Atlantic cold blob could intensify European heatwaves

Scientists observe a persistent cold anomaly – the so‑called “cold blob” – in the North Atlantic south of Greenland despite overall ocean warming. The anomaly is linked to a slowdown of the Atlantic Meridional Overturning Circulation (AMOC), caused by increased freshwater from melting Greenland ice that reduces the density of surface waters and hampers deep‑water formation.

The temperature contrast between the cold northern patch and the warmer waters further south strengthens a gradient that can bend the jet stream, creating large‑scale blocking high‑pressure systems over Europe. These blocks channel hot air from the Iberian Peninsula and the Sahara northward, contributing to extreme summer temperatures reminiscent of the 2003 and 2015 heatwaves. Researchers caution that while the blob alone does not prove causation, it serves as a warning sign that a key component of the global climate system may be destabilising, potentially increasing the frequency of severe European heatwaves.