Will temperature records be broken today? You bet they will. By the end of the day you can be sure we’ll be bombarded with headlines along the lines of ‘Records tumble as Britain wilts’ – or, in the case of the Guardian, ‘Record-breaking heat heightens fears of climate crisis’. But don’t get too excited. Read on a little and you will find that the records which have been broken will seem just a little less dramatic than they at first appeared. The reason we keep having ‘record-breaking’ heat is not so much because of climate change – although rising global temperatures are slightly increasing the chances of records being broken – but because there are so many records to break. This is especially the case since it became fashionable for meteorologists to start using daily temperature records: the highest, or lowest, temperatures recorded in a particular location on a particular day of the year.
The trouble is that this creates so many records it is inevitable they are being broken all the time. Last Sunday, the Observer ran the headline ‘US temperatures hit record levels as south west bakes in a heatwave’. If you thought that meant that America has just witnessed its highest temperatures ever, you were in for disappointment. It turned out that the records that had been equalled (not even broken) were the hottest 11 June in Phoenix, Arizona (equalling that measured on the same day in 1956), the hottest 11 June in Las Vegas (equalling 1956) and the hottest 11 June in Denver (equalling 2013).
Let’s do a little sum. There are 19,495 incorporated cities and towns in the US, and there are 365 days of the year – or rather 366 days with temperature records. Multiply these together and you find there are 7.1 million daily temperature records in the US to beat. Moreover, reliable temperature records only go back a century or so. The chances of getting through an entire year without a number of these records being broken is negligible. In fact, you would expect an average of 194 such records to be broken every single day (a figure you can arrive at by dividing 7.1 million records by the 36,500 days of the past century).
As for Britain, the Met Office uses a network of 270 automated weather stations around Britain capable of producing instant recordings. Ignoring all other weather stations which could potentially record their highest-ever temperature for 17 June today (with a slight delay), the automated network alone provides a potential for 98,550 daily weather records. No, it won’t mean ‘climate chaos’ if some of these fall – it will simply be an inevitable result of ‘record temperatures’ having become a debased currency.
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