Indeed, the ocean dominates the world's climate, driving three global cycles: water, carbon and energy.
Rain comes from evaporated seawater, transferring not just water but the solar energy that took it from the sea. Sea plants produce most of the world's oxygen; seawater takes up half the carbon dioxide put into the air. And the currents of the sea carry warmth from the tropics toward the poles—as the currents shift, the climate shifts as well.
Photo: John Spade/Flickr