Longer Ice‐Free Conditions and Increased Run‐Off From the Ice Sheet Will Impact Primary Production inYoung Sound,Greenland

The Arctic coastal ocean is among the habitats most impacted by climate change due to the

cumulative impact of several interacting drivers. The high‐Arctic Young Sound in north‐east Greenland is

characterized by a short ice‐free period (July–October). The system is influenced by high run‐off, mainly from

glacial meltwater during summer (June–September) affecting the turbidity. Our analysis showed that Young

Sound has experienced a longer period without sea ice since 1950 due to global warming and increased run‐off

due to melting of the land‐terminating glaciers. We applied a 3D ecosystem model for Young Sound to estimate

present‐day primary production and potential future change (25 and 50 years) in different scenarios of future

sea ice‐free periods and run‐off. The light model was improved by including suspended particulate matter

(SPM) released with the freshwater sources. A shorter period with sea ice coverage gave an increase of annual

primary production due to a longer productive season in the model. Increased glacial run‐off was found to

decrease annual primary production due to more light attenuation from SPM. However, a spatial displacement

of primary production was observed in the water column and between areas due to changes in light and nutrient

availability. When longer ice‐free periods and higher run‐off were combined, primary production showed a

modest increase overall except for areas with a deep productive layer suffering from stronger light limitation.

The present study can contribute to a better understanding and generalization of future productivity of

Greenland fjords.