A regional climate simulation projects fewer cyclones overall by century’s end, but more intense extreme winds and rainfall in parts of the basin.
The study compared a pre-industrial period with future conditions using a regional climate simulation covering 1821 to 2100. It found that the average number of Mediterranean cyclones falls by roughly one-third under RCP8.5, but the most intense cyclone-related winds increase in both the western and eastern Mediterranean.
Rainfall changes vary by region. During the most intense phase of precipitation-producing cyclones, rainfall increases in the western Mediterranean but remains similar in the east. In the eastern Mediterranean, these cyclones also shift southward. For events combining extreme rainfall and wind, the overall pattern is similar, except that their wind speeds decrease in the eastern Mediterranean.
What changes in the storms
The simulation showed that average cyclone frequency in the Mediterranean decreases by roughly one-third by the end of the 21st century under RCP8.5. Extreme rainfall occurs about six hours before a cyclone reaches its lowest pressure, while the strongest winds occur around that pressure minimum.
Rainfall-producing cyclones become wetter during their most intense phase in the western Mediterranean, while their rainfall remains similar in the eastern Mediterranean. In the east, these precipitation extremes shift southward; their average latitude does not significantly change in the west.
Extreme wind speeds increase in both regions. The study links this intensification to future wind extremes occurring near the left exit of a stronger jet streak, a narrow zone of fast-moving air high in the atmosphere. Compound events involving both extreme rainfall and wind show similar changes, except that their wind speeds decrease in the eastern Mediterranean.
Model evidence and limits
This is a climate-model projection, not a direct observation of future events. Researchers dynamically downscaled a global climate simulation with the Weather Research and Forecasting model to 20-kilometre resolution, comparing 1821–2100 and focusing on the RCP8.5 scenario.
The regional model reproduced the main cyclone hotspots and cyclone structure, but it overestimated extreme wind and rainfall intensity, especially in the eastern Mediterranean, and overestimated cyclone frequency there. A 20-kilometre grid cannot fully resolve convective processes. The projections therefore describe the outcome of one model chain and one future scenario rather than a complete range of possible futures.
