The Melting of Continental Ice in the Ocean and Its Impact on Surface and Bottom Waters

When continental ice comes into contact with ocean water the ice melts. This causes vertical motion in the water column, because the accompanying input of buoyancy occurs at locations which lie predominantly below the sea surface. Both melting and convective mixing must be considered in evaluating the impact of ice on the surrounding ocean. Some of the most important effects are demonstrated with a simple numerical model of the interaction between pure ice and stratified saline water. Specific examples are drawn from the Southern Ocean, which receives the majority of the ice discharged from today’s continental ice sheets, but the same principles could be applied to any region where continental ice has come into direct contact with the ocean. It is found that the melting of thick icebergs may have a relatively small impact on surface water properties and hence on the static stability of the water column. The upwelling of deeper waters induced by the melting process may even cause a minor warming and enrichment of heavy isotopes near the base of a surface mixed layer. Melting and mixing at the underside of floating ice shelves can produce a water mass of sufficient density to participate directly in the formation of bottom waters.