Marine carbon cycle processes are important for taking up atmospheric CO2 thereby reducing
climate change. Biological production is an important pathway of carbon from the surface to the deep
ocean where it is stored for thousands of years. Climate change can interact with marine ecosystems
via changes in the ocean stratification and ocean circulation. In this study we use the Community Earth System Model version 2 (CESM2) results to assess the effect of a
changing climate on biological production and plankton composition in the high latitude North Atlantic
Ocean. We find a shift in plankton type dominance from diatoms to small phytoplankton which reduces
net primary and export productivity. Using a conceptual carbon-cycle model forced with the CESM2 results,
we give a rough estimate of a positive plankton composition-atmospheric CO2 feedback of approximately
60 GtCO2/K warming in the North Atlantic which affects the 1.5K and 2.0K warming safe carbon budgets.