Map of the Arctic indicating samples collected during the CAO ARISE project

Warming of the Arctic is altering the physical environment, reducing sea ice cover and melting glaciers at unprecedented rates. The response of primary productivity by phytoplankton to enhanced light availability or increased glacial inflow will hinge on the availability of nutrient resources, especially nitrogen. Here, I will summarise our findings from the Changing Arctic Ocean programme on nutrient dynamics, cleaned from analysis of historical data sets and stable nitrogen isotopes. I will introduce new observations on the occurrence of marine nitrogen fixation in the cold Arctic Ocean and discuss implications for the future Arctic ecosystem.