Mysterious ‘blue blob’ in the North Atlantic slows down melting of Iceland’s glaciers

Publication in Geophysical Research Letters

During a fieldwork trip to maintain the weather stations, one of the researchers looks out over a valley, once carved out by a glacier which has now all but disappeared. (Photo: Finnur Pálsson, University of Iceland)

After a decades-long period of steady melting, the mass loss of Iceland’s glaciers has been slowing down since 2011. A new study shows that this slowdown is most likely caused by the development of the ‘Blue Blob’, a cooler spot in the North Atlantic Ocean to the south of Greenland. The researchers from Utrecht University, TU Delft and the University of Iceland are publishing their results today in Geophysical Research Letters.

The Blue Blob, where sea surface temperatures have gone down since 2011, is clearly visible at the bottom of the map. Areas where surface temperatures have risen are shown in red.

“Our high-resolution regional climate model shows that Icelandic glaciers started melting faster in the mid-1990s,” says Brice Noël, first author of the paper. “Surprisingly, this mass loss slowed down after 2011, as confirmed by satellites and local measurements.” The researchers conclude that this slowdown was triggered by cooling in the Blue Blob, after finding a strong linkage between glacier runoff and sea surface temperature.

Blue Blob

The ‘Blue Blob’ is a patch of cooler water in the North Atlantic Ocean, just south of Greenland, that appeared about a decade ago. Its formation has not been conclusively explained, but it has been linked to a weakened ocean current that typically transports warmer water from the tropics to the North Atlantic.

Only temporary

“The good news is that the Blue Blob will likely persist for another thirty years or so, further slowing down mass loss of Icelandic glaciers,” Noël says. “But our model shows that this effect is only temporary. The bad news is that after that time, the cooling effect of the Blue Blob will get weaker, and Iceland’s glaciers will start melting faster again. According to our model, Iceland could lose one third of its current glacier volume by 2100.”

Pictures taken during fieldwork on Vatnajökull, the largest ice cap of the island, to operate stakes and weather stations. Click to enlarge. (Photos by Finnur Pálsson, University of Iceland)


North Atlantic Cooling is Slowing Down Mass Loss of Icelandic Glaciers
Brice Noël*, Guðfinna Aðalgeirsdóttir, Finnur Pálsson, Bert Wouters*, Stef Lhermitte, Jan M. Haacker, and Michiel R. van den Broeke*
Geophysical Research Letters, 4 February 2022, DOI 10.1029/2021GL095697
* researchers affiliated with Utrecht University