July delivers temperature record amid human heat exposure warnings

As parts of Europe continue to swelter under ongoing heatwaves and soaring temperatures scientists say the first three weeks of July were the hottest in history.

Researchers at the Karlsruhe Intitite Fur Technologie (KIT) has issued a new report on this year’s temperature records in the Northern Hemisphere, with Italy was the European continent’s heat hotspot.

It revealed in the summer of the year 2023, several hot spells of variable length and intensity occurred partly simultaneously in different regions of the northern hemisphere. In their “Untersuchung der globalen Hitzewelle im Jahr 2023” (investigation of the global heat wave in 2023), researchers of the Forensic Disaster Analysis (FDA) Task Force Group of KIT’s CEDIM analysed the record temperatures reached and the population’s exposure to heat.

It said in some regions, previous all-time record temperatures were exceeded by some distance, in other areas new daily or monthly records were recorded. In June 2023, global mean ocean surface temperatures were at a record high.

The team said the Earth’s surface, including landmass, June 2023 has seen the warmest June since 1850. On a global scale, the first three weeks of July 2023 were the hottest three-week period ever. The daily record, a global surface temperature of 17.08 degrees Celsius was reached on July 6, closely followed by July 5 and 7 with 17.07 degrees Celsius each. In July 2023, extreme temperatures, and new country records – official confirmation by the World Meteorological Organization (WMO) is still pending –were reached in the Mediterranean countries, including North Africa and the Middle East. Record-breaking temperatures were also reported by the USA, Canada, and China.

“For a big temperature anomaly to develop over a longer term, a long-lasting and unusually large-scale flow pattern is required,” says Dr. Andreas Schäfer from the FDA Task Force Group of CEDIM. Pressure distribution in the middle troposphere at about 5.5 kilometres altitude plays an important role, as it influences upper airflow and the associated air mass transport.

“In July 2023, extraordinarily persistent high-pressure areas prevailed in the regions affected by the high temperatures. Here, descending air masses contributed significantly to warming and the local development of the heat wave,” Schäfer added.

The researchers also studied the population’s exposure to heat. In Germany, about seven million people were exposed to daily maximum temperatures higher than 25 degrees Celsius. These were about 40 percent more than the average number of the years 1980 to 1999. The number of persons exposed to daily temperatures of 35 degrees Celsius and higher even doubled to about 206,000. Compared to previous decades, heat exposure during the summer months was also much higher in Italy, Greece, Spain, the USA, China, and India.

In Europe, Italy suffered from the biggest heat issues. The country saw new record temperatures of more than 40 degrees. While only 4000 people per day had been exposed to such high temperatures from 1980 to 1999, this number increased to more than 127,000 in 2023.