And the ocean– how big is that?
Pretty big, as it turns out. Not big compared to the universe, or even our galaxy, but compared to what you see out your window? Pretty big.
There is really only one ocean, though we sometimes hear of “the seven seas” or “five oceans”. It is one immense body of (mostly) salt water covering 70% of the globe. Its average depth is about 12,000 feet, something over two miles, but at its deepest point (Challenger Deep, in the Mariana Trench) it plunges a startling seven miles beneath the surface.
The ocean contains 97% of the water on earth, and within its realm are extremes of pressure and temperature unimaginable on the surface of the planet. At the lowest point of the ocean, pressure is 1,000 times that of atmospheric pressure at sea level. Although temperatures in deep sea areas normally hover near freezing, at volcanic fissures on the ocean floor temperatures can reach 600 degrees Fahrenheit. And volcanic fissures are far from rare in the ocean; in fact, over 90% of the volcanic activity takes place at the bottom of the sea.
The influence of the ocean on the land masses it borders cannot be overstated. Vast currents circle the globe, determining not only seasonal weather such as hurricanes and typhoons, but longer-term climate as well. The best-known current, the Gulf Stream, conveys heat from the tropics to northern Europe; without this heat transfer the northern part of the continent would be sheathed in ice. And the movement of these massive volumes of water is inexorable and slow; a given cubic foot of water can take over 1,000 years to complete its journey and return to the tropics from which it sprang.
The ocean contains 99% of the biosphere– the space in which life on earth exists. Every animal, tree, blade of grass, human being on the surface of the planet could vanish overnight, but if the life in the sea remained our planet would still be home to between 50% and 80% of the life it currently supports.
So next time you visit the beach, spend some time visualizing the vast ecosystem stretching out before you, a web of life you can only– barely– see the surface of.
Image:Ryan Espanto via Wikimedia Commons.