Extreme heat is nothing new: the puzzling 1852 list

Extreme heat is nothing new: an 1852 list proves it

Is today's climate change really exceptional? On 18 July 1852, the British newspaper The Observer published an account of extreme heat events from the twelfth to the eighteenth century. The list includes episodes that defy the imagination: in 1152 eggs were cooked in the sand; in 1303–1304 the Seine, the Loire, the Rhine and the Danube were crossed on foot; in 1646 there were 58 consecutive days of excessive heat. And that's without mentioning that in 1830, during the revolutionary July days, the thermometer reached 36 °C in Paris – on the scale we use today – a temperature then considered worthy of exceptional record.

The temperature scales of the time add to the confusion. The 36 degrees in the original article were probably on the Réaumur scale, which would be equivalent to around 45 °C today. Some analyses suggest that in 1718 the Rømer scale was used, which would give 54.3 °C, although that doesn't match the Fahrenheit conversion also mentioned. The detail matters because any comparison with modern records requires homogenising the scales.

Historical data fuel two opposing camps. On one side are those who see these references as evidence that the climate has varied naturally and that current temperatures are not unprecedented. On the other are those who point out that, although there were spikes, the current trend exceeds any previous record and that phenomena such as the sustained heat of 2023 have no precedent. The debate is not new: as early as 1852 such data were being compiled in an effort to understand the patterns.

And while some blame cows and others blame industry, The Observer's list remains a reminder that extreme heat is not a modern invention. Perhaps climate gurus should take a look at the archives before declaring that 'it has never been like this before'.