New observations reveal where a key branch of AMOC crosses the Iceland-Faroe Ridge

How does cold, dense deep-water return southward as part of the Atlantic Meridional Overturning Circulation (AMOC)? Despite decades of research, the exact pathways across the Iceland–Faroe Ridge have remained uncertain.

A new study by researchers from Faroe Marine Research Institute – Havstovan, the DMI – Danish Meteorological Institute, and NORCE Research combines year-long current measurements from across the ~300 km ridge. The observations show that the strongest and most stable overflow occurs across the central part of the ridge, where cold, dense water follows two main pathways close to the seabed.

The findings also suggest why the overflow prefers the middle of the ridge: at both ends of the ridge, warm Atlantic water flows strongly poleward in the upper layers of the ocean. The observations show that this poleward flow is associated with a weaker outflow of cold water near the seabed. In the central part of the ridge, however, the warm current bends away, creating more favourable conditions for the cold bottom water to pass across.

“In 2020, we had strong indications, but we lacked direct measurements. Now we can see where an important part of the cold return flow actually crosses the ridge. This gives us a much better physical understanding of this part of the ocean circulation” says lead author Karin Margretha H. Larsen of Havstovan.

The cold overflow forms part of the deep limb of AMOC, making these observations highly relevant for improving our understanding and representation of Atlantic circulation in climate models.

As co-author Steffen Malskær Olsen (National Center for Climate Research – DMI) notes:
“The better we can map the inner workings of AMOC, the better we can test the models that are used to tell us how the system responds to a warmer climate. These new observations provide an important reference point.”

📖 Read the article: https://www.nature.com/articles/s41467-026-77220-w

Cite: Larsen, K.M.H., Eriksdóttir, G., Hansen, B. et al. Iceland-Faroe overflow revealed by in-situ observations. Nat Commun 17, 10257 (2026). https://doi.org/10.1038/s41467-026-77220-w