Climate change: the hottest year

By Richard North - January 11, 2025

The Met Office, yesterday was parading with glorious certainty the headline to a triumphal press release which read: “2024: record-breaking watershed year for global climate”.

2024, it told us in the text, was the warmest year on record globally and the first year that was likely more than 1.5°C above pre-industrial levels: a stark reminder global temperatures are continuing to rise.

Last year recorded the highest temperature in any year since 1850, and it will be the eleventh year in succession in the HadCRUT data series that has equalled or exceeded 1.0°C above the pre-industrial average period (1850-1900).

The global average temperature for 2024, it continued, was 1.53±0.08°C above the 1850-1900 global average, according to the HadCRUT5 temperature series, collated by the Met Office, the University of East Anglia and the National Centre for Atmospheric Science.

On that basis, 2024 is therefore “the warmest year on record and is likely the first calendar year exceeding 1.5°C. 2023’s value of 1.46°C exceeded the previous warmest year – 2016 – by 0.17°C, making 2024 and 2023 the warmest and second-warmest years on record”.

If nothing else, one has to admire the precision and certainty of this release and the remarkable ability to produce a single figure to represent the entire planet, with a precision down to two places of decimals, and comparable with the (evidently) equally accurate planetary figures from 1850-1900.

Considering the enormity of this wondrous task, I have long been wondering and writing about how this feat has been achieved so consistently over the years. And one can only hold in awe those who manage this stupendous task.

In the real world, though, I have doubts. For instance, when contemplating a universal, single figure to represent the entire planet, comparable over a period exceeding 150 years, I look around me and struggle to understand the validity of the concept.

For instance, there is a spot in my yard, between the shed and the flank of my neighbour’s house, which never gets really warm, even in the hottest day. At the other end of the garden where it is free from the shadow of the trees and houses, it can be ten degrees or warmer than my cold spot.

Ranging through what is a small urban garden on a sunny day, you will in fact find a wide range of temperatures at any one time and, through the day, temperatures will change significantly, both in absolute terms and relatively as the sun moves round the horizon.

And that is just during the day. Come nightfall, temperatures will again change, and vary throughout the night, even when the weather is fairly stable.

Now, take one 24-hour period and tell me what the temperature of my garden was. That can’t be done, there is no single temperature so one would have to resort to taking an average. But an average of what?

Does one have a single monitoring point and take an overage on a temporal basis? Or does one have multiple monitoring points across the garden, so that we take the spatial average and then average out those averages on a temporal basis?

In each case, one has to ask how many data points are necessary. Is simply a maximum and minimum enough, especially in unstable weather conditions?

But, just supposing we arrive at a single figure, how representative is that of the garden itself. It does not represent the conditions at any one time: it is an arithmetical artefact, which bears no relation to the conditions at any one time, nor in any particular spot.

And that is just one day. As I write, it is the coldest night of the year, with the temperature currently at -7ºC. The temperatures will fluctuate daily – and by night. In the summer, even in the depths of the night, we have experienced 30ºC.

If I now take my average of the averages for a single day and then repeat the process 365 times (366 on a leap year), I can then take the average of those figures, to give me the average of the averages of the averages – all boiled down to a single figure.

But what does that figure even mean? It doesn’t represent anything tangible, or anything actually physically experienced throughout the year.

This figure, though, is just for my garden. Repeat the process with different data points along the street and you will get very different results. For a start, most of the houses in the street don’t have gardens. The temperature profiles adjacent to them will be very different from mine.

The problem then is which location to take as “representative” of the whole, bearing in mind there may be five or so degrees difference between spots at any one time.

This problem is further compounded by changes over the longer term. If you are looking for a 100-year record, you have a problem. Fifty years ago, my garden wasn’t a garden. It was a weaving shed housing a loom which churned out fine, barathea cloth – the last one in Bradford.

Staying with the present, if we move from my location a couple of miles into the centre of Bradford city, the temperature profile is going to be very different. Apart from the urban island effect, its altitude is about 500 feet lower than ours. Depending on which adiabatic lapse rate applies, that alone could account for a 2-3 degree temperature difference.

And, for my locale, which point do we take as representative of the temperature? If Bradford city is used, it will bear no relation to ours, and vice versa. And nor will either reflect the conditions in the rural surrounds, and it will be very different from the conditions in Leeds. We can have snow feet deep and the residents there will be stepping in rainwater puddles.

Let’s now expand this exercise to West Yorkshire. What is the single, annual temperature for that region, and will it bear any relation at all to reality. And how will that compare with North Yorkshire – our Pennines against their Yorkshire Wolds and seaside towns and cities?

As we radiate from these spots progressively to cover England, then Wales, and creep up into Scotland, thence into Shetland and the Hebrides, what price a single annual temperature to cover the whole of Great Britian.

Now, of course, we have to do this country-by-country, from the frigid permafrost areas of Siberia to the baked plains of Australia, the deserts of the Sahara and the balmy, temperate climate of South Island, New Zealand.

That tiny sample, however, doesn’t even begin to convey the range of conditions experienced in the land masses throughout the globe, and then there are the oceans and seas covering about 71 percent of the planet’s surface, with their own temperature characteristics.

Somehow, then, from this huge range of conditions, we have to distil a single temperature – not for one day, which is hard enough, but for the whole year, through the seasons in the northern and southern hemispheres, the tropics and the polar regions.

All this must be represented by a single global temperature, and not only that, to two places of decimals using instruments which, largely, are only accurate to plus-or-minus one degree, with even less accuracy when one gets to the turn of the 20th Century.

One need not dwell on the huge range of literature which questions the accuracy and consistency of the measurements which go into making up this single figure, when one addresses the core concept.

The reality is that is single figure is an artefact – it isn’t real and it actually represents nothing other than a series of tendentious compilations, manufactured from data which themselves are often incomplete and not uncommonly invented.

Furthermore, the raw material itself isn’t real. This was admitted by the Lord High Priest of climate science himself, James Hansen, who told us in 2009 that he relied not on the actual measurements but the “Absolute Surface Air Temperature” (SAT).

This, we learn, is something which actually cannot be measured. Says Hansen, a temperature map using SAT data can only be created with the help of computer models, the same models that are used to create the daily weather forecasts.

We may, he says, start out the model with the few observed data that are available and fill in the rest with guesses (also called extrapolations) and then let the model run long enough so that the initial guesses no longer matter, but not too long in order to avoid that the inaccuracies of the model become relevant.

This may be done starting from conditions from many years, so that the average (called a “climatology”) hopefully represents a typical map for the particular month or day of the year.

For the global mean, he then tells as, “the most trusted models produce a value of roughly 14 Celsius, i.e. 57.2°F, but it may easily be anywhere between 56 and 58°F. Regionally, let alone locally, the situation is even worse”.

And yet, to two places of decimals, we must now accept that the planet is getting warmer and, as we freeze in our beds – stripped as we are of the heating allowance – we must accept that this year is to be warmer still.

For some reason which I cannot fathom, I get this sudden right wing feeling.