Stakeholders in the marine Arctic primarily interact with the Arctic coastal zone, the interface between the terrestrial and marine environments. The Arctic coastal margin is long and receives a disproportionately large fraction of the global river discharge. Production in the Arctic tends to be concentrated in the coastal zone and over the continental shelves, rather than in the Arctic basins. Understanding how climate-induced changes to Arctic vegetation and permafrost melt may impact river chemistry, which, in turn, will impact coastal marine production, is important for resource managers and community members who monitor and rely on coastal food resources. Under the High Latitude Application and Testing of Earth System Models (HiLAT) project we analyze and develop the capabilities of DOE’s Energy Exascale Earth System Model (E3SM) to represent bio-geo-chemical (BGC) dynamics of the high latitude marine ecosystem while under the Interdisciplinary Research for Arctic Coastal Environments (InteRFACE) project we are exploring the ability of Earth System Models (ESMs) to produce information relevant to Arctic stakeholders, i.e. measures of food security and fisheries relevant indices.

Our E3SM simulations indicate that while the concentration of Arctic river nitrogen can have a significant impact on annual average nitrogen and primary production in the coastal Arctic, with production increases of up to 20% in the river-influenced interior seas, the timing of the river nutrient inputs into the marine environment appears less important. Bloom timing and partitioning between small and large phytoplankton were minimally impacted by both river nutrient concentration and timing, suggesting that, in general, coastal Arctic ecosystem dynamics will continue to be primarily driven by light availability, rather than nutrients. Complicating our understanding of marine ecosystem dynamics, and potentially underestimating the full impact of rivers, particularly at the coast, E3SM currently does not represent the impact of dissolved organic matter on light attenuation. Empirical calculations illustrate the potential significance of this missing mechanism and show that CDOM could be as important as chl-a in attenuating light. Updating the light attenuation formulation in E3SM indicates that on river influenced shelves, i.e. the Laptev Sea, consideration of DOC’s impact on light attenuation decreased the shortwave radiation by 32% (15 W m s^-1) at 10 meters.

Climate change is causing rapid and more unpredictable shifts in environmental conditions that impact three of the key aspects of food security: availability, stability, and accessibility. Indigenous communities monitor the abundance and health of food webs and the environment as part of subsistence harvest practices. However, anticipating major transformations and changes in these systems is challenging and insights from model predictions may prove useful. We investigated how E3SM could contribute to questions related to aspects of Arctic food security. We highlight present model shortcomings that, if addressed, would move ESMs closer to being useful tools for understanding environmentally driven changes to harvestable food resources. Our proposed model-derived food security indicators illustrate how output from E3SM could be combined with other relevant information sources. These model products are a starting point and a tool for engaging community members that present, in an accessible way, the model's potential utility, or current lack thereof, to rights holders and stakeholders concerned about food security. To further explore how ESMs could contribute to understanding food security questions, we are investigating E3SM’s ability to contribute fisheries relevant indices, including a borealization index, a measure of the northward range expansions, and associated ecosystem changes. Our dynamic factor analysis, which reduces multiple ice and ocean variables into one common trend to represent a borealization index, suggests that increasing sea surface temperature and decreasing ice area appear to have the strongest positive influence on the borealization factor.