Fram Strait: an integrated signal of changes in the Arctic Ocean

Longterm monitoring studies in Fram Strait observing an integrated signal of changes in the Arctic combined with process studies further north enable us to learn more about the relative impact of the atmosphere and the ocean on the sea ice melt in the Arctic. The Arctic CO2 budget depends on various processes influenced by a warming climate. Measurements in Fram Strait help to assess the development of the Arctic as a sink for terrestrial organic carbon.

CTD (Conductivity-Temperature-Depth) is lowered from R/V Lance together with bottles for water samplingTo measure the water properties from the surface all the way to the seafloor, an instrument called CTD (Conductivity-Temperature-Depth) is lowered from the ship together with bottles for water sampling. Photo: Angelika Renner / Norwegian Polar Institute Deployment of automated water sampler from R/V LanceTo get data over longer periods of time, instruments are deployed on moorings. Here, the automated water sampler is just about to go into the water. Photo: Ella Darlington

The Fram Strait between Greenland and Svalbard is the only deep water passage between the central Arctic Ocean and the subpolar seas. As such, it represents a choke point where an integrated signal of changes in the Arctic can be observed. Building on longterm monitoring studies at the Norwegian Polar Institute, we will compare this signal to process studies upstream of the outflow to learn more about the relative roles of the atmosphere and the ocean in modulating the sea ice melt in the Arctic. A special focus will be on the period around the 2007 record low summer sea ice extent, the preconditioning that led to the loss in extent, and the resulting changes in the sea ice-ocean system, especially with regard to sea ice thickness and freshwater export.

Not only sea ice and freshwater, but also organic carbon, are exported through Fram Strait. River input from permafrost soils leads to an oceanic carbon pool in the Arctic Ocean that is as large as the atmospheric pool of CO2 and therefore any changes in the oceanic carbon cycle can influence the CO2 content in the atmosphere. With a warming climate, river runoff and thus organic carbon input to the Arctic are likely to increase. However, the fate of the imported carbon is unknown. Measuring the outflow through Fram Strait enables us to assess the efficiency of processes leading to CO2 uptake and release, and the outflow of carbon to lower latitude oceans. This will help us to confirm whether in the long term, a decrease in sea ice coverage and higher ice production will turn the Arctic Ocean into a more active sink for terrestrial organic carbon.