Analysis of Causal Links between Mediterranean Climate Extremes and Teleconnection Indices

It is well-established that the Mediterranean region is a climate change hotspot, with extreme phenomena increasing all across the basin. Heatwaves have intensified both in frequency and duration, resulting in unprecedented high temperatures that exacerbate health risks and strain energy resources. The region has also experienced a rise in intense precipitation events, leading to flash floods that pose significant threats to human lives, infrastructure, and agricultural yields. Moreover, the Mediterranean is witnessing a notable increase in the frequency and severity of wildfires, propelled by prolonged droughts and exacerbated by shifting precipitation patterns. These climatic extremes not only endanger the safety and well-being of local communities but also pose tough challenges to regional economies, which are heavily reliant on sectors such as agriculture and tourism. A key step in addressing extreme events is the timely prediction of these phenomena by identifying the key drivers that lead to their occurrence.

In our analysis, we aim to pinpoint the fundamental drivers behind extremes in the Mediterranean. The MED-HOT index, designed to evaluate regional climate extremes through concurrent analysis of changes in precipitation and temperature frequency and intensity, provides a comprehensive assessment of Mediterranean climate challenges, highlighting areas requiring immediate attention and intervention. Using the MED-HOT index for the identification of the extreme hot spot regions, we uncover the potential drivers and the associated time lags of extreme precipitation, temperature, and drought.  We apply the Peter and Clark momentary conditional independence (PCMCI) causal discovery algorithm to identify the prominent atmospheric teleconnection patterns driving extreme weather events in the Mediterranean Basin. The study suggests that teleconnection patterns in the North Atlantic notably impact precipitation, especially in the western parts of the Mediterranean Basin. Additionally, it is observed that the impact of teleconnections on extreme temperatures is more pronounced during the summer season. The results of this study are crucial for understanding the underlying drivers of extremes weather events and enhancing our preparedness to adapt to the impacts of climate change.