Driving the Ocean “Pump”—Formation of Dense Water in the Antarctic

Like a cake, the ocean is made up of several layers. The heaviest (highest density) layer of water on the bottom of the ocean is called Antarctic Bottom Water (AABW). AABW forms around the coast of Antarctica in areas where lots of sea ice is produced due to freezing temperatures and strong winds. When sea ice is formed, most of the salt from the sea water is left behind, so the water underneath the sea ice becomes very salty and cold, making it heavy and dense. This dense water sinks to the bottom of the ocean to become AABW. AABW acts like a pump, powering the circulation of ocean waters all over the world. With climate change, warming temperatures and melting ice sheets will influence the formation of AABW, which could affect global ocean circulation, climate, and the plants and animals living both in the oceans and on land.