Climate change intensifies the occurrence of extreme heat waves

The heat waves of 2022 and 2023 show that global climate change and its effects are accelerating, according to a new study.

The data collected in a new research led by scientists from the National Museum of Natural Sciences (MNCN), dependent on the Higher Council for Scientific Research (CSIC) in Spain, confirm that the heat waves recorded in 2022 and 2023 in the western Mediterranean, with Summers that reached temperature anomalies of +3.6 degrees Celsius and +2.9 respectively, exceeded the natural climate variations of the last 1,000 years.

The study, carried out in collaboration with researchers from the University of Zaragoza in Spain, the Institute of Geosciences (IGEO) of the CSIC and the universities Johannes Gutenberg (Germany) and Cambridge (United Kingdom), reveals that global climate change is intensifying these extreme phenomena and bringing forward their appearance, since predictions indicated that they were not going to occur until the end of the 21st century.

To reach these conclusions, the research team has combined the data obtained from historical reconstructions based on dendrochronology, which analyzes the growth rings of trees, and which in this study has allowed them to reach 1119; the temperature and precipitation data for which there are records, that is, since 1890, and the information provided by future projections based on different predictive models.

“These heat waves, which until now were considered extremely rare because they occurred with a cadence of about 10,000 years, could occur with a frequency of between 4 and 75 years under the current conditions caused by anthropogenic climate change, depending on the future greenhouse gas emissions scenarios,” warns MNCN researcher Ernesto Tejedor.

One of the key factors driving the heat waves in both years was the rapid increase in temperatures of the Atlantic Ocean and also the Mediterranean Sea, where temperatures rose twice as fast as the global average, aggravating the heat waves and droughts in the region. In fact, the climatic conditions of those two summers, in which there was less cloud cover from the Azores, favored the arrival of hot air from the Sahara to Europe and set records in the number of hours of maximum solar radiation, the reduction of ice the glaciers of the Pyrenees and the Alps and the decrease in river flow due to the extreme drought that caused a lack of rain in winter and spring. “In the specific case of Spain, the temperature anomaly allows us to mark 2022 as the year with the highest temperature records since 1890,” says Tejedor.

“Beyond the striking figures, the impact of the conditions caused by prolonged heat waves and droughts have seriously affected ecosystems, water services and biodiversity, as well as key sectors of the economy, such as tourism. and agriculture,” points out researcher Gerardo Benito, also from the MNCN. The extreme conditions of 2022 caused it to be the second year in the ranking of burned area in the western Mediterranean; the loss of carbon absorption capacity and more than 60,000 heat-related deaths in Europe, especially in countries such as Italy and Spain.

A 400-year-old specimen of black pine (Pinus uncinata) in the Pyrenees shows the consequences of high temperatures. (Photo: Ernesto Tejedor)

The study concludes that the extreme events previously predicted for the end of the 21st century are already occurring, underscoring the urgent need to adopt adaptation and mitigation measures to global climate change. According to researchers, Mediterranean economies, dependent on tourism and agriculture, are increasingly vulnerable to these changes, which will affect the development of these sectors in the future. “We must take significant adaptation and mitigation measures, since the heat waves predicted for the future are already occurring and will probably be more frequent in the coming years, with the social, economic and environmental consequences that this implies,” concludes Tejedor.

The study is titled “Recent heatwaves as a prelude to climate extremes in the western Mediterranean region.” And it has been published in the academic journal Nature npj Climate and Atmospheric Sciences. (Source: MNCN / CSIC)