A Photographic Journal

The Antarctic Convergence

Antarctica, with its 31 million cubic miles of ice, is the coldest place on the planet. It's so cold it chills the ocean around it, freezing much of it. Colder ocean water is denser, so when that freezing cold water meets the comparatively warmer water of the adjoining oceans, that colder Antarctic water sinks. Instead of mixing, it creates a partial barrier to the mingling of the waters.

A number of factors magnify the effect. As ocean water freezes, the sea ice that forms squeezes out the salt, increasing the salinity of the unfrozen water. The higher the salinity of ocean water, the denser it becomes. And the Southern Ocean has strong westerly currents that circle Antarctica, further diminishing the mixing.

The location of the Antarctic Convergence varies seasonally and on longer-term climatic trends. It's not a line on a map, but it is a very real barrier. Temperature, salinity, nutrients, biota; all vary dramatically depending on which side of the Convergence you are located. They are different habitats.