The importance of the oceans to life on Earth cannot be overstated. Liquid water covers more than 70% of our planet`s surface &, in past geological time, has spread over 85%. Life on Earth began in the oceans over 3.5 billion years ago & remained there for the great majority of that time. Today the seas still provide 99% of habitable living space, the largest repository of biomass, & holds the greatest number of undiscovered species on the planet. Our oceans are vital for the regulation of climate, & with global warming & decreasing land area, they have become increasingly important as the source of food, energy in the form of oil & gas, & for their mineral wealth. Oceans also form a key part of the biogeochemical cycles of carbon, nitrogen, & other elements critical to life. Nutrients in upwelling areas are spread by ocean currents, & the plankton of the seas supports a wealth of wildlife. In this Very Short Introduction Dorrik Stow analyses these most important components of our blue planet & considers their relationship with, & exploitation by, humans. He shows how the oceans are an essential resource to our overpopulated world, & discusses why exploration & greater scientific understanding of the oceans, their chemistry, & their mineral wealth are now a high priority. Stow also explores what we know of how oceans originate, & evolve & change; the shape of the seafloor & nature of its cover; the physical processes that stir the waters & mix such a rich chemical broth; & the inseparable link between oceans & climate. As polar ice melts & sea-levels rise, countless millions who have made their homes on low-lying lands close to the sea are threatened. As scientific exploration of the seas gathers pace, the new knowledge gained of the ocean-Earth systems & their interaction with the human environment is vital to our understanding of how we can preserve these ultimately fragile environments. ABOUT THE SERIES: The Very Short Introductions series from Oxford University Press contains hundreds of titles in almost every subject area. These pocket-sized books are the perfect way to get ahead in a new subject quickly. Our expert authors combine facts, analysis, perspective, new ideas, & enthusiasm to make interesting & challenging topics highly readable.