Climate Model Simulations of Effects of Increased Atmospheric CO2and Loss of Sea Ice on Ocean Salinity and Tracer Uptake

Abstract

Abstract Recent observations show a decrease in the extent of Northern Hemisphere sea ice; this decrease has been attributed to human activities. Climate model simulations are presented that examine how loss of sea ice affects the ocean salinity and density structure, and rates of uptake of an idealized transient tracer. The latter results are indicative of how loss of sea ice might affect the ocean’s rate of uptake of anthropogenic carbon from the atmosphere. In simulations in which there is no freshwater forcing due to sea ice forming or melting, the salinity minimum associated with Antarctic Intermediate Water is much weaker than in simulations of the present-day ocean. This suggests that this salinity minimum is maintained in part by a steady supply of freshwater from melting of Antarctic sea ice. In addition, in simulations with no freshwater forcing due to sea ice, vertical salinity and density gradients in the Southern and Arctic Oceans are weaker than in simulations of the present-day ocean. This ...