Physical Oceanography


Resilient northern overturning in a warming climate

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Main objectives: The overturning that takes place within the Nordic Seas impacts the world ocean and is of key importance for the North Atlantic climate system. Warm Gulf Stream-origin waters flow northward across the Greenland-Scotland Ridge into the Nordic Seas, release heat to the atmosphere, and are transformed into cold, dense waters. These waters return southward at depth by flowing through gaps in the ridge as overflow plumes. In a warming climate with reduced sea-ice extent, this overturning is projected to weaken. Contrary to this established view, the main hypothesis of the ROVER project is that an overlooked, climate-change induced mechanism may impart resilience to the overturning: As the sea ice recedes, increasing stretches of the boundary current system around the Nordic Seas and Arctic Ocean become exposed to the atmosphere. The resulting increased ocean heat loss in winter further densifies the water in the boundary current, which is a direct pathway supplying the lower limb of the overturning circulation in the Atlantic Ocean. Enhanced dense-water formation is counter-intuitive in a warming climate, but has the potential to safeguard the northern overturning and maintain a steady supply of dense water. In the ROVER project we explore this concept through an extensive field campaign combined with high-resolution realistic and idealized modeling. In particular, we aim to document the occurrence of water mass transformation in the boundary current system, understand its dynamics, quantify its extent, and assess its climatic importance. 

Funding: Consolidator Grant from the European Research Council

Project period: 2024 - 2028

Project coordinator: Kjetil Våge

Relevant publications:

- Moore et al (2022):
Sea-ice retreat suggests re-organization of water mass transformation in the Nordic and Barents Seas

- Våge et al. (2018):
Ocean convection linked to the recent ice edge retreat along east Greenland

ROVER in the media:

Open positions:
Please contact Kjetil Våge if you are interested in joining the group as a post doc or a graduate student.