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The Met Office’s Baseline

Andrew Montford, GWPF

Science, miscommunication, and its results

Yesterday, I looked at the Met Office’s UKCIP02 temperature predictions to see how they had fared in the 16 years since originally published. At the time, I wasn’t able to lay my hands on the original report and worked from a news report. However, since then, Ed Hawkins has helpfully pointed me to the original text. He also said that my analysis wasn’t correct because the temperatures given in the report were against a 1961-90 baseline. In other words, where the news report had said…

Annual average temperatures look set to rise by between 2C and 3.5C by the 2080’s

…in fact a large chunk of that rise had already taken place by the time of the report’s publication in 2002. The article is therefore rather misleading, since the reader is clearly led to believe that this is further warming. There is no discussion of baselines. This is surprising because the article’s author was Geoff Jenkins of the Hadley Centre, who must surely have understood the issues.

Looking at the UKCIP02 report itself, there is a similar problem. The executive summary says:

How will UK climate change?
Annual changes
11. Average annual temperatures across the UK may rise by between 2ºC and 3.5ºC by the 2080s, depending on the scenario.

So again, what is communicated seems to be rather different to the truth. It’s only in the body of the report that you learn about the effect of the baseline choice, so the “execs” and the public – who presumably do not read the full report – are misled.

In passing, it’s interesting to note yesterday’s press release for UKCP18, which says…

Summer temperatures could be up to 5.4°C hotter by 2070, while winters could be up to 4.2 °C warmer

…again without any discussion of baselines.

Anyway, I have now updated the graph to incorporate the reduced warming expectation. It looks like this.

So it’s still fair to say that, thus far, the predictions haven’t been a resounding success.

In passing I should note another small error in the original piece. I had thought that UKCIP02 was the first climate impacts report, but in fact there were earlier ones too. I have managed to lay my hands on the summary report for UKCIP98, but the one I’m really interested in is UKCIRG91 “The potential effects of climate change in the United Kingdom” which is now nearly 30 years old. This will capture some of the warming at the end of the 20th century, which will work in the Met Office’s favour, but it will be interesting how things pan out after nearly 20 years of warming “pause”.

If anyone can lay their hands on an electronic copy, or even a scan of a relevant graph, I’d be grateful. [Update: I found it on Amazon]