01.12.2025: Ocean Circulation and Climate Dynamics Colloquium
Dr. Goratz Beobide-Arsuaga, Institute of Oceanography, University of Hamburg: "How Internal Variability Shapes — and will Reshape — European Summer Heatwaves"
When? Monday 01 December 2025 at at 11 am
Where? Conference Room 5-1.214, Wischhofstr. 1-3 and online
via Meeting link:https://geomar.webex.com/geomar-en/j.php?MTID=ma73a9dd4db0f5cb6275b471e1c5e6005
Meeting number: 2789 008 5026
Password: nhPGUfGj553
Abstract:
European summer heatwaves emerge from a complex interplay of internal climate variability, involving remote oceanic anomalies, atmospheric circulation, and land–atmosphere feedbacks. While their non-linear relationships make extreme heatwaves difficult to anticipate, the processes leading to heatwaves offer an opportunity for predicting them a season in advance. Our recent work shows that spring North Atlantic sea-surface temperature anomalies (SSTAs) carry an imprint of the internal variability that preconditions European summer heatwaves. By combining large-ensemble climate simulations with an explainable artificial intelligence method, we find that distinct North Atlantic SSTA patterns emerge as precursors to severe heatwaves. These patterns relate to atmospheric circulation anomalies that influence soil-moisture conditions, setting the stage for amplified summer temperatures. However, internal variability itself is not stationary under a warming climate. Large-ensemble simulations reveal that anthropogenic forcing is reshaping both the magnitude and the variability of summer temperatures across Europe. In central and northern regions, enhanced moisture limitation strengthens land–atmosphere coupling and amplifies heatwave intensity, whereas in southern Europe a progressive drying trend has the opposite effect. As a result, the mechanisms that currently offer predictive insights are simultaneously being transformed by climate change, altering the future landscape of heatwave risk.
