Home World The temperature record in Rome dates back to 1841? Caution

The temperature record in Rome dates back to 1841? Caution

Edit: Modification of the date 1842 appearing in the title and the body of the article, instead of 1841.

Tourists seeking shade at the foot of the Colosseum, emergency services seeing dehydrated people flocking… Rome, like around twenty Italian cities, has been placed on “red alert” by the Italian Ministry of Health due to the heat wave which has been raging there for several days. 41.8°C were recorded in the Italian capital on Tuesday, a record according to the country’s press.

On Twitter, two personalities with several thousand followers claim that an even higher temperature, 42°C, was recorded in 1841. They add that the temperature was reached when there were no “cars” or “planes” at the time, an argument that minimizes the human impact on climate change.
“42°C in Rome in July 1841, before cars and planes, unrelated to CO2”, wrote the Italian Robin Monotti on July 16, in a tweet seen more than 3.5 million times.

The 42°C recorded in 1842 has not been recorded by modern standards. It must be taken with hindsight. – Twitter screenshot

Two days later, Silvano Trotta, a Frenchman, took up the same argument, in a tweet viewed 216,000 times.

This episode of heat in 1842 does not prove that the current warming is not accelerated by human activities. – Twitter screenshot


As Note user “DruIDeavide” on Twitter, the only mention of this temperature is on the Italian site Meteolive*, in an article written in 2002 by a contributor outside the site. Interested in Rome’s weather records, this anonymous contributor writing that the “absolute maximum temperature, +42.0°C, (was) recorded on July 27, 1841. The temperature was recorded from the Collegio Romano station located in the historic center of the city. »

A temperature of 33.6° Réaumur was indeed observed on July 27, 1841 in this meteorological station in the center of Rome, confirms to 20 minutes Luigi Iafrate, from Crea, the research center dependent on the Italian Ministry of Agriculture which manages the station. Converted, these 33.6° Réaumur give 42 degrees celsius. However, this old survey, dating from the first half of the 19th century, should be taken with a grain of salt. “The absence, at that time, of a modern meteorological shed (introduced in the use of meteorological records after 1850), makes me think that the data should be revised and submitted for validation”, warns Luigi Iafrate.

The current temperature record observed and validated at this weather station dates back to July 4, 1905, when 40.1°C was recorded. This record “is validated and has not yet been beaten”, recalls Luigi Iafrate, “since the absolute maximum of 18 (July 2023) did not exceed 39.3 degrees”.

Several organizations take temperature readings

If 39.3° were recorded at this station on Tuesday, then where does the record temperature of 41.8° C reported in the media come from? It just wasn’t registered in the same place. The survey was carried out at CSOA Forte Prenestino, in the east of the city. This temperature has been communicated by MeteoLazio, an unofficial weather site. There is currently no equivalent of MétéoFrance in Italy and various public and private organizations publish weather reports.

CSOA Forte Prenestino is not the international reference station for the city. For this, the World Meteorological Organization relies on data from an air force station in the north of the city.

July is on track to become the hottest month ever recorded by the European Copernicus observatory, whose consolidated data dates back to 1940. As for the fact that there have been heat episodes in the past, such as in 1841 in Rome, this does not cancel the reality of climate change taking place.

Scientific research has thus made it possible to establish that “over the last million years, the Earth has experienced a succession of glacial and interglacial periods”, remember the CEA site, a laboratory of which conducts climate research. However, “we observe that the climate has been warming for 150 years and much faster than what data from the natural archives show”. Thus, “during the release of the last glaciation, the Earth’s climate warmed up by around 5 degrees in 10,000 years, recalls the CEA. Current global warming is at least fourteen times faster! »

*Contacted, Meteolive did not respond.

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