.a. climate emergency) cannot have been the one and only driver for mean daily maximum temperatures across the UK over this period.

Now move your hand to cover the points before 1985. Why is it that we only see apocalyptic rates of warming from 1985 onward? Is carbon dioxide lazy or have we been inadvertently measuring UHIE at locations that are somewhat inappropriate for a scientific endeavour?

A Cheeky Dessert

The Intergovernmental Panel On Climate Change (IPCC) was founded in 1988. In 1988 I was a youngish-thing UK government scientist who had been put up for promotion from Higher Scientific Officer (HSO) to Senior Scientific Officer (SSO). As a HSO being groomed for SSO I tagged along behind my PSO (Principal Scientific Officer) to all manner of high level meeting.

One thing seriously bothered senior scientists back then and that was the move to take science funding out of the hands of scientists and put it in the hands of ‘suits’ within policy divisions. I may well talk about this in a future newsletter, but suffice it to say between 1988 and 1998 science died a painful death, not just in the UK, but in all countries following the same path. We called it “cheque-book science”, it marking the end of science run by scientists for science sake to science run by administrators for policy sake. Climate science, being a new field at the time, led the way.

Against the background of these momentous changes in science funding (that the public never got to hear about) we must set the establishment of the IPCC, whose remit was not to study the science per se, but gather evidence that supported their central tenet of the anthropogenic climate. Funding soon followed, as did all the papers, all the research teams, all the bright new PhDs and professorships, and all the well-funded departments. With a gravy train this big you bring chips to dip and rounds and rounds of bread and butter; you don’t bring vinegar and scorn (if you know what’s good for you).

So, about that cheeky dessert… what about we set up an indicator variable that marks the pre-IPCC period of 1865-1987 and the post-IPCC gravy train period of 1988-2021. What do we find?

We find this:

What this boils down to is total lack of evidence of tmax warming over the period 1865-1987 (p=0.471), and a statistically significant warming trend for 1988-2021 that amounts to 0.022°C per year or 2.2°C per century (p=0.009). It is only after establishment of the IPCC with those policy suits holding all the grant money do we see any warming to shout home about. Is this one of those coincidences where correlation doesn’t prove causation or something else?

My money is on coincidence (I did say I was being cheeky!) but the real issue of value here is understanding why we do not see any evidence of tmax warming over a 123 year period. To help us in this I’ve crayoned a pair of plots:

If you show the first of these to activists they’ll find some way of ignoring or dismissing it, it only being based on a sample of 34 weather stations, after all, that may not be representative. Ironically, this argument strengthens the notion that global warming isn’t global but activists tend to want their cake and eat it (as along as it is made from cricket flour). Failing that they’ll point out the analysis wasn’t made by an ‘approved being’, which is also ironic because I’m the very same guy that shovelled analyses of this nature under the noses of government officials up to the level of Assistant Secretary, and elected members of parliament up to the level of Secretary of State. With that came great responsibility for getting the numbers right - a skill I have thankfully retained to this day!

It may therefore be altogether more cunning to present the second slide first, since this will support their religious belief that we’re all doomed because of our sinfulness. Plus, you can always rub in the buttery fact that I too made it to the giddy grade of PSO (later to be called unified grade 7, a.k.a. G7) and headed a government statistical analysis unit to earn my crust. Once the preening and purring has set in (and imminent doom mentioned at least once) try the first slide, but brace yourself for abuse.

With that I think it high time we cracked open a packet of digestives!

Kettle On!