North Atlantic ‘cold blob’ linked to Europe’s record heat dome

As a historic heat dome continues to shatter temperature records across Europe, scientists are pointing to an unlikely accomplice: a persistent patch of cold ocean water in the North Atlantic that may be amplifying the continent's extreme heat.

The Cold Blob's Role

The heatwave battering Europe — which has obliterated June and all-time high temperature records in France, the United Kingdom, Germany, Switzerland, and the Benelux countries — may be partly driven by an area of anomalously cool water south of Iceland and Greenland known as the "cold blob." Studies suggest the cold blob influences atmospheric circulation by altering the path and speed of the jet stream that flows west to east across the continent. When cooler and warmer waters meet, the sharp temperature contrast changes the air above, making the jet stream wavier and slower, according to researchers. These changes can create conditions for high-pressure systems to park over Europe, such as the heat dome that has pushed temperatures above 40°C across multiple countries this week.france24+2

France recorded an unprecedented national average of 30°C and a new June record of 44.3°C, while the core of the heat dome shifted toward Germany, Central Europe, and the Baltic states heading into the weekend.severe-weather

Evidence of AMOC Weakening

A recent study led by Stefan Rahmstorf, a professor of physics and oceans at Potsdam University, found that the cold blob is caused by ocean currents bringing less heat into the region — not by increased heat loss through the sea surface. The findings, published in Nature, reinforce concerns that the cold blob signals a weakening of the Atlantic Meridional Overturning Circulation, the massive conveyor belt of ocean currents that transports tropical warmth toward Europe.cnn+2

The study concluded that the cooling extends deep into the ocean, well below where atmospheric conditions such as wind and cloud cover have influence, confirming the AMOC's role. Some research suggests the current system is at its weakest point in approximately 1,000 years.cnn

A Tipping Point Ahead?

Rahmstorf now gives greater than 50 percent odds of an AMOC shutdown occurring — a scenario he previously considered less likely. Such a collapse would bring harsher European winters, droughts in South Asia and parts of Africa, and higher sea levels around the North Atlantic. Meanwhile, the Washington Post reported that the cold blob shows no signs of easing this summer and may counterintuitively connect to even more heat domes in Western Europe during the months ahead.yahoo+2