2024/06/11-14 June Eastern Mediterranean Heatwave

The June 2024 Eastern Mediterranean heatwave likely exacerbated by human-driven climate change and natural variability

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Press Summary (First published 2024/07/17)

Event Description

From June 03 to June 27 2024, extreme heat has affected several countries in Southeastern Europe, Türkiye, and parts of the Middle East, with a peak intensity of the heatwave between 11 and 14 June 2024 . 

Türkiye and Greece experienced the highest temperature anomalies when compared to the 1991-2020 climate records. In Türkiye, the heatwave contributed to widespread wildfires, and in Greece, the high temperatures (up to 44.5 ºC) led to multiple fatalities, including tourists who succumbed to heat-related illnesses while hiking in remote areas​​. Authorities in these countries have issued heat warnings and taken measures such as closing schools and tourist attractions to protect the public​. Several record-high temperatures were recorded in Greece where mean monthly temperature anomalies ranged between +2.9 and +4.8 ºC above the 2010-2019 mean. According to the National Observatory of Athens/meteo.gr, June 2024 was the warmest at least since 1960 citing Copernicus data.  Cyprus experienced some of the highest temperatures, with records hitting around 44-45 °C. This heatwave has resulted in at least two deaths due to heatstroke and has placed a significant strain on healthcare systems​​. The heatwave also exacerbated the risk of wildfires, further endangering lives and property. In the rest of the Balkans, the heatwave led to significant power outages, affecting countries such as Montenegro, Bosnia and Herzegovina, Albania, and Croatia. These power failures disrupted daily life and services, compounding the challenges posed by the extreme heat​.

The Surface Pressure Anomalies reveal a positive anomaly over the Balkans and Türkiye, Cyprus, and Middle East, that is largely responsible for the extreme high temperatures. Temperature anomalies indicate warm anomalies reaching up to +10 °C in some parts of Southern Balkans and Asia Minor. Precipitation data shows absence of precipitation in a large part of the affected region, analyzed with some light precipitation (less than 5 mm/day) in Northern Greece and Türkiye. Windspeed data show light to moderate winds, with the highest values in the Aegean Sea and Middle East.

Climate and Data Background for the Analysis

The IPCC AR6 report provides a clear relationship between heatwaves and climate change. Climate change is significantly contributing to the increase in heatwaves through various mechanisms: Warming resulting from climate change has led to an increased frequency, intensity, and duration of heat-related events, including heatwaves, in most land regions, with high confidence (IPCC SR OC C6 - Page 27). Climate change is projected to alter land conditions, affecting temperature and rainfall in regions, which can enhance winter warming due to decreased snow cover and albedo in boreal regions, while reducing warming during the growing season in tropical areas with increased rainfall. Global warming and urbanization can enhance warming in cities and their surroundings, especially during heatwaves, with a higher impact on night-time temperatures than daytime temperatures (IPCC AR6 WGII FR - Page 1058). Observed surface air temperature has been increasing since the 20th century in the Eastern Mediterranean, intensifying the threat of heatwaves across the region. In the Balkans specifically, the frequency and duration of heatwaves have increased, associated with persistent high-pressure anomalies leading to so-called heat-dome conditions in the region, especially in the summer season. The combination of global warming and population growth in already-warm cities, as well as exposed dry areas that attract a high number of tourists in summer, are major drivers for increased heat exposure.

Our analysis approach rests on looking for weather situations similar to those of the event of interest having been observed in the past. For this event we have medium-high confidence in the robustness of our approach given the available climate data, as the event is common in the database.

ClimaMeter Analysis

We analyze here (see Methodology for more details) how events similar to the high temperature in the June 2024 Eastern Mediterranean heatwave changed in the present (2001–2023) compared to what they would have looked like if they had occurred in the past (1979–2001) in the region [15°E 40°E 30°N 45°N]. The Surface Pressure Changes show that similar events  do not display significant changes in the present climate than what they would have been in the past, but surface pressure today is higher over the Balkans and lower in Eastern Türkiye. The Temperature Changes show that similar events produce temperatures in the present climate at least 1.5 °C warmer than what they would have been in the past, with even higher values in Western Balkans and North Africa. The Precipitation Changes do not show any significant variations, apart from a significant decrease in Bulgaria and Southern Romania. Windspeed Changes indicate almost 5 km/h less windier conditions in Ionian and Adriatic Seas, and about 2 km/h less windier conditions in the Black Sea. Windier conditions today are found in parts of the Central Mediterranean and Levantine Seas. We also note that Similar Past Events previously mainly occurred in June, while in the present climate they are mostly occurring in May and July. Changes in Urban Areas reveal that Athens, Istanbul, and Nicosia are  0.3-0.8°C warmer in the present compared to the past.

Finally, we find that sources of natural climate variability, notably the Pacific Decadal Oscillation may have influenced the event. This means that the changes we see in the event compared to the past may be mostly due to human driven climate change.

Conclusion

Based on the above, we conclude that heatwaves similar to the June 2024 Eastern Mediterranean heatwave are up to 1.5 °C warmer than the heatwaves previously observed in this part of the world. We interpret the June 2024 Eastern Mediterranean heatwave as an unusual event whose characteristics can mostly be ascribed to human driven climate change.

Additional Information : Complete Output of the Analysis

The figure shows the average of surface pressure anomaly (msl) (a), average 2-meter temperatures anomalies (t2m) (e), cumulated total precipitation (tp) (i),  and average wind-speed (wspd) in the period of the event. Average of the surface pressure analogs found in the counterfactual [1979-2000] (b) and factual periods [2001-2022] (c), along with corresponding 2-meter temperatures (f, g),  cumulated precipitation (j, k), and wind speed (n, o).  Changes between present and past analogues are presented for surface pressure ∆slp (d),  2 meter temperatures ∆t2m (h), total precipitation ∆tp (i), and windspeed ∆wspd (p): color-filled areas indicate significant anomalies with respect to the bootstrap procedure. Violin plots for past (blue) and present (orange) periods for Quality Q analogs (q), Predictability Index D (r), Persistence Index Θ (s), and distribution of analogs in each month (t). Violin plots for past (blue) and present (orange) periods for ENSO (u), AMO (v) and PDO (w).  Number of the Analogues occurring in each subperiod (blue) and linear trend (black).  Values for the peak day of the extreme event are marked by a blue dot. Horizontal bars in panels (q,r,s,u,v,w) correspond to the mean (black) and median (red) of the distributions.