New research from ETH Zurich and the University of Bern indicates a significant increase in the frequency of supercell thunderstorms along the northern slopes of the Alps. These powerful rotating storms, capable of producing destructive winds, heavy rainfall, and large hail, present considerable risks to infrastructure, agriculture, and public safety.
The study suggests a correlation between a 3-degree Celsius rise in global temperatures and a potential 50% increase in supercell occurrences within the region. Supercells are recognized as some of Europe's most severe weather events, typically occurring during summer months, with a possibility of appearing in the Mediterranean during autumn. The Alpine region is a known hotspot, currently experiencing around 38 supercell events per season on its northern slopes and 61 on the southern side.
A newly developed, high-resolution climate model, validated with storm data from 2016 to 2021, has shown a strong ability to predict supercell events, although it did not capture smaller phenomena. This advanced modeling forecasts that a 3°C global temperature increase could lead to a 52% escalation in storm frequency north of the Alps and a 36% rise on the southern flanks. While Central and Eastern Europe are also expected to see more supercells, regions like the Iberian Peninsula and southwestern France may experience a decrease, highlighting the varied impacts of climate change across Europe.
Despite being less common than other thunderstorm types, supercells are disproportionately responsible for severe weather damage and significant insurance losses. In 2023, severe convective storms, including supercells, were the costliest natural hazard globally, with insured losses approaching €55 billion. The escalating threat necessitates a reassessment of weather risk assessments and disaster preparedness, as these extreme events have often been treated as outliers.
Enhanced forecasting methods are crucial for timely warnings and effective response strategies. Improved understanding of supercell formation and progression can lead to more accurate and longer lead times for identifying imminent threats. This enhanced predictive capability is vital for infrastructure planning, strengthening agricultural resilience, and ensuring public safety in the face of increasing severe weather events. The research emphasizes the need to incorporate supercell activity into broader climate change policy discussions and risk management strategies to build more resilient societies.