Blue Frontier Dispatches From America's Ocean Wilderness by David Helvarg "If there is much we still don't know about this, our final physical frontier, we know that it is our lifeblood. The seas cover 71 percent of the earth's surface, giving our ocean planet its blue marble appearance. Although the tropical rain forests have been called the lungs of the world, the oceans actually absorb far greater amounts of carbon dioxide. Microscopic phytoplankton in the top layer of the sea act as a biological pump, extracting some 2.5 billion tons of organic carbon out of the atmosphere annually (replacing it with 70% of the life-giving oxygen we need to survive). The top two feet of sea water contain as much heat as the entire atmosphere. Scientists recently have come to recognize ocean currents as key to the creation of climate, clouds and weather, but they still don't know enough about the internal workings of the sea (or have the historical records) to fully incorporate the ocean's thermodynamics into computer models of global warming. More is known about the dark side of the moon than is known about the depths of the oceans." "Along with its practical role in maintaining the tides of life, our ocean planet also holds a spiritual resonance for our species, calling us back to the common waterborne birth state we all have experienced on both an individual and evolutionary basis. Our bodies, like the planet, are 71 percent salt water; our blood exactly as salty as the sea was when our ancestors first emerged from it. This may explain why it's easier to fall asleep to the sound of the ocean. The rhythm of the waves is like our mother's heartbeat."