Denise Müller-Dum und Jens Kube

Dramatic weather records in the Mediterranean

The summer of 2023 was the hottest on record worldwide. The Mediterranean was one of the areas affected, with dramatic consequences.

Climate change is showing its drastic impact in more new records: the calendrical summer of 2023 was the hottest since record-keeping began in 1940. The Mediterranean region was especially hard-hit by the extreme heat in July. People in the Mediterranean countries suffered through daytime air temperatures of up to 45 degrees Celsius on land. In Sardinia, the temperature even reached 48 degrees Celsius, and in some parts of northern Africa it was even higher. Severe forest fires were one consequence of the heat wave; as a result, about ten percent of the land area of the Greek island of Rhodes was burnt. 

Mediterranean particularly affected by climate change

According to an analysis by the World Weather Attribution Initiative, the record heat wave of July 2023 would have been virtually impossible without human-induced climate change. The Mediterranean region is warming about 20 percent faster than the global average. The air temperature there is already 1.5 degrees Celsius higher than in the pre-industrial era. Among the reasons this region is warming faster than others are an increase in soil dryness and a decrease in atmospheric haze from aerosols. 

The heat wave also affected the sea, with an average Mediterranean surface temperature of 28.7 degrees on July 24, 2023, the highest ever.  The water temperature in the Mediterranean has been rising by 0.29 to 0.44 degrees per decade since the 1980s. For marine life, this means more stress in addition to pollution, overuse and acidification; mass die-offs of corals and sponges are becoming increasingly common. Many mollusk, fish, reptile and mammal species are threatened with extinction if climate change continues unabated.

Storms and bleak prospects for the future

The high water temperatures also favor the development of severe storms, as happened in early September 2023 when torrential rains devastated entire regions in Greece, Bulgaria and Turkey and caused two dams in Libya to fail, killing several thousand people.

The physical cause of the heavy rainfall was what meteorologists call an omega block that formed in early September. There was a stable high-pressure zone over central Europe. On its edges, in the North Atlantic and south of Greece, were two low-pressure zones that remained in place for an extended period. “Daniel,” the low-pressure system over the Mediterranean, received a constant supply of moisture for days due to the high water temperatures; this was the cause of the intense rainfall.

The list of dramatic weather records is sure to grow longer in the future. According to the World Weather Attribution Initiative, heat waves like the one in July 2023 could occur every two to five years in a world two degrees warmer than in the past. The Intergovernmental Panel on Climate Change (IPCC) has also warned about the effects of rising temperatures in the Mediterranean region. Many people will be affected by increasing heat and drought and the rising sea level. In some regions, they will face more frequent and more intense heavy rainfall. In the IPCC’s view, people and the ecosystem have limited possibilities for adapting to these changes.


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