A new study suggests that cold meltwater from Greenland is shifting the jet stream, leading to more frequent and intense heatwaves across Europe and the Mediterranean.
Key facts
- •Greenland ice melt creates a temperature front in the North Atlantic that forces the jet stream to meander, favoring high-pressure ridges over Europe.
- •An average of 81 billion tonnes of additional meltwater is released in the summer before years of extensive high-pressure ridging in Europe.
- •The study links the atmospheric mechanism to the 2003 European heatwave, which caused 70,000 deaths.
- •A 2022 Mediterranean derecho, which killed 12 people and featured winds over 60 metres per second, was also associated with this weather pattern.
- •Researchers warn that current climate models may underestimate the future intensity of heatwaves and droughts in the Mediterranean region.
The melting of the Greenland ice sheet is contributing to extreme heatwaves in Europe by altering North Atlantic ocean temperatures and shifting the jet stream. A study currently undergoing peer review identifies an "atmospheric bridge" that connects Greenland ice loss to the formation of high-pressure ridges over Europe. Researchers warn that as ice loss accelerates, current climate models may be underestimating the future frequency and intensity of heatwaves and droughts in the region.
By the numbers
The Atmospheric Bridge Mechanism
The research indicates that in the summer preceding years of extensive high-pressure ridging over Europe, an average of 81 billion tonnes of additional meltwater flows from the Greenland ice sheet. This cold, fresh water spreads through the North Atlantic during autumn and winter, cooling the sea surface and inhibiting mixing with warmer, saltier deep layers. This process creates a sharp temperature front between cold northern waters and warmer southern waters. As air masses interact with this temperature front, they generate cyclones that cause the jet stream to become wavier. The jet stream then meanders northward over western Europe, creating persistent high-pressure ridges. These ridges trap warm air from the central Atlantic and the Sahara desert, leading to sunny skies and extreme heat.
Implications for Future Weather Extremes
Marilena Oltmanns of the UK’s National Oceanography Centre, a co-author of the study, notes that climate models do not currently fully capture this process, suggesting that weather extremes in the Mediterranean may be underestimated. The study links this phenomenon to past disasters, including the 2003 heatwave that resulted in 70,000 deaths and a 2022 Mediterranean derecho that produced winds exceeding 60 metres per second and caused 12 fatalities. While some researchers, such as John Methven of the University of Reading, acknowledge that Greenland meltwater could influence the jet stream, they note that other factors like the weakening of the Atlantic Meridional Overturning Circulation (AMOC) or natural climate fluctuations may also play a role. Oltmanns warns that if North Atlantic cooling continues to affect the jet stream, Europe could face increased variability, including more frequent droughts and flooding.
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This article was independently rewritten by ManyPress editorial AI from reporting originally published by New Scientist.
