Image: O. Lecomte

Summary for a general audience

Why do we care about the sea ice in the Southern Ocean?


The sea ice in the Southern Ocean is involved in several processes that impact the ecosystem dynamics, the global carbon cycle and the evolution of the climate at both local and global scales. For instance, when sea ice forms, it rejects salt, increasing the salinity and thus the density of the ocean’s surface layer. The denser surface layer may then sinks towards the abysses of the ocean, leading to the formation of deep water. This mechanism constitutes a basis of the so called thermohaline circulation (Fig. 4). Thermohaline derives from thermo, referring to the temperature, and haline, referring to the salt content, i.e., two factors that influence the density of the water. The thermohaline circulation consists of a conveyor belt made up of several oceanic currents that transports masses of water all around the world. This transport of masses of water in turn influences the oceanic heat exchanges and carbon uptake.


Fig. 4 The thermohaline circulation (source: http://earthobservatory.nasa.gov).