Planktonic Ecosystem Response to Changes in Sea Ice in the Arctic Ocean: Model Results and Observations

We have developed a coupled 3D pan-arctic biology/sea ice/ocean model to investigate the impact of declining arctic sea ice on the marine planktonic ecosystem over the period 1988–2008. The biophysical model results agree with satellite observations of a generally downward trend in summer sea ice extent during the past two decades, resulting in an increase in the total photosynthetically active radiation (PAR) at the ocean surface and in the total marine primary productivity (PP) in the upper 100m over open water areas of the Arctic Ocean. The simulated arctic sea ice thickness decreases steadily over 1988–2008, leading to an increase in the total PAR and PP in sea ice-covered areas of 42% and 69%, respectively. The simulated PAR and PP increases mainly occur in the seasonally and permanently ice-covered Arctic Ocean. Due to the increase in PP, the modeled phytoplankton biomass increases by 60% over this same period; the modeled zooplankton biomass increases by 44% as a result of both increased phytoplankton biomass (food) and increased ocean temperature.