Privileged Planet: the magical Gulf stream (Introduction)

by David Turell , Sunday, November 14, 2021, 14:32 (894 days ago) @ David Turell

Its description is part of an article on the Earth's water:

http://oceans.nautil.us/feature/740/the-power-of-the-waves

"The process of thermohaline warming was first described in the 1850s by the American hydrographer Matthew Fontaine Maury, who characterized the oceans as a vast and efficient boiler house (the term derives from thermo (heat) and haline (salt), the two factors that influence the density of seawater). As Maury outlined in his landmark study The Physical Geography of the Sea (1855), “the furnace is the torrid zone, the Mexican Gulf and Caribbean Sea are the caldrons; the Gulf Stream is the conducting pipe” distributing tropical warmth towards Britain and western Europe. “It is the influence of this stream upon climate that makes Erin the “Emerald Isle of the Sea,” and that clothes the shores of Albion in evergreen robes, while in the same latitude, on this side, the coasts of Labrador are fast bound in fetters of ice,” he wrote: “There is a river in the ocean; in the severest droughts it never fails, and in the mightiest floods it never overflows. Its banks and bottoms are of cold water, while its current is of warm. The Gulf of Mexico is its fountain, and its mouth is in the Arctic Seas. It is the Gulf Stream. There is in the world no other such majestic flow of waters.”

"Maury’s rhapsodic description captures the vastness of the Gulf Stream phenomenon, while hinting at its widespread influence on Earth’s weather and climate. Such thermohaline currents are the engines of Earth’s weather, due to seawater’s efficiency at storing and transporting solar heat. Water covers 70 per cent of the planet’s total area, with around 97 per cent of that water contained in the oceans; most of the remainder is locked up in ice sheets and glaciers, and less than 0.001 per cent is ever present in the atmosphere: enough for only ten days’ rain. Thermohaline circulation transports a massive current of water around the globe, from northern oceans to southern oceans and back again. These currents—driven by differences in water density—slowly turn seawater over in the ocean, from top to bottom, like a vast conveyor belt, sending warm surface water downwards and forcing cold, dense, nutrient-rich water upwards. Cold seawater in the polar regions forms sea ice, as a consequence of which the surrounding water becomes saltier, since when sea ice forms, the salt is left behind. As the polar water grows saltier, its density increases, and it starts to sink. Surface water is then pulled in to replace the sinking water, which in turn grows cold and salty enough to sink, too. This movement is what initiates the deep-ocean currents that drive the global conveyer belt, with water always seeking an equilibrium; when cold, dense water sinks, sending warmer water welling up from below to balance out the loss at the surface.

"This results in an intermixing of the solar energy collected by the top layer of ocean and the nutrient-filled sediment of decayed plant and animal matter found at the bottom. Without the great conveyor belt stirring them up, along with the wind-driven upwelling that occurs near coastal regions, most of these nutrients would remain sequestered at the sea floor, leaving the oceans unable to support its dazzling array of life forms."

Comment: this is part of the perfect designed balance on Earth that supports life.