CLIMATE CHANGE IMPACTS ON ARCTIC SUBMARINE GROUNDWATER DISCHARGE

Climate change is impacting the exchange of groundwater and surface water in the coastal zone with responses dependent on hydrologic setting, sea-level rise rate, local climate, and geological setting. In permafrost environments, climate change is activating groundwater flow systems with potential implications for surface-subsurface connectivity and submarine groundwater discharge. Understanding of present and projected coastal high-latitude groundwater-ocean exchange is lacking due to limited field data and numerical models capable of simulating complex coastal Arctic processes. Here, we use a newly developed permafrost hydrological model that simulates variable-density groundwater flow and salinity-dependent freeze-thaw processes to investigate the impacts of sea-level rise coupled with land and ocean warming on the magnitude, distribution, and timing of submarine groundwater discharge. Results project an increase in the magnitude of submarine groundwater discharge with warming, particularly in the highest warming scenarios following the formation of a lateral talik. This increase is predominantly driven by increased freshwater discharge as a result of enhanced groundwater flow and land-sea connectivity. In contrast, sea-level rise decreases the magnitude of submarine groundwater discharge while also pushing the location of peak discharge landward. Enhanced understanding of changes in coastal zone groundwater flow and exchange due to climate change is critical with profound implications for coastal stability, carbon fluxes, and water resources.