Biological and Environmental Research - Earth and Environmental System Sciences
Earth and Environmental System Modeling

Relative Impact of Sea Ice and Temperature Changes on Arctic Marine Production

TitleRelative Impact of Sea Ice and Temperature Changes on Arctic Marine Production
Publication TypeJournal Article
Year of Publication2020
JournalJGR Biogeosciences
Volume125
Number7
Abstract / Summary

We use a modern Earth system model to approximate the relative importance of ice versus temperature on Arctic marine ecosystem dynamics. We show that while the model adequately simulates ice volume, water temperature, air‐sea CO2 flux, and annual primary production in the Arctic, it underestimates upper water column nitrate across the region. This nitrate bias is likely responsible for the apparent underestimation of ice algae production. Despite this shortcoming, the model appears to be a useful tool for exploring the impacts of environmental change on phytoplankton production and carbon dynamics over the Arctic Ocean. Our experiments indicate that under a warmer climate scenario, the percentage of ocean warming that could be apportioned to a reduction in ice area ranged from 11% to 100%, while decreasing ice area could account for 22–100% of the increase in annual ocean primary production. The change to CO2 air‐sea flux in response to ice and temperature changes averaged an Arctic‐wide 5.5 Tg C yr−1 (3.5%) increase, into the ocean. This increased carbon sink may be short‐lived, as ice cover continues to decrease and the ocean warms. The change in carbon fixation from phytoplankton in response to increased temperatures and reduced ice was generally more than a magnitude larger than the changes to CO2 flux, highlighting the importance of fully considering changes to the marine ecosystem when assessing Arctic carbon cycle dynamics. Our work demonstrates the importance of ice dynamics in controlling ocean warming and production and thus the need for well‐behaved ice and BGC models within Earth system models if we hope to accurately predict Arctic changes.

URLhttps://doi.org/10.1029/2019JG005343
DOI10.1029/2019JG005343
Journal: JGR Biogeosciences
Year of Publication: 2020
Volume: 125
Number: 7
Publication Date: 06/2020

We use a modern Earth system model to approximate the relative importance of ice versus temperature on Arctic marine ecosystem dynamics. We show that while the model adequately simulates ice volume, water temperature, air‐sea CO2 flux, and annual primary production in the Arctic, it underestimates upper water column nitrate across the region. This nitrate bias is likely responsible for the apparent underestimation of ice algae production. Despite this shortcoming, the model appears to be a useful tool for exploring the impacts of environmental change on phytoplankton production and carbon dynamics over the Arctic Ocean. Our experiments indicate that under a warmer climate scenario, the percentage of ocean warming that could be apportioned to a reduction in ice area ranged from 11% to 100%, while decreasing ice area could account for 22–100% of the increase in annual ocean primary production. The change to CO2 air‐sea flux in response to ice and temperature changes averaged an Arctic‐wide 5.5 Tg C yr−1 (3.5%) increase, into the ocean. This increased carbon sink may be short‐lived, as ice cover continues to decrease and the ocean warms. The change in carbon fixation from phytoplankton in response to increased temperatures and reduced ice was generally more than a magnitude larger than the changes to CO2 flux, highlighting the importance of fully considering changes to the marine ecosystem when assessing Arctic carbon cycle dynamics. Our work demonstrates the importance of ice dynamics in controlling ocean warming and production and thus the need for well‐behaved ice and BGC models within Earth system models if we hope to accurately predict Arctic changes.

DOI: 10.1029/2019JG005343
Citation:
Gibson, G, W Weijer, N Jeffery, and S Wang.  2020.  "Relative Impact of Sea Ice and Temperature Changes on Arctic Marine Production."  JGR Biogeosciences 125(7).  https://doi.org/10.1029/2019JG005343.