Future Sea Ice-Ocean and Biological Productivity Changes in the North Water Polynya Region under Policy Relevant Warming Levels

Jed Lenetsky , Alexandra Jahn, Partick Ugrinow, Christopher Wyburn-Powell, Rajan Patel, Hannah Zanowski

The North Water Polynya (NOW) is one of the most productive biological regions in the Arctic with high importance to Inuit and local communities of Nunavut and Greenland. To provide insights into the potential changes of this region as global temperatures rise, we investigated the sea ice, and physical and biological oceanic responses of the NOW to low (2 °C) and high (3.5 °C) levels of warming using the Community Earth System Model version 1. As global temperatures increase, we find that sea ice production decreases, spring open water area increases, and that the polynya disappears earlier in the summer as open water areas in the NOW region connect with open water in central Baffin Bay earlier. These sea ice changes contribute to increased stratification, which in turn, leads to increased concentrations of nutrient-rich West Greenland Irminger Waters (WGIW) throughout the NOW region. At low warming levels in the eastern NOW region, the WGIW replenishes the surface with nutrients despite increased stratification, leading to an increase in productivity relative to the historical period along the Greenlandic coastline. In contrast, for high warming in both the eastern and western NOW regions, biological productivity decreases because, despite increased nutrient availability at depth, coastal convection and mixing is unable to counter the increased stratification and bring those nutrients to the surface. Internal variability plays a negligible role in driving these future sea ice and ocean changes, highlighting the importance of limiting global temperature increases to 2 °C or less in order to avoid large changes to the NOW ecosystem.