Arctic Marine Heatwaves Surge as Atlantic Cold Blob Amplifies European Heat Waves

A recent study by the Alfred Wegener Institute documents a sharp rise in Arctic marine heatwaves. Since the 1980s, the frequency, intensity and duration of these events have increased, with sea‑surface temperatures reaching up to 4 °C above seasonal averages and lasting 10–40 days. The growth is linked to overall ocean warming and the loss of sea ice, which intensifies heat absorption.

Separate research ties a persistent cold‑water anomaly in the North Atlantic—known as the “cold blob” south of Greenland and Iceland—to more severe summer heat waves across Europe. The cold blob arises from a slowdown of the Atlantic Meridional Overturning Circulation and fresh meltwater from Greenland glaciers. It strengthens atmospheric blocking patterns, diverting the jet stream and fostering high‑pressure “heat domes” that bring hotter, drier conditions, especially to the Iberian Peninsula.

Together, the findings highlight how changing ocean temperatures in both polar and sub‑polar regions are reshaping weather extremes across the Northern Hemisphere.