You might not have heard of Antarctic bottom water, but according to this article it is declining. Why would that matter? Well first of all we had better check page 5 of the Google results to find out just what Antarctic bottom water is!
- The Free Dictionary (Acronyms division) helpfully tells us that Antarctic Bottom Water may be abbreviated AABW. That’s great to know because now I won’t have to type it out every time I want to talk about it. But, please don’t confuse it with these other things that also have the same initials; Association des Architectes du Brabant Wallon, Ayrshire Association of Business Women, or the Australian Antique Bottle Website.
- Science and the Sea provides this general information: AABW is the coldest and densest water anywhere on Earth. It is found in the bottom of the Atlantic, Indian and Pacific Oceans. It forms under the winter pack ice in the seas around Antarctica, as the salt leaches out of the frozen water above. This extra salty water, being dense and cold, flows down the continental slope two miles down to the bottom of the ocean. From there it keeps moving, even as far north as the Equator or beyond. AABW has been found around the Aleutian Islands!
- A letter to Nature says that AABW is the densest global-scale water mass and that it is highly constrained by ocean floor topography.
- From a paper delivered at the International Polar Year Oslo Conference in 2010 we learn that AABW is an important part of the Meridional Overturning Circulation, filling the lowest layers of the world ocean. Most of the AABW forms in the Weddell Sea.
- And finally from Physics World: AABW plays an important part in the Global conveyor belt, the huge currents that redistribute cooler water and salt throughout the world’s oceans and helps maintain the relatively mild climate.
From the article cited above I read that AABW has been disappearing at an average rate of about eight million metric tons per second over the past few decades. If this powerful current is reduced, the circulation of Earth’s oceanic waters may be affected in subtle ways, with unknown consequences. You read it here first.