The Weddell Sea is a massive embayment of the Southern Ocean, encompassing approximately 2.8 million square kilometers, making it the largest marginal sea of the Antarctic continent. It is one of the most ecologically productive and physically influential marine environments on the planet. This sea plays a significant role in global ocean circulation and climate regulation. The Weddell Sea environment is defined by its extreme cold and extensive ice cover.
Location in the Southern Hemisphere
The Weddell Sea is entirely contained within the Southern Hemisphere, the half of the Earth located south of the Equator. This hemisphere extends from 0° latitude down to the South Pole at 90° South. The sea’s expanse places it firmly in the cold climatic zone of the Antarctic region. The Southern Ocean, of which the Weddell Sea is a part, is the only ocean that lies completely within this lower half of the globe.
Defining Geographic Borders
The Weddell Sea is a deep southward extension of the Southern Ocean, centered roughly at 73° South latitude and 45° West longitude. The sea’s land boundaries form a wide bay along the Antarctic coastline. To the west, the sea is bordered by the Antarctic Peninsula. Its eastern boundary is defined by Coats Land, part of East Antarctica. The southern edge is fringed by the massive Filchner-Ronne Ice Shelf.
Unique Ice and Water Characteristics
The physical environment of the Weddell Sea is dominated by vast sea ice, which can cover over 75% of its area during the austral winter. This ice cover is not static; it is heavily influenced by the Weddell Gyre. The gyre is a cyclonic, clockwise-rotating current that circulates water around the sea, moving southwestward along Coats Land and then northward along the Antarctic Peninsula. This circulation pattern is a major factor in the movement and distribution of ice and water masses.
The Weddell Sea is globally important as a primary source of Antarctic Bottom Water (AABW), the coldest and densest water mass in the world’s oceans. AABW forms through the rejection of brine when sea ice freezes on the continental shelf, creating cold, salty, and dense water. This dense water sinks and flows out into the global ocean basins, driving the deep-water limb of the planet’s thermohaline circulation, often called the global ocean conveyor belt. This process links the sea directly to global climate regulation by circulating oxygen and nutrients worldwide.